Adsorption of Methyl Orange and Methylene Blue  from aqueous solutions using thermally treated biomass of pine leaves (Pinus kesiya)

Adsorption of Methyl Orange and Methylene Blue from aqueous solutions using thermally treated biomass of pine leaves (Pinus kesiya) | 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 Adsorption of Methyl Orange and Methylene Blue from aqueous solutions using thermally treated biomass of pine leaves (Pinus kesiya) Phuong Thao Huynh, Duy-Khoi Nguyen, Bich-Ngoc Duong, Phi-Ho Nguyen, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2862013/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The uptake of Methyl Orange (MO) and Methylene Blue (MB) from aqueous solutions onto Pine leaves (Pinus kesiya) was investigated in this work. The pine leaves was dried, grinded and thermally treated at 300 o C. Factors including pH solution, contact time, initial dye concentration were discovered to be relevant in the removal of dyes. Among four isotherm models (Langmuir, Sips, Freundlich, and Temkin), the experimental data was fitted the Langmuir model better than others. For MO and MB, the maximum Langmuir adsorption capacities were 136.99 mg.g − 1 and 140.85 mg.g − 1 , respectively. The kinetic studies demonstrated that the biosorption of MO and MB onto pine leaves was compatible with Elovich, pseudo-first-order, pseudo-second-order and intra-particle diffusion models. The thermodynamic studies showed that the uptake of the two dyes was regulated by physisorption, spontaneous, and endothermic in nature. Electrostatic interactions, as well as other non-covalent forces such as π–π interactions and hydrogen bonds, are mechanisms of dyes adsorption on heat treated pine leaves biomass. The current study found that pine leaves (Pinus kesiya) might be a potential biosorbent for the wastewater treatment due to their high availability and production, resulting in various environmental advantages. Methylene Blue Methyl Orange Pinus kesiya biosorption heat-treatment. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction Water pollution caused by textile manufacturers' incapacity to properly dispose of waste water is currently one of the world's significant issues. Textile industries contribute significantly to the world economy and pollution in several nations, including China and South African estuaries (Olisah, Adams, & Rubidge, 2021 ). As textile industries generate large amounts of highly colored wastewater containing a diverse range of persistent pollutants, dye-containing wastewater is a significant polluter of the environment that also affects human health (Al-Tohamy et al., 2022 ). Around 7.10 7 tons of synthetic dyes are produced globally each year, with over 10,000 tons of such dyes used by the textile industry (Chandanshive et al., 2020 ). Many harmful chemicals are employed in the dye manufacturing process, including dyes, surfactants, electrolytes, emulsifiers, media, starches, yeasts, and oxidants. When these chemicals are thrown improperly, they can harm nearby bacteria, fish, and aquatic creatures. These pollutants can also permeate the soil, remain there for extended periods, harm groundwater supplies, and endanger human life. Furthermore, textile-dyed wastewater is highly colored, often varies depending on the kind of dye, and has a high temperature, so it must be adequately cleaned before release to avoid environmental damage (Zhou, Lu, Zhou, & Liu, 2019 ). The removal of colorants from wastewater has faced many significant disadvantages, such as high costs, hazardous product production, and high energy needs. As a result, we must seek new solutions and create more ecologically friendly technology. Because conventional adsorbents are easy to find, easily accessible, renewable, ecologically benign, and can replace traditional adsorbents, biosorption is one of the most successful ways (Mustafa T. Yagub, Sen, Afroze, & H.M.Ang, 2014). To date, a range of low-cost adsorbents, such as potato peel (Guechi & Hamdaoui, 2015 ), dragon fruit leaves (Haddadian, Shavandi, Abidin, Razi, & Ismail, 2013 ), pine cone (Sen, Afroze, & M., 2011), rice straw (Cheng et al., 2015 ), fly ash (Das, Barman, & Thakur, 2012 ), and other materials, have been investigated. Adsorbents based on these biologics have been utilized to eliminate acidic, basic, and reactive dyes from waste water. All of these bio-wastes are common and have little monetary worth. Adsorption is extremely reliant on the pH solution , the dosage of the adsorbent, the temperature, and the concentration of other solutes present in the solution, according to the authors. There are some studies using pine cone and pine leaves for removal of methylene blue (MB) from aqueous solution (Ertugay & Malkoc, 2014 ; M.T. Yagub, Sen, & Ang, 2012 ). Pine tree cones and leaves were cleaned multiple times with distilled water to eliminate impurities such as grit before drying for two days in an oven at 65 o C. A crusher was then used to chop and grind dried pine materials. The powders were then passed through British Standard Sieves, with particles less than 100 µm collected in a plastic container for pine cones and particles less than 350 µm collected in a plastic container for pine leaves, both to be used as adsorbents. At 30°C, pine cone and pine leaf biomass had maximal monolayer adsorption capacities of 129.87 mg/g and 126.58 mg/g, respectively (M.T. Yagub et al., 2012 ). Fresh needles of Pinus sylvestris L. were dried at 80ºC for 48 h and cut into small pieces. Adsorption experiments were carried out 250–500 µm at adsorbent particle size (Ertugay & Malkoc, 2014 ). The maximum monolayer adsorption capacity of this material was found to be 101 mg/g at 45°C. FTIR spectrum result revealed the presence of adsorbing groups such as carboxyl, hydroxyl, and aromatic-CN stretching in the needles. These studies only investigated the MB adsorption capacity of pine needles but did not investigate the adsorption capacity with other organic dyes. The material used in these studies is unmodified pine needles and the mechanism of MB adsorption in water has not been specified. Pinus kesiya is popular in Southeast Asia for a range of applications such as boxes, pulp and paper, and temporary utility poles. Scientists have paid little attention to Pinus kesiya as an adsorbent to eliminate methylene blue and methyl orange from aqueous solutions, even though it is a cheap, easy-to-use, and ecologically benign material. In this study, we explore the MO and MB adsorption capability of heat-treated pine needles at 300 o C. The influence of critical adsorption factors on the adsorption efficiency was investigated. Isothermal, kinetic, and thermodynamic analyzes, as well as biomass properties before and after adsorption, were used to indicate the mechanism of dye adsorption of this material. 2. Materials and Methods 2.1. Adsorbent The waste pine leaves collected from Dalat, Vietnam were completely cleaned by soaking in clean water for a day to eliminate adherent dust particles, prior to being washed with distilled water until the colorless rinse water. Next, they were cut approximately 2 cm before drying at 80 o C for 24 hours to achieve a consistent weight. The samples were baked at 300 o C for 2 hours after being crushed and sieved to size in a range of [125µm, 212 µm]. To eliminate humidity, the material was kept in airtight plastic containers, which were then used in the adsorption experiments. Pine leaves before and after the treatment were presented in Fig. 1 . 2.2. Chemicals Methylene Blue (C 16 H 18 ClN 3 S.3H 2 O ; M.W: 373.9 g/mol; C.I. 52015) and Methyl Orange (C 14 H 14 N 3 O 3 SNa; M.W: 327.34 g/mol; C.I.13025) were producted by MERCK. To prepare 1000 ppm stock solutions, a precise weight of MO and MB diluted in 1000 mL of distilled water was 1.000 g and 1.1690 g, respectively. These lower concentration solutions were created by diluting stock solutions. pH of solutions was adjusted with 0.1M HCl and NaOH solution. 2.3. Determination of point of zero charge Prepared 10 flasks containing ​50 mL of 0.1 M KCl solution with the corresponding pH i values adjusted from ​​2 to 11. Added 0.1 g of material to the flasks prepared above, covered and stirred for 24 hours. Then, filtered the solution and measured the pH value (called pH f ). Determined the graph of dependency ΔpH (ΔpH = pH i - pH f ) on pH i . The zero charge point of the material (pH pzc ) was the intersection pointed between the plot and the Ox axis at the value ΔpH = 0. Carried out the test three times for each pH i value of the solution. 2.4. Adsorption experiments Effects of factors, such as pH (2–10), starting dye concentration (100–500 mg.L − 1 ), and contact duration (10–240 min) on the biosorption of MB and MO were examined and conducted in triplicate in batch. Herein, 0.1 g of material was placed to 50 mL capped glass bottles containing 100 mg.L − 1 of dye solutions. Shake the solution at 150 rpm at room temperature (25 0 C). After the adsorption, the mixture was filtered on the filter paper to get the solution. The residual concentration of the dye in the supernatant was determined by a UV–Vis spectrophotometer at a wavelength maximum of 665 nm and 465 nm for the MB and MO, respectively. The adsorption capacity and efficiency are determined as follows: $${\text{q}}_{\text{e}}\text{=}\frac{\left({\text{C}}_{\text{0}}\text{-}{\text{C}}_{\text{e}}\right)\text{V}}{\text{m}}$$ 1 $$\text{H%=}\frac{\left({\text{C}}_{\text{0}}\text{- }{\text{C}}_{\text{e}}\right)\text{.100%}}{{\text{C}}_{\text{0}}}$$ 2 Where C 0 and C e are concentrations of dye before and after the adsorption (mg.L − 1 ), respectively. q e is the adsorption capacity (mg.g − 1 ). V represents the volume (L) of the solution, and m is the mass of biosorbent utilized (g). 2.5. Kinetic studies To evaluate physiochemical interactions between material and dyes, the nature of sorption process, and rate-limiting step, all of which play an vital role for the design of commercial sorption systems, adsorption kinetic modeling is fitted with experimental data to determine kinetic parameters. As a consequence, the nonlinear equations (pseudo-first-order, pseudo-second-order, Elovich, and intra-diffusion models) were used to fit adsorption kinetic models to the kinetic study data as shown in Supplemental Information . 2.6. Adsorption studies Using equilibrium isotherm modeling plays an instrumental role in determining the distribution of dye molecules on the material surface, leading to an understanding of the dye-material adsorption mechanism. For this study, four isotherm models (Langmuir, Freundlich, Sips, Temkin) were fitted with experimental data to examine the sorption processes of cationic and anionic dyes onto the material. The fomulars and meanings of these models were shown in Supplemental Information . 2.7. Adsorption thermodynamics Thermodynamic investigations of the biosorption of dyes onto material were carried out at various temperatures (298–328 K). The following equations may be used to calculate parameters consisting of enthalpy changes (∆H 0 : KJ.mol − 1 ), entropy changes (∆S 0 : J mol − 1 .K − 1 ) and free energy changes (∆G 0 : KJ.mol − 1 ): \({\text{∆G}}^{\text{0}}\text{= }\text{-}\text{RTln}{\text{K}}_{\text{C}}\) (11) \({\text{∆G}}^{\text{0}}\text{= }{\text{∆H}}^{\text{0}}\text{-T.}{\text{∆S}}^{\text{0}}\) (12) \(\text{ln}{\text{K}}_{\text{C}}\text{= }\frac{{\text{-∆H}}^{\text{0}}}{\text{RT}}\text{+}\frac{{\text{∆S}}^{\text{0}}}{\text{R}}\) (13) Where R represents the universal gas constant (8.314 J.mol − 1 .K − 1 ), T represents the absolute temperature (Kelvin), and K C represents the equilibrium adsorption constant. The dye's ∆H 0 and ∆S 0 values were derived using the slope and intercept of the LnK C vs 1/T plot, respectively. The data utilized in the preceding study are all mean values from three replicate experiments. 3. Results and Discussion 3.1. Characterization of adsorbents Figure 2 depicted the material's surface as coarse, porous, and riddled with holes. The sizes of the holes were quite uniform that facilitated the adsorption process. This material had many holes so the adsorption process took place and achieved good adsorption efficiency in a short time. The S4800 Field Emission Scanning Electron Microscope was applied for visualize morphological features on the surface of materials (Hitachi, Japan). The EDX spectrossic examination revealed that the primary components of the substance were carbon and oxygen at a volume rate of 66.47% and 33.53%, respectively. The above ratio was due to the activation of the material at 300 0 C – this process helped to convert organic compounds found in the leaves such as Lignin, Holocellulose, etc. into gases. These gases flew away leaving blanks, which was the porosity mechanism that facilitated the adsorption process. Pine leaves are mostly made of cellulose and lignin, whose components serve as active sites for dye adsorption. To determine the active functional group on the surface of materials, FT-IR spectra of material before and after dye adsorption were determined by Nicolet iS5 FT-IR spectrometer (Thermo Fisher, USA) and shown in Fig. 3 . The spectra presented many peaks, indicating that pine leaves contain a variety of functional groups that may aid in the binding of dye molecules. The absorbance bands of material were discovered to comprise a large overlapping band at 3200–3500 cm − 1 , with a peak at 3412 cm − 1 , which can be attributed to hydroxyl group O-H stretching and intermolecular hydrogen bonding. This band's location and asymmetry suggested the presence of strong hydrogen bonds. This peak diminished following dye adsorption, showing that the O-H and hydrogen bonds in material were disrupted in order to react with dye. The signal at 2955 cm − 1 indicates vibration of CH n , mainly owing to C-CH 2 and C-CH bonds, whereas a peak of 1735 cm − 1 presents the C = O group of the carbonyl in the hemicellulose (W. Zhu et al., 2016 ). The existence of C = C stretching of the phenol group is shown by the peaks at 1600 cm − 1 . Whereas peaks at 1033 cm − 1 in the spectrum lead to a strong C-O bond due to the cellulose ether group (Silva et al., 2019 ). Except for minor differences, the spectra of the dye-loaded material exhibited comparable properties to the adsorbent in natural form. After the adsorption, the specific peaks are somewhat moved from their original positions, and the intensity changes. These findings indicated that functional groups contribute the adsorption of dye ions of the material via weak electrostatic contact or Van der Waals interactions. 3.1. Survey results of zero charge point (pH pzc ) and effect of pH on Dyes Adsorption The pH pzc value was about 7.5 based on the material's zero-charge graph. This finding allowed us to anticipate the material's adsorption capability for MB and MO at any pH value. When the pH of the solution was less than 7.5, the material's surface was positively charged, and excellent anion adsorption was favored. If the solution pH was more than 7.5, the material's surface would have a negative charge and improved cation adsorption (Banerjee & Chattopadhyay, 2017 ). This was the basis of investigating the factors influencing pH on adsorption capacity to determine the optimal pH value of MB and MO. Noticeably, there was a tendency to increase the adsorption capacity of MB from pH = 2 to 8, prior to equilibrium at pH > 8. When dissolved in water, MB (pK a = 3.8), a base-cationic dye, decomposed into MB + ions, and the lower the pH value (greater concentration of H + in the solution), the adsorption competition between MB + and H + lowered the material's MB adsorption capacity (Khnifira et al., 2022 ). Furthermore, carbonyl groups (C = O) and hydroxyl groups (O-H) on the adsorbent's surface can bind cationic dye molecules at the high pH. As a result, the material has a high MB adsorption capability in an alkaline environment (M.T. Yagub et al., 2012 ). The adsorption of MO (pK a = 3.4) onto material reduced from 40.28 to 35.50 mg.g − 1 when the pH climbed from 2 to 10, indicating that anionic dye adsorption onto pine leaves is pH-dependent and preferential under acidic conditions. The increased anionic dye adsorption at lower pH levels has been linked to the full protonation of the material surface functions, which provides strong electrostatic attraction to the MO dye molecules, allowing the dye to be quickly absorbed (Zubair et al., 2017 ). In contrast, increasing the pH causes an increase in anion OH − in the solution, which competes with anionic dye molecules, resulting in a drop in the q e of MO on material. This shows that electrostatic and chemical interactions were predominantly responsible for the uptake of anionic dyes onto pine leaf material (Zubair et al., 2020 ). In order to understand how pH affects adsorption behavior, the zeta potential of the adsorbent was measured at various pH values. As demonstrated in Fig. 4 , when the pH was less than 7.5, the material’s surface potential was positive, and the uptake of anion MO was improved due to electrostatic attraction. In contrast, the surface potential of material was negative, which was suitable for the uptake of cation MB. However, the adsorption capacity of MB was not diminished when the pH value is higher than 9. It indicates that the adsorption mechanism of MB follows not only electrostatic interaction but also hydrogen bonding between adsorbent and adsorbate. The material may be considered an H-donor, whereas MB was an H-acceptor. This mechanism can also occur during MO adsorption. According to the foregoing explanations, the optimal pH value of the material's MB and MO adsorption processes was 8 and 6. The study's findings were aligned with the findings of establishing the material's point of zero charges. Previous research has also observed similar behavior (Alseddig, Eljiedi, & Kamari, 2017 ; Yang et al., 2018 ). Furthermore, based on Fig. 5 a, it was inferred that the adsorption capacity of MB was larger than the adsorption capacity of MO at the ideal pH value. The degree of diffusion was governed by the size or shape of the molecule in organic dyes with complicated and bulky structures, such as MB and MO. To describe dye adsorption capability, use the structure and molecular weights of dyes (Sun et al., 2022 ). 3.3. Effect of contact time and the initial dyes concentration Because the contact duration of the dyes material adsorption process was a significant factor in the adsorption system design, Fig. 5 b depicts the effects of adsorption time on the adsorption capacity of anionic and cationic dyes. According to these curves, the adsorption of the molecules of MB and MO on the pine leaves is quick during the first 60 min to reach the equilibrium, which is 150 min for the MB and MO with maximum adsorbed amounts of 44.27 mg.g − 1 and 40.97 mg.g − 1 , respectively. The quick adsorption rate of the initial phase (fast phase) may be explained by the reality that he adsorption sites on the surface of our adsorbent are free at the start of the phenomenon. Once the dye molecules are immobilized, they block the pores, decreasing the rate of adsorption and resulting in a saturated array, which is why the second phase exists (slow phase). This trend is consistent with other research' conclusions . At room temperature, Fig. 6 a depicts the adsorption capabilities versus various starting dye concentrations. As the dye concentration rises from 100 to 500 mg.L − 1 , the quantity of dye adsorbed (mg.g − 1 ) of both MB and MO rose from 44.28 mg.g − 1 to 127.23 mg.g − 1 (MB) and from 40.98 mg.g − 1 to 118.62 mg.g − 1 (MO). The concentration of the dye influences dye removal. The mass transfer driving force rose as the starting concentrations increased, as did the interaction between dyes and adsorbent, resulting in increasing adsorption capacity. As shown in Fig. 6 b, raising the initial dye concentration from 100 to 500 mg.L − 1 reduced removal from 88.55–50.89% (MB) and 81.95–47.45%. (MO). This was discussed in detail that the adsorption capacity was complete and the adsorption efficiency was high when the concentration of MB and MO was low due to the low and constant weight of the adsorbent. Notwithstanding, the amount of MB and MO was very large at the high concentration, exceeding the number of fixed adsorption centers in the material, thus these uptake were incomplete, resulting in a decline in adsorption efficiency (W. Zhu et al., 2016 ; Zubair et al., 2020 ). 3.4. Adsorption mechanism of MB and MO onto material of pine leaves In addition to taking into account kinetics and isotherms models, as well as the characterisation of wasted material following the uptake of the dye, the mechanism of interaction of anionic and cationic dye molecules with biochar surface was further studied. The discussion of the findings is in the section below. 3.4.1. Adsorption equilibrium Adsorption isotherms display the distribution of adsorbent molecules between the liquid and solid phases when the uptake obtains equilibrium. Normally, an appropriate model can be determined by fitting experimental data with several isotherm models, such as Langmuir, Freundlich, Sips, and Temkin (Ertugay & Malkoc, 2014 ). The fitted plots from each isotherm for the adsorption of MB and MO onto material of Pinus kesiya were displayed in Fig. 7 . Table 1 reports the isotherm parameters discovered via non-linear regression analysis. Table 1 Calculated parameters (± SD) for MB and MO biosorption by Pinus kesiya material in single systems, acquired by non-linear regression analysis Models Parameters MB MO Langmuir K L (L.mg -1 ) 0.0268 ± 0.0061 0.0228 ± 0.0031 q max (mg.g -1 ) 150.67 ± 8.73 142.72 ± 5.13 R 2 0.9937 0.9981 Freundlich n 3.35 ± 0.60 3.10 ± 0.40 K F (L n .g) 26.41 ± 6.95 21.27 ± 4.44 R 2 0.9872 0.9939 Sips q s (L.g -1 ) 1.88 ± 2.90 2.31 ± 2.05 α s (L.mg -1 ) 0.0133 ± 0.0193 0.0168 ± 0.0136 β s 1.22 ± 0.44 1.10 ± 0.25 R 2 0.9930 0.9979 Temkin K T (L.mg -1 ) 0.3298 ± 0.1675 0.2508 ± 0.0724 b T (J.mol -1 ) 81.07 ± 11.45 82.49 ± 7.02 R 2 0.9913 0.9971 The Langmuir adsorption model explains the MB and MO dye adsorption on the material of pine leaves reasonably well. The Langmuir model's coefficients of determination (R 2 ) for the MB and MO biosorption data (R 2 = 0.9937 for MB and R 2 = 0.9981 for MO) were greater than those for the other models. It was discovered that material has a maximum adsorption capacity of 150.67 mg.g − 1 (MB) and 142.72 mg.g − 1 (MO), confirming physical monolayer adsorption. The homogeneous distribution of active sites on the adsorbent surface, which is implied by the Langmuir equation, maybe the reason why the Langmuir isotherm closely matches the experimental results (Sen et al., 2011). According to the nonlinear Freundlich isotherm, determining the constant K F (L n .g) and n coefficient (Table 1 ) . This coefficient between 1 and 10 was a favorable range for the biosorption process. This proved that pine leaves ( Pinus kesiya) were good biosorbent materials for MB and MO in an aqueous solution. Additionally, the Temkin model's energy values bT calculations were less than 8 kJ/mol, which supported the idea that these adsorbents underwent physical adsorption at the measured temperatures. Table 2 The maximum adsorption capacity of MB and MO calculated from the Langmuir model using various biosorbents. Source of adsorbents Adsorbent q max (mg.g − 1 ) Reference Millettia thonningii seed pods MB 14.09 (Jasper, Ajibola, & Onwuka, 2020 ) Casuarina equisetifolia pines MB 41.35 (Chandarana, Kumar, Seenuvasan, & Kumar, 2021 ) Peanut shells MB 67.42 (Benjelloun et al., 2022 ) Walnut shells MB 101.43 (Benjelloun et al., 2022 ) Potato (Solanum tuberosum) peel MB 105.26 (Guechi & Hamdaoui, 2015 ) Biochar-Derived Date Palm Fronds Waste MB 206.61 (Zubair et al., 2020 ) Cattle manure-derived low temperature biochar MB 241.99 (Y. Zhu et al., 2018 ) Pine leaves MB 150.67 This study Corn leaves MO 13.85 (Fadhil & Eisa, 2019 ) Dragon fruit foliage MO 17.67 (Haddadian et al., 2013 ) Pineapple leaf MO 47.62 (Kamaru, Sani, & Malek, 2015 ) Populous leaves MO 90.44 (Shah, Sharma, Dar, & Bamezai, 2021 ) Shaddock peels- MO 94.59 (Tao, Wu, & Cha, 2019 ) Biochar-Derived Date Palm Fronds Waste MO 163.13 (Zubair et al., 2020 ) Pine leaves MO 142.72 This study The data in Table 2 compares the adsorption capabilities of several biosorbents that have been previously reported in the literature to those of pine leaves. The Pinus kesiya material that was presented in this study functioned superbly, outperforming the majority of other comparable adsorbents that had previously been described. As a result, pine leaves provide MB and MO from an aqueous solution a potential, cost-effective biosorbent. 3.4.2. Adsorption kinetics In order to evaluate the effects of adsorption time on the uptake as well as the potential processes involved in removal, kinetic models were investigated (Villabona-Ortíz, Figueroa-Lopez, & Ortega-Toro, 2022 ). Figure 8 depicts the fitting of experimental data to the pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion models using non-linear regressions. Both cationic and anionic dyes were shown to quickly bind to material in the first few minutes of exposure. There are various steps to the process. Within the first minute, the surface adsorption occurs and dye molecules were transferred from the bulk phase to the surface of material. After that, dyes are injected into the pores of the material. Lastly, the equilibrium stage occurs and leads to a layered process (Jiang & Hu, 2019 ). Therefore, interparticle diffusion takes part in the adsorption procedure but is unable to regulate the total adsorption of dye molecules. As a result, the adsorption mechanism is driven by many mechanisms (Villabona-Ortíz et al., 2022 ). The characteristics in Table 2 show that all models successfully fit the kinetics of MB and MO on material, with an overall R 2 > 0.99 (Villabona-Ortíz et al., 2022 ). As a result, it can be concluded that the process is regulated by chemisorption and diffusive mechanisms. Additionally, the pseudo-second-order model provided an outstanding way of determining the experimental value of q e by that determined by the model, accurately describing the experimental data. Additionally, the fact that the intra-particle diffusion model's value of C is not zero, indicating that the sorption follows not only the intra-particle diffusion but also one or more additional diffusion processes in addition to the intra-particle diffusion (Dinh et al., 2018 ). Table 2 Kinetics parameters on the uptake of MB and MO of material of pine leaves Models Parameters MB MO Pseudo-first-order k 1 (min -1 ) 0.0594 ± 0.0102 0.0697 ± 0.0148 q e,cal (mg/g) 42.85 ± 1.1590 39.12 ± 1.22 R 2 0.9991 0.9990 Pseudo-second-order k 2 (g.mg -1 .min -1 ) 0.0021 ± 0.0004 0.0028 ± 0.0006 q e,cal (mg/g) 46.15 ± 0.98 41.92 ± 1.05 R 2 0.9997 0.9996 Elovich α (mg.g -1 .min) 55.54 ± 23.82 91.23 ± 42.45 Β (mg.g -1 ) 0.1677 ± 0.0126 0.1991 ± 0.0145 R 2 0.9998 0.9999 Intraparticle – diffusion k d (mg.g -1 .min) 1.3436 ± 0.1401 1.1347 ± 0.0471 C 26.01 ± 1.71 25.23 ± 0.57 R 2 0.9991 0.9999 Thus, it implies that chemisorption occurring due to chemical reactions between material surface functions and dye molecules may govern the sorption process of both anionic and cationic dyes on material (Dinh et al., 2019 ; Shooto, Thabede, Bhila, Moloto, & Naidoo, 2020 ). There were three main processes in the adsorption of MO and MB, which are as follows: On the surface of pine leaves, there are abundant active binding sites (oxygen functionalities) for dye molecules to bind to, indicating a fast rate of dye adsorption. There are also slow rates of dye adsorption, showing diffusion of dye molecules into material pores, and equilibrium-stage saturation of active sites. Similar outcomes were shown (Omer et al., 2022 ; Y. Zhu et al., 2018 ; Zubair et al., 2020 ). 3.4.3. Temperature Effect and Thermodynamic Parameters The biosorption isotherm is affected by temperature because it shows the thermodynamic equilibrium between dyes in aqueous solution and dyes biosorbed on the surface of material. Table 3 displays the findings of a study on the impact of temperature at various temperature levels (30, 40, and 50 o C). The capacity of MB and MO to adsorb to material increased with temperature, indicating that the adsorption process was an endothermic one that occurred spontaneously (Jiang & Hu, 2019 ). ΔG o has a negative value, and its upward trend is consistent with the temperature rise. The fact that ΔH o values are all positive and show that temperature has a direct impact on adsorption behavior shows that the uptakes of both dyes are spontaneous and that thermodynamic adsorption is beneficial. As the temperature rises, the adsorption capacity should grow as well. The ΔS o value was positive, indicating an increase in the degree of disorder at the interface between the dye solution and the material. The ΔH o value can also be utilized to look into the adsorption's chemical or physical properties. The physical purification stage is crucial for van der Waals interaction when ΔH o = 20 kJ/mol. When 20 kJ/mol < ΔH o 80 kJ/mol (Mosoarca, Vancea, Popa, Dan, & Boran, 2022 ). The material used in this experiment to purify MB and MO has a ΔH o value that is less than 80 kJ/mol, indicating that physisorption is at play, albeit a tiny chemical reaction may help the procedure. Table 3 Thermodynamic parameters for adsorption of MB and MO onto material of pine leaves T (K) LnK C ∆G (kJ/mol) ∆H (kJ/mol) ∆S (J/mol.K) MB 303 1,44 -3,64 41,11 147,46 313 1,88 -4,90 323 2,45 -6,60 MO 303 0,85 -2,14 39,74 137,98 313 1,27 -3,30 323 1,83 -4,90 4. Conclusions In this article, pine leaves ( Pinus kesiya ) were used as the potential material for the adsorption of MO and MB from an aqueous solution. The initial dye concentrations, pH, and contact duration all had an impact on the MO and MB adsorption by material. The findings of the non-linear kinetics and isotherms fitting indicate that the pseudo-second-order and Langmuir models are more suited to describe the MB and MO's adsorption characteristics on material. Increased temperature is beneficial for the adsorption process, as shown by the thermodynamic parameters, which also showed that the adsorption process is a spontaneous and practical purifying procedure. Furthermore, the adsorption of both kinds of dyes has been greatly aided by the surface functional groups (C = O, C-O, and -OH) of material (anionic and cationic). Through a number of processes, including electrostatic attraction, hydrogen bonds, and - interactions, it was determined that the adsorption process involves both chemisorption and physisorption. As a result, it can be said that material has potential as an economically sound substitute for removing the dye from an aqueous solution. Methylene blue and methyl orange can be eliminated from textile dyeing effluent using the research described here. Declarations All authors have read, understood, and have complied as applicable with the statement on "Ethical responsibilities of Authors" as found in the Instructions for Authors and are aware that with minor exceptions, no changes can be made to authorship once the paper is submitted. Ethical Approval. Not applicable Consent to Participate. Not applicable Consent to Publish. Not applicable Authors Contributions. Van-Phuc Dinh and Phuong Thao Huynh designed and directed the research. Van-Phuc Dinh, Phuong Thao Huynh, Duy-Khoi Nguyen, Bich-Ngoc Duong, and Phi-Ho Nguyen conceived and planned the experiments. Van-Phuc Dinh, Phuong Thao Huynh, Duy-Khoi Nguyen, Bich-Ngoc Duong, and Phi-Ho Nguyen carried out the experiments, analysed the data, and performed the isotherm and kinetic model analyses. Van-Phuc Dinh and Phuong Thao Huynh wrote the manuscript with inputs from all authors. All authors discussed the results and contributed to the final manuscript. All authors read and approved the final manuscript. Funding. This research was supported by a Grant-in-Aid for Scientific Research No. 09TĐ from Dalat University, Vietnam. Competing Interests. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Availability of data and materials. Not applicable References Al-Tohamy, R., Ali, S. S., Li, F., Okasha, K. M., Mahmoud, Y. A.-G., Elsamahy, T.,.. . Sun, J. (2022). A critical review on the treatment of dye-containing wastewater: Ecotoxicological and health concerns of textile dyes and possible remediation approaches for environmental safety. Ecotoxicology and Environmental Safety, 231. doi: https://doi.org/10.1016/j.ecoenv.2021.113160 Alseddig, A., Eljiedi, A., & Kamari, A. (2017). Removal of methyl orange and methylene blue dyes from aqueous solution using lala clam (Orbicularia orbiculata) shell. 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Shaddock peels-based activated carbon as cost-saving adsorbents for efficient removal of Cr (VI) and methyl orange. Environmental Science and Pollution Research volume 26 (19), 19828–19842. doi: https://doi.org/10.1007/s11356-019-05322-8 Villabona-Ortíz, Á., Figueroa-Lopez, K. J., & Ortega-Toro, R. (2022). Kinetics and Adsorption Equilibrium in the Removal of Azo-Anionic Dyes by Modified Cellulose. Sustainability, 14 (3640). doi: https://doi.org/10.3390/su14063640 Yagub, M. T., Sen, T. K., Afroze, S., & H.M.Ang. (2014). Dye and its removal from aqueous solution by adsorption: A review. Advances in Colloid and Interface Science, 209 , 172–184. doi: https://doi.org/10.1016/j.cis.2014.04.002 Yagub, M. T., Sen, T. K., & Ang, H. M. (2012). Equilibrium, Kinetics, and Thermodynamics of Methylene Blue Adsorption by Pine Tree Leaves. Water Air Soil Pollut, 223 , 5267–5282. doi: https://doi.org/10.1007/s11270-012-1277-3 Yang, L., Gao, J., Liu, Y., Zhang, Z., Zou, M., Liao, Q., & Shang, J. (2018). Removal of Methyl Orange from Water Using Sulfur-Modified nZVI Supported on Biochar Composite. Water Air Soil Pollut, 229 (355). doi: https://doi.org/10.1007/s11270-018-3992-x Zhou, Y., Lu, J., Zhou, Y., & Liu, Y. (2019). Recent advances for dyes removal using novel adsorbents: A review. Environmental Pollution, 252 , 352–365. doi: https://doi.org/10.1016/j.envpol.2019.05.072 Zhu, W., Liu, L., Liao, Q., Chen, X., Qian, Z., Shen, J.,.. . Yao, J. (2016). Functionalization of cellulose with hyperbranched polyethylenimine for selective dye adsorption and separation. Cellulose, 23 , 3785–3797. doi: https://doi.org/10.1007/s10570-016-1045-4 Zhu, Y., Yi, B., Yuan, Q., Wu, Y., Wang, M., & Yan, a. S. (2018). Removal of methylene blue from aqueous solution by cattle manure-derived low temperature biochar. RSC Advances, 8 , 19917–19929. doi: https://doi.org/10.1039/C8RA03018A Zubair, M., Jarrah, N. A., Manzar, M. S., Al-Harthi, M., Daud, M., Mu’azu, N. D., & Haladu, S. A. (2017). Adsorption of Eriochrome Black T from Aqueous Phase on MgAl-, CoAl- and NiFe- Calcined Layered Double Hydroxides: Kinetic, Equilibrium and Thermodynamic Studies. Journal of Molecular Liquids, 230 , 344–352. doi: http://dx.doi.org/10.1016/j.molliq.2017.01.031 Zubair, M., Mu’azu, N. D., Jarrah, N., Blaisi, N. I., Aziz, H. A., & Al-Harthi, M. A. (2020). Adsorption Behavior and Mechanism of Methylene Blue, Crystal Violet, Eriochrome Black T, and Methyl Orange Dyes onto Biochar-Derived Date Palm Fronds Waste Produced at Different Pyrolysis Conditions. Water Air Soil Pollut, 231–240. doi: https://doi.org/10.1007/s11270-020-04595-x Additional Declarations No competing interests reported. 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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-2862013","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":196856731,"identity":"7cbb9c07-f7d5-440f-9bd2-a0a09e7e0e85","order_by":0,"name":"Phuong Thao Huynh","email":"","orcid":"","institution":"Dalat University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Phuong","middleName":"Thao","lastName":"Huynh","suffix":""},{"id":196856732,"identity":"410bf9cf-2d39-4a94-a84c-5dccd2085e09","order_by":1,"name":"Duy-Khoi Nguyen","email":"","orcid":"","institution":"Duy Tan 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300\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003eo\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003eC\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-2862013/v1/a041754f63da741175a478fa.png"},{"id":36648858,"identity":"f0b75ae7-dda8-467f-bee1-ef3bf1fa8631","added_by":"auto","created_at":"2023-05-05 14:23:37","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":67423,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eComparative FT-IR spectra of Pine leaves before and after adsorption of dyes.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-2862013/v1/635f4238489d668a898c63fa.png"},{"id":36648854,"identity":"c99ce3ff-0751-4092-8ea9-f3dc6cda497e","added_by":"auto","created_at":"2023-05-05 14:23:37","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":27123,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDetermining the zero-charge point of material\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-2862013/v1/bb7998dd2f4bad58e0ef4942.png"},{"id":36649733,"identity":"0e96bd66-ae11-4c2d-9907-e74d7be7379a","added_by":"auto","created_at":"2023-05-05 14:31:37","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":16565,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eEffects of initial pH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003esolution\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e (a) and contact time (b) on MB and MO adsorption of \u003c/strong\u003ematerial\u003cstrong\u003e (C\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e0\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e=100 mg.L\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e-1\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e, dosage=0.1 g, and T=298 K)\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-2862013/v1/eea9c00491c549921ca0a9a3.png"},{"id":36648856,"identity":"acbf5bc0-3319-48fa-b040-a63c7dc7eb07","added_by":"auto","created_at":"2023-05-05 14:23:37","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":18878,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eEffect of initial dyes concentration (pH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003eMB\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e 8, pH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003eMO\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e 6, contact time 150 minutes, dosage 0.1 g, and T 298 K) on the uptake of MB and MO of material\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-2862013/v1/1293c561678db95cd0f004dd.png"},{"id":36649735,"identity":"6a4ee139-a248-48c3-b04d-24cb8aff5259","added_by":"auto","created_at":"2023-05-05 14:31:37","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":70675,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFit of the Langmuir, Freundlich, Temkin and Sips isotherms of MB and MO adsorption onto material of Pinus kesiya\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-2862013/v1/44b0e04bf49dfc88dc4dd90c.png"},{"id":36648861,"identity":"17dcf2e5-34ff-4987-9edc-61beb0e219e4","added_by":"auto","created_at":"2023-05-05 14:23:37","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":109955,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFit of the MB and MO adsorption onto the material of Pinus kesiya using the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle - diffusion kinetics models\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-2862013/v1/27d799081310b435f0b136db.png"},{"id":36797578,"identity":"cc2d7936-7f95-4a74-ada0-2cbcceb766b9","added_by":"auto","created_at":"2023-05-11 02:59:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1545180,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2862013/v1/824ec11a-9c9e-42d4-a88f-6ba75c695cfb.pdf"},{"id":36649732,"identity":"afaf9efb-0d11-47c5-9c87-ae858083ba93","added_by":"auto","created_at":"2023-05-05 14:31:37","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":18640,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-2862013/v1/8cb7c7d9641b7f0e8c5e47f7.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Adsorption of Methyl Orange and Methylene Blue from aqueous solutions using thermally treated biomass of pine leaves (Pinus kesiya)","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eWater pollution caused by textile manufacturers' incapacity to properly dispose of waste water is currently one of the world's significant issues. Textile industries contribute significantly to the world economy and pollution in several nations, including China and South African estuaries (Olisah, Adams, \u0026amp; Rubidge, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). As textile industries generate large amounts of highly colored wastewater containing a diverse range of persistent pollutants, dye-containing wastewater is a significant polluter of the environment that also affects human health (Al-Tohamy et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Around 7.10\u003csup\u003e7\u003c/sup\u003e tons of synthetic dyes are produced globally each year, with over 10,000 tons of such dyes used by the textile industry (Chandanshive et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Many harmful chemicals are employed in the dye manufacturing process, including dyes, surfactants, electrolytes, emulsifiers, media, starches, yeasts, and oxidants. When these chemicals are thrown improperly, they can harm nearby bacteria, fish, and aquatic creatures. These pollutants can also permeate the soil, remain there for extended periods, harm groundwater supplies, and endanger human life. Furthermore, textile-dyed wastewater is highly colored, often varies depending on the kind of dye, and has a high temperature, so it must be adequately cleaned before release to avoid environmental damage (Zhou, Lu, Zhou, \u0026amp; Liu, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe removal of colorants from wastewater has faced many significant disadvantages, such as high costs, hazardous product production, and high energy needs. As a result, we must seek new solutions and create more ecologically friendly technology. Because conventional adsorbents are easy to find, easily accessible, renewable, ecologically benign, and can replace traditional adsorbents, biosorption is one of the most successful ways (Mustafa T. Yagub, Sen, Afroze, \u0026amp; H.M.Ang, 2014). To date, a range of low-cost adsorbents, such as potato peel (Guechi \u0026amp; Hamdaoui, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), dragon fruit leaves (Haddadian, Shavandi, Abidin, Razi, \u0026amp; Ismail, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), pine cone (Sen, Afroze, \u0026amp; M., 2011), rice straw (Cheng et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), fly ash (Das, Barman, \u0026amp; Thakur, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), and other materials, have been investigated. Adsorbents based on these biologics have been utilized to eliminate acidic, basic, and reactive dyes from waste water. All of these bio-wastes are common and have little monetary worth. Adsorption is extremely reliant on the pH\u003csub\u003esolution\u003c/sub\u003e, the dosage of the adsorbent, the temperature, and the concentration of other solutes present in the solution, according to the authors.\u003c/p\u003e \u003cp\u003eThere are some studies using pine cone and pine leaves for removal of methylene blue (MB) from aqueous solution (Ertugay \u0026amp; Malkoc, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; M.T. Yagub, Sen, \u0026amp; Ang, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Pine tree cones and leaves were cleaned multiple times with distilled water to eliminate impurities such as grit before drying for two days in an oven at 65\u003csup\u003eo\u003c/sup\u003eC. A crusher was then used to chop and grind dried pine materials. The powders were then passed through British Standard Sieves, with particles less than 100 \u0026micro;m collected in a plastic container for pine cones and particles less than 350 \u0026micro;m collected in a plastic container for pine leaves, both to be used as adsorbents. At 30\u0026deg;C, pine cone and pine leaf biomass had maximal monolayer adsorption capacities of 129.87 mg/g and 126.58 mg/g, respectively (M.T. Yagub et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Fresh needles of \u003cem\u003ePinus sylvestris L.\u003c/em\u003e were dried at 80\u0026ordm;C for 48 h and cut into small pieces. Adsorption experiments were carried out 250\u0026ndash;500 \u0026micro;m at adsorbent particle size (Ertugay \u0026amp; Malkoc, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The maximum monolayer adsorption capacity of this material was found to be 101 mg/g at 45\u0026deg;C. FTIR spectrum result revealed the presence of adsorbing groups such as carboxyl, hydroxyl, and aromatic-CN stretching in the needles. These studies only investigated the MB adsorption capacity of pine needles but did not investigate the adsorption capacity with other organic dyes. The material used in these studies is unmodified pine needles and the mechanism of MB adsorption in water has not been specified.\u003c/p\u003e \u003cp\u003e \u003cem\u003ePinus kesiya\u003c/em\u003e is popular in Southeast Asia for a range of applications such as boxes, pulp and paper, and temporary utility poles. Scientists have paid little attention to \u003cem\u003ePinus kesiya\u003c/em\u003e as an adsorbent to eliminate methylene blue and methyl orange from aqueous solutions, even though it is a cheap, easy-to-use, and ecologically benign material. In this study, we explore the MO and MB adsorption capability of heat-treated pine needles at 300\u003csup\u003eo\u003c/sup\u003eC. The influence of critical adsorption factors on the adsorption efficiency was investigated. Isothermal, kinetic, and thermodynamic analyzes, as well as biomass properties before and after adsorption, were used to indicate the mechanism of dye adsorption of this material.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Adsorbent\u003c/h2\u003e \u003cp\u003eThe waste pine leaves collected from Dalat, Vietnam were completely cleaned by soaking in clean water for a day to eliminate adherent dust particles, prior to being washed with distilled water until the colorless rinse water. Next, they were cut approximately 2 cm before drying at 80\u003csup\u003eo\u003c/sup\u003eC for 24 hours to achieve a consistent weight. The samples were baked at 300\u003csup\u003eo\u003c/sup\u003eC for 2 hours after being crushed and sieved to size in a range of [125\u0026micro;m, 212 \u0026micro;m]. To eliminate humidity, the material was kept in airtight plastic containers, which were then used in the adsorption experiments. Pine leaves before and after the treatment were presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Chemicals\u003c/h2\u003e \u003cp\u003eMethylene Blue (C\u003csub\u003e16\u003c/sub\u003eH\u003csub\u003e18\u003c/sub\u003eClN\u003csub\u003e3\u003c/sub\u003eS.3H\u003csub\u003e2\u003c/sub\u003eO ; M.W: 373.9 g/mol; C.I. 52015) and Methyl Orange (C\u003csub\u003e14\u003c/sub\u003eH\u003csub\u003e14\u003c/sub\u003eN\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003eSNa; M.W: 327.34 g/mol; C.I.13025) were producted by MERCK. To prepare 1000 ppm stock solutions, a precise weight of MO and MB diluted in 1000 mL of distilled water was 1.000 g and 1.1690 g, respectively. These lower concentration solutions were created by diluting stock solutions. pH of solutions was adjusted with 0.1M HCl and NaOH solution.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Determination of point of zero charge\u003c/h2\u003e \u003cp\u003ePrepared 10 flasks containing ​50 mL of 0.1 M KCl solution with the corresponding pH\u003csub\u003ei\u003c/sub\u003e values adjusted from ​​2 to 11. Added 0.1 g of material to the flasks prepared above, covered and stirred for 24 hours. Then, filtered the solution and measured the pH value (called pH\u003csub\u003ef\u003c/sub\u003e). Determined the graph of dependency ΔpH (ΔpH\u0026thinsp;=\u0026thinsp;pH\u003csub\u003ei\u003c/sub\u003e - pH\u003csub\u003ef\u003c/sub\u003e) on pH\u003csub\u003ei\u003c/sub\u003e. The zero charge point of the material (pH\u003csub\u003epzc\u003c/sub\u003e) was the intersection pointed between the plot and the Ox axis at the value ΔpH\u0026thinsp;=\u0026thinsp;0. Carried out the test three times for each pH\u003csub\u003ei\u003c/sub\u003e value of the solution.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Adsorption experiments\u003c/h2\u003e \u003cp\u003eEffects of factors, such as pH (2\u0026ndash;10), starting dye concentration (100\u0026ndash;500 mg.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), and contact duration (10\u0026ndash;240 min) on the biosorption of MB and MO were examined and conducted in triplicate in batch. Herein, 0.1 g of material was placed to 50 mL capped glass bottles containing 100 mg.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of dye solutions. Shake the solution at 150 rpm at room temperature (25 \u003csup\u003e0\u003c/sup\u003eC). After the adsorption, the mixture was filtered on the filter paper to get the solution. The residual concentration of the dye in the supernatant was determined by a UV\u0026ndash;Vis spectrophotometer at a wavelength maximum of 665 nm and 465 nm for the MB and MO, respectively.\u003c/p\u003e \u003cp\u003eThe adsorption capacity and efficiency are determined as follows:\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$${\\text{q}}_{\\text{e}}\\text{=}\\frac{\\left({\\text{C}}_{\\text{0}}\\text{-}{\\text{C}}_{\\text{e}}\\right)\\text{V}}{\\text{m}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\text{H%=}\\frac{\\left({\\text{C}}_{\\text{0}}\\text{- }{\\text{C}}_{\\text{e}}\\right)\\text{.100%}}{{\\text{C}}_{\\text{0}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere C\u003csub\u003e0\u003c/sub\u003e and C\u003csub\u003ee\u003c/sub\u003e are concentrations of dye before and after the adsorption (mg.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), respectively. q\u003csub\u003ee\u003c/sub\u003e is the adsorption capacity (mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). V represents the volume (L) of the solution, and m is the mass of biosorbent utilized (g).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Kinetic studies\u003c/h2\u003e \u003cp\u003eTo evaluate physiochemical interactions between material and dyes, the nature of sorption process, and rate-limiting step, all of which play an vital role for the design of commercial sorption systems, adsorption kinetic modeling is fitted with experimental data to determine kinetic parameters. As a consequence, the nonlinear equations (pseudo-first-order, pseudo-second-order, Elovich, and intra-diffusion models) were used to fit adsorption kinetic models to the kinetic study data as shown in \u003cspan type=\"BoldItalic\" class=\"BoldItalic\" name=\"Emphasis\"\u003eSupplemental Information\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6. Adsorption studies\u003c/h2\u003e \u003cp\u003eUsing equilibrium isotherm modeling plays an instrumental role in determining the distribution of dye molecules on the material surface, leading to an understanding of the dye-material adsorption mechanism. For this study, four isotherm models (Langmuir, Freundlich, Sips, Temkin) were fitted with experimental data to examine the sorption processes of cationic and anionic dyes onto the material. The fomulars and meanings of these models were shown in \u003cspan type=\"BoldItalic\" class=\"BoldItalic\" name=\"Emphasis\"\u003eSupplemental Information\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.7. Adsorption thermodynamics\u003c/h2\u003e \u003cp\u003eThermodynamic investigations of the biosorption of dyes onto material were carried out at various temperatures (298\u0026ndash;328 K). The following equations may be used to calculate parameters consisting of enthalpy changes (∆H\u003csup\u003e0\u003c/sup\u003e: KJ.mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), entropy changes (∆S\u003csup\u003e0\u003c/sup\u003e: J mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and free energy changes (∆G\u003csup\u003e0\u003c/sup\u003e: KJ.mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e):\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"2\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{∆G}}^{\\text{0}}\\text{= }\\text{-}\\text{RTln}{\\text{K}}_{\\text{C}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e(11)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{∆G}}^{\\text{0}}\\text{= }{\\text{∆H}}^{\\text{0}}\\text{-T.}{\\text{∆S}}^{\\text{0}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e(12)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\text{ln}{\\text{K}}_{\\text{C}}\\text{= }\\frac{{\\text{-∆H}}^{\\text{0}}}{\\text{RT}}\\text{+}\\frac{{\\text{∆S}}^{\\text{0}}}{\\text{R}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e(13)\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\u003eWhere R represents the universal gas constant (8.314 J.mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), T represents the absolute temperature (Kelvin), and K\u003csub\u003eC\u003c/sub\u003e represents the equilibrium adsorption constant. The dye's ∆H\u003csup\u003e0\u003c/sup\u003e and ∆S\u003csup\u003e0\u003c/sup\u003e values were derived using the slope and intercept of the LnK\u003csub\u003eC\u003c/sub\u003e vs 1/T plot, respectively. The data utilized in the preceding study are all mean values from three replicate experiments.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Characterization of adsorbents\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e depicted the material's surface as coarse, porous, and riddled with holes. The sizes of the holes were quite uniform that facilitated the adsorption process. This material had many holes so the adsorption process took place and achieved good adsorption efficiency in a short time. The S4800 Field Emission Scanning Electron Microscope was applied for visualize morphological features on the surface of materials (Hitachi, Japan).\u003c/p\u003e \u003cp\u003eThe EDX spectrossic examination revealed that the primary components of the substance were carbon and oxygen at a volume rate of 66.47% and 33.53%, respectively. The above ratio was due to the activation of the material at 300\u003csup\u003e0\u003c/sup\u003eC \u0026ndash; this process helped to convert organic compounds found in the leaves such as Lignin, Holocellulose, etc. into gases. These gases flew away leaving blanks, which was the porosity mechanism that facilitated the adsorption process.\u003c/p\u003e \u003cp\u003ePine leaves are mostly made of cellulose and lignin, whose components serve as active sites for dye adsorption. To determine the active functional group on the surface of materials, FT-IR spectra of material before and after dye adsorption were determined by Nicolet iS5 FT-IR spectrometer (Thermo Fisher, USA) and shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The spectra presented many peaks, indicating that pine leaves contain a variety of functional groups that may aid in the binding of dye molecules.\u003c/p\u003e \u003cp\u003eThe absorbance bands of material were discovered to comprise a large overlapping band at 3200\u0026ndash;3500 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, with a peak at 3412 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which can be attributed to hydroxyl group O-H stretching and intermolecular hydrogen bonding. This band's location and asymmetry suggested the presence of strong hydrogen bonds. This peak diminished following dye adsorption, showing that the O-H and hydrogen bonds in material were disrupted in order to react with dye.\u003c/p\u003e \u003cp\u003eThe signal at 2955 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e indicates vibration of CH\u003csub\u003en\u003c/sub\u003e, mainly owing to C-CH\u003csub\u003e2\u003c/sub\u003e and C-CH bonds, whereas a peak of 1735 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e presents the C\u0026thinsp;=\u0026thinsp;O group of the carbonyl in the hemicellulose (W. Zhu et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). The existence of C\u0026thinsp;=\u0026thinsp;C stretching of the phenol group is shown by the peaks at 1600 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Whereas peaks at 1033 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the spectrum lead to a strong C-O bond due to the cellulose ether group (Silva et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eExcept for minor differences, the spectra of the dye-loaded material exhibited comparable properties to the adsorbent in natural form. After the adsorption, the specific peaks are somewhat moved from their original positions, and the intensity changes. These findings indicated that functional groups contribute the adsorption of dye ions of the material via weak electrostatic contact or Van der Waals interactions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Survey results of zero charge point (pH\u003csub\u003epzc\u003c/sub\u003e) and effect of pH on Dyes Adsorption\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe pH\u003csub\u003epzc\u003c/sub\u003e value was about 7.5 based on the material's zero-charge graph. This finding allowed us to anticipate the material's adsorption capability for MB and MO at any pH value. When the pH of the solution was less than 7.5, the material's surface was positively charged, and excellent anion adsorption was favored. If the solution pH was more than 7.5, the material's surface would have a negative charge and improved cation adsorption (Banerjee \u0026amp; Chattopadhyay, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). This was the basis of investigating the factors influencing pH on adsorption capacity to determine the optimal pH value of MB and MO.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eNoticeably, there was a tendency to increase the adsorption capacity of MB from pH\u0026thinsp;=\u0026thinsp;2 to 8, prior to equilibrium at pH\u0026thinsp;\u0026gt;\u0026thinsp;8. When dissolved in water, MB (pK\u003csub\u003ea\u003c/sub\u003e = 3.8), a base-cationic dye, decomposed into MB\u003csup\u003e+\u003c/sup\u003e ions, and the lower the pH value (greater concentration of H\u003csup\u003e+\u003c/sup\u003e in the solution), the adsorption competition between MB\u003csup\u003e+\u003c/sup\u003e and H\u003csup\u003e+\u003c/sup\u003e lowered the material's MB adsorption capacity (Khnifira et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Furthermore, carbonyl groups (C\u0026thinsp;=\u0026thinsp;O) and hydroxyl groups (O-H) on the adsorbent's surface can bind cationic dye molecules at the high pH. As a result, the material has a high MB adsorption capability in an alkaline environment (M.T. Yagub et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe adsorption of MO (pK\u003csub\u003ea\u003c/sub\u003e = 3.4) onto material reduced from 40.28 to 35.50 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e when the pH climbed from 2 to 10, indicating that anionic dye adsorption onto pine leaves is pH-dependent and preferential under acidic conditions. The increased anionic dye adsorption at lower pH levels has been linked to the full protonation of the material surface functions, which provides strong electrostatic attraction to the MO dye molecules, allowing the dye to be quickly absorbed (Zubair et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). In contrast, increasing the pH causes an increase in anion OH\u003csup\u003e\u0026minus;\u003c/sup\u003e in the solution, which competes with anionic dye molecules, resulting in a drop in the q\u003csub\u003ee\u003c/sub\u003e of MO on material. This shows that electrostatic and chemical interactions were predominantly responsible for the uptake of anionic dyes onto pine leaf material (Zubair et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn order to understand how pH affects adsorption behavior, the zeta potential of the adsorbent was measured at various pH values. As demonstrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, when the pH was less than 7.5, the material\u0026rsquo;s surface potential was positive, and the uptake of anion MO was improved due to electrostatic attraction. In contrast, the surface potential of material was negative, which was suitable for the uptake of cation MB. However, the adsorption capacity of MB was not diminished when the pH value is higher than 9. It indicates that the adsorption mechanism of MB follows not only electrostatic interaction but also hydrogen bonding between adsorbent and adsorbate. The material may be considered an H-donor, whereas MB was an H-acceptor. This mechanism can also occur during MO adsorption.\u003c/p\u003e \u003cp\u003eAccording to the foregoing explanations, the optimal pH value of the material's MB and MO adsorption processes was 8 and 6. The study's findings were aligned with the findings of establishing the material's point of zero charges. Previous research has also observed similar behavior (Alseddig, Eljiedi, \u0026amp; Kamari, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Yang et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Furthermore, based on Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, it was inferred that the adsorption capacity of MB was larger than the adsorption capacity of MO at the ideal pH value. The degree of diffusion was governed by the size or shape of the molecule in organic dyes with complicated and bulky structures, such as MB and MO. To describe dye adsorption capability, use the structure and molecular weights of dyes (Sun et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Effect of contact time and the initial dyes concentration\u003c/h2\u003e \u003cp\u003eBecause the contact duration of the dyes material adsorption process was a significant factor in the adsorption system design, Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003eb depicts the effects of adsorption time on the adsorption capacity of anionic and cationic dyes.\u003c/p\u003e \u003cp\u003eAccording to these curves, the adsorption of the molecules of MB and MO on the pine leaves is quick during the first 60 min to reach the equilibrium, which is 150 min for the MB and MO with maximum adsorbed amounts of 44.27 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 40.97 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. The quick adsorption rate of the initial phase (fast phase) may be explained by the reality that he adsorption sites on the surface of our adsorbent are free at the start of the phenomenon. Once the dye molecules are immobilized, they block the pores, decreasing the rate of adsorption and resulting in a saturated array, which is why the second phase exists (slow phase). This trend is consistent with other research' conclusions .\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAt room temperature, Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e6\u003c/span\u003ea depicts the adsorption capabilities versus various starting dye concentrations. As the dye concentration rises from 100 to 500 mg.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the quantity of dye adsorbed (mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) of both MB and MO rose from 44.28 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to 127.23 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (MB) and from 40.98 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to 118.62 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (MO). The concentration of the dye influences dye removal. The mass transfer driving force rose as the starting concentrations increased, as did the interaction between dyes and adsorbent, resulting in increasing adsorption capacity.\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e6\u003c/span\u003eb, raising the initial dye concentration from 100 to 500 mg.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e reduced removal from 88.55\u0026ndash;50.89% (MB) and 81.95\u0026ndash;47.45%. (MO). This was discussed in detail that the adsorption capacity was complete and the adsorption efficiency was high when the concentration of MB and MO was low due to the low and constant weight of the adsorbent. Notwithstanding, the amount of MB and MO was very large at the high concentration, exceeding the number of fixed adsorption centers in the material, thus these uptake were incomplete, resulting in a decline in adsorption efficiency (W. Zhu et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Zubair et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.4. Adsorption mechanism of MB and MO onto material of pine leaves\u003c/h2\u003e \u003cp\u003eIn addition to taking into account kinetics and isotherms models, as well as the characterisation of wasted material following the uptake of the dye, the mechanism of interaction of anionic and cationic dye molecules with biochar surface was further studied. The discussion of the findings is in the section below.\u003c/p\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e3.4.1. Adsorption equilibrium\u003c/h2\u003e \u003cp\u003eAdsorption isotherms display the distribution of adsorbent molecules between the liquid and solid phases when the uptake obtains equilibrium. Normally, an appropriate model can be determined by fitting experimental data with several isotherm models, such as Langmuir, Freundlich, Sips, and Temkin (Ertugay \u0026amp; Malkoc, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The fitted plots from each isotherm for the adsorption of MB and MO onto material of \u003cem\u003ePinus kesiya\u003c/em\u003e were displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e reports the isotherm parameters discovered via non-linear regression analysis.\u003c/p\u003e \u003cp\u003e \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\u003eCalculated parameters (\u0026plusmn;\u0026thinsp;SD) for MB and MO biosorption by Pinus kesiya material in single systems, acquired by non-linear regression analysis\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\"\u003e \u003cp\u003eModels\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eLangmuir\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eK\u003csub\u003eL\u003c/sub\u003e (L.mg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.0268\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0061\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0228\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0031\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003emax\u003c/sub\u003e (mg.g\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e150.67\u0026thinsp;\u0026plusmn;\u0026thinsp;8.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e142.72\u0026thinsp;\u0026plusmn;\u0026thinsp;5.13\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9937\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9981\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eFreundlich\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eK\u003csub\u003eF\u003c/sub\u003e (L\u003csup\u003en\u003c/sup\u003e.g)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.41\u0026thinsp;\u0026plusmn;\u0026thinsp;6.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21.27\u0026thinsp;\u0026plusmn;\u0026thinsp;4.44\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9872\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9939\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eSips\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003es\u003c/sub\u003e (L.g\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.88\u0026thinsp;\u0026plusmn;\u0026thinsp;2.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.31\u0026thinsp;\u0026plusmn;\u0026thinsp;2.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eα\u003csub\u003es\u003c/sub\u003e (L.mg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.0133\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0193\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0168\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0136\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eβ\u003csub\u003es\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9930\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9979\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eTemkin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eK\u003csub\u003eT\u003c/sub\u003e (L.mg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.3298\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1675\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.2508\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0724\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eb\u003csub\u003eT\u003c/sub\u003e (J.mol\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e81.07\u0026thinsp;\u0026plusmn;\u0026thinsp;11.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e82.49\u0026thinsp;\u0026plusmn;\u0026thinsp;7.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9913\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9971\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\u003eThe Langmuir adsorption model explains the MB and MO dye adsorption on the material of pine leaves reasonably well. The Langmuir model's coefficients of determination (R\u003csup\u003e2\u003c/sup\u003e) for the MB and MO biosorption data (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9937 for MB and R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9981 for MO) were greater than those for the other models. It was discovered that material has a maximum adsorption capacity of 150.67 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (MB) and 142.72 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (MO), confirming physical monolayer adsorption. The homogeneous distribution of active sites on the adsorbent surface, which is implied by the Langmuir equation, maybe the reason why the Langmuir isotherm closely matches the experimental results (Sen et al., 2011).\u003c/p\u003e \u003cp\u003eAccording to the nonlinear Freundlich isotherm, determining the constant K\u003csub\u003eF\u003c/sub\u003e (L\u003csup\u003en\u003c/sup\u003e.g) and n coefficient (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cem\u003e)\u003c/em\u003e. This coefficient between 1 and 10 was a favorable range for the biosorption process. This proved that pine leaves (\u003cem\u003ePinus kesiya)\u003c/em\u003e were good biosorbent materials for MB and MO in an aqueous solution.\u003c/p\u003e \u003cp\u003eAdditionally, the Temkin model's energy values bT calculations were less than 8 kJ/mol, which supported the idea that these adsorbents underwent physical adsorption at the measured temperatures.\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\u003eThe maximum adsorption capacity of MB and MO calculated from the Langmuir model using various biosorbents.\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=\"char\" char=\".\" 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\"\u003e \u003cp\u003eSource of adsorbents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAdsorbent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eq\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\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\u003e\u003cem\u003eMillettia thonningii\u003c/em\u003e seed pods\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Jasper, Ajibola, \u0026amp; Onwuka, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2020\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eCasuarina equisetifolia\u003c/em\u003e pines\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e41.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Chandarana, Kumar, Seenuvasan, \u0026amp; Kumar, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeanut shells\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e67.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Benjelloun et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWalnut shells\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e101.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Benjelloun et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2022\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePotato \u003cem\u003e(Solanum tuberosum)\u003c/em\u003e peel\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e105.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Guechi \u0026amp; Hamdaoui, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2015\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBiochar-Derived Date Palm Fronds Waste\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e206.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Zubair et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2020\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCattle manure-derived low temperature biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e241.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Y. Zhu et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2018\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePine leaves\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e150.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eThis study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorn leaves\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Fadhil \u0026amp; Eisa, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDragon fruit foliage\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Haddadian et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2013\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePineapple leaf\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e47.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Kamaru, Sani, \u0026amp; Malek, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2015\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePopulous leaves\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e90.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Shah, Sharma, Dar, \u0026amp; Bamezai, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2021\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eShaddock peels-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e94.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Tao, Wu, \u0026amp; Cha, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2019\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBiochar-Derived Date Palm Fronds Waste\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e163.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e(Zubair et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2020\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePine leaves\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e142.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eThis study\u003c/b\u003e\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\u003eThe data in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e compares the adsorption capabilities of several biosorbents that have been previously reported in the literature to those of pine leaves. The Pinus kesiya material that was presented in this study functioned superbly, outperforming the majority of other comparable adsorbents that had previously been described. As a result, pine leaves provide MB and MO from an aqueous solution a potential, cost-effective biosorbent.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e \u003ch2\u003e3.4.2. Adsorption kinetics\u003c/h2\u003e \u003cp\u003eIn order to evaluate the effects of adsorption time on the uptake as well as the potential processes involved in removal, kinetic models were investigated (Villabona-Ort\u0026iacute;z, Figueroa-Lopez, \u0026amp; Ortega-Toro, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Figure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e8\u003c/span\u003e depicts the fitting of experimental data to the pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion models using non-linear regressions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBoth cationic and anionic dyes were shown to quickly bind to material in the first few minutes of exposure. There are various steps to the process. Within the first minute, the surface adsorption occurs and dye molecules were transferred from the bulk phase to the surface of material. After that, dyes are injected into the pores of the material. Lastly, the equilibrium stage occurs and leads to a layered process (Jiang \u0026amp; Hu, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTherefore, interparticle diffusion takes part in the adsorption procedure but is unable to regulate the total adsorption of dye molecules. As a result, the adsorption mechanism is driven by many mechanisms (Villabona-Ort\u0026iacute;z et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe characteristics in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e2\u003c/span\u003e show that all models successfully fit the kinetics of MB and MO on material, with an overall R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.99 (Villabona-Ort\u0026iacute;z et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). As a result, it can be concluded that the process is regulated by chemisorption and diffusive mechanisms. Additionally, the pseudo-second-order model provided an outstanding way of determining the experimental value of q\u003csub\u003ee\u003c/sub\u003e by that determined by the model, accurately describing the experimental data. Additionally, the fact that the intra-particle diffusion model's value of C is not zero, indicating that the sorption follows not only the intra-particle diffusion but also one or more additional diffusion processes in addition to the intra-particle diffusion (Dinh et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2018\u003c/span\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 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eKinetics parameters on the uptake of MB and MO of material of pine leaves\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\"\u003e \u003cp\u003eModels\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMB\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003ePseudo-first-order\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ek\u003csub\u003e1\u003c/sub\u003e (min\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.0594\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0697\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0148\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003ee,cal\u003c/sub\u003e (mg/g)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.85\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1590\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e39.12\u0026thinsp;\u0026plusmn;\u0026thinsp;1.22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9991\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9990\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003ePseudo-second-order\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ek\u003csub\u003e2\u003c/sub\u003e (g.mg\u003csup\u003e-1\u003c/sup\u003e.min\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.0021\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0028\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0006\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003ee,cal\u003c/sub\u003e (mg/g)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e41.92\u0026thinsp;\u0026plusmn;\u0026thinsp;1.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9997\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9996\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eElovich\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eα (mg.g\u003csup\u003e-1\u003c/sup\u003e.min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e55.54\u0026thinsp;\u0026plusmn;\u0026thinsp;23.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e91.23\u0026thinsp;\u0026plusmn;\u0026thinsp;42.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eΒ (mg.g\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.1677\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0126\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1991\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0145\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9998\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9999\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eIntraparticle \u0026ndash; diffusion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ek\u003csub\u003ed\u003c/sub\u003e (mg.g\u003csup\u003e-1\u003c/sup\u003e.min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.3436\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1401\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.1347\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0471\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.01\u0026thinsp;\u0026plusmn;\u0026thinsp;1.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9991\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9999\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\u003eThus, it implies that chemisorption occurring due to chemical reactions between material surface functions and dye molecules may govern the sorption process of both anionic and cationic dyes on material (Dinh et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Shooto, Thabede, Bhila, Moloto, \u0026amp; Naidoo, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). There were three main processes in the adsorption of MO and MB, which are as follows: On the surface of pine leaves, there are abundant active binding sites (oxygen functionalities) for dye molecules to bind to, indicating a fast rate of dye adsorption. There are also slow rates of dye adsorption, showing diffusion of dye molecules into material pores, and equilibrium-stage saturation of active sites. Similar outcomes were shown (Omer et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Y. Zhu et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Zubair et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003e3.4.3. Temperature Effect and Thermodynamic Parameters\u003c/h2\u003e \u003cp\u003eThe biosorption isotherm is affected by temperature because it shows the thermodynamic equilibrium between dyes in aqueous solution and dyes biosorbed on the surface of material. Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e3\u003c/span\u003e displays the findings of a study on the impact of temperature at various temperature levels (30, 40, and 50\u003csup\u003eo\u003c/sup\u003eC). The capacity of MB and MO to adsorb to material increased with temperature, indicating that the adsorption process was an endothermic one that occurred spontaneously (Jiang \u0026amp; Hu, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eΔG\u003csup\u003eo\u003c/sup\u003e has a negative value, and its upward trend is consistent with the temperature rise. The fact that ΔH\u003csup\u003eo\u003c/sup\u003e values are all positive and show that temperature has a direct impact on adsorption behavior shows that the uptakes of both dyes are spontaneous and that thermodynamic adsorption is beneficial. As the temperature rises, the adsorption capacity should grow as well. The ΔS\u003csup\u003eo\u003c/sup\u003e value was positive, indicating an increase in the degree of disorder at the interface between the dye solution and the material.\u003c/p\u003e \u003cp\u003eThe ΔH\u003csup\u003eo\u003c/sup\u003e value can also be utilized to look into the adsorption's chemical or physical properties. The physical purification stage is crucial for van der Waals interaction when ΔH\u003csup\u003eo\u003c/sup\u003e = 20 kJ/mol. When 20 kJ/mol\u0026thinsp;\u0026lt;\u0026thinsp;ΔH\u003csup\u003eo\u003c/sup\u003e \u0026lt; 80 kJ/mol, the electrostatic contact plays a substantial role in the physical purification process. The adsorption mechanism is mostly chemical when ΔH\u003csup\u003eo\u003c/sup\u003e \u0026gt; 80 kJ/mol (Mosoarca, Vancea, Popa, Dan, \u0026amp; Boran, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The material used in this experiment to purify MB and MO has a ΔH\u003csup\u003eo\u003c/sup\u003e value that is less than 80 kJ/mol, indicating that physisorption is at play, albeit a tiny chemical reaction may help the procedure.\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 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThermodynamic parameters for adsorption of MB and MO onto material of pine leaves\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=\"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=\"left\" 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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eT (K)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLnK\u003csub\u003eC\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e∆G\u003c/p\u003e \u003cp\u003e(kJ/mol)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e∆H (kJ/mol)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e∆S (J/mol.K)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e\u003cb\u003eMB\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e303\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-3,64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e41,11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e147,46\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e313\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-4,90\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e323\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2,45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-6,60\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e\u003cb\u003eMO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e303\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0,85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-2,14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e39,74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e137,98\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e313\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-3,30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e323\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-4,90\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 \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eIn this article, pine leaves (\u003cem\u003ePinus kesiya\u003c/em\u003e) were used as the potential material for the adsorption of MO and MB from an aqueous solution. The initial dye concentrations, pH, and contact duration all had an impact on the MO and MB adsorption by material. The findings of the non-linear kinetics and isotherms fitting indicate that the pseudo-second-order and Langmuir models are more suited to describe the MB and MO's adsorption characteristics on material. Increased temperature is beneficial for the adsorption process, as shown by the thermodynamic parameters, which also showed that the adsorption process is a spontaneous and practical purifying procedure. Furthermore, the adsorption of both kinds of dyes has been greatly aided by the surface functional groups (C\u0026thinsp;=\u0026thinsp;O, C-O, and -OH) of material (anionic and cationic). Through a number of processes, including electrostatic attraction, hydrogen bonds, and - interactions, it was determined that the adsorption process involves both chemisorption and physisorption. As a result, it can be said that material has potential as an economically sound substitute for removing the dye from an aqueous solution. Methylene blue and methyl orange can be eliminated from textile dyeing effluent using the research described here.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAll authors have read, understood, and have complied as applicable with the statement on \"Ethical responsibilities of Authors\" as found in the Instructions for Authors and are aware that with minor exceptions, no changes can be made to authorship once the paper is submitted.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval. \u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Participate. \u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish. \u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors Contributions. \u003c/strong\u003eVan-Phuc Dinh and Phuong Thao Huynh designed and directed the research. Van-Phuc Dinh, Phuong Thao Huynh, Duy-Khoi Nguyen, Bich-Ngoc Duong, and Phi-Ho Nguyen conceived and planned the experiments. Van-Phuc Dinh, Phuong Thao Huynh, Duy-Khoi Nguyen, Bich-Ngoc Duong, and Phi-Ho Nguyen carried out the experiments, analysed the data, and performed the isotherm and kinetic model analyses. Van-Phuc Dinh and Phuong Thao Huynh wrote the manuscript with inputs from all authors. All authors discussed the results and contributed to the final manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding. \u003c/strong\u003eThis research was supported by a Grant-in-Aid for Scientific Research No. 09TĐ from Dalat University, Vietnam.\u003cstrong\u003e \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests.\u003c/strong\u003e The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials. \u003c/strong\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAl-Tohamy, R., Ali, S. S., Li, F., Okasha, K. M., Mahmoud, Y. A.-G., Elsamahy, T.,.. . Sun, J. (2022). 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Water Air Soil Pollut, 231\u0026ndash;240. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11270-020-04595-x\u003c/span\u003e\u003cspan address=\"10.1007/s11270-020-04595-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Methylene Blue, Methyl Orange, Pinus kesiya, biosorption, heat-treatment.","lastPublishedDoi":"10.21203/rs.3.rs-2862013/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2862013/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e \u003cem\u003eThe uptake of Methyl Orange (MO) and Methylene Blue (MB) from aqueous solutions onto Pine leaves (Pinus kesiya) was investigated in this work. The pine leaves was dried, grinded and thermally treated at 300\u003c/em\u003e \u003csup\u003e \u003cem\u003eo\u003c/em\u003e \u003c/sup\u003e \u003cem\u003eC. Factors including pH solution, contact time, initial dye concentration were discovered to be relevant in the removal of dyes. Among four isotherm models (Langmuir, Sips, Freundlich, and Temkin), the experimental data was fitted the Langmuir model better than others. For MO and MB, the maximum Langmuir adsorption capacities were 136.99 mg.g\u003c/em\u003e \u003csup\u003e \u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e \u003c/sup\u003e \u003cem\u003eand 140.85 mg.g\u003c/em\u003e \u003csup\u003e \u003cem\u003e\u0026minus;\u0026thinsp;1\u003c/em\u003e \u003c/sup\u003e, \u003cem\u003erespectively. The kinetic studies demonstrated that the biosorption of MO and MB onto pine leaves was compatible with Elovich, pseudo-first-order, pseudo-second-order and intra-particle diffusion models. The thermodynamic studies showed that the uptake of the two dyes was regulated by physisorption, spontaneous, and endothermic in nature. Electrostatic interactions, as well as other non-covalent forces such as π\u0026ndash;π interactions and hydrogen bonds, are mechanisms of dyes adsorption on heat treated pine leaves biomass. The current study found that pine leaves (Pinus kesiya) might be a potential biosorbent for the wastewater treatment due to their high availability and production, resulting in various environmental advantages.\u003c/em\u003e\u003c/p\u003e","manuscriptTitle":"Adsorption of Methyl Orange and Methylene Blue from aqueous solutions using thermally treated biomass of pine leaves (Pinus kesiya)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-05-05 14:23:32","doi":"10.21203/rs.3.rs-2862013/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"78c5477e-078b-40e0-8c3f-dce33594028e","owner":[],"postedDate":"May 5th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-05-11T02:59:16+00:00","versionOfRecord":[],"versionCreatedAt":"2023-05-05 14:23:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2862013","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2862013","identity":"rs-2862013","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}