Fenton-like modification of Bauhinia tomentosa seedpod for improved sequestration of methylene blue from water

Fenton-like modification of Bauhinia tomentosa seedpod for improved sequestration of methylene blue from water | 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 Fenton-like modification of Bauhinia tomentosa seedpod for improved sequestration of methylene blue from water Michael Tope Agbadaola, Damilola Adeola Akinyemi, Dorcas Abiodun Olatunji, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5856675/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 Water pollution by dyes remain an important problem that constantly reduces water quality, creating hazard to aquatic flora and fauna, as well as terrestrial life. Although adsorption has been a favourite technique exploited to remediate this growing menace due to its cost-effectiveness and environmental friendliness, adsorbents remain limited in their capacity to efficiently remove emerging dye contaminants from wastewater. In this work, we present an efficient method to improve the sequestration of an emerging contaminant, methylene blue dye (MB), from water through Fenton-like modification of adsorbents. Low-cost and readily-available Bauhinia tomentosa seedpod (BTSP) was modified with recyclable FeOCl nanosheets to produce Fenton-BTSP adsorbents. The modified and unmodified adsorbents were characterized using Fourier-transform infrared spectroscopy, dynamic light scattering, energy dispersive X-Ray, and scanning electron microscopy. Results showed successful modification of BTSP to form fine agglomerated particles with enhanced surface areas and pore spaces. Adsorption studies revealed optimal adsorption at pH 10, with equilibrium reached in 30 mins for the adsorbents. Isotherm modelling of the adsorption data suggests formation of multiple layers of MB molecules on the adsorbents at maximum monolayer capacity of 190.63 mg/g and 520.83 mg/g for BTSP and Fenton-BTSP, respectively. Kinetics modelling revealed chemical interaction between the adsorbents and dye molecules at a rate that is higher for Fenton-BTSP. Adsorbent regeneration was also improved after Fenton-like modification, contributing to the potential of Fenton-BTSP for industrial applications. Physical Chemistry Adsorption emerging contaminants methylene blue Fenton-like modification Bauhinia tomentosa Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction The consistent release of toxic effluents from industrial units to water bodies poses greatest risk to the quality of water, the largest irreplaceable asset given to man. Low water quality is a serious problem to aquatic flora and fauna, and has made access to portable water by terrestrial organisms almost impossible in developing and underdeveloped nations (Sun and Lockaby, 2012 ). To curtail this, the United Nations as part of its sustainable development goals (SDGs), has become more intentional in ensuring that portable water is available to all and sundry by 2030 (UN, 2015). Effluents from industries contain undesirable and potentially toxic chemicals in the form of textile dyes, pharmaceuticals, agrochemicals, among others. The components of these chemicals compromise the integrity and portability of water and render it unsafe for use (Caldwell et al., 2012 ). According to the World Health Organization (WHO) report in 2012 (WHO, 2012 ), about two million people die from diseases that arise from water pollution. In Nigeria, poor access to clean and portable water is a serious menace associated with the high rate of morbidity and mortality especially in infants and children. In a study carried out by the United Nations International Children's Emergency Fund (UNICEF), over seventy thousand children below the age of five die yearly as a result of water-borne diseases (UNICEF, 2014 ). Dyes is one of the major sources of water pollution. Dyes are used in almost every aspect of human life, particularly in the textile, leather, paper, rubber, plastics, printing, cosmetics, food, and pharmaceutical industry. Textile dyeing is a well-known and complicated manufacturing process that releases over 140,000 tons of untreated organic dyes into water annually worldwide (Ren et al., 2021 ). Dyes are generally resistant to light and oxidizing agents, and over ten thousand different dyes are commercially available, which are used to produce million tons of dyes yearly, majority of which are carcinogenic and non-degradable. This makes dyes the most abundant and arguably the most dangerous water pollutants (Robinson et al., 2001 ; Golka et al., 2004 ). Several water remediation methods have been explored and several attempts have been made to eliminate the menace posed by dyes on water. Coagulation (Hanif et al., 2021 ; Garvasis et al., 2020 ), chemical oxidation (Chan et al., 2012 ), photocatalysis and electrocatalysis (Yang et al., 2021 ; Chem et al., 2020; Zhang et al., 2020 ), membrane filtration (Sz et al., 2020 ; Schwayze et al., 2020), dialysis, ion exchange (Wang et al., 2014 ), solvent extraction, reverse osmosis, and adsorption (Tseng et al., 2003 ; Yagub et al., 2014 ; Ren et al., 2021 ; Olatunde et al., 2021 ; Omorogie et al., 2022;) has been used to treat dye-polluted wastewaters. Among all these, adsorption remains a favoured technique. This is due to its ease of use, cost-effectiveness, high removal efficiency, and environmental-friendliness. Adsorption employs plant and animal biomass, which are cheap and readily available, to remove toxic materials from wastewater. Different materials, including peanut hull (Brown et al., 2000 ), corn cob (Fan et al., 2011 ), coconut leaf (Jawad et al., 2016 ), mungbean husk (Saeed et al., 2009 ), orange peel (Nascimento et al., 2014 ), maize seed chaff (Babalola et al., 2016d ), algae (Elgarahy et al., 2019a ), sepia shell (Elgarahy et al., 2019b ), cellulose/clay composites (El-Aziz et al., 2018 ), are among the numerous biomass that have been previously used by other researchers for this purpose. In addition, several of these pristine waste materials have been chemically modified by other researchers to improve their adsorption efficiency. Examples of such modifications are chemically modified orange waste (Lasheen et al. 2012 ), modified nanocomposites (Li et al., 2020), Fenton-activated biogenic waste (Bulut and Tez, 2007 ), Fenton-modified peanut hull (Lv et al., 2022 ), citrate-modified bagasse (Mpatani et al., 2020 ), acid-treated peanut shell (El-Shafey, 2007 ). These modification processes improve adsorption capacity of biomass through two major ways: (i) disrupting the lignin and cellulose structures in the biomass, giving room for more toxic chemicals to be sequestered, and (ii) introducing more active functional groups to the biomass, therefore, improving the interaction between the biomass and the toxic chemicals (Lv et al., 2022 ). Herein, we present an efficient and eco-friendly modification method for improved sequestration of emerging contaminants from waste water. We employed the environmentally-friendly Fenton-like modification method, using recyclable nano FeOCl as Fenton chemical (Wang et al., 2020 ; Lv et al., 2022 ), to improve the sequestration potential of Bauhinia tomentosa seedpod for methylene blue (MB) removal from water. We studied the functional and morphological properties of the modified and unmodified adsorbents by Fourier transform infrared spectroscopy, Energy Dispersive X-Ray, and Scanning electron microscopy. In addition, we investigated the effect of different experimental conditions such as pH, dye concentration, adsorbent dose, and contact time, on their sorption capacity of the adsorbents, and analyzed their regeneration potential. 2. Materials and methods 2.1 Materials Methylene blue dye was procured from Xilong Scientific Co., Ltd, China. Ferric chloride hexahydrate was purchased from Avondale Laboratory Ltd, England, while acetone, acetic acid, ethanol, and hydrogen peroxide were purchased from BDH chemicals Ltd, England. Sodium chloride, potassium hydroxide, hydrochloric acid and sodium hydroxide were acquired from Molychem, India. All reagents were of analytical grade and were used without further purifications. 2.2 Preparation of adsorbent The Bauhinia tomentosa Linn seedpod (BTSP) used for this research was collected from Dominion University, Ibadan, Nigeria. Before collecting the samples, the flowering parts (seedpod, flowers, and leaves) of the plant was identified and authenticated at the herbarium unit of the Department of Botany, University of Ibadan, Nigeria (Authentication number UIH-23360). The seedpods were air-dried for four weeks until crisp and pulverized into fine powder using an industrial blender. The pulverized sample was sieved using a 100 µm sieve and either calcinated at 400 ℃ for 2 hrs and ground into fine powder to produce BTSP adsorbent, or Fenton-modified before calcination. Prepared sample was used immediately or stored at 4 ℃ in an air-tight container until use. 2.3 Fenton-like modification of adsorbent Fenton-like modification of the pulverized and sieved seedpods was carried out according to already established protocol of Lv et al. ( 2022 ) with little modification. Briefly, 10 g of ferric chloride hexahydrate (FeCl 3 .6H 2 0) was heated at 200 ℃ in an air-tight crucible for 2 hours in a muffle furnace. Unreacted ferric chloride was separated from the FeOCl nanosheets formed by repeated washing and centrifugation steps with acetone. 0.3 g of the FeOCl nanosheets and 5 g of the adsorbent material was added to a 250 mL beaker containing 100 ml of 2.5% H 2 O 2 , and the mixture was heated at 50 ℃ for 6 hrs under constant agitation. The Fenton-like modified adsorbent was continuously washed with distilled water by centrifugation until a colourless and water clear filtrate was obtained. The modified adsorbent was dried at 70 ℃ for 2 hrs and calcinated at 400 ℃ for 2 hrs and ground into fine powder to produce the Fenton-BTSP adsorbent. Calcinated sample was used immediately or stored in the refrigerator at 4 ℃ until required. 2.4 Characterization of adsorbents The functional groups present on the surface of BTSP and Fenton-BTSP was characterized by Fourier-transformed Infrared (FTIR) spectroscopy in the range of 4000 − 400 cm − 1 using a PerkinElmer FT-IR Spectrum 2 spectrophotometer (PerkinElmer, U.S.A.). The pH at which the overall charge on the surface of the adsorbents is zero, known as the pH-point of zero charge (pH-PZC), was investigated according to established protocol. The size of the adsorbents was measured by dynamic light scattering using a Zetasizer Nano S90 (Malvern instruments, U.K.). The surface morphology and elemental composition of the adsorbents was characterized by scanning electron microscopy (SEM) using a Hitachi SU 3500 scanning microscope (Hitachi, Japan) coupled to an energy dispersive X-ray (EDX) spectroscope at an accelerating voltage of 15 kV and resolution energy of 240 eV. Methylene blue absorbance was measured using a JENWAY 6305 UV-Vis spectrophotometer (JENWAY, U.K) at its wavelength of maximum absorption (662 nm). A more comprehensive protocol for each technique is provided as Supplementary Methods in the Supplementary Information. 2.5 Adsorption studies The adsorption of MB onto BTSP or Fenton-BTSP was carried out using the batch adsorption technique according to established protocols (Babalola et al., 2017 ; Omorogie et al., 2022). All experiments were carried out in duplicates and the average was used in each case. For each experiment, 20 mL of 100 mg/L MB was measured into separate plastic bottles containing 20 mg of BTSP or Fenton-BTSP. The bottles were corked tightly and agitated at room temperature at 150 rpm and 2 hrs, while optimizing adsorption conditions such as dye concentration, pH, contact time, and adsorbent dosage. For pH studies, the pH of MB was adjusted to the range of 2.0–12.0 using 0.1 M NaOH or HCl. The effect of dye concentration was studied by varying MB concentration at a range of 25–500 mg/L. Adsorbent mass was varied between 10 mg to 500 mg to study the influence of adsorbent dosage on the sorption of MB. To study the effect of contact time on sorption efficiency of the adsorbents, aliquots were removed from the shaker at different time intervals of 0.5 min to 120 min. In all cases, supernatants were collected by centrifugation at 4000 rpm for 5 mins and analyzed for residual concentration of MB using a UV/Vis Spectrophotometer at 662 nm. The absorbances were converted to concentration using the slope and intercept obtained from a calibration curve of different MB concentrations, which is available in the supplementary information (Supplementary Fig. 1 (SF 1)). The quantity ( qe ) of MB adsorbed by BTSP or Fenton-BTSP was calculated using Eq. 1 . $$\:{q}_{e}=\:{C}_{o}-\:{C}_{e}\times\:\frac{V}{W}$$ 1 where q e is the amount of MB adsorbed at equilibrium, C o (mg/L) and C e (mg/L) are the initial and final concentrations of MB, respectively, V (mL) is the volume of dye, and W (mg) is the weight of adsorbent. 2.6 Desorption studies Desorption experiment was carried out using inorganic and organic acids and bases as desorbents. Briefly, 20 mg of adsorbent was shaken with 20 mL of 100 mg/L of MB solution at the pH of maximum adsorption for 2 hrs at room temperature. After separating the supernatant from the adsorbent by centrifugation, 20 mL of varying concentrations (0.01, 0.05, 0.1, 0.25, and 0.5 M) of HNO 3 , KOH, acetic acid, or ethanol was added to the adsorbent and shaken for 30 mins at room temperature. The adsorbent was separated by centrifugation and the absorbance of the supernatant was analysed by UV-Vis at 662 nm. The percentage desorption (%D) was calculated using Eq. 2. %D = \(\:\frac{amount\:desorbed}{amount\:adsorbed}\) × 100% (2) 2.7 Adsorption isotherm and kinetics Four different isotherm models were used describe the adsorption equilibrium of varying concentrations of MB onto BTSP and Fenton-BTSP. Specifically, the adsorption data was fitted to the linear versions of Langmuir (Eqs. 3 and 4 ), Freundlich (Eq. 5 ), Dubinin-Radushkevich (Eqs. 6 , 7 and 8 ), and Temkin (Eq. 9 ) isotherm models. The linear pseudo-first order (Eq. 10 ), pseudo-second order (Eq. 11 ), and Elovich (Eq. 12 ) kinetic models were also employed to describe the mechanism of adsorption at different interaction times of MB with the adsorbent. $$\:\frac{{C}_{e}}{{q}_{e}}=\:\frac{1}{{q}_{m}b}+\frac{{C}_{e}}{{q}_{m}}$$ 3 $$\:{K}_{L}=\frac{1}{1+b{C}_{o}}$$ 4 $$\:In{q}_{e}=In{K}_{f}+\frac{1}{n}In{C}_{e}$$ 5 $$\:In{q}_{e}=In{q}_{m}-{B}_{D}{\epsilon\:}^{2}$$ 6 $$\:{\epsilon\:=\left[RT\:In\left(1+\frac{1}{{C}_{e}}\right)\right]}^{2}$$ 7 $$\:E=\frac{1}{2{B}_{D}}$$ 8 $$\:{q}_{e}={\gamma\:}_{T}In{K}_{T}+{\gamma\:}_{T}In{C}_{e}$$ 9 $$\:In{(q}_{e}-{q}_{t})=In{q}_{e}+{K}_{1}t$$ 10 $$\:\frac{t}{{q}_{t}}=\frac{1}{{K}_{2}{q}_{e}^{2}}+\frac{t}{{q}_{e}}$$ 11 $$\:{q}_{t}=\alpha\:+\beta\:Int$$ 12 where C o (mg/L) and C e (mg/L) are the initial and final concentrations of MB, respectively, q t (mg/g) and q e (mg/g) are the amounts of MB adsorbed at time t (min) and equilibrium, respectively, K L (L/mg), K F (mg/g), and K T (L/g) indicate the affinity coefficient-related bonding terms, b (J/mol) is the Langmuir constant, n is a dimensionless exponent in the Freundlich equation, B D (mol 2 /J) is related to the free energy of adsorption per mole of adsorbate, q m (mg/g) is the maximum theoretical monolayer saturation capacity, E (J/mol) is the apparent energy, R is the universal gas constant (8.3142 J/mol/K), T (K) is the absolute temperature, k 1 (min –1 ) and k 2 (g/mg/min) are the first order and second order rate constants, respectively, α (mg/g/min) and β (g/mg) represent the constants related to the initial reaction rate and the activation energy, respectively. 3. Results and discussion 3.1 Characterization of adsorbents The density of the bulk BTSP and Fenton-BTSP adsorbents are 0.68 and 0.72 g/cm 3 , respectively. The higher density of the Fenton-BTSP is probably due to the compact packing of iron that is present in the adsorbent. Elucidation of the adsorbents by FTIR revealed the presence of functional groups such as O-H, C = O, C-O, and C-N, as well as a Fe-O band at 568.23 cm − 1 , which was more pronounced in the Fenton-BTSP (Fig. 1 A). After adsorption of MB dye, some of these absorption frequencies exhibited substantial shifts or disappeared completely and new bands appeared. FTIR spectrum of the dye-loaded adsorbents are attached as Supplementary Figures in the Supplementary Information (SF 2 for BTSP and SF 3 for Fenton-BTSP), suggesting a chemical interaction between the adsorbents and MB molecules (Namasivayam et al., 1996 ; Babalola et al., 2017 ). The pH-PZC of the surface of BTSP and Fenton-BTSP was found to be 5.548 and 7.655, respectively (Fig. 1 B). The adsorbent is expected therefore, to acquire a positive surface charge below the pH-PZC in which the adsorption of anionic or acid dyes are enhanced, whereas above the pH-PZC, it acquires a negative surface charge thus favoring the adsorption of cationic or basic dyes. This indicates that the adsorption of MB, a cationic dye, should be optimum at a pH above the pH-PZC. Previous studies of MB have revealed that maximum adsorption was observed at a basic pH (Jawad et al., 2016 ; Mpatani et al., 2020 ). Figure 1 C shows the intensity-weighted size distribution of the adsorbent particles elucidated by DLS. The result showed different sizes of the adsorbents distributed mostly within the nanometer range. Both the BTSP and Fenton-BTSP showed similarity in their size distribution, which was averaged at ~ 60 nm and 200 nm, with larger, less-intense aggregated particles appearing within the micrometer range. This indicates that the adsorbents have very small (nano) sizes, which is an important criterial in selecting an adsorbent. The scanning electron micrographs of the adsorbents at a magnification of 500x is shown in Fig. 2 A-D. the micrograph shows agglomerated particles having irregular and rough surfaces with open pores and cavities. These cavities became loaded with MB dye (cloudy white patches) after adsorption (Fig. 2 B & D). The adsorbent particles contain elements such as C, Si, O, Al, K, Na, Ca, Mg, and Fe (Table 1 ). The amount of Fe present was greatly increased (~ 10x) in the Fenton-BTSP adsorbent, confirming successful modification of the BTSP with the Fenton-like compound (FeOCl). Micrographs of the adsorbents in the presence or absence of MB obtained at higher magnifications are shown in the Supplementary Figures (SF 4 for BTSP and SF 5 for Fenton-BTSP). Table 1 Elemental composition of BTSP and Fenton-BTSP adsorbents BTSP Fenton-BTSP Before adsorption After adsorption Before adsorption After adsorption Element Composition (%) Element Composition (%) Element Composition (%) Element Composition (%) Carbon (C) 20.45 Carbon (C) 19.78 Carbon (C) 24.32 Carbon (C) 23.90 Oxygen (O) 34.09 Oxygen (O) 33.48 Oxygen (O) 31.85 Oxygen (O) 30.61 Aluminium (Al) 8.22 Aluminium (Al) 9.79 Silicon (Si) 17.62 Silicon (Si) 20.30 Silicon (Si) 29.17 Silicon (Si) 26.68 Aluminium (Al) 1.96 Aluminium (Al) 2.21 Calcium (Ca) 1.10 Calcium (Ca) 1.18 Nitrogen(N) 1.05 Nitrogen(N) 1.37 Sodium (Na) 3.34 Sodium (Na) 3.58 Potassium (K) 0.21 Potassium (K) 0.28 Magnesium (Mg) 1.98 Magnesium (Mg) 3.06 Iron (Fe) 22.89 Iron (Fe) 21.32 Iron (Fe) 1.65 Iron (Fe) 2.45 3.2 Effect of different sorption conditions Adsorption conditions such as pH, adsorbent dosage, dye concentration, temperature, contact time, among others, can greatly influence the rate and mechanism of adsorption. The effect of pH, adsorbent dosage, dye concentration, and contact time is shown in Fig. 3 . By varying the pH of MB, maximum adsorption was obtained at a pH of 10 for both adsorbents with adsorption capacities of 60.94 mg/g and 72.80 mg/g for BTSP and Fenton-BTSP, respectively (Fig. 3 A), indicating improved efficiency of the adsorbent after Fenton-like modification. This is consistent with previous reports (Lv et al., 2022 ). Adsorption was minimum at pH 2 with adsorption capacity of 2.41 mg/g for BTSP and at pH 4 with an adsorption capacity of 0.98 mg/g for Fenton-BTSP. The low rate of adsorption of MB by the adsorbents at acidic pH may be due to high proton density, which leads to ionic repulsion between the positively charged MB dye and the surface of the adsorbent (Omorogie et al., 2022). This is consistent with the deductions made from our pH-PZC experiment, and with previous adsorption experiments on MB (Jawad et al., 2016 ; Mpatani et al., 2020 ). Variation of adsorbent dosage from 10–500 mg revealed a sharp decrease in adsorption capacity that is independent on Fenton modification. As the dose of the adsorbent increased from 10 mg to 500 mg, adsorption capacity witnessed a spontaneous decrease from 80.46 to 1.36 mg/g for BTSP and from 114.25 to 3.94 mg/g for Fenton-BTSP (Fig. 3 B). Such sharp decrease in adsorption capacity at increased dosage can be associated with increased clogging or aggregation of adsorbent particles, which lead to increased diffusion path for MB, resulting in a substantially low rate of adsorption (Asgher and Bhatti, 2010 ; Babalola et al., 2016a ). The result of varying concentrations of MB on the adsorption efficiency of BTSP and Fenton-BTSP is shown in Fig. 3 C. As the concentration of MB increases from 25 mg/L to 500 mg/L, the adsorption capacity of the adsorbents experienced a corresponding increase from 14.65 to 277.41 mg/g for BTSP and from 23.76 to 343.25 mg/g for Fenton-BTSP. This increase in adsorption capacity with increasing dye concentration is higher for the Fenton-BTSP, indicating improved efficiency due to modification with FeOCl, and can be associated with increased mass transfer driving force as the concentration of the dye increased. Such increase in mass transfer enhances the adsorption of more dye molecules by the adsorbent (Asgher and Bhatti, 2010 ; Babalola et al., 2016a ; Omorogie et al., 2022). To investigate the influence of adsorbent-dye contact time on the efficiency of adsorption, the time of adsorption was varied from 0.5 to 120 mins. The results (Fig. 3 D) shows that the adsorption capacity of BTSP and Fenton-BTSP increased substantially with increasing contact time up to a level where equilibrium is reached. For both BTSP and Fenton-BTSP, adsorption was rapid for the first 30 mins after which further increase in contact time exerted no effect on the adsorption capacity of the adsorbents. This is probably because after 30 minutes, there are no cavities or unoccupied active surfaces available on the adsorbents for MB to occupy (Olatunde et al., 2021 ). Although Fenton modification of the adsorbent did not affect the time it took the adsorbent to reach equilibrium, the adsorption capacity was, however, greater for Fenton-BTSP than for BTSP. . 3.3 Desorption of MB from adsorbents Regeneration is an important factor in selecting adsorbents for wastewater management. In this study, the regeneration of BTSP and Fenton-BTSP was tested by agitating MB-loaded adsorbents with varying concentrations of organic and inorganic acids and bases for 30 mins. The desorption of MB from BTSP was maximum using an organic acid (acetic acid) at all operational concentrations, with 0.1 M acetic acid giving the highest yield of desorbed MB (21.18%) after 30 mins of agitation (Fig. 4 A). In the case of Fenton-BTSP, the inorganic acid, HNO 3 desorbed the highest amount of MB at all operational concentrations, with optimal desorption (46.24%) observed using only 0.01 M of the acid (Fig. 4 B). These findings are consistent with the results of our pH studies, and indicates that, counter ions from an acid are needed to remove the basic MB dyes adsorbed on the adsorbents. It is also worthy of mention that desorption of MB from the Fenton-BTSP was more efficient than from BTSP. As can be seen from Fig. 2 A&B, the lowest amount of MB desorbed from BTSP was 3.53% using 0.05 M KOH. In comparison, the lowest amount of MB desorbed from the Fenton-BTSP was 17.38% using 0.1 M of KOH. Overall, desorption of MB was at least 2-folds higher in Fenton-BTSP compared to BTSP. This indicates that modification of the adsorbent with the Fenton FeOCl improved not only its adsorption property but also its regeneration and reusability potential. 3.4 Adsorption isotherm and kinetics Equilibrium isotherm models such as the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models, were employed to explain the sorption process of MB onto BTSP and Fenton-BTSP. In all cases, the corelation coefficient (R 2 ) was used to choose the best fit model. In the case of isotherm modelling, the experimental data revealed that the adsorption of MB onto BTSP probably followed the Temkin isotherm model, which has the highest correlation factor (R 2 = 0.6) and an equilibrium binding constant (γ T ) of 41.85 L/mg (Table 2 ). This indicates that the heat of sorption of MB onto the surface of BTSP decreases linearly as the surface of the adsorbent is covered by the dye (Temkin and Pyzhev, 1940 ). The maximum monolayer adsorption capacity for BTSP revealed by Langmuir and Dubinin-Radushkevich models were 190.63 mg/g and 42.53 mg/g, respectively, with an apparent energy (E) of 2226.85 J/mol (Table 2 ). For Fenton-BTSP, adsorption of MB followed the Freundlich isotherm model with a correlation coefficient that approaches unity (R 2 = 0.92) with an equilibrium binding constant (γ T ) of 60.11 L/mg (Table 2 ). This suggests the formation of multiple layers of MB dye on the surface of the adsorbent improving its sorption capacity compared to the unmodified BTSP. The maximum monolayer adsorption capacity for Fenton-BTSP revealed by Langmuir and Dubinin-Radushkevich fittings were 520.83 mg/g and 158.71 mg/g, respectively, with an apparent energy (E) of 148.48 J/mol (Table 1 ). These results further establish that modification of BTSP with FeOCl nanosheets indeed improved its maximum adsorption capacity, which is consistent with previous findings (Lv et al., 2022 ). The isotherm model plots are shown in the Supplementary Figures (SF 6). When compared to other adsorbents used to sequester MB from aqueous solution (Table 3 ), BTSP and Fenton-BTSP showed outstanding capacities in removing MB from wastewater, with Fenton-BTSP displaying the greatest potential. Adsorption kinetics describe the rate at which adsorbates are captured by the surface of the adsorbents (Unuabonah et al., 2017b). This information can be used to describe the dynamics and mechanism of dye uptake by the adsorbent. Here, linear kinetics models such as pseudo-first order, pseudo-second order, and Elovich models, were employed to describe the dynamics of MB uptake by BTSP and Fenton-BTSP (Table 4 ). Kinetics modelling of the adsorption data revealed that the adsorption of MB onto BTSP and Fenton-BTSP could followed both pseudo-second order kinetics (R 2 = 0.98 for BTSP and 0.99 for Fenton-BTSP) and Elovich kinetics (R 2 = 0.94 for BTSP and 0.89 for Fenton-BTSP). However, the pseudo-second order model gave the best fit to experimental data as adjudged by the highest correlation factor (Table 4 ), indicating that the mechanism of adsorption of MB onto BTSP and Fenton-BTSP followed the chemisorption process, where the adsorption of MB by the adsorbents was controlled by electron transfer (Hosseini et al., 2021 ; Adeniji et al., 2019 ; Asgher and Bhatti, 2010 ; Olu-Owolabi et al., 2012 ). The extremely low corelation coefficient factor from the pseudo-first order model (R2 = 0.026 for BTSP and 0.057 for Fenton-BTSP) suggests that the interaction between the MB dye and adsorbents is completely chemical and cannot be described by a physisorption mechanism. The kinetics model plots are shown in the Supplementary Figures (SF 7). The Elovich model revealed that the initial rate of adsorption of MB dye molecules onto the surface of the adsorbents experienced over 2-fold increase on modification with FeOCl. As can be seen in Table 3 , the initial reaction rate (α) is 4.34 mg/g/min for BTSP and 11.98 mg/g/min for Fenton-BTSP. This further suggests that Fenton modification of adsorbents can be a potent way of improving their capacity for dye sequestration and wastewater management. Table 2 Linear isotherm parameters for the adsorption of MB onto BTSP and Fenton-BTSP Model Parameters BTSP Fenton-BTSP Langmuir q m 190.63 520.83 R L 0.87 0.49 b 0.0011 0.010 R 2 0.17 0.70 Freundlich K F 1.11 15.78 1/n 0.82 0.56 R 2 0.58 0.92 Temkin γ T 41.85 60.11 K T 0.34 0.36 R 2 0.60 0.64 Dubinin-Radushkevich q m 42.53 158.71 B D 1.01E-07 2.27E-05 E 2226.85 148.48 R 2 0.011 0.74 Table 3 Comparison of adsorption capacities of some adsorbents on MB. Adsorbents Modification q m (mg/g) References Rice straw - 158.0 Jawad et al., 2020 Coconut leaf - 112.3 Jawad et al., 2016 Peanut hull - 64.0 Lv et al., 2022 Passion fruit waste - 44.7 Pavan et al., 2008 Dragon fruit peels - 192.3 Jawad et al., 2018 Bauhinia tomentosa seedpod (BTSP) - 190.63 This work Fenton-like modified Peanut hull FeOCl 132.4 Lv et al., 2022 Citrate-modified sugarcane bagasse Citrate 224.0 Mpatani et al., 2020 Silica-modified Soya waste Silica 47.0 Batool and Valiyaveettil, 2021 Base-modified pine corn NaOH 33.7 Yagub et al., 2014 Acid-modified defatted algae H 2 SO 4 7.8 Chandra et al., 2016 Fenton-like modified Bauhinia tomentosa (Fenton-BTSP) FeOCl 520.83 This work Table 4 Linear kinetics parameters for the adsorption of MB onto BTSP and Fenton-BTSP Model Parameters BTSP Fenton-BTSP Pseudo-first order K 1 0.040 0.047 q e 2.86 7.73 R 2 0.026 0.057 Pseudo-second order K 2 0.0046 0.0028 q e 26.39 71.74 R 2 0.98 0.99 Elovich α 4.34 11.98 β 4.72 16.041 R 2 0.94 0.89 4. Conclusion We report an easy modification method for adsorbents for improved uptake of emerging pollutants from wastewater. This modification method, involving the Fenton-like chemical, FeOCl, improved the surface morphology, functional composition, and overall efficiency of a cost-effective and easy-to-get plant waste from Bauhinia tomentosa to rapidly remove methylene blue (MB) dye from water with a maximum adsorption capacity of 520.83 mg/g as compared to 190.63 mg/g obtained for the unmodified adsorbent. We discovered that although the adsorption equilibrium time was not affected by modification, the rate of the adsorption of MB was increased by over 2-folds due to the Fenton-like modification. The unmodified (BTSP) and Fenton-like modified (Fenton-BTSP) adsorbents responded at different extents to differences in solution pH, dye concentration, adsorbent dosage, and reaction time. In addition to an improvement in the adsorption capacity on modification, it also appears that the regeneration of the adsorbents was greatly improved after modification. Modification of BTSP with FeOCl improved its surface morphology and functional composition in such a way that allows uptake of multilayers of MB dye on its surface via a chemisorption process, which explains the basis for its improved efficiency. It is therefore recommended that adsorbents be modified with the Fenton-like agent, FeOCl, for improved capacity and reusability in wastewater management. Declarations Author’s contribution M.T. Agbadaola conceptualized the idea in this manuscript, supervised this work as part of D.A. Olatunji’s BSc research project, generated some of the results contained in this work at the Institute of Molecular Biosciences, Karl Franzens Universität, Graz, Austria, analyzed all the data, wrote the first manuscript, revised, and reviewed the manuscript. D. A. Akinyemi co-supervised this work, revised and reviewed the manuscript. D. A. Olatunji generated some of the data in this manuscript as part of her BSc research project. J. O. Babalola conceptualized the idea in this manuscript, revised and reviewed the manuscript. All authors approved the final manuscript for publication. Competing Interests The authors declare that there are no conflicts of interest. Funding No funding was received for conducting this study. Acknowledgement M. T. Agbadaola acknowledges Prof. Sandro Keller at the Institute of Molecular Biosciences, Karl Franzens Universität, Graz, Austria, for allowing him to use his laboratory facility to generate some of the results that make up this manuscript. Data availability All data used to produce this manuscript will be made available upon request to the corresponding author. 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Supplementary Files SUPPLEMENTARYINFORMATIONfentonlikemodificationAgbadaolaetal..docx Fenton-like modification of Bauhinia tomentosa seedpod for improved sequestration of methylene blue from water Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5856675","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":403966315,"identity":"f88b7b88-f711-496c-9041-9d390394d767","order_by":0,"name":"Michael Tope Agbadaola","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8ElEQVRIiWNgGAWjYLACxgYQYm5g+ADksLETUs4G18LYwDgDJMBMihZmHpAIIS268xsYP37dYSfb397Y+Nnm1zZ5PmYGxg8fc3BrMTvGwCwteybZeMaZg83SuX23DduYGZglZ27Dq4VBWrKNObHhRmKDdG7PbUagFjZmXvxamH9LttUnzr+R2Pzbsue2PTFa2CQ/th1O3HAjsU2a4cftRCK0JLZZM545brzxzME2y96G28ltzIzN+P1y+PDhmz93VMvOO958+MaPP7dt57c3H/zwEY8WBnh0gNltEBF86iEKf8CZfwgqHgWjYBSMghEIACbAVx/4GAeXAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0001-9481-1645","institution":"Department of Chemical Sciences, Dominion University, Ibadan, Nigeria. Biophysics, Institute of Molecular Biosciences (IMB), University of Graz, NAWI Graz, Graz, Austria.","correspondingAuthor":true,"prefix":"","firstName":"Michael","middleName":"Tope","lastName":"Agbadaola","suffix":""},{"id":403966351,"identity":"cee15681-9561-48b0-91f7-b2a911769a06","order_by":1,"name":"Damilola Adeola Akinyemi","email":"","orcid":"","institution":"Department of Chemical Sciences, Dominion University, Ibadan, Nigeria","correspondingAuthor":false,"prefix":"","firstName":"Damilola","middleName":"Adeola","lastName":"Akinyemi","suffix":""},{"id":403966449,"identity":"f90c0595-0082-40c5-a204-b989bbd6d059","order_by":2,"name":"Dorcas Abiodun Olatunji","email":"","orcid":"","institution":"Department of Chemical Sciences, Dominion University, Ibadan, Nigeria","correspondingAuthor":false,"prefix":"","firstName":"Dorcas","middleName":"Abiodun","lastName":"Olatunji","suffix":""},{"id":403966450,"identity":"6ba6001b-f19f-45cf-9ae3-0d8d4a903ce2","order_by":3,"name":"Jonathan Oyebamiji Babalola","email":"","orcid":"","institution":"Bowen University, Iwo, Osun State, Nigeria.\tDepartment of Chemistry, University of Ibadan, Ibadan, Nigeria","correspondingAuthor":false,"prefix":"","firstName":"Jonathan","middleName":"Oyebamiji","lastName":"Babalola","suffix":""}],"badges":[],"createdAt":"2025-01-18 19:23:24","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-5856675/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5856675/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":74431210,"identity":"efb29799-c331-4c68-ae16-2672935127c5","added_by":"auto","created_at":"2025-01-22 08:48:23","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":63587,"visible":true,"origin":"","legend":"\u003cp\u003eCharacterization of adsorbents.\u003cstrong\u003e \u003c/strong\u003e(a) FTIR spectra of BTSP and Fenton-like modified BTSP. (b) pH-PZC plot of BTSP and Fenton-BTSP. (c) Size distribution of BTSP and Fenton-BTSP elucidated by DLS. All measurements were carried out at 298 K. Error bars are standard errors of two independent experiments.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-5856675/v1/ec9701015011b78678be693b.png"},{"id":74430783,"identity":"ab4681dd-c501-4b6e-a768-1036447b34e9","added_by":"auto","created_at":"2025-01-22 08:40:23","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":937518,"visible":true,"origin":"","legend":"\u003cp\u003eSurface morphology of adsorbents.\u003cstrong\u003e \u003c/strong\u003e(a) SEM-EDX spectra of BTSP at 500x before adsorption. (b) SEM-EDX spectra of BTSP at 500x after adsorption of MB. (c) SEM-EDX spectra of Fenton-BTSP at 500x before adsorption. (d) SEM-EDX spectra of Fenton-BTSP at 500x after adsorption of MB.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-5856675/v1/f8f300e60c58edbd47c4a808.png"},{"id":74431212,"identity":"0f1109c9-c36e-4c68-8daa-df4b9b793842","added_by":"auto","created_at":"2025-01-22 08:48:23","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":83910,"visible":true,"origin":"","legend":"\u003cp\u003eInfluence of different sorption conditions on the adsorption of MB onto BTSP and Fenton-BTSP.\u003cstrong\u003e \u003c/strong\u003e(a) Effect of pH (b) Effect of adsorbent dosage. (c) Effect of MB concentration. (d) Effect of contact time. Error bars are standard errors of two independent experiments.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-5856675/v1/8058833deb6a35c054886e08.png"},{"id":74430789,"identity":"42f0c5fc-6eaf-48cf-8c01-6cda4e25df13","added_by":"auto","created_at":"2025-01-22 08:40:23","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":105313,"visible":true,"origin":"","legend":"\u003cp\u003eDesorption of MB from BTSP and Fenton-BTSP using organic and inorganic acids and bases.\u003cstrong\u003e \u003c/strong\u003e(a) Desorption of MB from BTSP. (b) Desorption of MB from Fenton-BTSP. Adsorbent dose =20 mg; initial dye concentration = 100 mg/L; temperature = 298 K; desorption time = 30 min; agitation speed = 150 rpm. Error bars are standard errors of two independent experiments.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-5856675/v1/4879728344c52297d14e3e6b.png"},{"id":74432935,"identity":"81ae0c0d-bebf-4650-b616-b36fb3347cf4","added_by":"auto","created_at":"2025-01-22 09:04:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2199106,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5856675/v1/9760fa35-f0a5-48e3-a899-6c4a11722c9f.pdf"},{"id":74432626,"identity":"ac3b531c-3a52-4154-b642-6d1c79c60c40","added_by":"auto","created_at":"2025-01-22 08:56:23","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1815197,"visible":true,"origin":"","legend":"\u003cp\u003eFenton-like modification of Bauhinia tomentosa seedpod for improved sequestration of methylene blue from water\u003c/p\u003e","description":"","filename":"SUPPLEMENTARYINFORMATIONfentonlikemodificationAgbadaolaetal..docx","url":"https://assets-eu.researchsquare.com/files/rs-5856675/v1/bc9aa4d0daa95a205ad95c28.docx"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eFenton-like modification of Bauhinia tomentosa seedpod for improved sequestration of methylene blue from water\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe consistent release of toxic effluents from industrial units to water bodies poses greatest risk to the quality of water, the largest irreplaceable asset given to man. Low water quality is a serious problem to aquatic flora and fauna, and has made access to portable water by terrestrial organisms almost impossible in developing and underdeveloped nations (Sun and Lockaby, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). To curtail this, the United Nations as part of its sustainable development goals (SDGs), has become more intentional in ensuring that portable water is available to all and sundry by 2030 (UN, 2015).\u003c/p\u003e \u003cp\u003eEffluents from industries contain undesirable and potentially toxic chemicals in the form of textile dyes, pharmaceuticals, agrochemicals, among others. The components of these chemicals compromise the integrity and portability of water and render it unsafe for use (Caldwell et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). According to the World Health Organization (WHO) report in 2012 (WHO, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), about two million people die from diseases that arise from water pollution. In Nigeria, poor access to clean and portable water is a serious menace associated with the high rate of morbidity and mortality especially in infants and children. In a study carried out by the United Nations International Children's Emergency Fund (UNICEF), over seventy thousand children below the age of five die yearly as a result of water-borne diseases (UNICEF, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDyes is one of the major sources of water pollution. Dyes are used in almost every aspect of human life, particularly in the textile, leather, paper, rubber, plastics, printing, cosmetics, food, and pharmaceutical industry. Textile dyeing is a well-known and complicated manufacturing process that releases over 140,000 tons of untreated organic dyes into water annually worldwide (Ren et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Dyes are generally resistant to light and oxidizing agents, and over ten thousand different dyes are commercially available, which are used to produce million tons of dyes yearly, majority of which are carcinogenic and non-degradable. This makes dyes the most abundant and arguably the most dangerous water pollutants (Robinson et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Golka et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2004\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSeveral water remediation methods have been explored and several attempts have been made to eliminate the menace posed by dyes on water. Coagulation (Hanif et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Garvasis et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), chemical oxidation (Chan et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), photocatalysis and electrocatalysis (Yang et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Chem et al., 2020; Zhang et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), membrane filtration (Sz et al., \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Schwayze et al., 2020), dialysis, ion exchange (Wang et al., \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), solvent extraction, reverse osmosis, and adsorption (Tseng et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Yagub et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Ren et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Olatunde et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Omorogie et al., 2022;) has been used to treat dye-polluted wastewaters. Among all these, adsorption remains a favoured technique. This is due to its ease of use, cost-effectiveness, high removal efficiency, and environmental-friendliness. Adsorption employs plant and animal biomass, which are cheap and readily available, to remove toxic materials from wastewater. Different materials, including peanut hull (Brown et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2000\u003c/span\u003e), corn cob (Fan et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), coconut leaf (Jawad et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), mungbean husk (Saeed et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), orange peel (Nascimento et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), maize seed chaff (Babalola et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2016d\u003c/span\u003e), algae (Elgarahy et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e), sepia shell (Elgarahy et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2019b\u003c/span\u003e), cellulose/clay composites (El-Aziz et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), are among the numerous biomass that have been previously used by other researchers for this purpose.\u003c/p\u003e \u003cp\u003eIn addition, several of these pristine waste materials have been chemically modified by other researchers to improve their adsorption efficiency. Examples of such modifications are chemically modified orange waste (Lasheen et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), modified nanocomposites (Li et al., 2020), Fenton-activated biogenic waste (Bulut and Tez, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2007\u003c/span\u003e), Fenton-modified peanut hull (Lv et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), citrate-modified bagasse (Mpatani et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), acid-treated peanut shell (El-Shafey, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). These modification processes improve adsorption capacity of biomass through two major ways: (i) disrupting the lignin and cellulose structures in the biomass, giving room for more toxic chemicals to be sequestered, and (ii) introducing more active functional groups to the biomass, therefore, improving the interaction between the biomass and the toxic chemicals (Lv et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHerein, we present an efficient and eco-friendly modification method for improved sequestration of emerging contaminants from waste water. We employed the environmentally-friendly Fenton-like modification method, using recyclable nano FeOCl as Fenton chemical (Wang et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Lv et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), to improve the sequestration potential of \u003cem\u003eBauhinia tomentosa\u003c/em\u003e seedpod for methylene blue (MB) removal from water. We studied the functional and morphological properties of the modified and unmodified adsorbents by Fourier transform infrared spectroscopy, Energy Dispersive X-Ray, and Scanning electron microscopy. In addition, we investigated the effect of different experimental conditions such as pH, dye concentration, adsorbent dose, and contact time, on their sorption capacity of the adsorbents, and analyzed their regeneration potential.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials\u003c/h2\u003e \u003cp\u003eMethylene blue dye was procured from Xilong Scientific Co., Ltd, China. Ferric chloride hexahydrate was purchased from Avondale Laboratory Ltd, England, while acetone, acetic acid, ethanol, and hydrogen peroxide were purchased from BDH chemicals Ltd, England. Sodium chloride, potassium hydroxide, hydrochloric acid and sodium hydroxide were acquired from Molychem, India. All reagents were of analytical grade and were used without further purifications.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Preparation of adsorbent\u003c/h2\u003e \u003cp\u003eThe \u003cem\u003eBauhinia tomentosa\u003c/em\u003e Linn seedpod (BTSP) used for this research was collected from Dominion University, Ibadan, Nigeria. Before collecting the samples, the flowering parts (seedpod, flowers, and leaves) of the plant was identified and authenticated at the herbarium unit of the Department of Botany, University of Ibadan, Nigeria (Authentication number UIH-23360). The seedpods were air-dried for four weeks until crisp and pulverized into fine powder using an industrial blender. The pulverized sample was sieved using a 100 \u0026micro;m sieve and either calcinated at 400 ℃ for 2 hrs and ground into fine powder to produce BTSP adsorbent, or Fenton-modified before calcination. Prepared sample was used immediately or stored at 4 ℃ in an air-tight container until use.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Fenton-like modification of adsorbent\u003c/h2\u003e \u003cp\u003eFenton-like modification of the pulverized and sieved seedpods was carried out according to already established protocol of Lv et al. (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) with little modification. Briefly, 10 g of ferric chloride hexahydrate (FeCl\u003csub\u003e3\u003c/sub\u003e.6H\u003csub\u003e2\u003c/sub\u003e0) was heated at 200 ℃ in an air-tight crucible for 2 hours in a muffle furnace. Unreacted ferric chloride was separated from the FeOCl nanosheets formed by repeated washing and centrifugation steps with acetone. 0.3 g of the FeOCl nanosheets and 5 g of the adsorbent material was added to a 250 mL beaker containing 100 ml of 2.5% H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e, and the mixture was heated at 50 ℃ for 6 hrs under constant agitation. The Fenton-like modified adsorbent was continuously washed with distilled water by centrifugation until a colourless and water clear filtrate was obtained. The modified adsorbent was dried at 70 ℃ for 2 hrs and calcinated at 400 ℃ for 2 hrs and ground into fine powder to produce the Fenton-BTSP adsorbent. Calcinated sample was used immediately or stored in the refrigerator at 4 ℃ until required.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Characterization of adsorbents\u003c/h2\u003e \u003cp\u003eThe functional groups present on the surface of BTSP and Fenton-BTSP was characterized by Fourier-transformed Infrared (FTIR) spectroscopy in the range of 4000\u0026thinsp;\u0026minus;\u0026thinsp;400 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e using a PerkinElmer FT-IR Spectrum 2 spectrophotometer (PerkinElmer, U.S.A.). The pH at which the overall charge on the surface of the adsorbents is zero, known as the pH-point of zero charge (pH-PZC), was investigated according to established protocol. The size of the adsorbents was measured by dynamic light scattering using a Zetasizer Nano S90 (Malvern instruments, U.K.). The surface morphology and elemental composition of the adsorbents was characterized by scanning electron microscopy (SEM) using a Hitachi SU 3500 scanning microscope (Hitachi, Japan) coupled to an energy dispersive X-ray (EDX) spectroscope at an accelerating voltage of 15 kV and resolution energy of 240 eV. Methylene blue absorbance was measured using a JENWAY 6305 UV-Vis spectrophotometer (JENWAY, U.K) at its wavelength of maximum absorption (662 nm). A more comprehensive protocol for each technique is provided as Supplementary Methods in the Supplementary Information.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Adsorption studies\u003c/h2\u003e \u003cp\u003eThe adsorption of MB onto BTSP or Fenton-BTSP was carried out using the batch adsorption technique according to established protocols (Babalola et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Omorogie et al., 2022). All experiments were carried out in duplicates and the average was used in each case. For each experiment, 20 mL of 100 mg/L MB was measured into separate plastic bottles containing 20 mg of BTSP or Fenton-BTSP. The bottles were corked tightly and agitated at room temperature at 150 rpm and 2 hrs, while optimizing adsorption conditions such as dye concentration, pH, contact time, and adsorbent dosage. For pH studies, the pH of MB was adjusted to the range of 2.0\u0026ndash;12.0 using 0.1 M NaOH or HCl. The effect of dye concentration was studied by varying MB concentration at a range of 25\u0026ndash;500 mg/L. Adsorbent mass was varied between 10 mg to 500 mg to study the influence of adsorbent dosage on the sorption of MB. To study the effect of contact time on sorption efficiency of the adsorbents, aliquots were removed from the shaker at different time intervals of 0.5 min to 120 min. In all cases, supernatants were collected by centrifugation at 4000 rpm for 5 mins and analyzed for residual concentration of MB using a UV/Vis Spectrophotometer at 662 nm. The absorbances were converted to concentration using the slope and intercept obtained from a calibration curve of different MB concentrations, which is available in the supplementary information (Supplementary Fig.\u0026nbsp;1 (SF 1)). The quantity (\u003cem\u003eqe\u003c/em\u003e) of MB adsorbed by BTSP or Fenton-BTSP was calculated using Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:{q}_{e}=\\:{C}_{o}-\\:{C}_{e}\\times\\:\\frac{V}{W}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere q\u003csub\u003ee\u003c/sub\u003e is the amount of MB adsorbed at equilibrium, C\u003csub\u003eo\u003c/sub\u003e (mg/L) and C\u003csub\u003ee\u003c/sub\u003e (mg/L) are the initial and final concentrations of MB, respectively, V (mL) is the volume of dye, and W (mg) is the weight of adsorbent.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Desorption studies\u003c/h2\u003e \u003cp\u003eDesorption experiment was carried out using inorganic and organic acids and bases as desorbents. Briefly, 20 mg of adsorbent was shaken with 20 mL of 100 mg/L of MB solution at the pH of maximum adsorption for 2 hrs at room temperature. After separating the supernatant from the adsorbent by centrifugation, 20 mL of varying concentrations (0.01, 0.05, 0.1, 0.25, and 0.5 M) of HNO\u003csub\u003e3\u003c/sub\u003e, KOH, acetic acid, or ethanol was added to the adsorbent and shaken for 30 mins at room temperature. The adsorbent was separated by centrifugation and the absorbance of the supernatant was analysed by UV-Vis at 662 nm. The percentage desorption (%D) was calculated using Eq.\u0026nbsp;2.\u003c/p\u003e \u003cp\u003e%D = \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{amount\\:desorbed}{amount\\:adsorbed}\\)\u003c/span\u003e\u003c/span\u003e \u0026times; 100% (2)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.7 Adsorption isotherm and kinetics\u003c/h2\u003e \u003cp\u003eFour different isotherm models were used describe the adsorption equilibrium of varying concentrations of MB onto BTSP and Fenton-BTSP. Specifically, the adsorption data was fitted to the linear versions of Langmuir (Eqs.\u0026nbsp;\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e4\u003c/span\u003e), Freundlich (Eq.\u0026nbsp;\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e5\u003c/span\u003e), Dubinin-Radushkevich (Eqs.\u0026nbsp;\u003cspan refid=\"Equ5\" class=\"InternalRef\"\u003e6\u003c/span\u003e, \u003cspan refid=\"Equ6\" class=\"InternalRef\"\u003e7\u003c/span\u003e and \u003cspan refid=\"Equ7\" class=\"InternalRef\"\u003e8\u003c/span\u003e), and Temkin (Eq.\u0026nbsp;\u003cspan refid=\"Equ8\" class=\"InternalRef\"\u003e9\u003c/span\u003e) isotherm models. The linear pseudo-first order (Eq.\u0026nbsp;\u003cspan refid=\"Equ9\" class=\"InternalRef\"\u003e10\u003c/span\u003e), pseudo-second order (Eq.\u0026nbsp;\u003cspan refid=\"Equ10\" class=\"InternalRef\"\u003e11\u003c/span\u003e), and Elovich (Eq.\u0026nbsp;\u003cspan refid=\"Equ11\" class=\"InternalRef\"\u003e12\u003c/span\u003e) kinetic models were also employed to describe the mechanism of adsorption at different interaction times of MB with the adsorbent.\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\:\\frac{{C}_{e}}{{q}_{e}}=\\:\\frac{1}{{q}_{m}b}+\\frac{{C}_{e}}{{q}_{m}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$$\\:{K}_{L}=\\frac{1}{1+b{C}_{o}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e4\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ4\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$$\\:In{q}_{e}=In{K}_{f}+\\frac{1}{n}In{C}_{e}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e5\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ5\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ5\" name=\"EquationSource\"\u003e\n$$\\:In{q}_{e}=In{q}_{m}-{B}_{D}{\\epsilon\\:}^{2}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e6\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ6\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ6\" name=\"EquationSource\"\u003e\n$$\\:{\\epsilon\\:=\\left[RT\\:In\\left(1+\\frac{1}{{C}_{e}}\\right)\\right]}^{2}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e7\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ7\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ7\" name=\"EquationSource\"\u003e\n$$\\:E=\\frac{1}{2{B}_{D}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e8\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ8\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ8\" name=\"EquationSource\"\u003e\n$$\\:{q}_{e}={\\gamma\\:}_{T}In{K}_{T}+{\\gamma\\:}_{T}In{C}_{e}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e9\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ9\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ9\" name=\"EquationSource\"\u003e\n$$\\:In{(q}_{e}-{q}_{t})=In{q}_{e}+{K}_{1}t$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e10\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ10\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ10\" name=\"EquationSource\"\u003e\n$$\\:\\frac{t}{{q}_{t}}=\\frac{1}{{K}_{2}{q}_{e}^{2}}+\\frac{t}{{q}_{e}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e11\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ11\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ11\" name=\"EquationSource\"\u003e\n$$\\:{q}_{t}=\\alpha\\:+\\beta\\:Int$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e12\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere C\u003csub\u003eo\u003c/sub\u003e (mg/L) and C\u003csub\u003ee\u003c/sub\u003e (mg/L) are the initial and final concentrations of MB, respectively, q\u003csub\u003et\u003c/sub\u003e (mg/g) and q\u003csub\u003ee\u003c/sub\u003e (mg/g) are the amounts of MB adsorbed at time t (min) and equilibrium, respectively, K\u003csub\u003eL\u003c/sub\u003e (L/mg), K\u003csub\u003eF\u003c/sub\u003e (mg/g), and K\u003csub\u003eT\u003c/sub\u003e (L/g) indicate the affinity coefficient-related bonding terms, b (J/mol) is the Langmuir constant, n is a dimensionless exponent in the Freundlich equation, B\u003csub\u003eD\u003c/sub\u003e (mol\u003csup\u003e2\u003c/sup\u003e/J) is related to the free energy of adsorption per mole of adsorbate, q\u003csub\u003em\u003c/sub\u003e (mg/g) is the maximum theoretical monolayer saturation capacity, E (J/mol) is the apparent energy, R is the universal gas constant (8.3142 J/mol/K), T (K) is the absolute temperature, k\u003csub\u003e1\u003c/sub\u003e (min\u003csup\u003e\u0026ndash;1\u003c/sup\u003e) and k\u003csub\u003e2\u003c/sub\u003e (g/mg/min) are the first order and second order rate constants, respectively, α (mg/g/min) and β (g/mg) represent the constants related to the initial reaction rate and the activation energy, respectively.\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\u003eThe density of the bulk BTSP and Fenton-BTSP adsorbents are 0.68 and 0.72 g/cm\u003csup\u003e3\u003c/sup\u003e, respectively. The higher density of the Fenton-BTSP is probably due to the compact packing of iron that is present in the adsorbent. Elucidation of the adsorbents by FTIR revealed the presence of functional groups such as O-H, C\u0026thinsp;=\u0026thinsp;O, C-O, and C-N, as well as a Fe-O band at 568.23 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which was more pronounced in the Fenton-BTSP (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). After adsorption of MB dye, some of these absorption frequencies exhibited substantial shifts or disappeared completely and new bands appeared. FTIR spectrum of the dye-loaded adsorbents are attached as Supplementary Figures in the Supplementary Information (SF 2 for BTSP and SF 3 for Fenton-BTSP), suggesting a chemical interaction between the adsorbents and MB molecules (Namasivayam et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e1996\u003c/span\u003e; Babalola et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe pH-PZC of the surface of BTSP and Fenton-BTSP was found to be 5.548 and 7.655, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). The adsorbent is expected therefore, to acquire a positive surface charge below the pH-PZC in which the adsorption of anionic or acid dyes are enhanced, whereas above the pH-PZC, it acquires a negative surface charge thus favoring the adsorption of cationic or basic dyes. This indicates that the adsorption of MB, a cationic dye, should be optimum at a pH above the pH-PZC. Previous studies of MB have revealed that maximum adsorption was observed at a basic pH (Jawad et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Mpatani et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC shows the intensity-weighted size distribution of the adsorbent particles elucidated by DLS. The result showed different sizes of the adsorbents distributed mostly within the nanometer range. Both the BTSP and Fenton-BTSP showed similarity in their size distribution, which was averaged at ~\u0026thinsp;60 nm and 200 nm, with larger, less-intense aggregated particles appearing within the micrometer range. This indicates that the adsorbents have very small (nano) sizes, which is an important criterial in selecting an adsorbent.\u003c/p\u003e \u003cp\u003eThe scanning electron micrographs of the adsorbents at a magnification of 500x is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA-D. the micrograph shows agglomerated particles having irregular and rough surfaces with open pores and cavities. These cavities became loaded with MB dye (cloudy white patches) after adsorption (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB \u0026amp; D). The adsorbent particles contain elements such as C, Si, O, Al, K, Na, Ca, Mg, and Fe (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The amount of Fe present was greatly increased (~\u0026thinsp;10x) in the Fenton-BTSP adsorbent, confirming successful modification of the BTSP with the Fenton-like compound (FeOCl). Micrographs of the adsorbents in the presence or absence of MB obtained at higher magnifications are shown in the Supplementary Figures (SF 4 for BTSP and SF 5 for Fenton-BTSP).\u003c/p\u003e \u003cp\u003e \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\u003eElemental composition of BTSP and Fenton-BTSP adsorbents\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eBTSP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c8\" namest=\"c5\"\u003e \u003cp\u003eFenton-BTSP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eBefore adsorption\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eAfter adsorption\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eBefore adsorption\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003eAfter adsorption\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eElement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eComposition (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eElement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eComposition (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eElement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eComposition (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eElement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eComposition (%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarbon (C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCarbon (C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCarbon (C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e24.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eCarbon (C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e23.90\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOxygen (O)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOxygen (O)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e33.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOxygen (O)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e31.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eOxygen (O)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e30.61\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAluminium (Al)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAluminium (Al)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSilicon (Si)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e17.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSilicon (Si)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e20.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSilicon (Si)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSilicon (Si)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAluminium\u003c/p\u003e \u003cp\u003e(Al)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eAluminium\u003c/p\u003e \u003cp\u003e(Al)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e2.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalcium (Ca)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCalcium (Ca)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNitrogen(N)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNitrogen(N)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1.37\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSodium (Na)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSodium (Na)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePotassium (K)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003ePotassium (K)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.28\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMagnesium (Mg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMagnesium (Mg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eIron (Fe)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e22.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eIron (Fe)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e21.32\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIron (Fe)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIron (Fe)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Effect of different sorption conditions\u003c/h2\u003e \u003cp\u003eAdsorption conditions such as pH, adsorbent dosage, dye concentration, temperature, contact time, among others, can greatly influence the rate and mechanism of adsorption. The effect of pH, adsorbent dosage, dye concentration, and contact time is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. By varying the pH of MB, maximum adsorption was obtained at a pH of 10 for both adsorbents with adsorption capacities of 60.94 mg/g and 72.80 mg/g for BTSP and Fenton-BTSP, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA), indicating improved efficiency of the adsorbent after Fenton-like modification. This is consistent with previous reports (Lv et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Adsorption was minimum at pH 2 with adsorption capacity of 2.41 mg/g for BTSP and at pH 4 with an adsorption capacity of 0.98 mg/g for Fenton-BTSP. The low rate of adsorption of MB by the adsorbents at acidic pH may be due to high proton density, which leads to ionic repulsion between the positively charged MB dye and the surface of the adsorbent (Omorogie et al., 2022). This is consistent with the deductions made from our pH-PZC experiment, and with previous adsorption experiments on MB (Jawad et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Mpatani et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eVariation of adsorbent dosage from 10\u0026ndash;500 mg revealed a sharp decrease in adsorption capacity that is independent on Fenton modification. As the dose of the adsorbent increased from 10 mg to 500 mg, adsorption capacity witnessed a spontaneous decrease from 80.46 to 1.36 mg/g for BTSP and from 114.25 to 3.94 mg/g for Fenton-BTSP (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB). Such sharp decrease in adsorption capacity at increased dosage can be associated with increased clogging or aggregation of adsorbent particles, which lead to increased diffusion path for MB, resulting in a substantially low rate of adsorption (Asgher and Bhatti, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Babalola et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016a\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe result of varying concentrations of MB on the adsorption efficiency of BTSP and Fenton-BTSP is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC. As the concentration of MB increases from 25 mg/L to 500 mg/L, the adsorption capacity of the adsorbents experienced a corresponding increase from 14.65 to 277.41 mg/g for BTSP and from 23.76 to 343.25 mg/g for Fenton-BTSP. This increase in adsorption capacity with increasing dye concentration is higher for the Fenton-BTSP, indicating improved efficiency due to modification with FeOCl, and can be associated with increased mass transfer driving force as the concentration of the dye increased. Such increase in mass transfer enhances the adsorption of more dye molecules by the adsorbent (Asgher and Bhatti, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Babalola et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016a\u003c/span\u003e; Omorogie et al., 2022).\u003c/p\u003e \u003cp\u003eTo investigate the influence of adsorbent-dye contact time on the efficiency of adsorption, the time of adsorption was varied from 0.5 to 120 mins. The results (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eD) shows that the adsorption capacity of BTSP and Fenton-BTSP increased substantially with increasing contact time up to a level where equilibrium is reached. For both BTSP and Fenton-BTSP, adsorption was rapid for the first 30 mins after which further increase in contact time exerted no effect on the adsorption capacity of the adsorbents. This is probably because after 30 minutes, there are no cavities or unoccupied active surfaces available on the adsorbents for MB to occupy (Olatunde et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Although Fenton modification of the adsorbent did not affect the time it took the adsorbent to reach equilibrium, the adsorption capacity was, however, greater for Fenton-BTSP than for BTSP.\u003c/p\u003e \u003cp\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Desorption of MB from adsorbents\u003c/h2\u003e \u003cp\u003eRegeneration is an important factor in selecting adsorbents for wastewater management. In this study, the regeneration of BTSP and Fenton-BTSP was tested by agitating MB-loaded adsorbents with varying concentrations of organic and inorganic acids and bases for 30 mins. The desorption of MB from BTSP was maximum using an organic acid (acetic acid) at all operational concentrations, with 0.1 M acetic acid giving the highest yield of desorbed MB (21.18%) after 30 mins of agitation (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA). In the case of Fenton-BTSP, the inorganic acid, HNO\u003csub\u003e3\u003c/sub\u003e desorbed the highest amount of MB at all operational concentrations, with optimal desorption (46.24%) observed using only 0.01 M of the acid (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB). These findings are consistent with the results of our pH studies, and indicates that, counter ions from an acid are needed to remove the basic MB dyes adsorbed on the adsorbents. It is also worthy of mention that desorption of MB from the Fenton-BTSP was more efficient than from BTSP. As can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA\u0026amp;B, the lowest amount of MB desorbed from BTSP was 3.53% using 0.05 M KOH. In comparison, the lowest amount of MB desorbed from the Fenton-BTSP was 17.38% using 0.1 M of KOH. Overall, desorption of MB was at least 2-folds higher in Fenton-BTSP compared to BTSP. This indicates that modification of the adsorbent with the Fenton FeOCl improved not only its adsorption property but also its regeneration and reusability potential.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Adsorption isotherm and kinetics\u003c/h2\u003e \u003cp\u003eEquilibrium isotherm models such as the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models, were employed to explain the sorption process of MB onto BTSP and Fenton-BTSP. In all cases, the corelation coefficient (R\u003csup\u003e2\u003c/sup\u003e) was used to choose the best fit model. In the case of isotherm modelling, the experimental data revealed that the adsorption of MB onto BTSP probably followed the Temkin isotherm model, which has the highest correlation factor (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.6) and an equilibrium binding constant (γ\u003csub\u003eT\u003c/sub\u003e) of 41.85 L/mg (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This indicates that the heat of sorption of MB onto the surface of BTSP decreases linearly as the surface of the adsorbent is covered by the dye (Temkin and Pyzhev, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1940\u003c/span\u003e). The maximum monolayer adsorption capacity for BTSP revealed by Langmuir and Dubinin-Radushkevich models were 190.63 mg/g and 42.53 mg/g, respectively, with an apparent energy (E) of 2226.85 J/mol (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). For Fenton-BTSP, adsorption of MB followed the Freundlich isotherm model with a correlation coefficient that approaches unity (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.92) with an equilibrium binding constant (γ\u003csub\u003eT\u003c/sub\u003e) of 60.11 L/mg (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This suggests the formation of multiple layers of MB dye on the surface of the adsorbent improving its sorption capacity compared to the unmodified BTSP. The maximum monolayer adsorption capacity for Fenton-BTSP revealed by Langmuir and Dubinin-Radushkevich fittings were 520.83 mg/g and 158.71 mg/g, respectively, with an apparent energy (E) of 148.48 J/mol (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). These results further establish that modification of BTSP with FeOCl nanosheets indeed improved its maximum adsorption capacity, which is consistent with previous findings (Lv et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The isotherm model plots are shown in the Supplementary Figures (SF 6). When compared to other adsorbents used to sequester MB from aqueous solution (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), BTSP and Fenton-BTSP showed outstanding capacities in removing MB from wastewater, with Fenton-BTSP displaying the greatest potential.\u003c/p\u003e \u003cp\u003eAdsorption kinetics describe the rate at which adsorbates are captured by the surface of the adsorbents (Unuabonah et al., 2017b). This information can be used to describe the dynamics and mechanism of dye uptake by the adsorbent. Here, linear kinetics models such as pseudo-first order, pseudo-second order, and Elovich models, were employed to describe the dynamics of MB uptake by BTSP and Fenton-BTSP (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Kinetics modelling of the adsorption data revealed that the adsorption of MB onto BTSP and Fenton-BTSP could followed both pseudo-second order kinetics (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.98 for BTSP and 0.99 for Fenton-BTSP) and Elovich kinetics (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.94 for BTSP and 0.89 for Fenton-BTSP). However, the pseudo-second order model gave the best fit to experimental data as adjudged by the highest correlation factor (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e), indicating that the mechanism of adsorption of MB onto BTSP and Fenton-BTSP followed the chemisorption process, where the adsorption of MB by the adsorbents was controlled by electron transfer (Hosseini et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Adeniji et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Asgher and Bhatti, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Olu-Owolabi et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). The extremely low corelation coefficient factor from the pseudo-first order model (R2\u0026thinsp;=\u0026thinsp;0.026 for BTSP and 0.057 for Fenton-BTSP) suggests that the interaction between the MB dye and adsorbents is completely chemical and cannot be described by a physisorption mechanism. The kinetics model plots are shown in the Supplementary Figures (SF 7). The Elovich model revealed that the initial rate of adsorption of MB dye molecules onto the surface of the adsorbents experienced over 2-fold increase on modification with FeOCl. As can be seen in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the initial reaction rate (α) is 4.34 mg/g/min for BTSP and 11.98 mg/g/min for Fenton-BTSP. This further suggests that Fenton modification of adsorbents can be a potent way of improving their capacity for dye sequestration and wastewater management.\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\u003eLinear isotherm parameters for the adsorption of MB onto BTSP and Fenton-BTSP\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\u003eModel\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\u003eBTSP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFenton-BTSP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eLangmuir\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003em\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e190.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e520.83\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csub\u003eL\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eb\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.0011\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.010\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\u003e0.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.70\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\u003eK\u003csub\u003eF\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15.78\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1/n\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.56\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\u003e0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.92\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\u003eγ\u003csub\u003eT\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e60.11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eK\u003csub\u003eT\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.36\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\u003e0.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.64\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eDubinin-Radushkevich\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003em\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e158.71\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB\u003csub\u003eD\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.01E-07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.27E-05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2226.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e148.48\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\u003e0.011\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of adsorption capacities of some adsorbents on MB.\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\u003eAdsorbents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eModification\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eq\u003csub\u003em\u003c/sub\u003e (mg/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReferences\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRice straw\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e158.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eJawad et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2020\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCoconut leaf\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e112.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eJawad et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2016\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeanut hull\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e64.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLv et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePassion fruit waste\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e44.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePavan et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2008\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDragon fruit peels\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e192.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eJawad et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2018\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eBauhinia tomentosa\u003c/em\u003e seedpod (BTSP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e190.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eThis work\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFenton-like modified Peanut hull\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeOCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e132.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLv et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCitrate-modified sugarcane bagasse\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCitrate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e224.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMpatani et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSilica-modified Soya waste\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSilica\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e47.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBatool and Valiyaveettil, \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\u003eBase-modified pine corn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaOH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e33.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYagub et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2014\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAcid-modified defatted algae\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eChandra et al., 2016\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFenton-like modified \u003cem\u003eBauhinia tomentosa\u003c/em\u003e (Fenton-BTSP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeOCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e520.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eThis work\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\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLinear kinetics parameters for the adsorption of MB onto BTSP and Fenton-BTSP\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=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModel\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\u003eBTSP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFenton-BTSP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePseudo-first order\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eK\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.040\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.047\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003ee\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.73\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.026\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.057\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePseudo-second order\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eK\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.0046\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.0028\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003ee\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e26.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e71.74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eElovich\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eα\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e11.98\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eβ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e16.041\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.89\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"},{"header":"4. Conclusion","content":"\u003cp\u003eWe report an easy modification method for adsorbents for improved uptake of emerging pollutants from wastewater. This modification method, involving the Fenton-like chemical, FeOCl, improved the surface morphology, functional composition, and overall efficiency of a cost-effective and easy-to-get plant waste from \u003cem\u003eBauhinia tomentosa\u003c/em\u003e to rapidly remove methylene blue (MB) dye from water with a maximum adsorption capacity of 520.83 mg/g as compared to 190.63 mg/g obtained for the unmodified adsorbent. We discovered that although the adsorption equilibrium time was not affected by modification, the rate of the adsorption of MB was increased by over 2-folds due to the Fenton-like modification. The unmodified (BTSP) and Fenton-like modified (Fenton-BTSP) adsorbents responded at different extents to differences in solution pH, dye concentration, adsorbent dosage, and reaction time. In addition to an improvement in the adsorption capacity on modification, it also appears that the regeneration of the adsorbents was greatly improved after modification. Modification of BTSP with FeOCl improved its surface morphology and functional composition in such a way that allows uptake of multilayers of MB dye on its surface via a chemisorption process, which explains the basis for its improved efficiency. It is therefore recommended that adsorbents be modified with the Fenton-like agent, FeOCl, for improved capacity and reusability in wastewater management.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e \u003cb\u003eAuthor\u0026rsquo;s contribution\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eM.T. Agbadaola\u003c/em\u003e conceptualized the idea in this manuscript, supervised this work as part of D.A. Olatunji\u0026rsquo;s BSc research project, generated some of the results contained in this work at the Institute of Molecular Biosciences, Karl Franzens Universit\u0026auml;t, Graz, Austria, analyzed all the data, wrote the first manuscript, revised, and reviewed the manuscript. \u003cem\u003eD. A. Akinyemi\u003c/em\u003e co-supervised this work, revised and reviewed the manuscript. \u003cem\u003eD. A. Olatunji\u003c/em\u003e generated some of the data in this manuscript as part of her BSc research project. \u003cem\u003eJ. O. Babalola\u003c/em\u003e conceptualized the idea in this manuscript, revised and reviewed the manuscript. All authors approved the final manuscript for publication.\u003c/p\u003e\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe authors declare that there are no conflicts of interest.\u0026nbsp;\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eNo funding was received for conducting this study.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e \u003cp\u003e \u003cem\u003eM. T. Agbadaola\u003c/em\u003e acknowledges Prof. Sandro Keller at the Institute of Molecular Biosciences, Karl Franzens Universit\u0026auml;t, Graz, Austria, for allowing him to use his laboratory facility to generate some of the results that make up this manuscript.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eAll data used to produce this manuscript will be made available upon request to the corresponding author.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAdeniji EA, Abodunrin TO, Ogunnupebi TA, Koiki BA, Olatunde AM, Omorogie MO (2019) Surface Separation Equilibria and Dynamics of Cationic Dye Loaded onto Citric Acid and Sodium Hydroxide Treated Eggshells. 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Desalination Water Treat 189:386\u0026ndash;394. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5004/dwt.2020.25566\u003c/span\u003e\u003cspan address=\"10.5004/dwt.2020.25566\" 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":true,"hideJournal":true,"highlight":"","institution":"Dominion University, Ibadan, Nigeria","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":"Adsorption, emerging contaminants, methylene blue, Fenton-like modification, Bauhinia tomentosa","lastPublishedDoi":"10.21203/rs.3.rs-5856675/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5856675/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWater pollution by dyes remain an important problem that constantly reduces water quality, creating hazard to aquatic flora and fauna, as well as terrestrial life. Although adsorption has been a favourite technique exploited to remediate this growing menace due to its cost-effectiveness and environmental friendliness, adsorbents remain limited in their capacity to efficiently remove emerging dye contaminants from wastewater. In this work, we present an efficient method to improve the sequestration of an emerging contaminant, methylene blue dye (MB), from water through Fenton-like modification of adsorbents. Low-cost and readily-available \u003cem\u003eBauhinia tomentosa\u003c/em\u003e seedpod (BTSP) was modified with recyclable FeOCl nanosheets to produce Fenton-BTSP adsorbents. The modified and unmodified adsorbents were characterized using Fourier-transform infrared spectroscopy, dynamic light scattering, energy dispersive X-Ray, and scanning electron microscopy. Results showed successful modification of BTSP to form fine agglomerated particles with enhanced surface areas and pore spaces. Adsorption studies revealed optimal adsorption at pH 10, with equilibrium reached in 30 mins for the adsorbents. Isotherm modelling of the adsorption data suggests formation of multiple layers of MB molecules on the adsorbents at maximum monolayer capacity of 190.63 mg/g and 520.83 mg/g for BTSP and Fenton-BTSP, respectively. Kinetics modelling revealed chemical interaction between the adsorbents and dye molecules at a rate that is higher for Fenton-BTSP. Adsorbent regeneration was also improved after Fenton-like modification, contributing to the potential of Fenton-BTSP for industrial applications.\u003c/p\u003e","manuscriptTitle":"Fenton-like modification of Bauhinia tomentosa seedpod for improved sequestration of methylene blue from water","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-22 08:40:19","doi":"10.21203/rs.3.rs-5856675/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":"d4545355-ff6f-4bd1-9140-4f7e683170ce","owner":[],"postedDate":"January 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":43070618,"name":"Physical Chemistry"}],"tags":[],"updatedAt":"2025-01-22T08:40:19+00:00","versionOfRecord":[],"versionCreatedAt":"2025-01-22 08:40:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5856675","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5856675","identity":"rs-5856675","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}