Synthesis of lanthanum and waste lye modified-zeolite from fly ash and its application in constructed wetland for nitrogen and phosphorus removal

Synthesis of lanthanum and waste lye modified-zeolite from fly ash and its application in constructed wetland for nitrogen and phosphorus removal | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Synthesis of lanthanum and waste lye modified-zeolite from fly ash and its application in constructed wetland for nitrogen and phosphorus removal Zhimei Liu, Zhen Liang, Shengjun Wu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3343829/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract Excess inputs of nitrogen (N) and phosphorus (P) can lead to imbalance in water ecosystems and thus trigger eutrophication. In this study, a novel Lanthanum modified zeolite synthesized from fly ash (LZFA) was prepared and used as a modified substrate for constructed wetland (CW) to enhance N and P removal. Single-factor and surface methodology (RSM) were used to optimize the preparation. The results showed that the maximum adsorption capacities of N and P were 17.26 mg/g and 21.48 mg/g. The decline in sorption capacity or diffusion coefficients of LZFA for N compared to zeolite synthesized from fly ash (ZFA) is mainly due to the decrease in surface negative charge and cation exchange capacity. The mechanism of P adsorption is attributed to the formation of La-O-P monodentate, bidentate mononuclear or bidentate binuclear inner-sphere complexation. Meanwhile, the introduction of Ca in waste lye is also involved in the P reaction. The N and P removal rates of LZFA modified subsurface flow constructed wetland (SFCW) were 2.67% and 7.33% higher than SFCW modified with gravel. In practical production, if a circular chain from coal ash production to use in green plant fertilizer can be established, the cost of treating P can be significantly reduced. Lanthanum-modified zeolite Fly ash Nitrogen and phosphorus removal Constructed wetland Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction Rapid industrial development, urban construction, and changes in various human activities have resulted in a significant increase in the levels of nitrogen (N) and phosphorus (P) entering coastal waters, rivers, and lakes. Agriculture and urban activities are the main sources of P and N in aquatic ecosystems. This influx of N and P has subsequently led to diverse problems such as toxic algal blooms, loss of oxygen, fish kills, loss of biodiversity, loss of aquatic plant beds and coral reefs, and other problems (Carpenter et al.1998). The excessive addition of N and P to water bodies has a detrimental effect on aquatic ecosystems, leading to a decline in their health and functioning. This, in turn, negatively impacts the usability of water for various purposes such as drinking, industrial processes, agriculture, recreation, and more. Therefore, it is imperative to prioritize the removal of N and P from these aquatic ecosystems to mitigate these detrimental effects. Among many pollution control technologies, adsorption is very suitable for treating low concentration polluted water bodies due to its advantages of selective removal, reusability, simple operation, etc. It is crucial to develop low-cost adsorbent and apply it to practical projects. At present, it is one of the research hotspots to choose environment-friendly industrial and agricultural wastes as raw materials to prepare adsorption materials. Fly ash is a kind of particulate waste discharged from the combustion of coal-fired power plants. It is reported that the amount of fly ash generated by coal combustion in China has exceeded 100 million tons, and the emissions have increased year by year (Lin et al.2022). The stockpiling of a large amount of fly ash not only occupies a large amount of land resources, but also causes dust and pollutes the atmosphere and groundwater. At present, fly ash is mainly used as raw material or auxiliary material of cement in the construction industry, such as clinker partially replacing Portland cement and magnesium sulfate cement(Chen et al.2021). However, the utilization rate of this method is limited. It is reported that the global utilization rate of fly ash is 16% – 25% (Morales-Ospino et al.2020). Therefore, the development of new methods for forming high value-added products is the focus of attention of all countries, and the synthesis of zeolite is one of the utilization methods. Due to the similar composition of fly ash and zeolite, many researchers have synthesized zeolite for the purpose of ammonia removal. Among the various synthesis methods, the hydrothermal method is the most common and stable synthesis method. However, a large amount of waste alkali liquor will be produced during the synthesis process, causing secondary pollution. Zeolite is classified as a hydrated aluminosilicate compound. This framework comprises tetrahedrally coordinated aluminum, silicon, and oxygen atoms. The surface of zeolite carries a net negative charge and therefore has a limited ability to phosphorus adsorption. As for the utilization of waste alkali liquor, Xie et al ( 2014 ) used the waste lye and lanthanum chloride to synthesize lanthanum hydroxide. They found that the generated lanthanum hydroxide is amorphous, has a higher specific surface area and higher phosphate adsorption performance than the commercially available lanthanum hydroxide. As for studies on phosphorus removal by zeolite, the absorption capacity of zeolite phosphate is usually enhanced by introducing metals, such as calcium, iron, magnesium or rare earth elements. While lanthanum is a rare earth element, research shows that lanthanum has high affinity for phosphate and can form solid and insoluble LaPO 4 (Liu et al.2020). Lanthanum can be introduced into zeolite through alkali solution immersion and calcinations (Liu et al.2017). Lanthanum-modified zeolite has received more attention in removing phosphorus from water (Min et al.2019; Copetti et al. 2016 ). It is reported that the adsorption capacity of lanthanum-modified zeolite is about 2 times higher than that of natural and synthetic zeolite. The above research has done some exploration work in the resource utilization of waste lye and the modificarion method of zeolite with lanthanum under alkaline conditions, but there are still the following problems: (1) Only the waste lye and lanthanum chloride in the synthetic zeolite from fly ash were used to synthesize lanthanum hydroxide, and it was found that the generated lanthanum hydroxide had high P adsorption performance. There are few reports on the removal of N and P by loading waste lye and lanthanum chloride into synthetic zeolite; (2) lack of systematic and comprehensive research on the mechanism of N and P removal based on loading waste lye and lanthanum chloride into synthetic zeolite, including P removal mechanism under the condition of the coexistence of lanthanum and other metal ions in waste lye (Fe, Ca) and the efficiency of N removal after lanthanum-modified synthetic zeolite; (3) Most current adsorbent materials are based on performance evaluations in a laboratory setting, and less consideration is given to actual use in the environment. In this work, we developed a synthesis zeolite based on fly ash for the removal of N and P by the modification method of waste lye and lanthanum chloride. In experiment condition, the preparation of an efficient adsorbent by combining waste lye, zeolite synthesized from fly ash, and Lanthanum chloride was analysis. Then, the adsorption performances and mechanisms of the developed adsorbent were evaluated. Finally, for the consideration of practical application potential, the adsorbents were made into granular pellets to evaluate the effectiveness of their application in Subsurface Flow Constructed Wetland (SFCW) for N and P removal. 2. Materials and methods 2.1 Materials Fly ash(FA)was collected from Jiulongpo District, Chongqing City (China). All chemical reagents were analytical grade and purchased from Chongqing Chemical Reagent Co., Ltd. (China) and used without further purification. All solutions were prepared with distilled water. The working solutions containing different concentrations of ammonium chloride (NH 4 Cl) and potassium dihydrogen phosphate (KH 2 PO 4 ) were prepared by stepwise dilution of the stock solutions. 2.2 Preparation of lanthanum-modified zeolite synthesized from fly ash Zeolite based on fly ash (ZFA) was obtained by alkali melt hydrothermal Method. First, NaOH solid/FA ratio of 1:0.6 was mixed uniformly, and then roasted at 600°C for 2h in a muffle furnace. Second, the hydrothermal synthesis method was used to obtain the optimum synthesis conditions of NaOH solutions of 1 M, FA/NaOH solution ratio of 1:7, synthesis temperatures of 25°C, and 1h of conversion time. Lanthanum-modified zeolite synthesized from fly ash (LZFA) was obtained by hydrothermal treatment of a ZFA sample in a certain concentration LaCl 3 solution at 25℃, followed by a neutralization procedure using the produced waste alkaline solution until the pH reached a certain value. Subsequently, the mixture was washed and roasted at a certain temperature. 2.3 Response Surface Model Design The response surface method is to study the relationship between the response and the input factors, and its goal is to optimize the response. Box–Behnken experimental design (BBD) is a standard response surface design method and can be used to evaluate the effect of 3 factors. In this experiment, it was applied to optimize the LZFA preparation process and to investigate the interactive effects of concentration LaCl 3 (mM), solution pH and Roasting temperature (℃). The software of Design Expert 8.0.6.1 was used for designing and analyzing the experimental data. Second order model is generally used to predict the objective function and can be expressed according to Eq. (1), in which y is the response value (P removal); \({{\beta }}_{0}\) offset term; \({{\beta }}_{\text{i}}\) is the linear coefficient of \({\text{X}}_{\text{i}}\) ; \({{\beta }}_{\text{i}\text{i}}\) is the quadratic effect coefficient of \({ \text{X}}_{\text{i}}\) ; \({{\beta }}_{\text{i}\text{j}}\) is the effect coefficient of the interaction between \({\text{X}}_{\text{i}}\) ;nd \({\text{X}}_{\text{j}}\) ; \({\text{X}}_{\text{i}}{\text{X}}_{\text{j}}\) is the effect of factor interaction effect, \({\text{X}}_{\text{i}}\) is the independent variable effect of the ith factor, and \({\text{X}}_{\text{i}}^{2}\) is the squared effect of the factor. \(\text{y}={{\beta }}_{0}+\sum {{\beta }}_{\text{i}}{\text{X}}_{\text{i}}+\sum {{\beta }}_{\text{i}\text{j}}^{2}{\text{X}}_{\text{i}}{\text{X}}_{\text{j}}+\sum {{\beta }}_{\text{i}\text{i}}{\text{X}}_{\text{i}}^{2}\) (1) (Pourfadakari et al., 2021 ) 2.4 Batch experiments Synthetic N and P solutions were prepared by dissolving potassium dihydrogen phosphate (KH 2 PO4) and ammonium chloride (NH 4 Cl) in deionized water. All batch experiments were implemented in 250 mL stoppered conical flasks on a thermo-static shaker with continuous stirring at 200 rpm. 1g LZFA or ZFA was added to 100ml of 5mg/L N and P solution. After being shaken at room temperature for 24 h, sample solutions were filtered through a 0.45 µm membrane syringe filter. The concentrations of N and P in the filtered solution were accurately determined using two different methods: the Nessler's reagent spectrophotometry for N and the molybdenum antimony anti-spectrophotometry for P.The measurements were carried out using a reliable UV–vis spectrophotometer (model UV-759S, Jinghua, China) at specific wavelengths of 420 nm and 700nm, respectively. To ensure the reliability of the results, quality control testing was implemented, including the use of blank samples and duplicate analyses. These measures were taken to guarantee the accuracy and precision of the obtained data. The adsorption equilibrium time was found to be 4 hours. The amount of contaminant absorbed from the aqueous solution was expressed as ammonium and phosphate adsorption capacity per unit mass of the zeolite (q) as: $$\text{q}=\frac{（{\text{C}}_{\text{e}}-{\text{C}}_{0}）\text{V}}{\text{m}}$$ 2 where, C o is the initial ammonium concentration (mg/L), C e is the equilibrium ammonium concentration (mg/L), V is the batch volume (L) and m is the zeolite mass (g). 2.4.1 Effect of initial pH The effect of initial pH on the solution was investigated by adjusting the initial pH to a range of 4 to 13 using 0.1M HCl and 0.1M NaOH. The initial concentration of N and P in the solution was 5 mg/L. LZFA was added at a dosage of 10g/L. The experiments were conducted at a temperature of 25°C with a rotation speed of 200rpm for a constant temperature vibration duration of 4.0 hours. 2.4.2 Effect of anions and cations The effect of anions and cations was investigated by examining the effects of cations K + , Na + , Ca 2+ , and Mg 2+ on the adsorption of N. The concentrations of these cations tested ranged from 0mg/L to 80mg/L, including 0, 20, 40, 60, and 80mg/L. Similarly, for the adsorption of P, the effects of anions HCO 3 - , SO 4 2- , CO 3 2- , and Cl - were studied. The concentrations of these anions tested ranged from 0mg/L to 80mg/L, including 0, 20, 40, 60, and 80mg/L. 2.4.3 Isotherm and Kinetics experiments Ten groups of N-P mixed solution were prepared, each containing 100ml with an initial concentration of 5mg/L for both N and P. To each group, 1g of LZFA or ZFA was added into 100ml of the mixed solution. The solutions were then subjected to shake at 200rpm under constant at room temperature. The shaking durations for each group were set at 10, 30, 60, 120, 240, 360, 480, 600, 720, and 1440 minutes, respectively. In order to conduct the isotherm experiment, 100ml of mixed solutions containing N and P were prepared with varying concentrations. The concentrations tested were 5, 10, 20, 40, 60, 80, 100, 200, and 300mg/L, respectively. The equilibrium data were fitted to the Langmuir and Freundlich isotherm models, and their equations were shown as the following equations, respectively, Languir adsorption isotherm equation: $${\text{q}}_{\text{e}}=\frac{{\text{q}}_{\text{m}}{\text{K}}_{\text{L}}{\text{C}}_{\text{e}}}{1+{\text{K}}_{\text{L}}{\text{C}}_{\text{e}}}$$ 3 Freundlich adsorption isotherm equation: $${\text{q}}_{\text{e}}={\text{K}}_{\text{F}}{\text{C}}_{\text{e}}^{\frac{1}{\text{n}}}$$ 4 where, q e and q m are the equilibrium adsorption capacity and maximum adsorption capacity (mg/g), Ceis the solute concentration at adsorption equilibrium (mg/L), K L ,K F and n is the adsorption constant, respectively. To analyze the kinetic mechanism of the adsorption process, the experimental data were fitted into three models: the pseudofirst-order model described by Eq. ( 5 ), the pseudo-second-order model described by Eq. ( 6 ), and the intra-particle diffusion model described by Eq. ( 7 ) Pseudo first-order equation : $${\text{q}}_{\text{t}}={\text{q}}_{\text{e}}[1-{\text{e}\text{x}\text{p}}^{(-{\text{k}}_{1}\text{t})}]$$ 5 Pseudo second-order equation : $${\text{q}}_{\text{t}}=\frac{{\text{k}}_{2}{\text{q}}_{\text{e}}^{2}\text{t}}{1+{\text{K}}_{2}{\text{q}}_{\text{e}}\text{t}}$$ 6 Where, k 1 , k 2 are pseudo first-order and pseudo second-order kinetic constants, respectively (min − 1 ). q e is the equilibrium adsorption capacity (mg/g). Intra-particle diffusion equation : $${\text{q}}_{\text{t}}={\text{k}}_{\text{d}\text{i}}{\text{t}}^{1/2}+\text{C}$$ 7 Where, K di is the internal diffusion rate constant (mg/(g.min 0.5 ), C is the boundary layer thickness (mg/g). The chemical composition and elemental oxidation states of the material surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) using a Thermo Scientific ESCALAB 250Xi spectrometer with a monochromatic Al Kα X-ray source. The morphology and microstructure were examined by field-emission scanning electron microscopy (FE-SEM) on a JEOL JSM-7600F microscope operating at 5 kV. Structural characterization was performed by X-ray diffraction (XRD) using a Rigaku SmartLab diffractometer with Cu Kα radiation (λ = 1.5418 Å) over a 2θ range of 20–80° with a step size of 0.02°. The molecular structure and chemical bonding were investigated by Fourier transform infrared spectroscopy (FTIR) on a Thermo Scientific Nicolet iS50 spectrometer over the wavenumber range of 400–4000 cm -1 with a resolution of 4 cm -1 . 2.5 SFCW experiment setup 2.5.1 LZFA granular substrate production The LZFA, clay and starch were homogeneous mixed with the mass ratio of 2: 1: 1, then were added water and stirred into a paste to make granular substrate. Finally, dry naturally at room temperature for 3 days and calcined in a muffle furnace 300℃ for 2 hours. 2.5.2 Experiment Design The experiment employed the Subsurface Flow Constructed Wetland (SFCW) as the application model. The SFCW microcosms were built by a Polyethylene cylinder (50 cm in height and 45cm in diameter).Three different substrate materials were used to construct SFCW microcosm. Three groups of SFCW, i.e., LZFA-based SFCW (L-SFCW), LZFA + Gravel-based FCW (L + G-SFCW), Gravel-based CW (G-SFCW) were constructed with three replicates in each group. The substrate consisted of a 5cm layer of soil at the top layer, followed by a 10 cm layer of LZFA (L-SFCW), a 5 cm layer of gravel and a 5 cm layer of LZFA (L + G-SFCW ), a 10 cm layer of gravel (G-SFCW ). The particle sizes of gravel and LZFA were approximately 2–3 cm. Ten young reeds (30–40 cm in height) was planted in each SFCW microcosm with cuttings. The simulated influent contained 5 mg/L ± 12.55 of N and 1 ± 0.87 mg/L of P. The pH of the influent varied from 6.68 to 7.82, providing a suitable environment for the survival of various organisms. The simulated influent was introduced into SFCW microcosms and the water level is maintained at approximately 5cm. The SFCW microcosms were operated in subsurface flow with a hydraulic retention time (HRT) of 3 days. 2.5.3 Water sampling and analysis The influent and effluent of SFCW were sampled and analyzed every 3 days. The concentrations of N and P were measured using the Nasher's reagent method and the ammouimmolybdate spectrophotometric method, respectively. 3. Results and discussion 3.1 Optimization of the lanthanum-modified zeolite synthesized from fly ash preparation The three main Influence factors on P removal by LZFA was investigated by the single-factor method. The optimum conditions were determined to be in pH range of 9–10, lanthanum chloride concentration of 10.8mM and roasting temperature of 200 ℃(Fig S1 ). In order to further optimize the process conditions, the response surface model was applied to the P removal analysis. As shown in Table 1 , the levels of independent factors of the Box–Behken experimental design were chosen based on the Fig S1 .The relationship between response (P removal rate) and three effect factors (concentration, pH and roasting temperature) was analyzed based on the BBD experimental design. The result of each experiment was shown in Table S1 . According to the Design-Expert test results, the regression equation of the quadratic model represented in coded form is as follows: Y = 96.42 + 1.34A-0.12B + 1.45C-0.13AB-0.11AC + 0.0001BC-0.13A 2 -3.79B 2 -8.02C 2 where Y represents P removal rate, A represents lanthanum chloride concentration, B represents pH and C represents roasting temperature. The results of the ANOVA for the quadratic model were shown in Table 2 . The F value of the model test was 154.39 and the P-value was < 0.0001, indicating that the entire quadratic equation simulation was significant. While, the “Lack of fit F-value” of 7.75 (P = 0.0383) indicated that lack of fit is significant, which demonstrated the model was poorly fitted. Furthermore, the signal-to-noise ratio (A.P.=32.79)) and reliability of the conducted experiments were confirmed by a low coefficient of variation (C.V. = 0.59%), which was a cue to a goodness fit of the regression model. The value of R 2 (0.9950) was determined to be close to that of R 2 adj (0.9885). Therefore, the quadratic equation model can be used to simulate the response of P removal rate. The quadratic model test included single factor, two-factor interaction term and square term. When the p-value is less than 0.05, it means that the corresponding factors are significant. It was observed that the A 2 , B 2 and C 2 had significant responses to the model (Table 3 ), while the interactions between factors were not significant (Table 3 ). In addition, through the F value, it can be seen that the effect order of each factor on P removal is roasting temperature > lanthanum chloride concentration > pH. Through response surface analysis, the optimum conditions for P removal were as follows: the concentration of lanthanum chloride was 13.56mM, the pH was 8.93, and the roasting temperature was 208.72℃. To verify the correctness of the model, the comparison between the predicted value and the actual value of P removal rate was listed in Table S2 under the best optimization conditions. It was shown that the experimental value was in good agreement with the calculation result from the model with the error is less than 1.0%. Compared with the ZFA, we observed the 8.3% decline of N removal rate under the optimal condition of P removal rate. It was indicated that the modification of lanthanum had the negative effect on the removal of N. Table 1 Different levels of BBD factors Variables Coded factor level -1 -1 1 LaCl 3 concentration (mM) 5.4 10.8 16.2 pH 6 9 12 Roasting temperature(℃) 100 200 300 Table 2 Variance analysis of regression coefficients for quadratic model Source Sum of Squares df Mean Square F value P-value Prob > F Model 393.47 9 43.72 154.39 <0.0001 Significant A 14.31 1 14.31 50.54 0.0002 B 0.11 1 0.11 0.39 0.5521 C 16.88 1 16.88 59.60 0.0001 AB 0.068 1 0.068 0.24 0.6401 AC 0.044 1 0.044 0.16 0.7049 BC 0.000 1 0.000 0.000 1.0000 A2 7.13 1 7.13 25.17 0.0015 B2 60.51 1 60.51 213.69 <0.0001 C2 270.89 1 270.89 956.62 <0.0001 Residual 1.98 7 0.28 Lack of Fit 1.69 3 0.56 7.75 0.0383 Significant Pure Error 0.29 4 0.073 Cor Total 395.46 16 R 2 , R 2 adj (coefficient of determination) of the model is 0.9981, 0.9955. 3.2. Adsorbent characterization From the Fig. 1 a, it was found that the fly ash was mainly amorphous spherical glass beads of different sizes, and some irregular, rougher lumpy and flaky particles were also observed. The physical phase analysis (XRD) contains a large amount of quartz (SiO 2 ) and mullite (3AI 2 O.2SiO 2 ) (Fig. 1 d) and accounted for 76.07% of the total (Table 5). After the synthesis of zeolite, the spherical glass beads disappeared and irregular and rough products appeared (Fig. 1 b) and the Na content increased from 0.71–36.12% (Table S3), indicating that Na ions were adsorbed on the zeolite. After modification by lanthanum, it was observed that the increase of La 2 O 3 content caused the significant decrease of Na content, which proved that the part of Na ions was exchanged with lanthanum ions. The XRD results (Fig. 1 d) showed that the formation of sodium square zeolite (Al 2 H 3.6 Na 2. 16 O 9.24 Si 1.68 ), due to a new characteristic peak appearance at 13.9°, 24.2°, 42.7°of 2 theta. Meanwhile, it was accompanied by the appearance of intermediate products (sodium silicate PDF 016–0818, 01-071-0657 with 6 water and sodium carbonate PDF 008-0448) in the zeolite formation process. After lanthanum-modified zeolite based on fly ash, a new characteristic peak appeared at 6.1°, 15.5°, 23.3°, 30.9° of 2 theta (PDF 038–0237) ,which indicating the formation of X-type zeolite ( Al 2 H 12.4 Na 2 O 15.2 Si 2.5 ). Lanthanum oxide appeared (PDF 022–0641) with the inconspicuous peak intensity, possibly due to the dispersion of lanthanum on the zeolite surface, as well as the lower lanthanum concentration. The measured values of the adsorbent parameters, including specific surface area, total pore volume, average diameter of total pore and micropore, micropore area, micropore volume, are given in Table S4. After ZFA was modified by lanthanum, the specific surface area increased from 3.79 to 207.12 m 2 /g, the total pore volume increased from 0.021to 0.217 cm3/g, the average pore diameter decreased from 21.60 to 4.19 nm, the micropore area increased from 1.507 m 2 /g to 158.32 m 2 /g, the pore volume increased from 0.000768 cm 3 /g to 0.083 cm 3 /g, and the micropore diameter changed little. This study is similar to the results of Huang et al. (Huang et al., 2014 ). The structural change indicated that a large amount of amorphous lanthanum hydroxide is formed and deposited on the surface of the zeolite (Fig. 1 c), causing the large specific surface area. In addition, after the exchange of La 3+ and interlayer cations, zeolite occurs part of the delamination. The structural change will favor P adsorption. 3.3 Performance study of N and P removal 3.3.1 Adsorption kinetics and isotherm It can be seen from the kinetic parameters listed in Table S5, Fig. 2 a. Compared with the pseudo-first-order kinetic model (R 2 = 0.622(N), R 2 = 0.596(P)), the pseudo-second-order kinetic model (R 2 = 0.921(N), R 2 = 0.913(P)) can better describe the N and P adsorption kinetics of LZFA. For N, the equilibrium absorptive capacity (0.412mg/g) of the pseudo-second-order kinetic model of LZFA was lower that (0.447 mg/g) of LFA. For the P, the equilibrium absorptive capacity of the pseudo-second-order kinetic model of LZFA was 0.481mg/g. As shown in Fig. 2 c, the sorption consists of three rate processes: (1) the faster liquid film diffusion around the particle; (2) the intraparticle diffusion process including surface and free diffusion of the adsorbed species into the particle (3) convergence to equilibrium diffusion.In order to identify the diffusion mechanism and compare the difference in the sorption process, the intra-particle diffusion parameters (film diffusion coefficient K d1, the intraparticle diffusion coefficient K d2, convergence to equilibrium diffusion coefficient K d3 ) were summarized in Table S5. Results showed that the value of K d1 was three times higher than that of K d2 and K d3 for all N and P adsorption, revealing that the particle diffusion was the rate-limiting step. For the N, after lanthanum modification, all three diffusion coefficients decreased, indicating the effect of the modification treatment on N diffusion. For the N and P, all three diffusion coefficients of LZFA were lowered than that of Shi et al. (Shi et al., 2019 ), which may be related to the higher dosing amount and lower initial N concentration. It may reduce the surface loading of LZFA, thereby reducing the mass transfer drive affecting the diffusion rate of films and particles The Langmuir and Freundlich models were employed to fit the experimental data (Fig. 2 b) and the maximum sorption capacity and correlation coefficients were summarized in Table S6. It was found that the Langmuir model (R 2 = 0.957(N), R 2 = 0.801(P)) was higher than that of the Freundlich model (R 2 = 0.797(N), R 2 = 0.549(P)) for the N and P sorption, indicating that Langmuir can better fit the isothermal adsorption process, which is a monolayer adsorption.The maximum sorption capacity (Q max ) of LZFA on N was 17.26mg/g, lower than that of ZFA(21.32 mg/g). The maximum sorption capacity (Q max ) of LZFA on the P was 21.48 mg/g. The reported parameters of the N and P adsorption performance of mineral adsorbent materials were shown in Table 3 . It was found that the adsorption capacity of this study on the N and P was higher than that of the iron-aluminum modified mineral materials and waste synthetic materials and nearly 9 times lower than that of chemical synthesis materials. Therefore, from the perspective of practical use, the suitable adsorbent materials should be select according to the requirements of water quality and material cost. Table 3 Comparision of adsorption capacity for N and P with other adsorbents Absorbent Q m N (mg/g) Q m P (mg/g) Equilibrium time (h) pH Reference Al modified natural zeolite 30 7 2.5 5 Guaya et al., 2015 La-Mg comppsite 159.30 49.72 3 3-11P 3–9 N Wei e al., 2021 Zeolites synthesized by fly ash 13.7 3.44 28 5 Ji et al., 2015 Na@La modified zeolite 17.92 9.53 2 4–8 N 4–6 P Sang et al., 2020 Ferric modified zeolite 1.55 0.16 3 — Gao et al., 2019 Cetylpyridinium bromide modified zeolite 6.26 2.12 8 Li et al., 2017 Zeolite synthesized from fly ashes (silica-rich and calcium-rich ) 9.57 3.06 7.5 Ji et al., 2013 muscovite/phillipsite composite 110 126 12 P 8 N 7 Abukhadra et al ., 2011 La modified zeolite based on fly ash 17.26 21.48 4 7 This study 3.3.2. Effect of environmental conditions From Fig. 3 c, the N removal of LZFA was optimized at pH 7 with the maximum removal rate (81.88%) and adsorption capacity (0.409 mg/g). The P removal of LZFA was optimized at pH 7 with the maximum removal rate (95.98%) and adsorption capacity (0.480 mg/g). At pH values below 7, N in a solution primarily exists in the form of NH 4 + , which facilitates its adsorption (Widiastuti et al., 2011 ). However, a lower pH indicates a higher concentration of hydrogen ions in the solution. Since the radius of hydrogen ions is smaller than that of ammonia ions, they are more likely to undergo ion exchange with the LZFA. This ion exchange process can diminish the effectiveness of N removal in an acidic environment. The pH PZC of the LZFA is 2.56 (Fig. 4 b). The pH of 7 is higher than the isoelectric point, resulting in a negatively charged surface, which is favorable for adsorption. However, as the pH exceeds 9, the concentration of hydrated ammonia molecules increases, causing N in the solution to predominantly exist in the form of NH 3 . Consequently, ion exchange processes become limited, leading to a reduction in the removal effectiveness of N. The P adsorption on metal oxides is commonly attributed to electrostatic interactions and complex formation via ligand exchange (Yang et al., 2023 ;Liu et al., 2022 ). However, pH pzc of the LZFA was 2.56 (Fig. 4 b), the electrostatic interactions are not responsible for P adsorption at pH 7. Instead, the main mechanism appears to involve the formation of lanthanum-P complexes through the exchange of La-OH groups, which are generated on the surface of adsorbent, with P ions. At pH>pH PZC, , the La–OH groups are involved in the formation of inner sphere species by means of monodentate and bidentate complexation (Salehi et al., 2020;Bacelo et al., 2020 ).Under alkaline conditions (pH>8), the surface of the adsorbent is gradually composed of ≡ MO - groups. The increase of the concentration of OH - formed competitive adsorption with P ions, thereby reducing the removal efficiency of P. Furthermore, an increase in pH beyond 11 results in the gradual conversion of HPO 4 2- to PO 4 3- , leading to a decrease in P removal due to the elevated charge of the ion PO 4 3- . It can be seen from Fig. 3 a that K + has the greatest negative effect on the adsorption of N with the increase of cation concentration as was previously reported with natural zeolites (Huang et al., 2010 ). The remaining ions have no obvious effect. The reason is that the hydration radius of K + is small and easily adsorbed on the surface of LZFA, forming a strong competition with N ions. It can be seen from Fig. 3 b that the adsorption amount of P gradually decreases with the increase of the anion concentration, and the decreasing order of the P adsorption amount of anions is HCO 3 - >SO 4 2- >CO 3 2- >Cl - . The primary reason for this discrepancy lies in the varying binding mechanisms of different anions to metal oxides. For instance, Cl - and SO 4 2- are adsorbed onto the outer surface of the material through electrostatic adsorption forces, while CO 3 2- forms inner sphere complexes that interact with P (Yu et al., 2020). Research has shown that the solubility product constant (K sp ) of La 2 (CO 3 ) 3 ( 3.98×10 –34 ) is smaller than the Ksp of LaPO 4 (3.7×10 –23 ) (Koilraj et al., 2017). While, HCO 3 - easily ionizes into CO 3 2, , so it has a significant impact on the adsorption of P. 3.4 Mechanisms of N and P adsorption 3.4.1 N adsorption analysis It can be seen from Fig. 4 a that the cation exchange capacity of FAZ is 77.3 cmol/kg and the cation exchange capacity of LZFA significantly decreased to 55.0 cmol/kg after lanthanum modification. It showed that the decrease in cation exchange is responsible for the decrease in N removal by LZFA. The decrease of cation exchange after lanthanum modification may be related to lanthanum coverage on the surface of zeolite (Xie et al., 2014 ). It can be seen from Fig. 4 b that the pH PZC of ZFA is 4.9 and the pH PZC of LZFA is 2.56. The decrease in isoelectric point after lanthanum modification may be related to lanthanum loading, location and zeolite structure. From Fig. 4 b, it can be seen that the negative charge of LZFA significantly decreased compared with ZFA under the condition of pH>6. From the analysis of electrostatic force, the decrease of negative charge will reduce the adsorption of ammonia, indicating that electrostatic adsorption is also one of the main reasons for the decrease of N adsorption. 3.4.2 P adsorption analysis As depicted in Fig. 5 , a robust and wide absorption band centered at approximately 3367 cm -1 is observed following the adsorption of N and P by the LZFA. This absorption band can be attributed to the stretching vibrations of O-H bonds (He YH., 2018 ). The appearance of absorption peaks at 1477 cm -1 , 1367 cm -1 , and 1435 cm -1 after the adsorption of N and P indicated the presence of characteristic N-H peaks associated with N in the solid state (Huang et al., 2014 ;Wahab et al., 2010 ). This observation suggests that N is adsorbed onto the material. Additionally, the peak at around 1650 cm -1 corresponds to the bending vibration of adsorbed water (Zavareh et al., 2018 ). Notably, new absorption peaks emerged at approximately 614 cm -1 and 540 cm -1 , with the intensity of these peaks increasing with higher concentrations of absorbed P. These two absorption peaks are indicative of the bending vibration of O-P-O, implying that the mechanism underlying P removal involves the formation of inner sphere complexes through ligand exchange (Shi et al., 2019 ). Figure 6 a demonstrated the emergence of characteristic N and P spectra following their adsorption. The P 2p binding energy was determined to be 135.27 eV (Fig. 6 d), displaying a shift of approximately 1.27 eV towards higher energy levels compared to the standard P2p spectrum of KH 2 PO 4 (∼134.0 eV). This shift indicates a change in the chemical speciation of P. Analyzing Table S7, an increase in the relative N content from 0.44% before adsorption to 1.29% was observed, indicating the adsorption of N onto the material. Conversely, a decrease in the Na peak was observed (Fig. 6 a), suggesting the ion exchange of N with sodium ions. Moreover, the relative P content increased from 0.51% before adsorption to 3.28%, confirming the adsorption of phosphorate onto the material. The XPS spectrum of La3d exhibited two distinctive sets of characteristic peaks (Fig. 6 b). Prior to phosphorate adsorption, the binding energies of La3d 5/2 were measured at 836.03 eV and 839.09 eV, while the binding energies of La3d 3/2 were observed at 852.77 eV and 855.66 eV. Subsequent to P adsorption, the binding energies of La3d 5/2 shifted to 837.44 eV and 840.68 eV, and the binding energies of La3d 3/2 shifted to 854.11 eV and 857.52 eV. Both La3d5/2 and La3d3/2 exhibited a shift towards higher binding energies after P adsorption, with ΔLa3d 5/2 increasing from 3.06 to 3.24 and ΔLa3d3/2 increasing from 2.89 to 3.41. These observations indicated the formation of inner layer complexes between P and lanthanum-modified fly ash zeolite (Hao et al., 2019 ;Yin et al., 2022 ༛Huang et al., 2022 ). The O1s spectrum can be divided into three oxygen types: lattice oxygen (M-O), hydroxyl oxygen (M-OH), and adsorbed water (Sunding et al., 2011 ). The peaks corresponding to these oxygen types are depicted in Fig. 6 c. Following P adsorption, the peak positions of both lattice oxygen and hydroxyl oxygen undergo changes. The relative content of hydroxyl oxygen (M-OH) decreased from 93.88–80.48%, while the relative content of lattice oxygen (M-O) increased from 3.07–17.71% (Table S8). These observations indicated that the hydroxyl groups on the surface of LZFA were displaced by P through ligand exchange (Wang et al., 2022 ;Yu et al., 2015) Furthermore, the ratio of hydroxyl content before and after P adsorption indicates the configuration of the inner layer complex formed. A ratio of 0.5 suggests monodentate binding between the surface hydroxyl group and P, while a ratio of 2.0 indicates bidentate binding. (Wan et al., 2017 ). In this study, the hydroxyl group ratio of 1.17 before and after P adsorption on LZFA indicated the potential formation of monodentate, bidentate mononuclear, or bidentate binuclear inner complexes during the adsorption process. Figure 6 e,f demonstrated that the binding energy of Ca2p shifted to higher values after the adsorption of N and P, while Fe2p does not exhibit significant changes. Scanning electron microscopy-energy dispersive X-ray spectroscopy (Fig S2) showed P distribution correlated with lanthanum and calcium, but not iron, further demonstrating the role of lanthanum and calcium in P removal. 3.5 Application in the constructed wetland 3.5.1 N and P removal The changes of influent and effluent concentrations of P (PO 4 3- -P) were shown in Fig. 7 a and Table 4 . The P concentrations varied from 0.624 to 1.358 mg/L, veraging 0.965 ± 0.180 mg/L. After three months of operation, the effluent P levels were 0.00289–0.0432 mg/L (mean 0.0184 ± 0.0085 mg/L) for the L-SFCW, 0.00736–0.0377 mg/L (mean 0.0298 ± 0.0198 mg/L) for the L + G-SFCW, and 0.0276–0.167 mg/L (mean 0.086 ± 0.0297 mg/L) for the G-SFCW. The P removal efficiencies of L-SFCW and L + G-SFCW were 7.33% and 6.12% higher, respectively compared to the G-SFCW. The L-SFCW achieved the lowest effluent P concentration, averaging approximately 0.02 mg/L. These results indicate the lanthanum-modified zeolite media substantially improve P removal performance in SFCW systems treating low influent P wastewater. According to Table 4 , P removal rates exceeding 90% were achieved in various treatments. This can be attributed to the extensive ion uptake area provided by the well-developed root system of reeds (Wang et al., 2018 ) and the adsorption of P by iron-containing materials present in the soil (Yan et al., 2019 ). Zamora et al (Zamora et al., 2019 ) conducted a study indicating that in the presence of vegetation, with an average influent P-PO 4 concentration of 9.11 ± 1.4 mg/L, the wetland system achieved a removal rate of over 60%, further supporting the role of vegetation in P removal. Moreover, the utilization of lanthanum-modified fly ash zeolite as a wetland media material can enhance the effectiveness of P removal. Similar studies, Shang et al. (Shang et al., 2022 ) prepared lanthanum-ammonia modified hydrothermal biochar (La-A-HC) which improved total P removal in wetlands by 14.8% compared to unmodified biochar at 5 mg/L influent P. These findings provide strong evidence for the significant role of lanthanum-modified adsorbent materials in wetland applications. In the practical context of P control in lake reservoirs, the application of Phoslock, a lanthanum-modified bentonite developed in Australia (Lürling et al., 2014 ), has been utilized for P control treatments in lakes. However, it was observed that the low phosphorate concentrations (< 0.02 mg P/L) could be achieved, high dosages (Phoslock:P = 200:1 w/w) are required. This poses challenges in terms of solid powder recovery and the high dosage required, particularly in areas with stringent water quality requirements. The LZFA represents a promising alternative wetland media given enhanced removal demonstrated here under phosphate-spiked conditions. Further research should examine long-term performance under complex influent quality using real lake and runoff sources. Additionally, investigating lanthanum's impacts on wetland ecology, including aquatic plants and microorganisms, is important for understanding broader implications of its application. As shown in Fig. 7 b and Table 4 , the influent N (NH 4 + -N) concentration varied between 1.992 mg/L and 7.900 mg/L, with an average value of 4.945 ± 1.415 mg/L. After three months of operation, the effluent N levels were 0.079–0.665 mg /L (mean 0.342 ± 0.157 mg/L) for the L-SFCW, 0.104-0.467mg/L (mean 0.364 ± 0.169 mg/L) for the L + G-SFCW, and 0.128–1.130 mg/L (mean 0.467 ± 0.236 mg/L) for the G-SFCW. The removal rates of N of the L + G-SFCW and L-SFCW increased by 2.67% and 1.87%, respectively, compared to the G-SFCW. This suggests that the media materials have positive effect on N removal, although not significantly pronounced. The mechanisms involved in N removal in artificial wetlands encompass processes such as ammonia volatilization, microbial ammonification, nitrification, denitrification, plant uptake, and substrate adsorption. Studies have indicated that nitrification and denitrification are the primary methods of N removal in artificial wetlands (Bueno et al., 2015 ). As shown in Table 12, the removal of N using gravel as a wetland substrate can achieve approximately 90%, highlighting the role of microbial degradation and plant uptake in wetland systems. However, the adsorption potential of matrix materials containing metal ions as wetland substrates should not be overlooked. For instance, previous research has shown that metal ions (e.g., Al 3+ , Fe 2+ , Mn 4+ ) can be removed through ion-exchange adsorption with NH 4 + using mining and metallurgical slag as substrate materials, leading to ammonia removal (Sakadevan et al., 1998).In this study, LZFA was used as matrix material, which showed some improvement in N removal compared with gravel, proving the adsorption of sodium ions from zeolite, but the improvement was not significant under environmentally complex conditions. Table 4 Statistical data of influent and effluent concentration and removal efficiencies (mean ± standard deviation) (32 statistical data from August 1th ,2022 to November 2th,2022) Parameter Influent Effluent (L) Effluent (L + G) Effluent (G) NH 4 + -N Concentration (mg/L) 4.945 ± 1.415 0.342 ± 0.157 0.364 ± 0.169 0.467 ± 0.236 Removoal (%) 92.58 ± 3.801 a 91.78 ± 4.89 ab 89.91 ± 5.48 b PO 4 3− -P Concentration (mg/L) 0.965 ± 0.180 0.0184 ± 0.0085 0.0298 ± 0.0198 0.086 ± 0.0297 Removoal (%) 97.96 ± 1.064 a 96.75 ± 2.307 a 90.63 ± 4.294 b Note: Different letters represent significant differences between treatments (one way-ANOVA results by LSD) 3.5.2 Cost analysis The production process of LZFA involves various factors, such as the consumption of raw materials, energy usage, and additional processing costs. According to a market inquiry conducted in February 2023, the estimated cost of these raw materials ranges from 5620 to 6444 RMB per ton. The production equipment for fly ash zeolite is relatively simple, with the main energy consumption occurring during the roasting process. Based on the comparison with the processing cost of iron ore pellets and considering the variations in the sintering process, an approximate estimate of the energy cost is around 200 RMB per ton. Additional processing costs, including equipment maintenance, labor, and overhead, were estimated at 50% of the total direct costs, putting the total production cost between 8730 and 9960 RMB per ton. With a 20% profit margin, the estimated market selling price ranges from 10476 to 11952 RMB per metric ton of LZFA. Fly ash is an industrial byproduct that currently incurs a disposal cost of approximately 4000 RMB per ton. However, LZFA exhibits properties such as N and P saturation, making it suitable for use as a slow-release fertilizer for vegetation. The retail price of comparable slow-release plant fertilizers is around 4000 RMB per ton. Therefore, the actual net cost per ton of LZFA is estimated to be in the range of 2476–3952 RMB, calculated as the production cost of 10476–11952 RMB/ton minus the avoided disposal cost and potential fertilizer revenue of 4000 RMB/ton each. Furthermore, experimental adsorbent synthesized from this process demonstrated a maximum P adsorption capacity of 21.48 kg per ton. Considering an adsorption cost of approximately 150 RMB per kg of P, the total cost of P removal is estimated at 3214 RMB per ton of adsorbent. Consequently, establishment of a circular production chain could significantly reduce the cost of P treatment from this waste stream. 4. Conclusions In this study, LZFA was prepared by combining waste lye, ZFA, and lanthanum chloride and used as a modified substrate for CW to remove N and P. Single-factor and surface methodology (RSM) were used to optimize the preparation. The optimum conditions of LaCl 3 concentration (13.56mM), pH (8.93) and roasting temperature (208.72℃) were recorded from desirability function. N and P adsorption onto LZFA can be best explained with Langmuir isotherm and the maximum adsorption capacities were 17.26 mg/g and 21.48 mg/g. The optimum pH for N and P removal is 7. Coexistent HCO 3 - ,SO 4 2- ,CO 3 2- and Cl - revealed an adverse effect on P adsorption following the order of HCO 3 - >SO 4 2- >CO 3 2- >Cl - . The decline in sorption capacity or diffusion coefficients of LZFA for N compared to ZFA is mainly due to the decrease in surface negative charge and cation exchange capacity. The mechanism of P adsorption is attributed to the formation of La-O-P monodentate, bidentate mononuclear or bidentate binuclear inner-sphere complexation. Meanwhile, the introduction of Ca in waste lye is also involved in the P reaction. The N and P removal rates of LZFA modified SFCW, mixed substrates with LZFA and gravel (i.e., L-SFCW, L + G-SFCW) were 2.67% and 1.87%, 7.33% and 6.12% higher, respectively than SFCW modified with gravel. LZFA had a significant enhancement on P removal in the constructed wetland and was not significant for N enhancement. In practical production, if a circular chain from coal ash production to use in green plant fertilizer can be established, the cost of treating P can be significantly reduced. Declarations Acknowledgements This work was funded by the National Natural Science Foundation of China (NO. 31670541, 31270573). The authors also thank Material Research and Testing Center, Wuhan University of Technology for their technical support of the characteristics of the original and modifed substrates. Author contribution Shuqin Xie: Investigation, visualization, writing—original draft preparation. Mingyang Liu: investigation. Xiangling Zhang: conceptualization, supervision, funding acquisition, writing—review and editing. Chao Yang: experimental operation. Yueling Zhang: experimental operation. Yaojun Qin: experimental operation. Chuntao He: investigation. Yankai Dou: writing—review and editing. Chenguang Gao: writing-original draft preparation. Ye Yuan: experimental operation. Funding National Natural Science Foundation of China,31670541,Xiangling Zhang,31270573,Xiangling Zhang Data availability The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Acknowledgments This work was supported by leading special project of the Chinese Academy of Sciences (No. Y93Z090N10). A uthorship contribution statement Liu zhimei: Conceptualization, Data curation, Formal analysis, Methodology, Writing-original draft, Writing-review & editing. Liang Zhen: Conceptualization, Formal analysis, Methodology, Writing-review & editing. Wu Shengjun: Conceptualization, Methodology , Funding acquisition, Project administration, Resources, Supervision Funding Leading special project of the Chinese Academy of Sciences, Y93Z090N10, Shengjun Wu Data Availability Data will be made available on request Ethics approval. Not applicable. Consent to participate. Not applicable. Consent for publication. Not applicable. Competing interests. The authors declare no competing interests References Abukhadra M R, Mostafa M(2019) Effective decontamination of phosphate and ammonium utilizing novel muscovite/phillipsite composite; equilibrium investigation and realistic application. Sci. Total Environ. 667:101-111. Bacelo H, Pintor A M , Santos S C, Boaventura R A, Botelho C M(2020) Performance and prospects of different adsorbents for phosphorus uptake and recovery from water. Chem. Eng. J. 381: 122566. 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Colloid Interface Sci.445: 303-311. Zamora S, Marín-Muñíz J L, Nakase-Rodríguez C, Fernández-Lambert G, Sandova, L(2019) Wastewater Treatment by Constructed Wetland Eco-T echnology: Influence of Mineral and Plastic Materials as Filter Media and Tropical Ornamental Plants. Water. 11, 2344. Zavareh S, Farrokhzad Z, Darvishi F(2018) Modification of zeolite 4A for use as an adsorbent for glyphosate and as an antibacterial agent for water. Ecotox Environ Safe.155: 1-8. Zhang M, Song G, Gelardi D L, Huang L, Khan E, Mašek O, Ok, Y S(2020) Evaluating biochar and its modifications for the removal of ammonium, nitrate, and phosphate in water. Water Res. 186, 116303. Supplementary Files ElectronicSupplementaryMaterial.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 20 Nov, 2023 Reviewers invited by journal 25 Oct, 2023 Editor invited by journal 13 Oct, 2023 Editor assigned by journal 28 Sep, 2023 First submitted to journal 19 Sep, 2023 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3343829","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":243211797,"identity":"1b3556a6-3aa2-47aa-b49e-557e76133afd","order_by":0,"name":"Zhimei Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA20lEQVRIie3QsQrCMBCA4ZNCuhx2LRTaV7gSEIc+TIqQSaTgA1gQ6uIDdPMVBMFZCTr5AEKXgoOr0MVB0HRxKkY3h/zzfdwlADbbH9Z3ABwgAOYuVH2jJDQS9iZ4knGZSW4m0JI2X1CAN5WaiYu8ybJt2AcheEKOAFcd1p8PQ+IlVZzBfncZE5sASnk2kRFSlRa9XPAx4RR8HBiJ0mRW6E8IhuSn+RcknmsiGNMEiL4hbKoXVXGBKOMlCc5Mb/E8tWnwUUXR6qrq++MZeq46fiQde38bt9lsNltXL7hMPSp6mz/gAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0001-8187-5797","institution":"CIGIT: Chongqing Institute of Green and Intelligent Technology","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Zhimei","middleName":"","lastName":"Liu","suffix":""},{"id":243211798,"identity":"1c1c59b4-9102-4e46-b777-db699ffb6b2d","order_by":1,"name":"Zhen Liang","email":"","orcid":"https://orcid.org/0000-0002-1505-1973","institution":"Southwest University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Zhen","middleName":"","lastName":"Liang","suffix":""},{"id":243211799,"identity":"d099dc09-1eef-438a-93ff-a14dad8db5b3","order_by":2,"name":"Shengjun Wu","email":"","orcid":"","institution":"Chongqing Institute of Green and Intelligent Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Shengjun","middleName":"","lastName":"Wu","suffix":""}],"badges":[],"createdAt":"2023-09-11 07:24:05","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3343829/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3343829/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":45482624,"identity":"e5b1d092-5187-4118-84eb-40d4274464b8","added_by":"auto","created_at":"2023-10-30 20:51:03","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":638902,"visible":true,"origin":"","legend":"\u003cp\u003eScanning electron microscope images of FA(a), ZFA(b), and LZFA(c); X-ray diffraction pattern(d)\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-3343829/v1/a74daf1c9f0ef607522a1dac.png"},{"id":45483593,"identity":"6a7b4245-8fb7-4e9a-b522-353eaf53564d","added_by":"auto","created_at":"2023-10-30 20:59:03","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":310446,"visible":true,"origin":"","legend":"\u003cp\u003ekinetic (a), isotherm (b) and the internal diffusion model (c) of LZFA (pH=6.9, temperature= 25°C, adsorbent dosage=10g/L)\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-3343829/v1/95e57f1f26a414d1593473ea.png"},{"id":45482626,"identity":"731831ad-f17b-4559-864c-e31c5e5aaa08","added_by":"auto","created_at":"2023-10-30 20:51:03","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":287445,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of anions(a), cations (b) and pH (c) on the adsorption capacity and removal of N and P\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-3343829/v1/43fe636f3c2018e43eea874e.png"},{"id":45482630,"identity":"e1d2b37a-9316-404c-8ab0-a021d309a31e","added_by":"auto","created_at":"2023-10-30 20:51:03","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":108465,"visible":true,"origin":"","legend":"\u003cp\u003eCation exchange capacity (a) and Zeta potentials(b) of LZFA\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-3343829/v1/12c2aab3c3c783d883b254c4.png"},{"id":45482627,"identity":"cca0d35b-1473-41f5-8417-88eaff2c39d8","added_by":"auto","created_at":"2023-10-30 20:51:03","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":226988,"visible":true,"origin":"","legend":"\u003cp\u003eThe fourier-transform infrared spectra of LZFA befor (a) and after adsorption N and P of 5mg/L(b), 500mg/L(c)\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-3343829/v1/8d0c75477675d1ced50f5d2a.png"},{"id":45482631,"identity":"46509729-3ad7-4556-8284-e8109bd32e91","added_by":"auto","created_at":"2023-10-30 20:51:03","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":421111,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray photoelectron spectra of LZFA before and after adsorption N and P of 5mg/L: (a) full spectrum; (b) La 3d region; (c) O 1s region; (d)P 2p region; (e) Ca 2p region; (f) Fe 2p region\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-3343829/v1/96bb20fced7f510979132d5e.png"},{"id":45482629,"identity":"d71ec9f6-a712-40ae-8703-e02cda511f24","added_by":"auto","created_at":"2023-10-30 20:51:03","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":316687,"visible":true,"origin":"","legend":"\u003cp\u003ePO\u003csub\u003e4\u003c/sub\u003e-P (a) and NH\u003csub\u003e4\u003c/sub\u003e-N (b) concentration of influent and effluent of SFCWs.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-3343829/v1/3a4db5102750e0415aa4c52c.png"},{"id":45484156,"identity":"d2c3800d-9d11-4937-ad84-e79e30e5bce3","added_by":"auto","created_at":"2023-10-30 21:07:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2750106,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3343829/v1/66aa6f4b-444b-4830-b3d2-f084c5c2c1e0.pdf"},{"id":45483594,"identity":"4126f9b1-28f2-4754-a96b-e72d71fc06b6","added_by":"auto","created_at":"2023-10-30 20:59:03","extension":"docx","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":512317,"visible":true,"origin":"","legend":"","description":"","filename":"ElectronicSupplementaryMaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-3343829/v1/403de328f85f45191b76177d.docx"}],"financialInterests":"","formattedTitle":"Synthesis of lanthanum and waste lye modified-zeolite from fly ash and its application in constructed wetland for nitrogen and phosphorus removal","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eRapid industrial development, urban construction, and changes in various human activities have resulted in a significant increase in the levels of nitrogen (N) and phosphorus (P) entering coastal waters, rivers, and lakes. Agriculture and urban activities are the main sources of P and N in aquatic ecosystems. This influx of N and P has subsequently led to diverse problems such as toxic algal blooms, loss of oxygen, fish kills, loss of biodiversity, loss of aquatic plant beds and coral reefs, and other problems (Carpenter et al.1998). The excessive addition of N and P to water bodies has a detrimental effect on aquatic ecosystems, leading to a decline in their health and functioning. This, in turn, negatively impacts the usability of water for various purposes such as drinking, industrial processes, agriculture, recreation, and more. Therefore, it is imperative to prioritize the removal of N and P from these aquatic ecosystems to mitigate these detrimental effects.\u003c/p\u003e \u003cp\u003eAmong many pollution control technologies, adsorption is very suitable for treating low concentration polluted water bodies due to its advantages of selective removal, reusability, simple operation, etc. It is crucial to develop low-cost adsorbent and apply it to practical projects. At present, it is one of the research hotspots to choose environment-friendly industrial and agricultural wastes as raw materials to prepare adsorption materials.\u003c/p\u003e \u003cp\u003eFly ash is a kind of particulate waste discharged from the combustion of coal-fired power plants. It is reported that the amount of fly ash generated by coal combustion in China has exceeded 100\u0026nbsp;million tons, and the emissions have increased year by year (Lin et al.2022). The stockpiling of a large amount of fly ash not only occupies a large amount of land resources, but also causes dust and pollutes the atmosphere and groundwater. At present, fly ash is mainly used as raw material or auxiliary material of cement in the construction industry, such as clinker partially replacing Portland cement and magnesium sulfate cement(Chen et al.2021). However, the utilization rate of this method is limited. It is reported that the global utilization rate of fly ash is 16% \u0026ndash; 25% (Morales-Ospino et al.2020). Therefore, the development of new methods for forming high value-added products is the focus of attention of all countries, and the synthesis of zeolite is one of the utilization methods.\u003c/p\u003e \u003cp\u003eDue to the similar composition of fly ash and zeolite, many researchers have synthesized zeolite for the purpose of ammonia removal. Among the various synthesis methods, the hydrothermal method is the most common and stable synthesis method. However, a large amount of waste alkali liquor will be produced during the synthesis process, causing secondary pollution. Zeolite is classified as a hydrated aluminosilicate compound. This framework comprises tetrahedrally coordinated aluminum, silicon, and oxygen atoms. The surface of zeolite carries a net negative charge and therefore has a limited ability to phosphorus adsorption.\u003c/p\u003e \u003cp\u003eAs for the utilization of waste alkali liquor, Xie et al (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) used the waste lye and lanthanum chloride to synthesize lanthanum hydroxide. They found that the generated lanthanum hydroxide is amorphous, has a higher specific surface area and higher phosphate adsorption performance than the commercially available lanthanum hydroxide.\u003c/p\u003e \u003cp\u003eAs for studies on phosphorus removal by zeolite, the absorption capacity of zeolite phosphate is usually enhanced by introducing metals, such as calcium, iron, magnesium or rare earth elements. While lanthanum is a rare earth element, research shows that lanthanum has high affinity for phosphate and can form solid and insoluble LaPO\u003csub\u003e4\u003c/sub\u003e (Liu et al.2020). Lanthanum can be introduced into zeolite through alkali solution immersion and calcinations (Liu et al.2017). Lanthanum-modified zeolite has received more attention in removing phosphorus from water (Min et al.2019; Copetti et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). It is reported that the adsorption capacity of lanthanum-modified zeolite is about 2 times higher than that of natural and synthetic zeolite.\u003c/p\u003e \u003cp\u003eThe above research has done some exploration work in the resource utilization of waste lye and the modificarion method of zeolite with lanthanum under alkaline conditions, but there are still the following problems: (1) Only the waste lye and lanthanum chloride in the synthetic zeolite from fly ash were used to synthesize lanthanum hydroxide, and it was found that the generated lanthanum hydroxide had high P adsorption performance. There are few reports on the removal of N and P by loading waste lye and lanthanum chloride into synthetic zeolite; (2) lack of systematic and comprehensive research on the mechanism of N and P removal based on loading waste lye and lanthanum chloride into synthetic zeolite, including P removal mechanism under the condition of the coexistence of lanthanum and other metal ions in waste lye (Fe, Ca) and the efficiency of N removal after lanthanum-modified synthetic zeolite; (3) Most current adsorbent materials are based on performance evaluations in a laboratory setting, and less consideration is given to actual use in the environment.\u003c/p\u003e \u003cp\u003eIn this work, we developed a synthesis zeolite based on fly ash for the removal of N and P by the modification method of waste lye and lanthanum chloride. In experiment condition, the preparation of an efficient adsorbent by combining waste lye, zeolite synthesized from fly ash, and Lanthanum chloride was analysis. Then, the adsorption performances and mechanisms of the developed adsorbent were evaluated. Finally, for the consideration of practical application potential, the adsorbents were made into granular pellets to evaluate the effectiveness of their application in Subsurface Flow Constructed Wetland (SFCW) for N and P removal.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials\u003c/h2\u003e \u003cp\u003eFly ash(FA)was collected from Jiulongpo District, Chongqing City (China). All chemical reagents were analytical grade and purchased from Chongqing Chemical Reagent Co., Ltd. (China) and used without further purification. All solutions were prepared with distilled water. The working solutions containing different concentrations of ammonium chloride (NH\u003csub\u003e4\u003c/sub\u003eCl) and potassium dihydrogen phosphate (KH\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e) were prepared by stepwise dilution of the stock solutions.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Preparation of lanthanum-modified zeolite synthesized from fly ash\u003c/h2\u003e \u003cp\u003eZeolite based on fly ash (ZFA) was obtained by alkali melt hydrothermal Method. First, NaOH solid/FA ratio of 1:0.6 was mixed uniformly, and then roasted at 600\u0026deg;C for 2h in a muffle furnace. Second, the hydrothermal synthesis method was used to obtain the optimum synthesis conditions of NaOH solutions of 1 M, FA/NaOH solution ratio of 1:7, synthesis temperatures of 25\u0026deg;C, and 1h of conversion time.\u003c/p\u003e \u003cp\u003eLanthanum-modified zeolite synthesized from fly ash (LZFA) was obtained by hydrothermal treatment of a ZFA sample in a certain concentration LaCl\u003csub\u003e3\u003c/sub\u003e solution at 25℃, followed by a neutralization procedure using the produced waste alkaline solution until the pH reached a certain value. Subsequently, the mixture was washed and roasted at a certain temperature.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Response Surface Model Design\u003c/h2\u003e \u003cp\u003eThe response surface method is to study the relationship between the response and the input factors, and its goal is to optimize the response. Box\u0026ndash;Behnken experimental design (BBD) is a standard response surface design method and can be used to evaluate the effect of 3 factors. In this experiment, it was applied to optimize the LZFA preparation process and to investigate the interactive effects of concentration LaCl\u003csub\u003e3\u003c/sub\u003e (mM), solution pH and Roasting temperature (℃).\u003c/p\u003e \u003cp\u003eThe software of Design Expert 8.0.6.1 was used for designing and analyzing the experimental data. Second order model is generally used to predict the objective function and can be expressed according to Eq.\u0026nbsp;(1), in which y is the response value (P removal);\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({{\\beta }}_{0}\\)\u003c/span\u003e\u003c/span\u003e offset term; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({{\\beta }}_{\\text{i}}\\)\u003c/span\u003e\u003c/span\u003e is the linear coefficient of\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{X}}_{\\text{i}}\\)\u003c/span\u003e\u003c/span\u003e; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({{\\beta }}_{\\text{i}\\text{i}}\\)\u003c/span\u003e\u003c/span\u003e is the quadratic effect coefficient of\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({ \\text{X}}_{\\text{i}}\\)\u003c/span\u003e\u003c/span\u003e; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({{\\beta }}_{\\text{i}\\text{j}}\\)\u003c/span\u003e\u003c/span\u003e is the effect coefficient of the interaction between\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{X}}_{\\text{i}}\\)\u003c/span\u003e\u003c/span\u003e;nd \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{X}}_{\\text{j}}\\)\u003c/span\u003e\u003c/span\u003e; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{X}}_{\\text{i}}{\\text{X}}_{\\text{j}}\\)\u003c/span\u003e\u003c/span\u003eis the effect of factor interaction effect, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{X}}_{\\text{i}}\\)\u003c/span\u003e\u003c/span\u003eis the independent variable effect of the ith factor, and\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{X}}_{\\text{i}}^{2}\\)\u003c/span\u003e\u003c/span\u003e is the squared effect of the factor.\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\text{y}={{\\beta }}_{0}+\\sum {{\\beta }}_{\\text{i}}{\\text{X}}_{\\text{i}}+\\sum {{\\beta }}_{\\text{i}\\text{j}}^{2}{\\text{X}}_{\\text{i}}{\\text{X}}_{\\text{j}}+\\sum {{\\beta }}_{\\text{i}\\text{i}}{\\text{X}}_{\\text{i}}^{2}\\)\u003c/span\u003e \u003c/span\u003e(1) (Pourfadakari et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Batch experiments\u003c/h2\u003e \u003cp\u003eSynthetic N and P solutions were prepared by dissolving potassium dihydrogen phosphate (KH\u003csub\u003e2\u003c/sub\u003ePO4) and ammonium chloride (NH\u003csub\u003e4\u003c/sub\u003eCl) in deionized water. All batch experiments were implemented in 250 mL stoppered conical flasks on a thermo-static shaker with continuous stirring at 200 rpm. 1g LZFA or ZFA was added to 100ml of 5mg/L N and P solution. After being shaken at room temperature for 24 h, sample solutions were filtered through a 0.45 \u0026micro;m membrane syringe filter. The concentrations of N and P in the filtered solution were accurately determined using two different methods: the Nessler's reagent spectrophotometry for N and the molybdenum antimony anti-spectrophotometry for P.The measurements were carried out using a reliable UV\u0026ndash;vis spectrophotometer (model UV-759S, Jinghua, China) at specific wavelengths of 420 nm and 700nm, respectively. To ensure the reliability of the results, quality control testing was implemented, including the use of blank samples and duplicate analyses. These measures were taken to guarantee the accuracy and precision of the obtained data. The adsorption equilibrium time was found to be 4 hours.\u003c/p\u003e \u003cp\u003eThe amount of contaminant absorbed from the aqueous solution was expressed as ammonium and phosphate adsorption capacity per unit mass of the zeolite (q) as:\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\text{q}=\\frac{（{\\text{C}}_{\\text{e}}-{\\text{C}}_{0}）\\text{V}}{\\text{m}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere, C\u003csub\u003eo\u003c/sub\u003e is the initial ammonium concentration (mg/L), C\u003csub\u003ee\u003c/sub\u003e is the equilibrium ammonium concentration (mg/L), V is the batch volume (L) and m is the zeolite mass (g).\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.4.1 Effect of initial pH\u003c/h2\u003e \u003cp\u003eThe effect of initial pH on the solution was investigated by adjusting the initial pH to a range of 4 to 13 using 0.1M HCl and 0.1M NaOH. The initial concentration of N and P in the solution was 5 mg/L. LZFA was added at a dosage of 10g/L. The experiments were conducted at a temperature of 25\u0026deg;C with a rotation speed of 200rpm for a constant temperature vibration duration of 4.0 hours.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.4.2 Effect of anions and cations\u003c/h2\u003e \u003cp\u003eThe effect of anions and cations was investigated by examining the effects of cations K\u003csup\u003e+\u003c/sup\u003e, Na\u003csup\u003e+\u003c/sup\u003e, Ca\u003csup\u003e2+\u003c/sup\u003e, and Mg\u003csup\u003e2+\u003c/sup\u003e on the adsorption of N. The concentrations of these cations tested ranged from 0mg/L to 80mg/L, including 0, 20, 40, 60, and 80mg/L. Similarly, for the adsorption of P, the effects of anions HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e, SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e, CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e, and Cl\u003csup\u003e-\u003c/sup\u003e were studied. The concentrations of these anions tested ranged from 0mg/L to 80mg/L, including 0, 20, 40, 60, and 80mg/L.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e2.4.3 Isotherm and Kinetics experiments\u003c/h2\u003e \u003cp\u003eTen groups of N-P mixed solution were prepared, each containing 100ml with an initial concentration of 5mg/L for both N and P. To each group, 1g of LZFA or ZFA was added into 100ml of the mixed solution. The solutions were then subjected to shake at 200rpm under constant at room temperature. The shaking durations for each group were set at 10, 30, 60, 120, 240, 360, 480, 600, 720, and 1440 minutes, respectively. In order to conduct the isotherm experiment, 100ml of mixed solutions containing N and P were prepared with varying concentrations. The concentrations tested were 5, 10, 20, 40, 60, 80, 100, 200, and 300mg/L, respectively.\u003c/p\u003e \u003cp\u003eThe equilibrium data were fitted to the Langmuir and Freundlich isotherm models, and their equations were shown as the following equations, respectively,\u003c/p\u003e \u003cp\u003eLanguir adsorption isotherm equation:\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$${\\text{q}}_{\\text{e}}=\\frac{{\\text{q}}_{\\text{m}}{\\text{K}}_{\\text{L}}{\\text{C}}_{\\text{e}}}{1+{\\text{K}}_{\\text{L}}{\\text{C}}_{\\text{e}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eFreundlich adsorption isotherm equation:\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$${\\text{q}}_{\\text{e}}={\\text{K}}_{\\text{F}}{\\text{C}}_{\\text{e}}^{\\frac{1}{\\text{n}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e4\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere, q\u003csub\u003ee\u003c/sub\u003e and q\u003csub\u003em\u003c/sub\u003e are the equilibrium adsorption capacity and maximum adsorption capacity (mg/g), Ceis the solute concentration at adsorption equilibrium (mg/L), K\u003csub\u003eL\u003c/sub\u003e,K\u003csub\u003eF\u003c/sub\u003e and n is the adsorption constant, respectively.\u003c/p\u003e \u003cp\u003eTo analyze the kinetic mechanism of the adsorption process, the experimental data were fitted into three models: the pseudofirst-order model described by Eq.\u0026nbsp;(\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e5\u003c/span\u003e), the pseudo-second-order model described by Eq.\u0026nbsp;(\u003cspan refid=\"Equ5\" class=\"InternalRef\"\u003e6\u003c/span\u003e), and the intra-particle diffusion model described by Eq.\u0026nbsp;(\u003cspan refid=\"Equ6\" class=\"InternalRef\"\u003e7\u003c/span\u003e)\u003c/p\u003e \u003cp\u003ePseudo first-order equation :\u003cdiv id=\"Equ4\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$${\\text{q}}_{\\text{t}}={\\text{q}}_{\\text{e}}[1-{\\text{e}\\text{x}\\text{p}}^{(-{\\text{k}}_{1}\\text{t})}]$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e5\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ePseudo second-order equation :\u003cdiv id=\"Equ5\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ5\" name=\"EquationSource\"\u003e\n$${\\text{q}}_{\\text{t}}=\\frac{{\\text{k}}_{2}{\\text{q}}_{\\text{e}}^{2}\\text{t}}{1+{\\text{K}}_{2}{\\text{q}}_{\\text{e}}\\text{t}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e6\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere, k\u003csub\u003e1\u003c/sub\u003e, k\u003csub\u003e2\u003c/sub\u003e are pseudo first-order and pseudo second-order kinetic constants, respectively (min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). q\u003csub\u003ee\u003c/sub\u003e is the equilibrium adsorption capacity (mg/g).\u003c/p\u003e \u003cp\u003eIntra-particle diffusion equation :\u003cdiv id=\"Equ6\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ6\" name=\"EquationSource\"\u003e\n$${\\text{q}}_{\\text{t}}={\\text{k}}_{\\text{d}\\text{i}}{\\text{t}}^{1/2}+\\text{C}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e7\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere, K\u003csub\u003edi\u003c/sub\u003e is the internal diffusion rate constant (mg/(g.min\u003csup\u003e0.5\u003c/sup\u003e), C is the boundary layer thickness (mg/g).\u003c/p\u003e \u003cp\u003eThe chemical composition and elemental oxidation states of the material surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) using a Thermo Scientific ESCALAB 250Xi spectrometer with a monochromatic Al Kα X-ray source. The morphology and microstructure were examined by field-emission scanning electron microscopy (FE-SEM) on a JEOL JSM-7600F microscope operating at 5 kV. Structural characterization was performed by X-ray diffraction (XRD) using a Rigaku SmartLab diffractometer with Cu Kα radiation (λ\u0026thinsp;=\u0026thinsp;1.5418 \u0026Aring;) over a 2θ range of 20\u0026ndash;80\u0026deg; with a step size of 0.02\u0026deg;. The molecular structure and chemical bonding were investigated by Fourier transform infrared spectroscopy (FTIR) on a Thermo Scientific Nicolet iS50 spectrometer over the wavenumber range of 400\u0026ndash;4000 cm\u003csup\u003e-1\u003c/sup\u003e with a resolution of 4 cm\u003csup\u003e-1\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.5 SFCW experiment setup\u003c/h2\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.5.1 LZFA granular substrate production\u003c/h2\u003e \u003cp\u003eThe LZFA, clay and starch were homogeneous mixed with the mass ratio of 2: 1: 1, then were added water and stirred into a paste to make granular substrate. Finally, dry naturally at room temperature for 3 days and calcined in a muffle furnace 300℃ for 2 hours.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e2.5.2 Experiment Design\u003c/h2\u003e \u003cp\u003eThe experiment employed the Subsurface Flow Constructed Wetland (SFCW) as the application model. The SFCW microcosms were built by a Polyethylene cylinder (50 cm in height and 45cm in diameter).Three different substrate materials were used to construct SFCW microcosm. Three groups of SFCW, i.e., LZFA-based SFCW (L-SFCW), LZFA\u0026thinsp;+\u0026thinsp;Gravel-based FCW (L\u0026thinsp;+\u0026thinsp;G-SFCW), Gravel-based CW (G-SFCW) were constructed with three replicates in each group. The substrate consisted of a 5cm layer of soil at the top layer, followed by a 10 cm layer of LZFA (L-SFCW), a 5 cm layer of gravel and a 5 cm layer of LZFA (L\u0026thinsp;+\u0026thinsp;G-SFCW ), a 10 cm layer of gravel (G-SFCW ). The particle sizes of gravel and LZFA were approximately 2\u0026ndash;3 cm. Ten young reeds (30\u0026ndash;40 cm in height) was planted in each SFCW microcosm with cuttings. The simulated influent contained 5 mg/L\u0026thinsp;\u0026plusmn;\u0026thinsp;12.55 of N and 1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.87 mg/L of P. The pH of the influent varied from 6.68 to 7.82, providing a suitable environment for the survival of various organisms. The simulated influent was introduced into SFCW microcosms and the water level is maintained at approximately 5cm. The SFCW microcosms were operated in subsurface flow with a hydraulic retention time (HRT) of 3 days.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e2.5.3 Water sampling and analysis\u003c/h2\u003e \u003cp\u003eThe influent and effluent of SFCW were sampled and analyzed every 3 days. The concentrations of N and P were measured using the Nasher's reagent method and the ammouimmolybdate spectrophotometric method, respectively.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003e3.1 Optimization of the lanthanum-modified zeolite synthesized from fly ash preparation\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eThe three main Influence factors on P removal by LZFA was investigated by the single-factor method. The optimum conditions were determined to be in pH range of 9\u0026ndash;10, lanthanum chloride concentration of 10.8mM and roasting temperature of 200 ℃(Fig \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). In order to further optimize the process conditions, the response surface model was applied to the P removal analysis. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the levels of independent factors of the Box\u0026ndash;Behken experimental design were chosen based on the Fig \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e.The relationship between response (P removal rate) and three effect factors (concentration, pH and roasting temperature) was analyzed based on the BBD experimental design. The result of each experiment was shown in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e. According to the Design-Expert test results, the regression equation of the quadratic model represented in coded form is as follows:\u003c/p\u003e \u003cp\u003eY\u0026thinsp;=\u0026thinsp;96.42\u0026thinsp;+\u0026thinsp;1.34A-0.12B\u0026thinsp;+\u0026thinsp;1.45C-0.13AB-0.11AC\u0026thinsp;+\u0026thinsp;0.0001BC-0.13A\u003csup\u003e2\u003c/sup\u003e-3.79B\u003csup\u003e2\u003c/sup\u003e-8.02C\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003cp\u003ewhere Y represents P removal rate, A represents lanthanum chloride concentration, B represents pH and C represents roasting temperature.\u003c/p\u003e \u003cp\u003eThe results of the ANOVA for the quadratic model were shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The F value of the model test was 154.39 and the P-value was \u0026lt;\u0026thinsp;0.0001, indicating that the entire quadratic equation simulation was significant. While, the \u0026ldquo;Lack of fit F-value\u0026rdquo; of 7.75 (P\u0026thinsp;=\u0026thinsp;0.0383) indicated that lack of fit is significant, which demonstrated the model was poorly fitted. Furthermore, the signal-to-noise ratio (A.P.=32.79)) and reliability of the conducted experiments were confirmed by a low coefficient of variation (C.V. = 0.59%), which was a cue to a goodness fit of the regression model. The value of R\u003csup\u003e2\u003c/sup\u003e (0.9950) was determined to be close to that of R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003eadj\u003c/sub\u003e (0.9885). Therefore, the quadratic equation model can be used to simulate the response of P removal rate. The quadratic model test included single factor, two-factor interaction term and square term. When the p-value is less than 0.05, it means that the corresponding factors are significant. It was observed that the A\u003csup\u003e2\u003c/sup\u003e, B\u003csup\u003e2\u003c/sup\u003e and C\u003csup\u003e2\u003c/sup\u003e had significant responses to the model (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), while the interactions between factors were not significant (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). In addition, through the F value, it can be seen that the effect order of each factor on P removal is roasting temperature\u0026thinsp;\u0026gt;\u0026thinsp;lanthanum chloride concentration\u0026thinsp;\u0026gt;\u0026thinsp;pH. Through response surface analysis, the optimum conditions for P removal were as follows: the concentration of lanthanum chloride was 13.56mM, the pH was 8.93, and the roasting temperature was 208.72℃.\u003c/p\u003e \u003cp\u003eTo verify the correctness of the model, the comparison between the predicted value and the actual value of P removal rate was listed in Table S2 under the best optimization conditions. It was shown that the experimental value was in good agreement with the calculation result from the model with the error is less than 1.0%. Compared with the ZFA, we observed the 8.3% decline of N removal rate under the optimal condition of P removal rate. It was indicated that the modification of lanthanum had the negative effect on the removal of N.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDifferent levels of BBD factors\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eCoded factor level\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLaCl\u003csub\u003e3\u003c/sub\u003e concentration\u003c/p\u003e \u003cp\u003e(mM)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRoasting temperature(℃)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eVariance analysis of regression coefficients for quadratic model\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSource\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSum of\u003c/p\u003e \u003cp\u003eSquares\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003cp\u003eSquare\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003cp\u003eProb\u0026thinsp;\u0026gt;\u0026thinsp;F\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModel\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e393.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e43.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e154.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSignificant\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e14.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e14.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e50.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.0002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.5521\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e16.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e16.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e59.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.0001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.068\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.068\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.6401\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.044\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.044\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.7049\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.0000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.0015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e60.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e60.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e213.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e270.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e270.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e956.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResidual\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLack of Fit\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.0383\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSignificant\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePure Error\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.073\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCor Total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e395.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003eadj\u003c/sub\u003e (coefficient of determination) of the model is 0.9981, 0.9955.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Adsorbent characterization\u003c/h2\u003e \u003cp\u003eFrom the Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, it was found that the fly ash was mainly amorphous spherical glass beads of different sizes, and some irregular, rougher lumpy and flaky particles were also observed. The physical phase analysis (XRD) contains a large amount of quartz (SiO\u003csup\u003e2\u003c/sup\u003e) and mullite (3AI\u003csub\u003e2\u003c/sub\u003eO.2SiO\u003csub\u003e2\u003c/sub\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed) and accounted for 76.07% of the total (Table\u0026nbsp;5). After the synthesis of zeolite, the spherical glass beads disappeared and irregular and rough products appeared (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb) and the Na content increased from 0.71\u0026ndash;36.12% (Table S3), indicating that Na ions were adsorbed on the zeolite. After modification by lanthanum, it was observed that the increase of La\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e content caused the significant decrease of Na content, which proved that the part of Na ions was exchanged with lanthanum ions.\u003c/p\u003e \u003cp\u003eThe XRD results (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed) showed that the formation of sodium square zeolite (Al\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e3.6\u003c/sub\u003eNa\u003csub\u003e2. 16\u003c/sub\u003eO\u003csub\u003e9.24\u003c/sub\u003eSi\u003csub\u003e1.68\u003c/sub\u003e), due to a new characteristic peak appearance at 13.9\u0026deg;, 24.2\u0026deg;, 42.7\u0026deg;of 2 theta. Meanwhile, it was accompanied by the appearance of intermediate products (sodium silicate PDF 016\u0026ndash;0818, 01-071-0657 with 6 water and sodium carbonate PDF 008-0448) in the zeolite formation process. After lanthanum-modified zeolite based on fly ash, a new characteristic peak appeared at 6.1\u0026deg;, 15.5\u0026deg;, 23.3\u0026deg;, 30.9\u0026deg; of 2 theta (PDF 038\u0026ndash;0237) ,which indicating the formation of X-type zeolite ( Al\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e12.4\u003c/sub\u003e Na\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e15.2\u003c/sub\u003eSi\u003csub\u003e2.5\u003c/sub\u003e). Lanthanum oxide appeared (PDF 022\u0026ndash;0641) with the inconspicuous peak intensity, possibly due to the dispersion of lanthanum on the zeolite surface, as well as the lower lanthanum concentration. The measured values of the adsorbent parameters, including specific surface area, total pore volume, average diameter of total pore and micropore, micropore area, micropore volume, are given in Table S4. After ZFA was modified by lanthanum, the specific surface area increased from 3.79 to 207.12 m\u003csup\u003e2\u003c/sup\u003e/g, the total pore volume increased from 0.021to 0.217 cm3/g, the average pore diameter decreased from 21.60 to 4.19 nm, the micropore area increased from 1.507 m\u003csup\u003e2\u003c/sup\u003e/g to 158.32 m\u003csup\u003e2\u003c/sup\u003e/g, the pore volume increased from 0.000768 cm\u003csup\u003e3\u003c/sup\u003e/g to 0.083 cm\u003csup\u003e3\u003c/sup\u003e/g, and the micropore diameter changed little. This study is similar to the results of Huang et al. (Huang et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The structural change indicated that a large amount of amorphous lanthanum hydroxide is formed and deposited on the surface of the zeolite (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec), causing the large specific surface area. In addition, after the exchange of La\u003csup\u003e3+\u003c/sup\u003e and interlayer cations, zeolite occurs part of the delamination. The structural change will favor P adsorption.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Performance study of N and P removal\u003c/h2\u003e \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e \u003ch2\u003e3.3.1 Adsorption kinetics and isotherm\u003c/h2\u003e \u003cp\u003eIt can be seen from the kinetic parameters listed in Table S5, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea. Compared with the pseudo-first-order kinetic model (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.622(N), R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.596(P)), the pseudo-second-order kinetic model (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.921(N), R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.913(P)) can better describe the N and P adsorption kinetics of LZFA. For N, the equilibrium absorptive capacity (0.412mg/g) of the pseudo-second-order kinetic model of LZFA was lower that (0.447 mg/g) of LFA. For the P, the equilibrium absorptive capacity of the pseudo-second-order kinetic model of LZFA was 0.481mg/g.\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, the sorption consists of three rate processes: (1) the faster liquid film diffusion around the particle; (2) the intraparticle diffusion process including surface and free diffusion of the adsorbed species into the particle (3) convergence to equilibrium diffusion.In order to identify the diffusion mechanism and compare the difference in the sorption process, the intra-particle diffusion parameters (film diffusion coefficient K\u003csub\u003ed1,\u003c/sub\u003e the intraparticle diffusion coefficient K\u003csub\u003ed2,\u003c/sub\u003e convergence to equilibrium diffusion coefficient K\u003csub\u003ed3\u003c/sub\u003e ) were summarized in Table S5. Results showed that the value of K\u003csub\u003ed1\u003c/sub\u003e was three times higher than that of K\u003csub\u003ed2\u003c/sub\u003e and K\u003csub\u003ed3\u003c/sub\u003e for all N and P adsorption, revealing that the particle diffusion was the rate-limiting step. For the N, after lanthanum modification, all three diffusion coefficients decreased, indicating the effect of the modification treatment on N diffusion. For the N and P, all three diffusion coefficients of LZFA were lowered than that of Shi et al. (Shi et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), which may be related to the higher dosing amount and lower initial N concentration. It may reduce the surface loading of LZFA, thereby reducing the mass transfer drive affecting the diffusion rate of films and particles\u003c/p\u003e \u003cp\u003eThe Langmuir and Freundlich models were employed to fit the experimental data (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb) and the maximum sorption capacity and correlation coefficients were summarized in Table S6. It was found that the Langmuir model (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.957(N), R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.801(P)) was higher than that of the Freundlich model (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.797(N), R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.549(P)) for the N and P sorption, indicating that Langmuir can better fit the isothermal adsorption process, which is a monolayer adsorption.The maximum sorption capacity (Q\u003csub\u003emax\u003c/sub\u003e) of LZFA on N was 17.26mg/g, lower than that of ZFA(21.32 mg/g). The maximum sorption capacity (Q\u003csub\u003emax\u003c/sub\u003e) of LZFA on the P was 21.48 mg/g. The reported parameters of the N and P adsorption performance of mineral adsorbent materials were shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. It was found that the adsorption capacity of this study on the N and P was higher than that of the iron-aluminum modified mineral materials and waste synthetic materials and nearly 9 times lower than that of chemical synthesis materials. Therefore, from the perspective of practical use, the suitable adsorbent materials should be select according to the requirements of water quality and material cost.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparision of adsorption capacity for N and P with other adsorbents\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbsorbent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eQ\u003csub\u003em\u003c/sub\u003e N\u003c/p\u003e \u003cp\u003e(mg/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eQ\u003csub\u003em\u003c/sub\u003e P\u003c/p\u003e \u003cp\u003e(mg/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEquilibrium time (h)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eReference\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAl modified natural zeolite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGuaya et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2015\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLa-Mg comppsite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e159.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e49.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3-11P\u003c/p\u003e \u003cp\u003e3\u0026ndash;9 N\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eWei e al., 2021\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eZeolites synthesized by fly ash\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eJi et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2015\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNa@La modified zeolite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4\u0026ndash;8 N\u003c/p\u003e \u003cp\u003e4\u0026ndash;6 P\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSang et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFerric modified zeolite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGao et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2019\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCetylpyridinium bromide modified zeolite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eLi et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2017\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eZeolite synthesized from fly ashes (silica-rich and calcium-rich )\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eJi et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2013\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003emuscovite/phillipsite composite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e110\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e126\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12 P\u003c/p\u003e \u003cp\u003e8 N\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAbukhadra et al ., 2011\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLa modified zeolite based on fly ash\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eThis study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section3\"\u003e \u003ch2\u003e3.3.2. Effect of environmental conditions\u003c/h2\u003e \u003cp\u003eFrom Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec, the N removal of LZFA was optimized at pH 7 with the maximum removal rate (81.88%) and adsorption capacity (0.409 mg/g). The P removal of LZFA was optimized at pH 7 with the maximum removal rate (95.98%) and adsorption capacity (0.480 mg/g).\u003c/p\u003e \u003cp\u003eAt pH values below 7, N in a solution primarily exists in the form of NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e, which facilitates its adsorption (Widiastuti et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). However, a lower pH indicates a higher concentration of hydrogen ions in the solution. Since the radius of hydrogen ions is smaller than that of ammonia ions, they are more likely to undergo ion exchange with the LZFA. This ion exchange process can diminish the effectiveness of N removal in an acidic environment. The pH\u003csub\u003ePZC\u003c/sub\u003e of the LZFA is 2.56 (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb). The pH of 7 is higher than the isoelectric point, resulting in a negatively charged surface, which is favorable for adsorption. However, as the pH exceeds 9, the concentration of hydrated ammonia molecules increases, causing N in the solution to predominantly exist in the form of NH\u003csub\u003e3\u003c/sub\u003e. Consequently, ion exchange processes become limited, leading to a reduction in the removal effectiveness of N.\u003c/p\u003e \u003cp\u003eThe P adsorption on metal oxides is commonly attributed to electrostatic interactions and complex formation via ligand exchange (Yang et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2023\u003c/span\u003e;Liu et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). However, pH\u003csub\u003epzc\u003c/sub\u003e of the LZFA was 2.56 (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb), the electrostatic interactions are not responsible for P adsorption at pH 7. Instead, the main mechanism appears to involve the formation of lanthanum-P complexes through the exchange of La-OH groups, which are generated on the surface of adsorbent, with P ions. At pH\u003epH\u003csub\u003ePZC,\u003c/sub\u003e, the La\u0026ndash;OH groups are involved in the formation of inner sphere species by means of monodentate and bidentate complexation (Salehi et al., 2020;Bacelo et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).Under alkaline conditions (pH\u003e8), the surface of the adsorbent is gradually composed of \u0026equiv;\u0026thinsp;MO\u003csup\u003e-\u003c/sup\u003egroups. The increase of the concentration of OH\u003csup\u003e-\u003c/sup\u003e formed competitive adsorption with P ions, thereby reducing the removal efficiency of P. Furthermore, an increase in pH beyond 11 results in the gradual conversion of HPO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e to PO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e3-\u003c/sup\u003e, leading to a decrease in P removal due to the elevated charge of the ion PO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e3-\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIt can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea that K\u003csup\u003e+\u003c/sup\u003e has the greatest negative effect on the adsorption of N with the increase of cation concentration as was previously reported with natural zeolites (Huang et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). The remaining ions have no obvious effect. The reason is that the hydration radius of K\u0026thinsp;+\u0026thinsp;is small and easily adsorbed on the surface of LZFA, forming a strong competition with N ions. It can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb that the adsorption amount of P gradually decreases with the increase of the anion concentration, and the decreasing order of the P adsorption amount of anions is HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e\u0026gt;SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e\u0026gt;CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e\u0026gt;Cl\u003csup\u003e-\u003c/sup\u003e. The primary reason for this discrepancy lies in the varying binding mechanisms of different anions to metal oxides. For instance, Cl\u003csup\u003e-\u003c/sup\u003e and SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e are adsorbed onto the outer surface of the material through electrostatic adsorption forces, while CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e forms inner sphere complexes that interact with P (Yu et al., 2020). Research has shown that the solubility product constant (K\u003csub\u003esp\u003c/sub\u003e) of La\u003csub\u003e2\u003c/sub\u003e(CO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e( 3.98\u0026times;10\u003csup\u003e\u0026ndash;34\u003c/sup\u003e) is smaller than the Ksp of LaPO\u003csub\u003e4\u003c/sub\u003e (3.7\u0026times;10\u003csup\u003e\u0026ndash;23\u003c/sup\u003e) (Koilraj et al., 2017). While, HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e easily ionizes into CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2,\u003c/sup\u003e, so it has a significant impact on the adsorption of P.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Mechanisms of N and P adsorption\u003c/h2\u003e \u003cdiv id=\"Sec21\" class=\"Section3\"\u003e \u003ch2\u003e3.4.1 N adsorption analysis\u003c/h2\u003e \u003cp\u003eIt can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea that the cation exchange capacity of FAZ is 77.3 cmol/kg and the cation exchange capacity of LZFA significantly decreased to 55.0 cmol/kg after lanthanum modification. It showed that the decrease in cation exchange is responsible for the decrease in N removal by LZFA. The decrease of cation exchange after lanthanum modification may be related to lanthanum coverage on the surface of zeolite (Xie et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIt can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb that the pH\u003csub\u003ePZC\u003c/sub\u003e of ZFA is 4.9 and the pH\u003csub\u003ePZC\u003c/sub\u003e of LZFA is 2.56. The decrease in isoelectric point after lanthanum modification may be related to lanthanum loading, location and zeolite structure. From Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, it can be seen that the negative charge of LZFA significantly decreased compared with ZFA under the condition of pH\u003e6. From the analysis of electrostatic force, the decrease of negative charge will reduce the adsorption of ammonia, indicating that electrostatic adsorption is also one of the main reasons for the decrease of N adsorption.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section3\"\u003e \u003ch2\u003e3.4.2 P adsorption analysis\u003c/h2\u003e \u003cp\u003eAs depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, a robust and wide absorption band centered at approximately 3367 cm\u003csup\u003e-1\u003c/sup\u003e is observed following the adsorption of N and P by the LZFA. This absorption band can be attributed to the stretching vibrations of O-H bonds (He YH., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The appearance of absorption peaks at 1477 cm\u003csup\u003e-1\u003c/sup\u003e, 1367 cm\u003csup\u003e-1\u003c/sup\u003e, and 1435 cm\u003csup\u003e-1\u003c/sup\u003e after the adsorption of N and P indicated the presence of characteristic N-H peaks associated with N in the solid state (Huang et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2014\u003c/span\u003e;Wahab et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). This observation suggests that N is adsorbed onto the material. Additionally, the peak at around 1650 cm\u003csup\u003e-1\u003c/sup\u003e corresponds to the bending vibration of adsorbed water (Zavareh et al., \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Notably, new absorption peaks emerged at approximately 614 cm\u003csup\u003e-1\u003c/sup\u003e and 540 cm\u003csup\u003e-1\u003c/sup\u003e, with the intensity of these peaks increasing with higher concentrations of absorbed P. These two absorption peaks are indicative of the bending vibration of O-P-O, implying that the mechanism underlying P removal involves the formation of inner sphere complexes through ligand exchange (Shi et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea demonstrated the emergence of characteristic N and P spectra following their adsorption. The P\u003csub\u003e2p\u003c/sub\u003e binding energy was determined to be 135.27 eV (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ed), displaying a shift of approximately 1.27 eV towards higher energy levels compared to the standard P2p spectrum of KH\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e (\u0026sim;134.0 eV). This shift indicates a change in the chemical speciation of P. Analyzing Table S7, an increase in the relative N content from 0.44% before adsorption to 1.29% was observed, indicating the adsorption of N onto the material. Conversely, a decrease in the Na peak was observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea), suggesting the ion exchange of N with sodium ions. Moreover, the relative P content increased from 0.51% before adsorption to 3.28%, confirming the adsorption of phosphorate onto the material. The XPS spectrum of La3d exhibited two distinctive sets of characteristic peaks (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb). Prior to phosphorate adsorption, the binding energies of La3d\u003csub\u003e5/2\u003c/sub\u003e were measured at 836.03 eV and 839.09 eV, while the binding energies of La3d\u003csub\u003e3/2\u003c/sub\u003e were observed at 852.77 eV and 855.66 eV. Subsequent to P adsorption, the binding energies of La3d\u003csub\u003e5/2\u003c/sub\u003e shifted to 837.44 eV and 840.68 eV, and the binding energies of La3d\u003csub\u003e3/2\u003c/sub\u003e shifted to 854.11 eV and 857.52 eV. Both La3d5/2 and La3d3/2 exhibited a shift towards higher binding energies after P adsorption, with ΔLa3d\u003csub\u003e5/2\u003c/sub\u003e increasing from 3.06 to 3.24 and ΔLa3d3/2 increasing from 2.89 to 3.41. These observations indicated the formation of inner layer complexes between P and lanthanum-modified fly ash zeolite (Hao et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2019\u003c/span\u003e;Yin et al., \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2022\u003c/span\u003e༛Huang et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe O1s spectrum can be divided into three oxygen types: lattice oxygen (M-O), hydroxyl oxygen (M-OH), and adsorbed water (Sunding et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). The peaks corresponding to these oxygen types are depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec. Following P adsorption, the peak positions of both lattice oxygen and hydroxyl oxygen undergo changes. The relative content of hydroxyl oxygen (M-OH) decreased from 93.88\u0026ndash;80.48%, while the relative content of lattice oxygen (M-O) increased from 3.07\u0026ndash;17.71% (Table S8). These observations indicated that the hydroxyl groups on the surface of LZFA were displaced by P through ligand exchange (Wang et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2022\u003c/span\u003e;Yu et al., 2015) Furthermore, the ratio of hydroxyl content before and after P adsorption indicates the configuration of the inner layer complex formed. A ratio of 0.5 suggests monodentate binding between the surface hydroxyl group and P, while a ratio of 2.0 indicates bidentate binding. (Wan et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). In this study, the hydroxyl group ratio of 1.17 before and after P adsorption on LZFA indicated the potential formation of monodentate, bidentate mononuclear, or bidentate binuclear inner complexes during the adsorption process. Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ee,f demonstrated that the binding energy of Ca2p shifted to higher values after the adsorption of N and P, while Fe2p does not exhibit significant changes. Scanning electron microscopy-energy dispersive X-ray spectroscopy (Fig S2) showed P distribution correlated with lanthanum and calcium, but not iron, further demonstrating the role of lanthanum and calcium in P removal.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Application in the constructed wetland\u003c/h2\u003e \u003cdiv id=\"Sec24\" class=\"Section3\"\u003e \u003ch2\u003e3.5.1 N and P removal\u003c/h2\u003e \u003cp\u003eThe changes of influent and effluent concentrations of P (PO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e3-\u003c/sup\u003e-P) were shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea and Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The P concentrations varied from 0.624 to 1.358 mg/L, veraging 0.965\u0026thinsp;\u0026plusmn;\u0026thinsp;0.180 mg/L. After three months of operation, the effluent P levels were 0.00289\u0026ndash;0.0432 mg/L (mean 0.0184\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0085 mg/L) for the L-SFCW, 0.00736\u0026ndash;0.0377 mg/L (mean 0.0298\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0198 mg/L) for the L\u0026thinsp;+\u0026thinsp;G-SFCW, and 0.0276\u0026ndash;0.167 mg/L (mean 0.086\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0297 mg/L) for the G-SFCW. The P removal efficiencies of L-SFCW and L\u0026thinsp;+\u0026thinsp;G-SFCW were 7.33% and 6.12% higher, respectively compared to the G-SFCW. The L-SFCW achieved the lowest effluent P concentration, averaging approximately 0.02 mg/L. These results indicate the lanthanum-modified zeolite media substantially improve P removal performance in SFCW systems treating low influent P wastewater.\u003c/p\u003e \u003cp\u003eAccording to Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, P removal rates exceeding 90% were achieved in various treatments. This can be attributed to the extensive ion uptake area provided by the well-developed root system of reeds (Wang et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) and the adsorption of P by iron-containing materials present in the soil (Yan et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Zamora et al (Zamora et al., \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) conducted a study indicating that in the presence of vegetation, with an average influent P-PO\u003csub\u003e4\u003c/sub\u003e concentration of 9.11\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4 mg/L, the wetland system achieved a removal rate of over 60%, further supporting the role of vegetation in P removal. Moreover, the utilization of lanthanum-modified fly ash zeolite as a wetland media material can enhance the effectiveness of P removal. Similar studies, Shang et al. (Shang et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) prepared lanthanum-ammonia modified hydrothermal biochar (La-A-HC) which improved total P removal in wetlands by 14.8% compared to unmodified biochar at 5 mg/L influent P. These findings provide strong evidence for the significant role of lanthanum-modified adsorbent materials in wetland applications.\u003c/p\u003e \u003cp\u003eIn the practical context of P control in lake reservoirs, the application of Phoslock, a lanthanum-modified bentonite developed in Australia (L\u0026uuml;rling et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), has been utilized for P control treatments in lakes. However, it was observed that the low phosphorate concentrations (\u0026lt;\u0026thinsp;0.02 mg P/L) could be achieved, high dosages (Phoslock:P\u0026thinsp;=\u0026thinsp;200:1 w/w) are required. This poses challenges in terms of solid powder recovery and the high dosage required, particularly in areas with stringent water quality requirements. The LZFA represents a promising alternative wetland media given enhanced removal demonstrated here under phosphate-spiked conditions. Further research should examine long-term performance under complex influent quality using real lake and runoff sources. Additionally, investigating lanthanum's impacts on wetland ecology, including aquatic plants and microorganisms, is important for understanding broader implications of its application.\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb and Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the influent N (NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N) concentration varied between 1.992 mg/L and 7.900 mg/L, with an average value of 4.945\u0026thinsp;\u0026plusmn;\u0026thinsp;1.415 mg/L. After three months of operation, the effluent N levels were 0.079\u0026ndash;0.665 mg /L (mean 0.342\u0026thinsp;\u0026plusmn;\u0026thinsp;0.157 mg/L) for the L-SFCW, 0.104-0.467mg/L (mean 0.364\u0026thinsp;\u0026plusmn;\u0026thinsp;0.169 mg/L) for the L\u0026thinsp;+\u0026thinsp;G-SFCW, and 0.128\u0026ndash;1.130 mg/L (mean 0.467\u0026thinsp;\u0026plusmn;\u0026thinsp;0.236 mg/L) for the G-SFCW. The removal rates of N of the L\u0026thinsp;+\u0026thinsp;G-SFCW and L-SFCW increased by 2.67% and 1.87%, respectively, compared to the G-SFCW. This suggests that the media materials have positive effect on N removal, although not significantly pronounced.\u003c/p\u003e \u003cp\u003eThe mechanisms involved in N removal in artificial wetlands encompass processes such as ammonia volatilization, microbial ammonification, nitrification, denitrification, plant uptake, and substrate adsorption. Studies have indicated that nitrification and denitrification are the primary methods of N removal in artificial wetlands (Bueno et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). As shown in Table\u0026nbsp;12, the removal of N using gravel as a wetland substrate can achieve approximately 90%, highlighting the role of microbial degradation and plant uptake in wetland systems. However, the adsorption potential of matrix materials containing metal ions as wetland substrates should not be overlooked. For instance, previous research has shown that metal ions (e.g., Al\u003csup\u003e3+\u003c/sup\u003e, Fe\u003csup\u003e2+\u003c/sup\u003e, Mn\u003csup\u003e4+\u003c/sup\u003e) can be removed through ion-exchange adsorption with NH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e using mining and metallurgical slag as substrate materials, leading to ammonia removal (Sakadevan et al., 1998).In this study, LZFA was used as matrix material, which showed some improvement in N removal compared with gravel, proving the adsorption of sodium ions from zeolite, but the improvement was not significant under environmentally complex conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eStatistical data of influent and effluent concentration and removal efficiencies (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation) (32 statistical data from August 1th ,2022 to November 2th,2022)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInfluent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEffluent (L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEffluent (L\u0026thinsp;+\u0026thinsp;G)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eEffluent (G)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNH\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e-N\u003c/p\u003e \u003cp\u003eConcentration (mg/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.945\u0026thinsp;\u0026plusmn;\u0026thinsp;1.415\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.342\u0026thinsp;\u0026plusmn;\u0026thinsp;0.157\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.364\u0026thinsp;\u0026plusmn;\u0026thinsp;0.169\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.467\u0026thinsp;\u0026plusmn;\u0026thinsp;0.236\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRemovoal (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e92.58\u0026thinsp;\u0026plusmn;\u0026thinsp;3.801 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e91.78\u0026thinsp;\u0026plusmn;\u0026thinsp;4.89 \u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e89.91\u0026thinsp;\u0026plusmn;\u0026thinsp;5.48 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e3\u0026minus;\u003c/sup\u003e-P\u003c/p\u003e \u003cp\u003eConcentration (mg/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.965\u0026thinsp;\u0026plusmn;\u0026thinsp;0.180\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.0184\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0085\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0298\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0198\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.086\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0297\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRemovoal (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e97.96\u0026thinsp;\u0026plusmn;\u0026thinsp;1.064 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e96.75\u0026thinsp;\u0026plusmn;\u0026thinsp;2.307 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e90.63\u0026thinsp;\u0026plusmn;\u0026thinsp;4.294 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: Different letters represent significant differences between treatments (one way-ANOVA results by LSD)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003e3.5.2 Cost analysis\u003c/h2\u003e \u003cp\u003eThe production process of LZFA involves various factors, such as the consumption of raw materials, energy usage, and additional processing costs. According to a market inquiry conducted in February 2023, the estimated cost of these raw materials ranges from 5620 to 6444 RMB per ton. The production equipment for fly ash zeolite is relatively simple, with the main energy consumption occurring during the roasting process. Based on the comparison with the processing cost of iron ore pellets and considering the variations in the sintering process, an approximate estimate of the energy cost is around 200 RMB per ton. Additional processing costs, including equipment maintenance, labor, and overhead, were estimated at 50% of the total direct costs, putting the total production cost between 8730 and 9960 RMB per ton. With a 20% profit margin, the estimated market selling price ranges from 10476 to 11952 RMB per metric ton of LZFA.\u003c/p\u003e \u003cp\u003eFly ash is an industrial byproduct that currently incurs a disposal cost of approximately 4000 RMB per ton. However, LZFA exhibits properties such as N and P saturation, making it suitable for use as a slow-release fertilizer for vegetation. The retail price of comparable slow-release plant fertilizers is around 4000 RMB per ton. Therefore, the actual net cost per ton of LZFA is estimated to be in the range of 2476\u0026ndash;3952 RMB, calculated as the production cost of 10476\u0026ndash;11952 RMB/ton minus the avoided disposal cost and potential fertilizer revenue of 4000 RMB/ton each. Furthermore, experimental adsorbent synthesized from this process demonstrated a maximum P adsorption capacity of 21.48 kg per ton. Considering an adsorption cost of approximately 150 RMB per kg of P, the total cost of P removal is estimated at 3214 RMB per ton of adsorbent. Consequently, establishment of a circular production chain could significantly reduce the cost of P treatment from this waste stream.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eIn this study, LZFA was prepared by combining waste lye, ZFA, and lanthanum chloride and used as a modified substrate for CW to remove N and P. Single-factor and surface methodology (RSM) were used to optimize the preparation. The optimum conditions of LaCl\u003csub\u003e3\u003c/sub\u003e concentration (13.56mM), pH (8.93) and roasting temperature (208.72℃) were recorded from desirability function. N and P adsorption onto LZFA can be best explained with Langmuir isotherm and the maximum adsorption capacities were 17.26 mg/g and 21.48 mg/g. The optimum pH for N and P removal is 7. Coexistent HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e,SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e,CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e and Cl\u003csup\u003e-\u003c/sup\u003e revealed an adverse effect on P adsorption following the order of HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e\u0026gt;SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e\u0026gt;CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2-\u003c/sup\u003e\u0026gt;Cl\u003csup\u003e-\u003c/sup\u003e. The decline in sorption capacity or diffusion coefficients of LZFA for N compared to ZFA is mainly due to the decrease in surface negative charge and cation exchange capacity. The mechanism of P adsorption is attributed to the formation of La-O-P monodentate, bidentate mononuclear or bidentate binuclear inner-sphere complexation. Meanwhile, the introduction of Ca in waste lye is also involved in the P reaction. The N and P removal rates of LZFA modified SFCW, mixed substrates with LZFA and gravel (i.e., L-SFCW, L\u0026thinsp;+\u0026thinsp;G-SFCW) were 2.67% and 1.87%, 7.33% and 6.12% higher, respectively than SFCW modified with gravel. LZFA had a significant enhancement on P removal in the constructed wetland and was not significant for N enhancement. In practical production, if a circular chain from coal ash production to use in green plant fertilizer can be established, the cost of treating P can be significantly reduced.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements This work was funded by the National Natural Science Foundation of China (NO. 31670541, 31270573). The authors also thank Material Research and Testing Center, Wuhan University of Technology for their technical support of the characteristics of the original and modifed substrates. Author contribution Shuqin Xie: Investigation, visualization, writing\u0026mdash;original draft preparation. Mingyang Liu: investigation. Xiangling Zhang: conceptualization, supervision, funding acquisition, writing\u0026mdash;review and editing. Chao Yang: experimental operation. Yueling Zhang: experimental operation. Yaojun Qin: experimental operation. Chuntao He: investigation. Yankai Dou: writing\u0026mdash;review and editing. Chenguang Gao: writing-original draft preparation. Ye Yuan: experimental operation. Funding National Natural Science Foundation of China,31670541,Xiangling Zhang,31270573,Xiangling Zhang Data availability The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by leading special project of the Chinese Academy of Sciences \u0026nbsp; \u0026nbsp; (No. Y93Z090N10).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA\u003c/strong\u003e\u003cstrong\u003euthorship contribution statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLiu zhimei: Conceptualization,\u0026nbsp;Data curation, Formal analysis,\u0026nbsp;Methodology, Writing-original draft, Writing-review \u0026amp; editing.\u0026nbsp;Liang Zhen: Conceptualization, Formal analysis, Methodology,\u0026nbsp;Writing-review \u0026amp; editing.\u0026nbsp;Wu Shengjun: Conceptualization, Methodology\u0026nbsp;,\u0026nbsp;Funding acquisition, Project administration, Resources, Supervision\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLeading special project of the Chinese Academy of Sciences,\u0026nbsp;Y93Z090N10, Shengjun Wu\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData will be made available on request\u003c/p\u003e\n\u003cp\u003eEthics approval. Not applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eConsent to participate. Not applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eConsent for publication. Not applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCompeting interests. The authors declare no competing interests\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbukhadra M R, Mostafa M(2019) Effective decontamination of phosphate and ammonium utilizing novel muscovite/phillipsite composite; equilibrium investigation and realistic application. Sci. Total Environ. 667:101-111.\u003c/li\u003e\n\u003cli\u003eBacelo H, Pintor A M , Santos S C, Boaventura R A, Botelho C M(2020) Performance and prospects of different adsorbents for phosphorus uptake and recovery from water. Chem. Eng. J. 381: 122566.\u003c/li\u003e\n\u003cli\u003eBueno E, Mania D, Frostegard Ǻ, Bedmar E J, Bakken L R, Delgado M J (2015) Anoxic growth of Ensifer meliloti 1021 by N2O-reduction, a potential mitigation strategy. 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Water Res. 186, 116303.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"environmental-science-and-pollution-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"espr","sideBox":"Learn more about [Environmental Science and Pollution Research](https://www.springer.com/journal/11356)","snPcode":"11356","submissionUrl":"https://submission.nature.com/new-submission/11356/3","title":"Environmental Science and Pollution Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Lanthanum-modified zeolite, Fly ash, Nitrogen and phosphorus removal, Constructed wetland","lastPublishedDoi":"10.21203/rs.3.rs-3343829/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3343829/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eExcess inputs of nitrogen (N) and phosphorus (P) can lead to imbalance in water ecosystems and thus trigger eutrophication. In this study, a novel Lanthanum modified zeolite synthesized from fly ash (LZFA) was prepared and used as a modified substrate for constructed wetland (CW) to enhance N and P removal. Single-factor and surface methodology (RSM) were used to optimize the preparation. The results showed that the maximum adsorption capacities of N and P were 17.26 mg/g and 21.48 mg/g. The decline in sorption capacity or diffusion coefficients of LZFA for N compared to zeolite synthesized from fly ash (ZFA) is mainly due to the decrease in surface negative charge and cation exchange capacity. The mechanism of P adsorption is attributed to the formation of La-O-P monodentate, bidentate mononuclear or bidentate binuclear inner-sphere complexation. Meanwhile, the introduction of Ca in waste lye is also involved in the P reaction. The N and P removal rates of LZFA modified subsurface flow constructed wetland (SFCW) were 2.67% and 7.33% higher than SFCW modified with gravel. In practical production, if a circular chain from coal ash production to use in green plant fertilizer can be established, the cost of treating P can be significantly reduced.\u003c/p\u003e","manuscriptTitle":"Synthesis of lanthanum and waste lye modified-zeolite from fly ash and its application in constructed wetland for nitrogen and phosphorus removal","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-10-30 20:50:58","doi":"10.21203/rs.3.rs-3343829/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2023-11-20T05:20:32+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2023-10-25T21:14:25+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Environmental Science and Pollution Research","date":"2023-10-13T13:18:44+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2023-09-28T05:18:43+00:00","index":"","fulltext":""},{"type":"submitted","content":"Environmental Science and Pollution Research","date":"2023-09-20T01:45:06+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"environmental-science-and-pollution-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"espr","sideBox":"Learn more about [Environmental Science and Pollution Research](https://www.springer.com/journal/11356)","snPcode":"11356","submissionUrl":"https://submission.nature.com/new-submission/11356/3","title":"Environmental Science and Pollution Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"76cd1c06-f3fd-44aa-ba0e-f08e6ff44db6","owner":[],"postedDate":"October 30th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2023-10-30T20:50:58+00:00","versionOfRecord":[],"versionCreatedAt":"2023-10-30 20:50:58","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3343829","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3343829","identity":"rs-3343829","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}