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Sr2Mg(BO3)2 was prepared by a solution combustion method at 900 °C for 6 hour in air. The prepared adsorbent was characterized by X-Ray Diffraction (XRD). The XRD pattern of Sr2Mg(BO3)2 is in agreement with the ICDD File No: 01-076-9795. The particle morphology of the adsorbent was investigated by scanning electron microscope (SEM). The average size of particles is about 3–10 µm. The Congo red dye was removed from aqueous solution using Sr2Mg(BO3)2. The effect of time, initial concentration, pH, temperature and dosage on adsorption were investigated. The Freundlich model fitted according to equilibrium data and maximum adsorption capacity is 886.952 mg/g. According to theories of pseudo-second-order kinetics, the removal procedure involves chemical adsorption. According to the thermodynamic data, negative ΔG values indicated that adsorption of Sr2Mg(BO3)2 occurred spontaneously and negative ΔH values, the adsorption process was exothermic. Sr2Mg(BO3)2 is a useable material for Congo red dye removal. [ABSTRACT FROM AUTHOR]

BACKGROUND: Adsorption is a widely used technique for separating impurities in various industries. This method offers flexibility in design and operation and results in the production of high‐quality purified wastewater. This experimental research investigates the effectiveness of carbon‐based adsorbents, such as graphene, graphene oxide and carbon dots, in removing impurities and increasing hydrogen peroxide concentration through adsorption. RESULTS: Various characterization techniques were used to investigate each adsorbent's chemical properties and surface morphology, including Fourier transform infrared spectroscopy, X‐ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and Brunauer–Emmett–Teller analysis. According to adsorption tests under the defined conditions, the synthesized graphene showed the highest efficiency in impurities removal from hydrogen peroxide, with purity level of 45%. Graphene showed higher efficiency than graphene oxide and carbon dot samples, with a purity of 36% and 32%, respectively. Various factors, such as time, temperature and adsorbent dosage, were investigated at different stages of the experiments. The results show that the adsorption of impurities on carbon‐based adsorbents is an exothermic process. CONCLUSION: It was shown that graphene structure results in an adsorption capacity of up to 147.06 mg g−1, which was increased by 45% in comparison to graphene oxide and carbon dot as adsorbents. To gain further insights, isothermal and kinetic experiments on the adsorption of hydrogen peroxide were performed. The results indicate compliance with the Freundlich isotherm, suggesting multilayer adsorption and pseudo‐second‐order kinetics. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The advancement in industrial and agricultural activities and the discharge of improperly treated effluent increase the pollution load on the environment. In this regard, organic contamination has posed a severe concern; among various organic pollutants, phenol is a highly toxic pollutant. For the adsorption of phenol, a low-cost activated carbon (AC) was prepared from fox nutshell using H3PO4 as an activating agent in a N2 atmosphere. Fox nutshell is an agricultural waste containing only 5% ash content, which is beneficial for the adsorption of phenol. The optimum conditions used for preparing AC were: 1 h of carbonization time, 700 oC of carbonization temperature, and a 3:1 impregnation ratio. The prepared AC is named ACPA-700-1.5. The physicochemical properties of prepared ACPA-700-1.5 were: yield 30.38%, average pore diameter 2.32 nm, pore volume 1.53 cm3/g, and surface area 2636 m2/g. Finally, batch and fixed-bed column adsorption tests were performed using ACPA-700-1.5. The best-fitting isotherm model was the Freundlich isotherm model, indicating heterogeneous adsorption. Pseudo-second-order was the best-fitting kinetics model. The results showed that the prepared ACPA-700-1.5 exhibited a maximum capacity of 101.83 mg/g. The column adsorption study showed that a lower flow rate and a higher bed height were suitable for maximum adsorption performance. The maximum bed capacity of 75.64 mg/g was achieved at a bed height of 4 cm and a flow rate of 5 mL/min. Given its high adsorption capacity and extremely fast adsorption rate, ACPA-700-1.5 is a promising adsorbent for removing phenolic contaminants from wastewater. [ABSTRACT FROM AUTHOR]

Rapid industrialisation has led to severe environmental pollution, mainly due to the discharge of organic pollutants into the waterbodies. The removal of organic compounds such as dyes and phenolic pollutants from the industrial effluents before it is discharged should be the top priority. This article synthesised a novel chitosan cross-linked polyaniline grafted graphene oxide (CS-PANI@GO) composite with variable morphology, enhanced surface area, low cost, biocompatibility, and notable characteristics of high malachite green (MG) and phenol adsorption capacity. The physicochemical properties of CS-PANI@GO were studied by FESEM, FTIR, XRD, RAMAN, BET, and BJH pore size distribution. FESEM analysis demonstrated that the surface of CS-PANI@GO composite is porous in nature. The BET surface area of the composite is 88.91 m2/g. The effect of various parameters such as temperature, pH of the solution, initial concentration of MG and phenol, adsorption time, and dosage were investigated, and the optimal values were recorded. The adsorption performance of CS-PANI@GO composite for both MG and phenol follows the pseudo-second-order model suggests chemisorption occurs in the process. For MG dye, the adsorption equilibrium data follows the Freundlich model and for phenol, the data follows the Langmuir model. The maximum uptake for MG dye and phenol were 699.022 mg/g and 198.254 mg/g, respectively. Thermodynamic data demonstrated that the process of MG and phenol adsorption was spontaneous, endothermic, and feasible. The recyclability study shows that after five cycles of regeneration, the composite has excellent adsorption performance. The adsorption mechanism is also proposed to be hydrogen bond, π-π interaction, and electrostatic attraction. Based on the present adsorption results under various parameter conditions, the synthesised novel CS-PANI@GO composite could be applied as an efficient adsorbent for the treatment of dyes and phenolic pollutants from wastewater. [ABSTRACT FROM AUTHOR]

Understanding of dicofol's behavior in soil is crucial for more precise pest control and minimal environmental effect. Therefore, the goal of this study was to assess how the physicochemical characteristics of 10 selected soils effects the sorption and degradation of dicofol behavior. The behavior of dicofol, including its adsorption and desorption properties as well as its rates of hydrolysis and photolysis degradation, was thoroughly examined via definitive studies. Standard batch equilibration mode for sorption revealed that it was dependent on the physical and chemical properties of the soil. Exothermic and spontaneous adsorption processes, which were characterized by a negative Gibbs free energy value, were convincingly proven by thermodynamic study. The current investigation's ΔG estimations varied from −18.6 kjmol−1 for soil-6 to −24.25 kjmol−1 for soil-9. The soil-7 with a notable organic matter content (1.81%) showed the maximum adsorption, and subsequently producing a C-type isotherm that was analyzed using a linear and Freundlich model. An analytical process using UV-VIS spectrophotometry to determine the fate of dicofol in soil matrices. Hydrolysis and photolysis studies yielded minimum half-lives of 13.4 and 1.32 days, respectively. It has been demonstrated that dicofol molecules interact strongly with soils, principally via physio-sorption mechanisms. In contrast to its strong soil affinity and permanence, dicofol exhibits a counterintuitive behavior that makes it vulnerable to sunlight-induced deterioration. Future studies will concentrate on enhancing these pathways to assist sustainable pesticide management strategies and creative pollution mitigation techniques. [ABSTRACT FROM AUTHOR]

This study explores the adsorption potential of hydrothermally treated waste derived algal biomass for removing methylene blue (MB) dye. Synthesizing a modified hydrochar through hydrothermal carbonization (150°C, 35 bar) followed by NaOH modification, we observed enhanced thermal stability and distinctive chemical changes. Optimal conditions were determined at pH 6 and 1 h contact time. Soluble salts with cations were identified as impacting adsorption efficiency, with increased interference for higher cation charges. Thermodynamic parameters (ΔG, ΔH, and ΔS) indicated a spontaneous and exothermic process, the calculated values (−5.417 to −6.907 kJ mol−1, −29.0 kJ mol−1, −73.8 J K−1 mol−1) aligned with this behavior. Adsorption isotherms favored the Freundlich model, revealing heterogeneous multilayer adsorption, with a maximum capacity of 97%. Kinetic studies supported the pseudo‐first‐order model. This detailed exploration provides insights into thermodynamics, kinetics, and the impact of adsorption parameters on MB removal, emphasizing the practicality of alkaline‐modified hydrochar as an effective, sustainable adsorbent. [ABSTRACT FROM AUTHOR]

Abstract Layered double hydroxides (LDH) are compounds with unique structures of hydroxide functional groups on their surfaces, and they have the proper arrangement of divalent and trivalent cations to adjust their unique catalytic actions. LDH was synthesized utilizing the co-precipitation technique and was thermally treated at 300 °C. The prepared compounds were chemically and structurally elucidated using FT-IR, XRD, SEM, BET, TG-DTA, and XPS characterization. We found that the thermal treatment of the prepared magnesium/nickel-LDH resulted in dehydration and dehydroxylation in its chemical structure. The crystallinity, the surface area, and the pore volume of the formed meso- and micropores were improved considerably after the thermal treatment. The efficiency of the uptake process was increased from 84 to 97% after the thermal treatment process, and the adsorption process tracked the Freundlich adsorption isotherm and pseudo-second-order kinetic model. The kinetics indicated the occurrence of three stages, and the diffusion of dye molecules into the pores was the rate-determining step. Different real water sample treatments showed the applicability of the thermally treated Mg/Ni/Al-LDH in the treatment process under optimized conditions. The presented mechanism of the uptake process using the prepared compounds comprises several interactions between the dye molecules and the thermally treated Mg/Ni/Al-LDH. The study presented the new application for Mg/Ni/Al-LDH in the as-prepared and thermally treated forms to uptake Congo-red (CR) dye from textile effluents.

This study investigates the removal of Congo red dye from aqueous solution using functionalized generation 3.0 and 5.0 Polyamidoamine dendrimer – silica gel composite (G-3PS, G-5PS). Fourier Transform-Infra Red spectroscopy, Brunauer Emmett and Teller, Thermogravimetric Analysis, pH at point of zero charge, and Scanning Electron Microscopy measurements have been applied to characterize the synthetic nanohybride composite, these techniques revealed the successful functionalization of both dendrimer molecules and subsequent immobilization onto silica gel. The implications of varying adsorption parameters such as contact time, initial concentration of adsorbate, temperature and pH on both composites were studied. Experimental data obtained from batch adsorption processes were fitted into two equilibrium isotherms (Langmuir and Freundlich) and 3 kinetic models (Pseudo-First-Order, Pseudo-Second-Order, Intra Particle Diffusion). Adsorption mechanism was mainly governed by film diffusion due to electrostatic interactions between the functionalized dendrimer surface and Congo red molecules. Thermodynamic parameters illustrate that the adsorption is endothermic and spontaneous. Findings suggest the Nanocomposites G-3PS G-5PS) are good adsorbents for the removal of Congo red dye from aqueous solutions. [ABSTRACT FROM AUTHOR]

Industrial wastewater discharge, tainted with hazardous substances, including dyes like methylene blue (MB) from the textile sector, further emphasizes the need for water treatment to produce safe drinking water. This study explores the potential of olive mill solid waste, an abundant and cost-effective agricultural waste in Mediterranean regions, to yield high-quality activated carbon (AC) with zinc chloride activation for MB adsorption. The activation process, carried out at a modest temperature of 500 °C without the need for an inert atmosphere, resulted in AC with remarkable characteristics, boasting a substantial surface area of 1184 cm2·g−1 and a total pore volume of 0.824 cm3·g−1. Extensive characterization of the AC was carried out through a large range of surface techniques. The pH of the solution had minimal influence on MB adsorption, the maximum removal was 95%, which was under slightly acidic pH conditions (5.8), and the adsorbent dose was 0.4 g·L−1 for a 50 mg·L−1 MB concentration. Equilibrium data pertaining to MB adsorption were subjected to fitting with different models, namely Langmuir, Freundlich, and Temkin. Notably, the Langmuir model exhibited the best fit, revealing a maximum monolayer adsorption capacity of 500 mg·g−1 at 25 °C, and the adsorption kinetics closely followed a pseudo-second-order model. [ABSTRACT FROM AUTHOR]

Toxic metal wastewater is a challenge for exposed terrestrial and aquatic environments, as well as the recyclability of the water, prompting inputs for the development of promising treatment methods. Consequently, the rGO/ZnONP nanocomposite was synthesized at room temperature for four hours and was tested for the adsorption of cadmium and lead in wastewater. The optimized nanocomposite had the lowest band gap energy (2.69 eV), and functional group interactions were at 516, 1220, 1732, 3009, and 3460 cm−1. The nanocomposite showed good ZnO nanoparticle size distribution and separation on rGO surfaces. The nanocomposite's D and G band intensities were almost the same, constituting the ZnO presence on rGO from the Raman spectrum. The adsorption equilibrium time for cadmium and lead was reached within 10 and 90 min with efficiencies of ~100%. Sips and Freundlich best fitted the cadmium and lead adsorption data (R2 ~ 1); therefore, the adsorption was a multilayer coverage for lead and a mixture of heterogenous and homogenous coverage for cadmium adsorption. Both adsorptions were best fitted by the pseudo-first-order model, suggesting the multilayer coverage dominance. The adsorbent was reused for three and seven times for cadmium and lead. The nanocomposite showed selectivity towards lead (95%) and cadmium (100%) in the interfering wastewater matrix. Conclusively, the nanocomposite may be embedded within upcoming lab-scale treatment plants, which could lead to further upscaling and it serving as an industrial wastewater treatment material. [ABSTRACT FROM AUTHOR]

The bentonite clay has been activated by acid treatment and utilized as a lower‐cost and eco‐friendly adsorbent required to remove Fast Green FCF dye from the aqueous solution. At first acid activated bentonite clay minerals were analyzed by various analytical techniques like Fourier Transform Infrared Spectroscopy (FTIR), x‐ray diffraction (XRD), and x‐ray fluorescence (XRF) analysis. The batch adsorption research was performed to investigate the Fast Green FCF dye adsorption onto the acid‐treated (Bent) bentonite clay. Sorption studies investigated the impacts of adsorbent dosage, initial pH, and time of contact on Fast Green FCF color elimination. The adsorption capacity decreased as the pH was above 7 and then remained almost the same after a pH value of 9. At acidic conditions (below pH value 7), the capacity of adsorption diminished by a decrease in the pH of the solution. The results indicated that the maximum capacity of adsorption has been obtained at an adsorbent dosage of 0.1 g. As the dosage of the adsorbent was improved, several active sites that were available at the time of the dye adsorption increased. As a result, the dye percentage that was removed from the clay increased. Besides these, adsorption kinetics, adsorption equilibrium isotherm, and thermodynamics studies have been also conducted. While studying the adsorption kinetics pseudo‐2nd‐order kinetics has been seen to be more appropriate as compared to pseudo‐1st‐order model. The experimental findings indicated that the attachment of the dye to the clay surface followed the "Langmuir adsorption" isotherm rather than the Freundlich adsorption isotherm with a monolayer coverage of 18.93 mg/g. From the thermodynamics study, it was revealed that the process of adsorption takes place instantly at high temperatures. [ABSTRACT FROM AUTHOR]

Chlorophenols are one of the major organic pollutants responsible for the contamination of water bodies. This study explores the application of Ni-Zn/CeO2 nanocomposites, synthesized via the aqueous co-precipitation method, as effective adsorbents for the 4-chlorophenol removal from aqueous solutions. The nanocomposites' chemical and structural characteristics were assessed using different physical characterization methods, viz. X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, zeta potential, using a Box-Behnken design within response surface methodology, optimal conditions of pH 3, temperature 20 °C, contact time 120 min, adsorbent dosage 0.05 g, and 4-chlorophenol concentration 50 ppm are identified. Among the nanocomposites tested, NZC 20:10:70, with 20% Ni and 10% Zn, achieves enhanced performance, removing 99.1% of 4-chlorophenol within 2 h. Adsorption kinetics follow the pseudo-second-order model and equilibrium data fit the Freundlich isotherm. Thermodynamic analysis indicates an exothermic and spontaneous process. The adsorption capacity of NZC 20:10:70 shows significant enhancement, growing from 19.85 mg/g at 10 ppm to 96.33 mg/g at 50 ppm initial concentration. Physical characterization confirms NZC 20:10:70's superior properties, including a high surface area of 118.471 m2/g. Evaluating economic viability, NZC 20:10:70 demonstrates robust reusability, retaining 85% efficiency over eight regeneration cycles. These results highlight NZC 20:10:70 as a promising adsorbent for effective and sustainable chlorophenol removal in water treatment. [ABSTRACT FROM AUTHOR]

Abstract Andesite was employed to effectively extract mercury(II) in an aqueous solution. After evaluating its characteristics, andesite was characterized by applying modern techniques such as BET and TGA methods. The study employed SEM and TEM measurements to analyze the variation in the surface shape and crystallinity of the metal due to adsorption. Using the EDX process, the chemical composition, weight, and atomic percentage of each element of andesite were determined. FTIR techniques were also used to confirm the TEM–EDX findings. Zeta potential was estimated. Cycles of regeneration and desorption have been examined. 99.03% was the highest uptake percentage. Adsorbent quantity (0.0025–0.05) g/L, contact time (5–60) min, pH (2–10), temperature (25–60) °C, and dose (0.0027, 0.0044, 0.0125, 0.0155, and 0.0399) mg/L all affect the amount of removal that increases with the increase in contact time, pH, dose, and temperature but drops as the metal ion concentration rises. The ideal values for contact time, pH, metal ion concentration, dose, and temperature were found to be, respectively, 30 min, 0.0155 mg/l, 0.02 g/l, and 40 °C. The calculation of thermodynamic parameters, including ΔH, ΔG, and ΔS, was imperative in establishing that the mechanism of heavy metal adsorption on andesite was endothermic, exhibiting a physical nature that escalated with temperature rise. The Freundlich adsorption equation's linear form is matched by the adsorption of mercury(II) on andesite; constant n was 1.85, 1.06, 1.1, and 1.1, whereas the Langmuir constant qm was found to be 1.85, 2.41, 3.54, and 2.28 mg/g at 25–60 °C. Furthermore, adsorption follows a pseudo-second-order rate constant of (3.08, 3.24, 3.24, and 13) g/mg/min under identical temperature conditions, as opposed to a first-order rate constant of 4, 3, 2.6, and 2. Hg2+, NH4 +, Cl−, Br−, NO3 −, SO4 2−, Na+, K+, H2S, and CH3SH were all extracted from wastewater by this application.

Andesite was employed to effectively extract mercury(II) in an aqueous solution. After evaluating its characteristics, andesite was characterized by applying modern techniques such as BET and TGA methods. The study employed SEM and TEM measurements to analyze the variation in the surface shape and crystallinity of the metal due to adsorption. Using the EDX process, the chemical composition, weight, and atomic percentage of each element of andesite were determined. FTIR techniques were also used to confirm the TEM–EDX findings. Zeta potential was estimated. Cycles of regeneration and desorption have been examined. 99.03% was the highest uptake percentage. Adsorbent quantity (0.0025–0.05) g/L, contact time (5–60) min, pH (2–10), temperature (25–60) °C, and dose (0.0027, 0.0044, 0.0125, 0.0155, and 0.0399) mg/L all affect the amount of removal that increases with the increase in contact time, pH, dose, and temperature but drops as the metal ion concentration rises. The ideal values for contact time, pH, metal ion concentration, dose, and temperature were found to be, respectively, 30 min, 0.0155 mg/l, 0.02 g/l, and 40 °C. The calculation of thermodynamic parameters, including ΔH, ΔG, and ΔS, was imperative in establishing that the mechanism of heavy metal adsorption on andesite was endothermic, exhibiting a physical nature that escalated with temperature rise. The Freundlich adsorption equation's linear form is matched by the adsorption of mercury(II) on andesite; constant n was 1.85, 1.06, 1.1, and 1.1, whereas the Langmuir constant qm was found to be 1.85, 2.41, 3.54, and 2.28 mg/g at 25–60 °C. Furthermore, adsorption follows a pseudo-second-order rate constant of (3.08, 3.24, 3.24, and 13) g/mg/min under identical temperature conditions, as opposed to a first-order rate constant of 4, 3, 2.6, and 2. Hg2+, NH4+, Cl−, Br−, NO3−, SO42−, Na+, K+, H2S, and CH3SH were all extracted from wastewater by this application. [ABSTRACT FROM AUTHOR]

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High rainfall areas suffer from severe leaching loss of sulfate owing to their negatively charged nature. Sorption of sulfur (S) onto soil particles protect it from leaching out of the system. The S-sorption characteristics in humid soils from north-eastern India was studied with the objective to identify factors controlling S-sorption behavior in these acidic soils. Soils were collected from six different locations of north-eastern India. The soils were equilibrated with increasing concentrations of S for the sorption study, and later equilibrated with 0.01 N CaCl2 for desorption study. Results were fitted to three different isotherm models (Freundlich, Langmuir and Tempkin). The data fitted well to all three isotherm models. However, Freundlich adsorption isotherm yielded the best fit. Sorption parameters like S-sorption maxima (k), bonding energy (b), adsorption capacity (K), bonding energy constant (A) were positively correlated with the clay and, crystalline iron (Fe) and aluminum (Al) content in soil. Supply parameter increased with the increasing concentration of sulfate, while equilibrium buffering capacity was found decreasing. Soils from Nongpoh and Mustem with higher clay and crystalline Fe and Al content exhibited higher S-sorption capacity, whereas those of Padu having lowest clay content reported least S-sorption. It is recommended that in a soil having low S-sorption capacity, the minimal amount of S should be applied at a time. [ABSTRACT FROM AUTHOR]

RESUMO Este trabalho teve por objetivos avaliar que parâmetros obtidos dos modelos de isotermas de Freundlich e Langmüir melhor refletem a adsorção de Pb, Cu e Zn em solos intemperizados e identificar a relação entre os parâmetros selecionados e os atributos químicos e físicos das doze classes de solos mais representativas do Brasil. Os locais de coleta foram os mais abrangentes possíveis, englobando “pedons“ das regiões Sul, Sudeste e Norte do país. Avaliou-se, através da análise de trilha o desdobramento do coeficiente de correlação entre variáveis dependentes obtidas através das isotermas de adsorção (parâmetros de adsorção) e variáveis independentes (atributos químicos e físicos do solo), em efeitos diretos e indiretos para os elementos Pb, Cu e Zn. Os atributos do solo: argila (ARG); carbono orgânico (Corg.); capacidade de troca catiônica efetiva (CTCE); ferro citrato ditionito-bicarbonato (FeD); teor de alumínio total (Al2O3), foram os que apresentaram maiores coeficientes de correlação simples com os parâmetros de adsorção e foram utilizados no modelo da análise de trilha para explicar adsorção de metais pesados. As principais conclusões deste trabalho foram: a análise de trilha mostrou-se como uma ferramenta importante no estudo do comportamento dos metais pesados no solo; a constante KF (constante da equação de Freundlich) para todos os elementos apresentou o coeficiente de determinação mais elevado e o menor valor do efeito da variável residual e, as variáveis que mais contribuíram com a adsorção de metais pesados foram Corg., CTCE, pH, ARG e Al2O3.

Herein a novel gum acacia‐alginate nanogel (GAA) was synthesized via ultrasound‐assisted crosslinking by DPPH and applied for the removal of coomassie brilliant blue (CBB) dye. The fabrication of GAA and its interaction with CBB was specified via FTIR, XRD, SEM, and TEM techniques. The process parameters at which maximum adsorption efficiency, qe (80.12 mg/g), and % efficiency >94 % were achieved include dosage (0.8 g/L), time (80 min), initial dye concentration (20 mg/L), and pH (6). Ultrasound‐assisted uptake was greater than stirring‐assisted due to acoustic cavitation′s hydrodynamic and thermal processes. Pseudo‐second‐order model described the adsorption kinetics and the diffusion mechanism suggested that the rate‐determining step was controlled by both the intraparticle diffusion and the liquid film models. Isotherms showed an excellent fit to the Freundlich model based on higher R2 (0.998) and lower standard error of estimate values (SEE=0.367). The −ΔG° values (−8.152, −8.292, −8.433, −8.586 kJ/mol) indicated that the adsorption process was feasible and spontaneous. The removal of CBB ensued via hydrogen bonding, electrostatic, π‐π, and n‐π interactions. The maximum adsorption capacity of 182.096 mg/g, eco‐friendly characteristics along with regeneration competence depicted that GAA could be effective for scavenging CBB from wastewater. [ABSTRACT FROM AUTHOR]

Today, increasing dyes pollution is of great importance for life. Leaving the dyes used in industries such as textiles without being discharged pollutes other water sources. In order to prevent this, different methods are used in the literature. In this study, SrAl2B2O7, a borate metal, was used to remove methyl blue (MB), an anionic dye, by batch adsorption method. Strontium aluminoborate (SrAl2B2O7) was prepared using a solution combustion method at 950 °C for 4 h in air. The prepared adsorbent was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The particle morphology of the adsorbent was investigated using scanning electron microscope (SEM). By using N2 adsorption–desorption, the Brunnauer, Emmet, and Teller (BET) specific surface area was found to be 1.9578 m2 g−1. The surface charge of the dye-adsorbed SrAl2B2O7 was determined based on zeta-potential measurements. Langmuir (R2=0.9897), Freundlich (R2=0.985), Dubinin & Radushkevic (R2=0.976), Scatchard (R2=0.881), Temkin & Pyzhev (R2=0.978) isotherms were calculated in the study. SrAl2B2O7 showed good adsorption performance for methyl blue (MB) with maximum adsorption capacities of 29.069 mg g−1 (Langmuir). Adsorption processes were also studied in detail. Thermodynamic and kinetic models; pseudo-first-order (R2=0.415), pseudo-second-order (R2=0.999), Elovich (R2=0.968) showed that adsorption using SrAl2B2O7 in MB removal is endothermic and pseudo-second order. [ABSTRACT FROM AUTHOR]

AbstractThe adsorption performance of 2-mercaptobenzothiazole from an aqueous solution on activated carbon synthesized through grape marc was explored. In this research, the agricultural waste was chemically treated with phosphoric acid (40% H3PO4, 170 °C, 3 h), then pyrolyzed at 650 °C for 2 h, to obtain the GMAC-650 to be used as an adsorbent. The resulting material was characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, and Brunauer–Emmett–Teller (BET). Maximum uptake (∼99%) is obtained under ideal conditions: an adsorbent dose of 0.8 g L−1 and pH = 8 for an initial concentration of 10 mg L−1 at 45 °C. The adsorption equilibrium data were fitted to the following isotherm models: Langmuir and Freundlich. For optimal equilibrium isotherm selection, a comparison of linear and non-linear methods for the adsorption of MBT. It was based on four error functions: the coefficient of determination R2, the sum of squared errors, the Chi-square (χ2), and the root mean square error. The current work has shown that the non-linear method is a more adequate method for estimating the parameters of the isotherm compared with the linear method. The comparative analysis of the models shows that the Freundlich model is more appropriate for describing equilibrium data. [ABSTRACT FROM AUTHOR]

AbstractIn the study, the removal of dye (methyl blue) from aqueous solutions by batch/agitation adsorption method was investigated using Pinus brutia (PB). For this purpose, first, PB wood was collected and made into wood chips (PB), and then Pinus brutia biochar (PBB) was made. The PBB was modified to gain nano-magnetic properties. The biochar structure was characterized by FT-IR. PBB and nM-PBB were used for the removal of MB dye. The adsorbent amount, temperature, pH, time and dye concentration were investigated in the adsorption process with adsorption isotherms, kinetics and thermodynamics to estimate their MB removal efficiency. Sorption equilibrium for MB dye was reached by nM-PBB within 60 min and adsorption efficiency up to 99.007% was reached. While the adsorption kinetics followed a pseudo-second-order kinetic model, the Langmuir isotherm model, with a maximum adsorption capacity of 107.527 mg/g (nM-PBB), showed homogeneous physiochemical adsorption. The efficiency was found to be a spontaneous endothermic reaction. It can be suggested that nM-PBB can be used to remove MB. [ABSTRACT FROM AUTHOR]

The survey of protein adsorption is important due to the significant application of proteins in food, medicine, biotechnology, environment, and separation science. Therefore, in the current investigation, the adsorption of bovine serum albumin (BSA) onto a functionalized mesoporous (MCM-41) using layered double hydroxide (MCM-41@LDH) was investigated under different conditions such as the amount of adsorbent, pH of the solution, contact time, and protein concentration. The optimization process was carried out using central composite design (CCD). After the characterization of the modified mesoporous, more investigations were conducted to assess the adsorption of BSA onto MCM-41@LDH, including adsorption isotherm, kinetics, and thermodynamics. It was revealed that Freundlich isotherm and secondorder kinetics provided the best fit for support of MCM-41@LDH. The values of Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were determined as -3100.47 kJ mol-1 K-1 (at 298.15 K), -3101.12 kJ mol-1, and -0.002 kJ mol-1, respectively. According to CCD analysis and desirability function of 1.0, the optimal conditions for BSA adsorption were determined to be a pH value of 4.50, BSA concentration of 250 mg l-1, support amount of 0.016 g, and contact time of 55 min. The obtained findings can be used for purification, separation, and removal of BSA from complex samples. [ABSTRACT FROM AUTHOR]

Adsorption has been traditionally modeled using equilibrium models like the Langmuir and the Freundlich isotherm models, and kinetic models such as pseudo-first and pseudo-second order equations. However, most of these equations are not in an Indepedant, and single-equation form. A novel mathematical framework that combines adsorption kinetics and isotherm equations to an independant, single-equation form is presented herin. The adsorption isotherm equations were first solved using the mass balance equations to derive an independant equation, eliminating the intermediate variables. This derivation was done for the commonly used adsorption isotherms such as Langmuir, Freundlich, Langmuir-Freundlich and Linear isotherms. The simplified equations can be used for predicting solid phase adsorption (qe) and aqueous phase concentration (Ce) in terms of equilibrium constants, and was called as Equilibrium Adsorption Solution Equation (EASE). This EASE equation was further integrated into adsorption kinetic equations to give a solution which can also predict kinetic adsorption. This framework was named as Combined Adsorption Kinetic and Equilibrium (CAKE) equation and was further validated with experimental data. The CAKE equation offers the following advantages: By using this combined equation, both the kinetics and equilibrium concentrations of the batch adsorption systems can be predicted. Further, the intermediate variables are eliminated, and the final equation involving only model constants such as maximum adsorption capacity (qmax), affinity constant (ka), initial concentration (Co), and kinetic rate constants (kt) are required to to calculate pollutant concentration at any given time. The model was validated using an experimental dataset of 2,4-Dichlorophenol adsorption studies on activated carbon. The CAKE and EASE models fitted the experimental datasets very well with an R2 of 0.85, and a normalized absolute percentage error (NAPE) of 7.5%., thus validating the developed equations. [ABSTRACT FROM AUTHOR]

The presence of sulfur in transportation fuels has bad consequences for health and the environment, and there are many techniques used for removing or eliminating sulfur content, especially hydrodesulfurization. Hydrodesulfurization is the classical technique for desulfurization, but it is characterized by working at elevated temperatures and pressures as well as high costs. For this, there are many alternative methods, such as adsorptive, oxidative, extractive, and so on. The adsorptive desulfurization (ADS) is one of the most promising methods for sulfur reduction because of its ability to work under ambient conditions and ADS can significantly enhance the quality of light naphtha by reducing its sulfur content and improving its suitability for downstream processes such as catalyst poisoning and corrosion. The calcite prepared from eggshell was investigated here as an adsorbent for sulfur compounds from light naphtha. The adsorbent was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The investigation of adsorbent activity was done by batch adsorption, and the chosen studied variables are temperature, adsorbent dosage, and contact time with ranges of 20–40 C°, 1–3 g, and 15–45 min, respectively, which were designed according to the Box–Behnken experimental design and the experiment results were analyzed using Minitab software version 17. The results show that the sulfur-removing efficacy ranged between 45 and 60%, while optimum sulfur removal efficiency is 61% at the following operation conditions: 40 °C, 3 g, and 45 min for temperature, adsorbent dosage, and adsorption time respectively.Adsorption isotherms Langmuir and Freundlich were examined, and the results show the Freundlich isotherm is more suitable to describe the adsorption of these sulfur compounds.

Adsorption is vital for the elimination of Cr6+ and Pb2+ ions in the contaminated solution medium. A ternary blend made up of chitosan, nylon 6 and polyurethane foam (CS/Ny 6/PUF) blend in the ratio of 2:1:1 has been investigated. These blends are used as an adsorbent due to the insoluble nature in acidic and basic medium. The adsorption efficacy was analyzed by modifying pH, contact time, and adsorbent dosage. The maximum uptake of metal ions has been exhibited in the pH range 5. An equilibrium adsorption statistic indicated that adsorption isotherm follows the Freundlich model. The adsorption kinetic parameters specified that the adsorption of chromium has shown pseudo-second-order and lead pseudo-first-order reaction. HIGHLIGHTS CS/NY 6/PUF blends adsorption efficacy was analyzed by modifying pH.; Contact time, and adsorbent dosage.; Langmuir and Freundlich adsorption isotherm was utilized.; An adsorption harmony of metal particles was adsorbed by the adsorbent.; The adsorption of chromium and lead ions exhibits pseudo-second-order and pseudo-first-order kinetic reaction.;

Adsorption equilibrium on bioadsorbents was studied, and fitted to Langmuir, Freundlich and Dubinin-Radushkevich isothermal models, using yam peels (YP) and oil palm wastes (OPW) as bioadsorbents in the removal of hexavalent chromium present in aqueous solution, in a batch system, evaluating the effect of temperature, adsorbent dose and particle size on the process. Thermodynamic parameters were estimated by the Van't Hoff graphical method. It was found that the highest adsorption capacity was obtained at 0.03 g of adsorbent, 55 °C and 0.5 mm of particle size. The equilibrium of adsorption on OPW is described by Langmuir and Freundlich isotherms, while that of YP by Dubinin- Radushkevich's model, indicating the adsorption is given by the ion exchange between the active centers and the metallic ion. The thermodynamic study determined that the elimination of YP is endothermic, irreversible, and not spontaneous and that for OPW it is exothermic, spontaneous at low temperatures, and irreversible. [ABSTRACT FROM AUTHOR]

Chitosan was prepared and coupled with Furfural. The resulting chitosan furfural Schiff base was characterized using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Brunauer Emmett Teller (BET) analysis. It was observed that Chitosan furfural Schiff base shows characteristic absorption peaks at 3290.35cm-1„ 1644.47cm-1, 1552.69 cm-1„ which confirms the stretching vibration attributed to OH and NH groups of chitosan, NH=C (Imine linkage) of the Schiff base and aromatic ring of the furfural respectively. The SEM analysis, showed a rough large pore surface, the BET analysis revealed a large surface area of 339.85 m²/g, a pore diameter of 2.94nm, and a pore volume of 0.1194 cm³,/g. The material was used to adsorb aqueous 2, 4-Dinitrophenol (2, 4-DNP). The results obtained were evaluated with Langmuir and Freundlich adsorption isotherm. The material data fitted best with Freundlich isotherm R2 value of 0.9690 when compared to Langmuir isotherm R2 value of 0.8560. This indicates that the material proved uptake onto heterogeneous adsorbent surfaces. The R2 values are regarded as a measure of the best fit of experimental data on the isotherm model. [ABSTRACT FROM AUTHOR]

The objective of this work is to use sediments of an Algerian dam in adsorbing cationic dye, methylene blue (MB) onto aqueous solution, and test their aptitudes in the fixation of organic pollutants. The raw mud sediment (RMS) is characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, Fourier-transform infrared spectroscopy, and BET method (Brunauer-Emmett-Teller). The results show that the sediments consist of clay phases; the RMS featured a high surface area of 102.42 m²·g-1 using the Hang method and 42.39 m²·g-1 by BET. Adsorption results show that the adsorption kinetics is rapid and adjusted to best fit the pseudo-second-order model. The equilibrium adsorption data analyzed by the Langmuir, Freundlich, and Temkin isotherm models revealed that the isotherm of the solution with initial concentration C0 < 100 mg·L-1 obeys to the Freundlich isotherm, and those of concentrations greater than 100 mg·L-1 follows the Langmuir model (R² = 0.9919), equilibrium adsorption 93.72 mg·g-1 for an initial concentration of 1,000 mg·L-1 was achieved at a temperature of 293 K and pH of 6. The values of the activation parameters such as free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were also determined. The results indicate that the process of adsorption of MB on the RMS is spontaneous (ΔG° < 0) and exothermic (ΔH° < 0). This study reveals that RMS can be used as an effective low-cost adsorbent of MB from aqueous solutions. [ABSTRACT FROM AUTHOR]

Studying the transport of petroleum hydrocarbons in cadmium-/naphthalene-contaminated calcareous soils is crucial to comprehensive assessment of environmental risks and developing appropriate strategies to remediate petroleum hydrocarbons pollution in karst areas. In this study, n-hexadecane was selected as a model petroleum hydrocarbon. Batch experiments were conducted to explore the adsorption behavior of n-hexadecane on cadmium-/naphthalene-contaminated calcareous soils at various pH, and column experiments were performed to investigate the transport and retention of n-hexadecane under various flow velocity. The results showed that Freundlich model better described the adsorption behavior of n-hexadecane in all cases (R2 > 0.9). Under the condition of pH = 5, it was advantageous for soil samples to adsorb more n-hexadecane, and the maximum adsorption content followed the order of: cadmium/naphthalene-contaminated > uncontaminated soils. The transport of n-hexadecane in cadmium/naphthalene-contaminated soils at various flow velocity was well described by two kinetic sites model of Hydrus-1D with R2 > 0.9. Due to the increased electrostatic repulsion between n-hexadecane and soil particles, n-hexadecane was more easily able to breakthrough cadmium/naphthalene-contaminated soils. Compared to low flow velocity (1 mL/min), a higher concentration of n-hexadecane was determined at high flow velocity, with 67, 63, and 45% n-hexadecane in effluent from cadmium-contaminated soils, naphthalene-contaminated soils, and uncontaminated soils, respectively. These findings have important implications for the government of groundwater in calcareous soils from karst areas. [ABSTRACT FROM AUTHOR]

Improper management of organic industrial wastes, such as empty fruit bunch (EFB) from the palm oil industry and pressmud, i.e., a by-product of the sugar refinery industry can lead to environmental problems. This study aims to investigate the potential of pressmud and EFB as adsorbent materials in wastewater pollution removal. The chemical analysis in this study revealed that the EFB sample contained 7.30% of SiO2, 2.11% of Fe2O3, 1.91% of MgO, 28.02% of CaO, 37.59% of K2O, 1.45% of P2O5, 14.51% of Cl, 4.39% of SO3, and 2.38% of other elements. Meanwhile, the pressmud sample contained 14.32% of SiO2, 1.39% of SO3, 81.71% of CaO, 1.03% of Fe2O3, and the remaining 1.56% of other compounds. The possible adsorption capacities of pressmud and EFB were determined using the Langmuir and Freundlich isotherms. The absorption of Cd, Cr, Cu, Fe, Mn, Ni, and Zn in these samples was analyzed using the Langmuir and Freundlich isotherm models. By comparing both models, the research revealed that the Langmuir model provided a more precise description of the adsorption process for the EFB and pressmud samples and was competently compared to the Freundlich model, as indicated by the highest R2 values. The results indicate the potential of EFB and pressmud as promising reactive materials for heavy metal adsorption, and this involves recognizing possibilities for repurposing these economical and sustainable waste materials. [ABSTRACT FROM AUTHOR]

chromium is one of the most important water pollutants being Cr(VI) the one with the greatest environmental impact. The objective of this work is to evaluate the adsorption capacity of a biosorbent formed by chitosan-orange peel (CTS-OP) to remove hexavalent chromium from water. The novelty of this work is the evaluation of the drying process effect (oven, vacuum, and freeze-drying) on chromium adsorption capacity. Adsorbents are characterized using X-ray diffraction, FTIR spectroscopy and adsorption kinetics and isotherms measuring Cr(VI) concentration using UV-Vis absorption at 540 nm after complexing with 1,5-diphenylcarbazide. Adsorption capacity is enhanced at pH 2.0 and OPW particle size of 0.300 microns. The shoulder that appears at 944 cm-1 after Cr(VI) adsorption in all three kind of CTS-OPW beads, indicate that chromate ion is bonding with the sorbent. The chi-squared analysis (χ²) indicate that Freundlich isotherm fits better that Langmuir isotherm for all CTS-OPW beads, and the best fit is obtained with Elovich model for kinetic studies. The adsorption capacity of the CTS-OPW beads was also evaluated for the three types of drying. It can be concluded that vacuum oven-dried beads have the highest hexavalent chromium adsorption capacity, 33.89 mg g-1, followed by freeze-dried beads, 32.4 mg g-1, and finally oven- dried beads with a qmax value of 27.5 mg g-1. [ABSTRACT FROM AUTHOR]

In this study, the adsorption capacity of different types of zeolite (3A, 4A, and 5A) for adsorbing CO2 from a mixture of CH4, N2, and water vapor was investigated with and without the use of ultrasonic waves. In this study, functional groups of O–H, Si–O–Al and Si–O–Si bands were identified in Fourier transform infrared (FTIR) spectroscopy of these adsorbents. X-ray diffraction patterns (XRD) for zeolite 3A and 5A showed the structure of chabazite and for zeolite 4A the structure of sodalite. In the Brunauer-Emmett-Teller (BET) test, the specific surface area of zeolites was measured as 16, 11.96 and 437 m2g−1, respectively. Ultrasonic waves increased the adsorption capacity of zeolites to adsorb CO2 at lower temperatures 80.64 to 175.44 mgg−1. Zeolite 5A has a higher affinity for CO2 than CH4 or N2, the selectivity of CO2/ N2 and CO2/ CH4 were 19.55 and 24.17, respectively. Data from adsorption experiments were used to learn an artificial neural network (ANN), and the ANN provided acceptable results for predicting the adsorption process.

Vertisols are important cropping soils in tropical and subtropical areas, but in many regions, decades of cropping has substantially reduced concentrations of plant‐available phosphorus (P), especially in the subsoil layers. Phosphorus behaviour in P‐depleted Vertisols has received comparatively little attention, and the availability of P following the addition of inorganic P fertilisers at different concentrations is poorly understood. In this study, we evaluated short‐term P sorption and desorption behaviour in cropped Vertisols in relation to specific soil physical and chemical properties. We collected the surface and subsurface of 15 Australian soils with a broad range of physical and chemical properties, comprising nine Vertisols, three Ferralsols, two Lixisols and one Calcisol. For each soil, we generated sorption and desorption curves (fitted with a Freundlich equation), determined soil physical and chemical properties likely to influence P sorption and evaluated the relationships between the measured soil properties and the Freundlich equation sorption coefficients. The P sorption curves differed drastically between soils, with the sorption equation coefficients (aS × b) significantly correlated with the P buffering index (PBI) and clay content. Clay content itself was correlated with citrate‐extractable Fe and Al oxides and BET surface area. Vertisols formed on basaltic parent materials had greater Fe and Al oxide concentrations, resulting in an overall greater P sorption capacity. Sorption and desorption hysteresis were mostly small. The reacting materials in these soils probably had limited ability to continue to react with P. The Vertisols differed in their capacity to replenish P in the soil solution by desorbing different proportions of previously sorbed P, although the proportion of desorbable P generally increased with greater concentrations of sorbed P. These results suggest that for fertiliser management in these soils, smaller volumes of P enrichment combined with higher P concentrations may result in a greater P recovery by the crop. [ABSTRACT FROM AUTHOR]

In this study, Pseudomonas putida biomass was used to remove ceftriaxone from aqueous solutions. Biosorption was studied by living bacteria to achieve maximum biosorption. In order to investigate the shape, the biomass structure was analysed by SEM and FT-IR analyses. The effect of important parameters such as pH, contact time, adsorbent amount, and initial concentration of ceftriaxone solution, temperature, and the effect of ionic intensity on biosorption were studied. This study is an experimental study 250 ml Erlenmeyer was used as a batch reactor for the experiment. With increasing initial concentration, the removal efficiency increased. The best results were obtained at optimum pH = 7, adsorbent dose of 0.1 g, and initial ceftriaxone concentration of 50 mg/l after contact time of 120 minutes at the temperature of37 ∘ C and more than 50% of ceftriaxone was removed. Various isotherms including Langmuir and Freundlich were used to analyse equilibrium data at 37°C. The maximum adsorption capacity of this adsorbent was 109.5 mg/g. The results showed that the Freundlich isotherm is more consistent with the experimental data. Data fitting in the Freundlich adsorption isotherm model indicates non-uniformity of the absorbent surface. [ABSTRACT FROM AUTHOR]

Chitosan has been acknowledged as the emerging prominent pollutant remover with environmentally friendly properties. Herein, we have developed magnetic chitosan (MC) microsphere with functional group enrichment using polyethylene glycol diglycidyl ether (PEGDE) and ethylenediaminetetraacetic acid (EDTA) to remove aqueous methylene blue. The success of the functional group enrichment was proven by the characterization carried out in Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and Scanning Electron Microscope (SEM) analyses. The adsorption capacity of methylene blue onto the prepared MC increased as much as 37.62% after the addition of EDTA. The optimum adsorption parameters recorded in this study were 30minutes contact time and pH level of 10. At such optimum conditions, the adsorption capacity and removal percentage reached 5.04±0.03 mg/g and 80.64±0.12%, respectively. Adsorption studies using various models revealed that the best fit of experimental data with that of theoretical was generated by the Freundlich model equation (R2 = 0.95283; root-mean-square-errors = 27.22). Exothermic adsorption was observed according to the thermodynamic study (∆H = -124.43 kJ/mol). In conclusion, our adsorbent prepared from green materials and methods could effectively remove the methylene blue from water medium.

Abstract Analytical isotherm models such as Langmuir isotherm, Freundlich isotherm, and other linear isotherms are commonly used for modeling adsorption datasets for a wide range of adsorption studies. Most of these studies consider pH to be fixed. However, pH is an important parameter that varies widely. Hence, the model parameters developed for one set of experiments cannot be used in another scenario where the pH is different. Surface complexation models that can simulate pH changes are complex, multi-parameter models that are difficult to use. The modified Langmuir–Freundlich (MLF) isotherm developed earlier by us could simulate pH-dependent adsorption on goethite-coated sands. However, it has only been tested for arsenic adsorption on goethite-coated sands. Therefore, chromium adsorption datasets were considered to extend this MLF isotherm for other metal ions. Two different adsorbents, viz. coconut root activated carbon (CoAC) and palm male flower activated carbon (PaAC), were selected for the adsorption modeling of Cr(VI) using the MLF isotherm model. An improved modeling strategy was developed for fitting the MLF isotherm, which required only a single pH versus adsorption dataset, instead of several isotherms at different pH values. The new methodology could simulate the pH-dependent adsorption satisfactorily for various experimental datasets. The maximum adsorption capacity was 88.64 (mg/g) and 100.1 (mg/g) for PaAC and CoAC, respectively. The affinity constant for this model (K a) was found to be 0.007 (L/mg) for PaAC dataset and 0.0106(L/mg) and 0.004 (L/mg) for the CoAC dataset. The average R 2 values of fitting were calculated and found to be 0.98 for PaAC and 0.85 for CoAC. The average root mean square error (RSME) of the fitting of the model was 0.07 (less than 10%). This modeling strategy required less experimental data and did not require advanced characterization studies. Therefore, this study indicates that the MLF isotherm can be extended to other contaminants and for different adsorbents to model the pH-dependent adsorption.

Activated carbon was produced from orange peel using H2SO4 and ZnCl2 as activating agents at a temperature of 400 ℃. The impregnation was done in 1:1 (wt/v). FTIR analysis of the precursor and activated carbon shows different functional groups present in the precursor and activated carbon. The FTIR spectral also shows shifts in bands and changes in wave number between the precursor and activated carbon indicating chemical transformation during activation and carbonization. SEM analysis was used to study the internal structure and pores development of the activated carbon. The methylene blue adsorption capacity of the activated carbon was determined using standard methods. Langmuir and Freundlich adsorption isotherms were employed in determining the adsorption process and Pseudo first-order and Pseudo secondorder kinetics were employed in determining the rate of adsorption by the adsorbents. [ABSTRACT FROM AUTHOR]