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The PVSDM model was used for single and binary dye adsorption systems. This model is commonly used for adsorption in single systems, but this is the first time used in a binary mixture of dyes in the literature. To that end, a new adsorbent derived from Bauhinia forficata waste was created and described for eventual use in the treatment of a dye combination (methylene blue and crystal violet). The single and binary isotherms revealed that increasing the temperature decreases the methylene blue adsorption capacity while increasing the crystal violet adsorption capacity. The Langmuir and extended Langmuir models described the single and binary systems, respectively. Maximum adsorption capacities of 229.13 mg g−1 at 298 K for methylene blue and 324.12 mg g−1 at 328 K for crystal violet were obtained. The thermodynamic parameters showed that the adsorption process for both dyes is spontaneous, being exothermic for the methylene blue and endothermic for the crystal violet. Similar decay curves for the single and binary systems were observed. The PVSDM was able to describe both single and binary adsorption systems. The external mass transfer and the surface diffusion change according to the initial dye concentration and the system type (single or binary). [Display omitted] • The capacity of the single systems was 190.9 and 267.7 mg g−1, for the MB and CV. • The capacity for the mixture was 185.51 and 266.6 mg g−1 for the MB and CV. • The PVSDM model was able to describe the adsorption of single and binary systems. • The external mass transfer and surface diffusion changed according to the system. [ABSTRACT FROM AUTHOR]

A porous activated carbon from Hovenia dulcis was prepared using zinc chloride (ZnCl 2) as an activating agent and applied to remove diuron in aqueous solutions. The carbon presented a smooth and regular surface, with an area of 898 m² g−1, narrow pores of average diameter equal to 1.242 nm, and volume of 0.296 cm3 g−1. Adsorption was favored by increasing the pH and temperature. Isothermal curves formed a characteristic plateau of the Langmuir monolayer isotherm. Thermodynamic results indicated that herbicide adsorption was spontaneous, favorable, and endothermic (ΔH0 = 35.9093 kJ mol−1). The decay of the diuron concentration displays that equilibrium is attained in 120 min. The best results were obtained at pH 6, temperature of 328 K and 200 rpm and C 0 of 200 mg·L−1. Langmuir model had the best adjustment, obtaining maximum adsorption capacity of 96.68 mg·g−1. Pore volume and surface diffusion model (PVSDM) was suitably represent the decline comportment of diuron. The adsorption mechanism was rate controlled by the external and internal mass transfer. In the treatment of a river water sample contaminated with diuron, activated carbon revealed high performance, reaching 95% removal of the emerging pollutant. [Display omitted] [ABSTRACT FROM AUTHOR]

The present review was carried out to analyze the works developed using the adsorption technology to remove the anti-inflammatory ketoprofen (KET). The main factors that inflated the KET adsorption were analyzed. It was found that, among the developed adsorbents, those from ZnAl/biochar, algae-derived porous carbon, and powdered activated carbon were highly efficient, reaching maximum capacities of 1081, 443, and 362 mg g−1, respectively. It was found that the adsorption capacity tends to be higher when the pH is close to the value of pK a of the KET and when the adsorbent has a higher pH pzc. From the kinetics of KET adsorption, it was found that the adsorbent dosage and the initial KET concentration causes an inverse effect on the equilibrium time and adsorption capacity for all the system. Isothermal studies confirmed the predominance of monolayer adsorption present on homogeneous surfaces corresponding to the Langmuir isotherm; however, it is also possible to observe more heterogeneous surfaces corresponding to the Freundlich and Sips isotherm. The thermodynamics nature of the process was found to be exothermic and endothermic, demonstrating a possible relation with the Gibbs solvation energy. The adsorption mechanism indicates that the KET tends to be adsorbed due to physical interactions (hydrogen bonding, π-π interactions). In general, the adsorption technique proved to be an efficient technology in removing KET, where several adsorbents have already been developed and successfully applied in its removal. The next step is to overcome the laboratory scale barrier and apply these materials to treat real effluents. In addition, studies should be more focused on continuous and multi-component processes, providing results for future real-scale applications. [Display omitted] • Ketoprofen is found in effluent treatment plants and rivers, with a concentration that varies from 3.15 ng L−1 to 209 μg L−1. • Adsorbents and their adsorption capacities were analyzed, indicating that biochar mixed with ZnAl has the highest values. • The adsorption capacity was directly dependent on the pH, pK a, and pH point of zero charge. • Langmuir's isotherm, followed by Freundlich's, was the more suitable model for describing several systems. • The main mechanisms of ketoprofen uptake were hydrogen bonding and electrostatic interactions. [ABSTRACT FROM AUTHOR]

The production of the edible mushroom Agaricus bisporus occurs on a world scale, where tons are constantly produced. At the same time, this production generates a large amount of waste that needs to be adequately conditioned. Therefore, mushroom residues were used to develop activated carbon for the removal of 2,4-D—the developed adsorbent showed a microporous structure with several spaces on the surface. The FTIR analysis showed that the activated carbon has functional groups such as aromatic rings, carboxylate, hydroxyl. It was found that the optimum adsorption of the 2,4-D occurs at pH 4 and adsorbent dosage of 0.4 g L−1; The equilibrium data were better fitted to the Freundlich model. However, for calculating the thermodynamic parameters, it was considered the Langmuir equilibrium constant (K L). The value of Langmuir Q max was 241.7 mg g−1 at 298 K. The thermodynamic behavior indicated a spontaneous and favorable, and exothermic. The magnitude of the adsorption enthalpy is in agreement with physical adsorption. System equilibrium was attained before 30 min regardless of 2,4-D concentration. The kinetic curves showed good statistical adjustment to the linear driving force (LDF) model, with capacity values close to the experimental ones (q exp = 194.6 mg g−1; q pred = 187.3 mg g−1), at 100 mg L−1 of 2,4-D. The adsorbent removed up to 70% of the simulated effluent when using the Jacuí river as the sample. Regeneration studies showed that the activated carbon could be used up to 9 times without losing significant efficiency. Last, the process cost production was estimated to be 2.39 USD kg−1 of activated carbon. Therefore, it can be concluded that activated carbon developed from edible mushroom residues is a promising alternative as an adsorbent for the treatment of actual effluents containing 2,4-D herbicide. [Display omitted] • Activated carbon from the residues of the mushroom (Agaricus bisporus). • Adsorption of the 2,4-dichlorophenoxyacetic herbicide. • The value of Langmuir Q max was 241.7 mg g−1 at 298 K. • The cost production was 2.39 USD kg−1 of activated carbon. • The material can be reused 9 times. [ABSTRACT FROM AUTHOR]

In the present work, multi-walled carbon nanotubes (MWCNTs) were used as support material for the impregnation of metallic nanoparticles (MNPs) produced by green synthesis. The influences of the plant extracts (pomegranate (Punica Granatum), Eucalyptus , and pecan (Carya illinoinensis , leaves), metal species (copper and iron), metallic concentrations, and type of functionalization (OH and COOH) on the characteristics of the obtained materials were studied. The precursor and impregnated MWCNTs were characterized through X-ray diffraction, Fourier transformed infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, point of charge, N 2 adsorption/desorption isotherms and, X-ray photoelectron spectroscopy. All the synthesized materials were tested as adsorbents to remove glyphosate (GLY) in an aqueous medium. The MWCNTs were resistant to withstand the synthesis process, preserving its structure and morphological characteristics. The copper and iron on the surface of MWCNTS confirm the successful synthesis and impregnation of the MNPs. The MWCNTs impregnated with high metallic concentrations showed favorable adsorption of GLY. The adsorption capacity and percentage of removal were 21.17 mg g−1 and 84.08%, respectively, for the MWCNTs impregnated with iron MNPs using the pecan leaves as a reducing agent. The results indicated that an advanced adsorbent for GLY could be obtained by green synthesis, using MWCNTs as precursors and pecan leaves as a reducing agent. [Display omitted] • Advanced adsorbents were developed by the green synthesis method. • Carbon nanotubes were used as support, and plant extracts as reducing agents. • The presence of Cu and Fe on the surface confirm the successful synthesis. • The material synthesized with pecan extract and Fe presented the best performance. • The adsorption capacity and percentage of removal were 21.17 mg g-1 and 84.08%. [ABSTRACT FROM AUTHOR]

Fruit wastes of the Ceiba speciosa forest species were employed as raw material for preparing activated carbon towards removing phenol from water. Concave cavities spread over the entire material surface were observed from characterization results, resulting in a high surface area, 842 m2 g−1. Adsorption isotherm and kinetic studies were performed under the best conditions of pH (7) and adsorbent dosage (0.83 g L−1). An increase in temperature from 298 K to 328 K disfavored the phenol adsorption, decreasing from 156.7 to 145 mg g−1 for the best-fit model, Langmuir. The thermodynamic results indicated that the phenol adsorption was spontaneous, favorable, and exothermic. The phenol concentration decay shows that the equilibrium is reached at 120 min. The pore volume and surface diffusion model (PVSDM) was employed satisfactorily to describe the phenol decay behavior. The surface diffusion coefficient values were in the range of 10−9 cm2 s−1. The external and the internal mass transfer were the rate-controlling mechanisms. Therefore, the application of fruit wastes from Ceiba speciosa as raw material for preparing activated carbon proved very efficient towards removing phenol from an aqueous medium. The activated carbon is an alternative material to suppress water contamination due to phenol-derived species. [Display omitted] • Novel activated carbon produced from Ceiba speciosa. • Highly adsorptive activated carbon towards phenol. • Porous activated carbon with high surface area. • PVSDM model describes the phenol decay behavior. [ABSTRACT FROM AUTHOR]

• Eco-friendly strategy for groundwater defluorination. • Adsorption on calcinated sludge. • Process was efficient at pH of 5.5, and using 5 g L−1 of calcinated sludge. • The groundwater attained the WHO standard within 60 min. • The maximum adsorption capacity was 2.04 mg g−1. The excess of fluoride ions (F−) in water for human supply is a serious public health. The recommended concentration of F− ions by the World Health Organization (WHO) is 1.5 mg L-1. Several groundwater sources around the world contain high F− concentrations, and require treatment before human consumption. It was developed an eco-friendly and low-cost strategy for groundwater defluorination, i.e., adsorption onto calcinated sludge. This strategy was efficient at pH of 5.5 and using 5 g L-1 of calcinated sludge. The groundwater attained the WHO standard within 60 min. The kinetic model of pseudo-second-order obtained a better adjustment to the experimental data. The equilibrium curve at 25 °C was better represented by the Tóth model. The maximum adsorption capacity was 2.04 mg g-1. Therefore, adsorption using calcinated sludge can be considered as an eco-friendly and low-cost strategy for groundwater defluorination. [ABSTRACT FROM AUTHOR]

The mass transport mechanism of the In(III) adsorption on chitin and chitosan was elucidated in this research. The chitosan and chitin presented specific surface area values of 3.60 and 4.30 m2 g−1, with average pore radius of 14.30 and 33.10 Ǻ, respectively. It was identified in chitosan and chitin, typical groups, such as N H and C O. It was found that both materials present a rigid surface without the presence of visible pores and cavities, with a geometry that resembles plates. Further analysis indicates the presence of the In(III) on the surface of both materials. The isotherm experiments indicated that the temperature caused an increase in the adsorption capacity for both materials. The Langmuir model was chosen for describing the equilibrium in both cases. The External Mass Transfer Model (EMTM) and Pore Volume and Surface Diffusion Model (PVSDM) were used for describing the indium concentration decay curves for the chitosan and chitin. Nevertheless, the modified Biot number (between 8.82 × 10−4 and 2.71) indicated that, in this case, the external mass transfer was the dominant mechanism. In addition, chitin and chitosan were efficient adsorbents for In(III), since that only 0.35 mg L−1 of In(III) remained in solution after adsorption. Chitosan provided faster adsorption kinetics, and this fact was attributed to its higher external surface area. The findings revealed that the overall mass transport mechanism is as follows: the indium species in the bulk solution are transferred to the adsorbent surface and then, adsorbed by surface precipitation and/or coordination bonds. • Mass transport mechanism of In(III) adsorption on chitin and chitosan was studied. • Biot numbers ranged from 8.82 × 10−4 to 2.71. • External mass transfer was the dominant mechanism. • Chitosan provided faster adsorption kinetics than chitin. • Surface precipitation and/or coordination bonds occurred during adsorption. [ABSTRACT FROM AUTHOR]

• Ten adsorbents were used to concentrate In(III) from real leachates. • The operation was analyzed by ANN and ANFIS. • ANN and ANFIS were able to predict the In(III) adsorption capacity. • Chitosan was able to concentrate indium from the LCD leachates. • Chitosan attained adsorption capacity of 1000 mg g–1 within 20 min of operation. Ten different adsorbent materials were tested to adsorb indium (III) from leachates of LCD screens, aiming to concentrate this valuable material. Artificial neural network (ANN) and adaptive neuro–fuzzy inference system (ANIFS) were applied to analyze the indium (III) adsorption. The input variables for the network models were: specific surface area, point of zero charge, adsorbent dosage and contact time. Adsorption capacity (q) was used as output variable. The adsorption capacity values ranged from 8.203 to 1000 mg g–1. The ANN modeling presented the best fit when the Levenberg–Marquardt algorithm was used. The ANFIS modeling presented the optimum performance when the hybrid method was used. Among the tested adsorbents, chitosan presented the best performance; attaining adsorption capacity of 1000 mg g–1 within 20 min. This is an excellent value since the maximum indium concentration in LCD screens is 0.613 mg g–1. This high capacity was attributed to the coordination ligation between chitosan and indium (III). [ABSTRACT FROM AUTHOR]

• Adsorption of potential toxic dyes (methylene blue and crystal violet) was studied. • A promising adsorbent was produced and tested during adsorption tests. • A physical model was applied on the entire adsorption data set. • Steric explanations supported a better understanding of the adsorption mechanism. • Two energies described the interactive effects of the adsorption systems. This paper analyzes the adsorption of two potential toxic dyes, i.e. methylene blue (MB) and crystal violet (CV) onto Bauhinia forficata residual fruit powder (BFRFP) as a new promising adsorbent. The experiments aimed at retrievement of adsorption data are carried out at T = 298–328 K and are coupled with an adsorbent characterization to better highlight the MB and CV dyes adsorption mechanism. MB adsorption capacity at saturation (ACS) varies from 181.48 to 201 mg.g−1, while for CV dye, it ranges from 263.06 to 282.61 mg.g−1. This difference is not very significant but reflects that the BFRFP has a higher affinity to remove CV dye. Comparing with some alternative adsorbents, the BFRFP adsorbent shows to be a competitive material for the removal of MB and CV dyes from polluted water. A model assuming that MB and CV dyes are removed via a formation of two layers on BFRFP is chosen as the one that, from a physical point of view, better interpret their adsorption mechanisms. The prediction of the number of dyes adsorbed on BFRFP is approximately equal to 1 for both the dyes, testifying that they are removed without an aggregation process and with slanted position. The physical model generates two energies to describe the interactive effects between both dyes and BFRFP adsorbent (dye- BFRFP) and between dyes (dye-dye). Results show that physical interactions occur during the adsorption process. [ABSTRACT FROM AUTHOR]

[Display omitted] • High surface area activated carbon derived from Diospyros kaki fruit waste; • Remarkable adsorption capacity for aqueous-phase atrazine; • Linear driving force (LDF) model provides good fit to kinetic data; • Activated carbon efficient to remove atrazine in real river samples. In this work, Diospyros kaki fruit waste was employed as a precursor material to develop a high surface area activated carbon, which efficiently removed the toxic herbicide atrazine (ATZ) from synthetic water solutions and river waters. The alternative activated carbon presented excellent characteristics and structure, including high values of specific surface area (1067 m2 g−1) and pore volume (0.530 cm3 g−1) and some important functional groups on the surface. The temperature positively influenced the adsorption capacity, from 194.20 to 211.51 mg g−1. The Freundlich model was the proper one to represent the equilibrium data. Thermodynamic parameters confirmed the endothermic nature of the adsorption process. Kinetic studies confirmed that equilibrium was reached until 240 min, regardless of ATZ initial concentration. The LDF model adjusted well to the kinetic data, resulting in a diffusion coefficient ranging from 0.89x10-9 to 1.63x10-9 cm2 s−1 as the ATZ concentration increased. The activated carbon also decreased 85% of the ATZ concentration in a river water sample. Overall, the activated carbon developed from Diospyros kaki fruit waste presented an efficient ATZ removal from aqueous matrices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Activated carbon (AC) from araçá fruit husks for atrazine adsorption. • It was a microporous material with a surface area of 431 m2 g−1. • The adsorption capacity was 35.67 mg g−1 at 328 K, and ΔH0 was 129.5 kJ mol−1. • Adsorption occurs due to electrostatic, H-bonds, π–π and n–π interactions. • The "araça" derived AC was promising in removing atrazine from aqueous solutions. The residual husks of the edible fruits of Psidium cattleianum were carbonized with FeCl 3 as an activating agent and used as an adsorbent to remove the toxic herbicide. After the carbonization step, changes in the material's structure were found. Activated carbon showed characteristics of microporous materials with a pore volume of 0.280 cm3 g−1 and surface area of 431 m2 g−1. Micrographs revealed the emergence of new cavities with a uniform and circular shape. The FTIR spectra showed the disappearance of some bands, remaining bands belonging to functional groups containing carbon, oxygen, and hydrogen. The XRD patterns confirmed the amorphous structure of the material even after the carbonization step, composed of amorphous graphitic carbon. EDS analysis showed that the carbon percentage increased and the oxygen decreased after the carbonization. The experiments were performed at neutral pH using 1 g L−1 of adsorbent. In equilibrium isotherms, the temperature played a considerable role in the adsorption capacity, increasing from 26.39 mg g−1 to 35.67 mg g−1 when the temperature varied from 298 to 328 K. The Liu isotherms were the ones that best fit the isotherm data. The changes in the adsorption enthalpy were endothermic (ΔH° 129.5 kJ mol−1). The general order kinetic model was the most adequate for kinetic data, presenting the lowest values of the Bayesian Information Criterion. Thus, activated carbon developed from the residues of the "araça" fruit showed promise in removing atrazine from aqueous solutions, with the great advantage of its high efficiency under neutral pH solutions and mild temperatures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adsorption of ketoprofen and paracetamol from water; • Novel activated carbon from endocarp of the species Butia capitata ; • High surface area and pore volume coupled to excellent adsorption capacity; • Elucidation of molecular interactions in a mixture of compounds. • Competitive activated carbon with estimated cost of 2.54 USD kg-1. In this work, endocarp of the species Butia capitata was employed as precursor material to prepare a novel activated carbon with intrinsic properties to remove ketoprofen and paracetamol from water efficiently. The activated carbon presented a predominantly microporous structure, with an average pore diameter of 1.23 nm, a total pore volume of 0.449 cm3 g−1, and a high specific surface area, 820 m2 g−1. The adsorption kinetics showed a rapid initial decay for both pharmaceuticals, with the system entering equilibrium after 120 min for ketoprofen and 180 min for paracetamol. The pseudo-second-order model presented the best fit for ketoprofen and the Elovich model for paracetamol. The adsorption equilibrium data show that temperature can increase or decrease the adsorption capacity, being found a maximum adsorption capacity of 108.79 and 100.60 mg g−1 for the ketoprofen and paracetamol, respectively. The Freundlich and Langmuir models presented the best statistical adjustments for the adsorption of ketoprofen and paracetamol, respectively. The thermodynamic analysis confirmed an endothermic process for ketoprofen (ΔH0 = 11.98 kJ mol−1) and exothermic for paracetamol (ΔH0 = -13.37 kJ mol−1). The recycle tests revealed that the adsorbent has an average decrease for removal percentage of only 1.88 % for ketoprofen and 1.57 % for paracetamol. Estimations costs indicate that the price of 1 kg of activated carbon costs is 2.39 USD at minimum. Last, the material presented a highly efficient adsorptive activity to treat a synthetic mixture containing several pharmaceutical compounds and salts, reaching 84.82% removal. [ABSTRACT FROM AUTHOR]

• Novel Hyper Cross-Linked Resin: ICYN-PPA, a new and cost-effective adsorbent synthesized in a single step from commercially available materials. • High Adsorption Capacity: ICYN-PPA exhibits a remarkable adsorption capacity of 112.8 mg g−1 for efficient removal of Bisphenol A from aqueous solutions. • Fast Kinetics: The system reaches equilibrium in just 350 min, showcasing the rapid adsorption kinetics of ICYN-PPA. • Thermal Stability: ICYN-PPA's exceptional thermal stability makes it a promising candidate for decontamination processes in BPA-containing effluents. • Environmentally Friendly Solution: ICYN-PPA offers a sustainable approach to mitigate Bisphenol A's harmful effects on human health and aquatic life, contributing to environmental preservation. The widespread utility of Bisphenol A (BPA) in the production of diverse plastic substances including mineral water bottles, food packets, toys, tickets, etc. leads to its release to the environment through industrial effluents that contaminate both the surface and underground water. Given its higher toxicity and harmful effects on both human health and aquatic life, the adsorption of BPA has been the subject of recent studies at present. Herein, we disclose the synthesis of a new hyper cross-linked resin (ICYN-PPA), derived from commercially available 3,3′-(piperazine-1,4-diyl)bis(propan-1-amine) and tris(2,3-epoxypropyl) isocyanurate in a single step reaction, and its adsorptive performance for the removal of BPA from aqueous solution. The thermally stable ICYN-PPA, which is porous and exhibits different sizes of particles on its surface, displayed optimum removal of BPA. The isothermal studies were well represented by the Koble-Corrigan model, where the capacity increased from 216.6 to 228.6 mg g−1 with an increasing temperature of 318 K. The linear driving force model (LDF) was efficient in representing the kinetic data. Whereas the system tends to reach equilibrium after 350 min. The surface diffusion coefficients were 1.301 × 10−16 and 1.859 × 10−16 cm2 s−1 for BPA adsorption on isocyanurate based hyper crosslinked resins. The thermodynamic parameters confirmed the endothermic nature of the process (ΔH0 = 35.83 kJ mol−1) based on physical interactions. [ABSTRACT FROM AUTHOR]

• A new adsorbent was prepared from the residue of Butiacapitate. • The adsorption of pharmaceutical molecules was studied. • Adsorption of ketoprofen was endothermic, while paracetamol was exothermic. • A double-layer model with two energies deriving from statistical physics was applied. • This study highlights the important aspects of the adsorption mechanism. This paper describes the removal process via adsorption of paracetamol (PRC) and ketoprofen (KTP) on activated charcoal prepared from the residue of the fruit of Butiacapitate. Some adsorbent characterizations are carried out for a plausible analysis of the adsorption results and for the description of adsorption mechanism. Modelling investigations show that the double layer derived from statistical physiscs can be adopted to interpret the adsorption data. Interestingly, the adsorption mechanism can be elucidated via the model parameters determined at different temperatures. The performance of the adsorbent in terms of maximum adsorption capacity increased from 101.16 to 134.52 mg/g for KTP molecules and decreased from 98.19 to 73 mg/g for PRC molecules, by increasing the temperature, which are in line with the experimental values retrieved. These tendencies of adsorption capacities may be related to the behavior of the number of PRC and KTP pharmaceuticals captured per functional group of the adsorbent. Overall, the modeling results show also that the values of adsorption energies associated to the two layers of KTP and PRC molecules on the adsorbent surface are lower than 40 kJ/mol, implying that only physical type interactions occur in the removal process of these pharmaceutical molecules. [ABSTRACT FROM AUTHOR]

In this paper, the adsorption of the herbicide 2,4-D and the drug ketoprofen on wheat husks Fagopyrum esculentum treated with H 2 SO 4 is experimentally and analytically analyzed. The adsorbent is fully characterized through some techniques such as FT-IR, SEM, and XRD. Adsorption tests are carried out to optimize the performances in terms of adsorbent dosage and solution pH. Subsequently, the impact of temperature is determined through the realization of adsorption isotherms. A multilayer model is employed to microscopically interpret the adsorption mechanism of both the investigated compounds. The modelling analysis shows that the number of molecules bound per adsorption site varied from 0.68 to 2.77 and from 2.23 to 3.59 for ketoprofen and herbicide 2,4-D, respectively. These estimated values testify that an aggregation process occurs during adsorption. The global number of formed layers of each adsorbate is also determined, showing a significant reduction from 5.73 to 2.61 for ketoprofen and from 1.79 to 1.5 for herbicide 2,4-D with the temperature. For a complete understanding of the adsorption mechanism, the saturation adsorption capacity and adsorption energy were calculated and interpreted. Overall, it may be inferred that physical interactions govern how these contaminants adsorb on the tested adsorbent. [Display omitted] • The adsorption of the herbicide 2,4-D and the drug ketoprofen was investigated. • The wheat husks Fagopyrum esculentum was employed as an adsorbent. • Application of physical adsorption model to ascribe new interpretations of the adsorption mechanism. • Description of the adsorption orientation of both pollutants. • Estimation and interpretation of adsorption energies. [ABSTRACT FROM AUTHOR]

• Application of sta-phy modelling coupled to DFT calculations is essential for understanding the adsorption mechanisms. • The mono-layer model with one energy site (M 1:1) successfully represented the phenomena occurring on a microscopic level. • Changes in orientation with increased temperature decrease atrazine interaction with the AC by increasing self-repulsion. • The neutrality of the diuron can evenly balance the charges on the surface, increasing the adsorption efficiency. • Electrostatic mapping supplies a perspective to the interpretation and evolution of the modelled steric parameters. Atrazine and diuron are two pesticide compounds with very low surface interaction capacity, whose adsorption efficiency remains a challenge in environmental remediation applications. In this work, statistical physics (sta-phy) modelling and density functional theory (DFT) calculations have explored several still unveiled mechanisms involved. A model activated carbon (AC) sample was produced with Hovenia dulcis fruit residues, a local invasive tree species. The adsorption process was spontaneous and endothermic, and the adsorption capacities (Q m) increased as the temperature increased. The number of adsorbate molecules per site (n) decreased as the density of the receptor site (N m) increased, revealing that the temperature influences the geometry of the molecules during the surface interaction. According to the electrostatic mapping provided by the DFT calculations, it was possible to infer that the obtained Q m values for atrazine, between 42.54 and 73.20 mg g−1, can be a response caused by its own self-repulsion. For diuron, due to its increased neutrality, the potential balance of the electrostatic charges between adsorbate-adsorbent tends to be more effective, resulting in higher Q m values, ranging from 97.91 to 119.7 mg g−1. Therefore, the combination of sta-phy modelling with quantum mechanics calculations is a powerful tool for mechanism interpretation, capable of providing complementary insights into the adsorption process from both adsorbent and adsorbate perspectives. [ABSTRACT FROM AUTHOR]

• The functionalization of Physalis peruviana biomass with H 2 SO 4 is reported. • The surface chemistry of this modified biomass was characterized. • Adsorption of ketoprofen and 2,2-dichlorophenoxyactic acid is studied. • Application of physical model on adsorption isotherms. In this research, a functionalization of Physalis peruviana biomass with H 2 SO 4 and its application in the adsorption of ketoprofen and 2,2-dichlorophenoxyactic acid is reported. In particular, the adsorption properties of this biomass were improved through a sulfuric acid treatment to enhance its removal performance of organic molecules. Surface chemistry of this modified biomass was also characterized. Experimental adsorption isotherms of these organic pollutants were determined at 298 – 328 K and pH 2. A multilayer statistical physics model was used in the data modeling to analyze the corresponding adsorption mechanism. Results showed that the endothermic multilayer adsorption of ketoprofen was a multi-molecular process where molecular aggregation could be expected. On the other hand, the adsorption of 2,2-dichlorophenoxyactic acid on this functionalized biomass was multi-anchoring. Adsorption energies (ΔE 1) varied from 4.13 to 5.53 kJ/mol for KTP and from 7.54 to 7.96 kJ/mol for 2,4-D herbicide. These results showed that physical adsorption forces were involved in the removal of these organic molecules with this functionalized biomass because the adsorption energies < 40 kJ/mol. [ABSTRACT FROM AUTHOR]

[Display omitted] • The combined simulations are valuable tools for a thorough mechanism unveiling. • 2,4-D accommodates itself to the sites under its highest steric hindrance. • Adsorption is translated to the full occupation of first receptor sites. • Thermal effects and electrostatic repulsion play a key role in efficiency. In this study, six statistical physics (sta-phy) models were used to further describe and enlighten the mechanisms behind the adsorption of a low interaction model molecule through the interpretations of the real and ideal gas. Density functional theory (DFT) was employed for the simulation of electronic structure and reactivity parameters (E g , η, μ, and ω). Experimental assays were carried out with a representative activated carbon sample and 2,4-dichlorophenoxyacetic acid (2,4-D) pesticide as a base for the modeling and simulation. According to the classical interpretations, the adsorption was a monolayer exothermic process dependent on temperature. From the sta-phy perspective, the Hill model for monolayer adsorption with two energies best described the process. According to the estimations, the number of molecules adsorbed increases with increasing temperature, yet the number of primary adsorption sites (n) decreases with increasing temperature. The concentrations at a half-saturation (C i), in turn, increase with the increase in temperature. At last, by combining the sta-phy estimations with the DFT interpretations, it was possible to infer that, in addition to the thermal effects, electrostatic repulsion is a possible contribution that increases as the primary receptor sites are occupied. Therefore, the combination of simulations can provide answers to unclear mechanistic steps and help predict the contribution of the adsorbate to the estimated sta-phy parameters, with a very high degree of precision as statistically validated. [ABSTRACT FROM AUTHOR]

[Display omitted] • New insights into glyphosate adsorption on modified carbon nanotubes; • Steric and energetic interpretations based on statistical physics models; • The adsorption occurs through the formation of a monolayer; • Intermolecular interactions between glyphosate molecules can be neglected; • Glyphosate adsorption occurs at MPNs-Fe present on the adsorbent. The present work used a statistical physics approach to present new insights into the adsorption of the pesticide glyphosate on modified carbon nanotubes via green synthesis (MWCNT/MPNs-Fe). The experimental equilibrium curves obtained for this system under pH 4 at temperatures 298, 308, 318, and 328 K were simulated from monolayer, double layer, and multilayer models, with 1 and 2 energies, considering real and ideal fluid approaches. Taking into account the statistical indicators and the physical meaning of the parameters, exploring simplifying hypotheses, the Hill model with 1 energy and ideal fluid approach (M1) presented the best prediction of the experimental data, indicating that glyphosate adsorption occurs by the formation of a monolayer and that pesticide interaction with MWCNT/MPNs-Fe are characterized by only one energy. Based on this approach, to assess the steric aspects of the system, the number of molecules adsorbed per site (n), the density of receptor sites (N m), adsorption capacity at saturation (Q sat), and concentration at half-saturation (W) were interpreted. As for the energetic aspects, the adsorption energy (ΔE) was inferred. The combination of parameters to its evolution with temperature and the magnitude of ΔE indicated an exothermic process involving a physical interaction mechanism. Finally, the new insights showed that the MWCNT/MPNs-Fe adsorbent favored pesticide adsorption by interacting glyphosate molecules with the metallic iron nanoparticles present on the adsorbent surface. [ABSTRACT FROM AUTHOR]