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The study aims to determine adsorption isotherms through dynamic methods, including elution by characteristic point (ECP) and frontal analysis (FA), using a model system of beta zeolite and an aqueous sorbitol solution. The investigation specifically focuses on self‐packed fixed‐bed columns with a low number of theoretical plates Nt. It details the packing method optimization for these columns and identifies key challenges. Ultraviolet‐visible (UV/Vis) and refractive index (RI) detectors, including parameters such as rise time trise and wavelength λ, are thoroughly compared in this study. Various models are assessed for their appropriateness in predicting the isotherms. The study's practical implications have the potential to enhance research and industrial applications in the field of adsorption, particularly with regard to the optimization of adsorbent materials and detection methods. [ABSTRACT FROM AUTHOR]

Starch-g-poly(acrylic acid)/Pterocladia capillacea–derived activated carbon (St-g-P(AA)/P-AC) composites were prepared via aqueous solution graft copolymerization using starch, acrylic acid, and activated carbon of red alga Pterocladia capillacea (0–10%) with N,N′-methylenebisacrylamide crosslinker and ammonium persulfate (NH4)2S2O8 initiator. Fourier-transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) were used to characterize St-g-P(AA)/P-AC composites. Additionally, St-g-P(AA)/P-AC composites were investigated for methylene blue (MB) dye removal from water. The impact of the beginning concentration of MB dye, temperature, pH, and adsorption time on MB dye removal was examined. The maximum adsorption capacity obtained at pH 8 was 496.29 mg/g at 0.02 mg/L composites dose and 100 mg/L MB dye. The properties of adsorption were studied by the adsorption isotherm, kinetic, and thermodynamic models. The pseudo-first-order and Freundlich isotherm models demonstrated the kinetics and equilibrium adsorptions data, respectively. The maximum monolayer capacity (qm) was 1428.57 mg/g from Langmuir isotherm. Thermodynamic parameters indicated that the MB dye adsorption is exothermic physisorption and spontaneous. The results show that St-g-P(AA)/P-AC composites were effective for MB dye adsorption from water solution and could be recycled. [ABSTRACT FROM AUTHOR]

A novel electrochemical molecularly imprinted composite (MIC)-based sensor for detection of triclosan was developed. MIC was synthesized from o-phenylenediamine (o–PD), -COOH functionalized multiwalled carbon nanotube (cf-MWCNT), and triclosan by cyclic voltammetry on molybdenum nanoparticle (Mo-NP) embedded cf-MWCNT (Mo-cf-MWCNT) coated glassy carbon (GC) electrode, following removal of surface triclosan to form MIC/Mo-cf-MWCNT/GC. In our earlier work, two novel electrodes MIC/cf-MWCNT/GC and MIC/GC were fabricated. The presence of cf-MWCNT coating substrate on GC in MIC/cf-MWCNT/GC had improved the sensing performance than MIC/GC since presence of this substrate had decreased the electrochemical band gap (Eg) and increased Debye length (λd), Gibb's free energy of adsorption (− ΔGads), electrochemical surface area (Ae), and surface redox site concentration (C*). Therefore, further improvement in sensing performance can be carried out by utilizing Mo-NP in the cf-MWCNT coating substrate using MIC to be the sensing material. This novel electrode (MIC/Mo-cf-MWCNT/GC) provided a limit of detection (LOD) of 900 ppt of triclosan, which was lower than the LOD achieved by using MIC/cf-MWCNT/GC (10 ppb) and MIC/GC (40 ppb). Adsorption isotherm was constructed for MIC/Mo-cf-MWCNT/GC delivering − ΔGads value of 59.049 kJ/mol indicating stronger chemisorption. To understand the role of Mo-cf-MWCNT in detection of triclosan, cyclic voltammetry, electrochemical impedance spectroscopy, and electrochemical band gap studies were conducted. This MIC/Mo-cf-MWCNT/GC showed good selectivity towards triclosan in presence of interfering ions. [ABSTRACT FROM AUTHOR]

In this study, Zn-Al-SO42− LDH-functionalized biochar was fabricated using the co-precipitation method. The biochar was synthesized from waste cow dung using a low-temperature pyrolysis process (300 °C). The materials were fully characterized by TGA, FTIR, EDS, SEM, and XRD analysis. Then, a comparative study was performed to investigate the adsorption capacity of the materials against an anionic dye (i.e., methyl orange (MO)). The LDH-functionalized biochar demonstrated high adsorption capacity (400 mg/g in 120 min, at pH 5) compared to the raw biochar (212 mg/g in 120 min, at pH 5). The effect of various adsorption parameters (e.g., pH of the dye solution, temperature, initial concentration, adsorbent dosage, and contact time) was investigated. The adsorption of MO on LDH-functionalized biochar followed the Freundlich isotherm and pseudo-second-order kinetics, while the raw biochar followed the Langmuir isotherm and pseudo-second-order kinetics. The thermodynamic data indicated the endothermic nature of adsorption and an increase in the degree of randomness during adsorption. The enhanced adsorption capacity of the Zn-Al LDH-functionalized char was attributed to the synergistic effect of the surface adsorption into the porous biochar matrix, interlayer adsorption, and ion exchange capacity of the LDHs. Therefore, modification of waste cow dung–derived biochar with Zn-Al LDH can be a promising approach to fabricate a highly efficient adsorbent for toxic dyes from wastewater. [ABSTRACT FROM AUTHOR]

The sequestration of orange G (OG) and indigo carmine (IC) dye by utilizing novel incense stick (IS) ash adsorbent was examined in the current study. The dye uptake capacity of the adsorbent was explored through several batch experiments. The efficiency of the adsorbent was studied by different factors viz. adsorbent dose, agitation time, pH, temperature, and dye concentration. The study of the kinetic model described that the pseudo-second-order model was more effective for orange G and indigo carmine dye removal. Adsorption equilibrium was examined by the Langmuir and Freundlich model. The data obtained from the isotherm study for both dyes were well described and fitted to the Langmuir model. The incense stick ash adsorbent material was characterized by SEM, EDAX, BET, and FTIR techniques. The porosity of the adsorbent surface is described by the BET surface area of 6.934 m2/g and the micropore surface area of 4.550 m2/g. At a dye concentration of 50 mg/L and adsorbent dosage of 200 mg, the maximum dye uptake for orange G and indigo carmine was found 26.10 mg/g and 20.53 mg/g, respectively. For OG dye, the values of the thermodynamic parameters ∆H0 and ∆S0 were 40.99 kJ/mol and 0.015 kJ/mol, and for IC dye, 58.81 kJ/mol and 0.191 kJ/mol respectively. Regeneration performance of the used adsorbent was investigated by alkaline treatment. In comparison to the IC dye, the OG dye desorbs at a greater rate of 42.56%. According to this study, using incense stick ash to remove textile dyes would be a cost-effective and environmentally friendly green alternative. [ABSTRACT FROM AUTHOR]

Ternary bio-adsorbent was synthesized by using sisal fiber as a base with the integration of conductive polymer; polyaniline (PANI), supported with zero-valent iron nanoparticles by chemical activation with potassium hydroxide. The activation temperature impact on adsorption properties of Sisal fiber composite activated carbon was studied. The activation temperatures had a major effect on adsorption process as 100% removal efficiency was attained at 800 °C activated temperature. Scanning electron microscopy (SEM) was used for surface analysis of the adsorbent. Adsorption isotherms (Langmuir, Freundlich and Temkin) were examined and the negative values of 1 / n F demonstrated that the adsorption data does not match with Freundlich model for chemisorption. The pseudo second order and Elovich kinetics correlation coefficients for the retention of Fe and Cd to solid-phase interface at SF-800/NP/PANI (C) offered a better correlation for the bio-adsorption of Fe and Cd than pseudo first order kinetic. However, the pseudo second order kinetic attained a surpassing interaction for the bio-adsorption of Fe (0.989) than Cd (0.966); while the Elovich kinetic attained a surpassing interaction for the bio-adsorption of Cd (0.975) than Fe (0.945). The recovery and recycling stability of the bio-adsorbent composites were studied. [ABSTRACT FROM AUTHOR]

AbstractHeavy metal environmental pollution is rapidly increasing due to the increase in industrialization and urbanization. Industrial processes, such as paint production, mining, and raw materials producing industries release effluents rich in heavy metals, like Pb2+, Cd2+, Cu2+, and Cr3+. These heavy metals are dangerous because they persist in nature, are non-biodegradable and they have high tendency to accumulate in the environment and in living organisms who are exposed to them. This work studied the removal of heavy metals (Cu, Pb, Cr, and Cd) from aqueous solution using Moringa oleifera root powder (MORP) as the adsorbent. The MORP was characterized by SEM, FTIR, BET, and XRD. Batch adsorption experiments carried out investigated the effects of adsorbate concentration, adsorbent dosage, agitation time, pH and temperature on adsorption. The optimum parameters are: contact time (90 min); pH (9); adsorbent dose (0.6); metal ion concentration (30 mg L−1) for Cr and 40 mg L−1 for the rest; and temperature (50 °C) for Cu and Pb, and 70 °C for Cr and Cd. These experimental data were analyzed with 5 isotherm models (Temkin, Flory–Huggins, Langmuir, D–R and Freundlich). The result obtained fitted best to Temkin isotherm in comparison to others. Kinetic studies revealed that the pseudo-second order kinetic model best described the adsorption (with high R2 values ranging from 0.9810–0.9976) compared to pseudo-first order and intra-particle diffusion kinetics model. Results of the thermodynamic study showed that the sorption process was endothermic for Cu and Pb, but exothermic for Cd and Cr. The adsorbent showed good adsorptive tendencies toward the ions studied, and could be applied on an industrial scale for the remediation of metal contaminated water. [ABSTRACT FROM AUTHOR]

This study presents the use of novel Ganga-sand-encapsulated polyaniline granules for effective remediation of textile and pharmaceutical wastewater. The prepared Ganga-sand-encapsulated polyaniline granules were characterised using scanning electron microscope (morphology) and Fourier transform infrared techniques. The effect of adsorbent dose, contact time, pH and concentration influence on the adsorption performance of Ganga-sand-encapsulated polyaniline granules for the removal of methylene blue dye (textile waste) and doxycycline antibiotic (pharmaceutical waste) was studied. Kinetic and isotherm studies were also carried out to investigate the adsorption process further. The maximum adsorptive removal efficacy of methylene blue and doxycycline was found as 98.2% and 85.1%, respectively, at the optimised condition of adsorbent dose: 8 g/L, time: 120 min, pH: 12 and concentration: 50 ppm. From adsorption kinetics, it was established that the adsorption process followed pseudo-second-order (PSO) rather than pseudo-first-order (PFO). The correlation coefficient values for PFO and PSO models were 0.9012 and 0.9992, respectively, for methylene blue dye adsorption on Ganga-sand-encapsulated polyaniline granules. The adsorption isotherm study established that the adsorption process followed the Langmuir model rather than the Freundlich model. This study found that Ganga-sand-encapsulated polyaniline granules can be a promising adsorbent for textile and pharmaceutical wastewater treatment. [ABSTRACT FROM AUTHOR]

Context: In this comparative study of the adsorption of l-phenylalanine (l-Phe) on two modified low-activated carbons (ACK and ACZ) at four temperatures (293–313 K), steric and energetic characteristics of adsorption were investigated. An advanced statistical physics multilayer model involving single-layer and double-layer adsorption scenarios was developed to interpret the l-Phe adsorption phenomenon. Modeling results indicate that two and three l-Phe layers were arranged depending on the tested adsorption systems. The estimated number of l-Phe molecules per leading adsorption site varied from 1.71 to 2.09 and from 1.76 to 1.86 for systems l-Phe-ACK and l-Phe-ACZ, respectively. The results show that a multimolecular adsorption mechanism might connect this amino acid molecule on ACZ and ACK surfaces in a non-parallel location. These parameters changed as follows, according to the adsorbed quantity at saturation analysis: Qasat (l-Phe-ACK) ˃ Qasat (l-Phe-ACZ). This indicates that ACK material was more efficient and valuable for l-Phe adsorption than ACZ. It was also shown that the adsorption capacity decreases as the temperature increases, proving the exothermicity of the adsorption process. This analytical substantiation is confirmed by calculating the binding energies, suggesting the occurrence of physical bonds between l-Phe amino acid molecules and ACK/ACZ binding sites and among l-Phe–l-Phe molecules. Pore size distribution was interpreted and calculated by applying the Kelvin theory to data from single adsorption isotherms. All used temperatures depicted a distribution of pores below 2 nm. The docking analysis involving l-Phe and the ACZ and ACK adsorbents reveal a significant resemblance in how receptors detect ligands. Consequently, the findings from the docking process confirm that the calculated binding affinities fall within the spectrum of adsorption energy. Methods: This study analyzed the adsorption capacity of the l-Phe through a model proposed by statistical physics formalism. Molecular docking was used to determine the various types of interactions between the two activated carbons. Two aspects, including orientation of l-Phe on the site, number of molecules per site n, interaction energy, density of receptor site, and adsorption capacity, were discussed to elucidate the influence of activation on the two adsorbents. [ABSTRACT FROM AUTHOR]

In this study, an adsorption method using a synergistic effect between ultrasound and negative pressure cavitation was developed for the efficient recovery of paclitaxel from the culture supernatants of Taxus chinensis onto an adsorbent Diaion HP-20. The equilibrium adsorption data were matched to Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms, and the Langmuir model was found to be the best fit. As the ultrasonic power and negative pressure intensity increased, the adsorption capacity and adsorption rate constant increased, and the intraparticle diffusion resistance sharply decreased. The combined ultrasound and negative pressure cavitation method achieved the best adsorption, and the synergistic effect was up to 65% at ultrasonic powers/negative pressure intensities of 80 W/–50 mmHg to 250 W/–200 mmHg. Paclitaxel adsorption onto Diaion HP-20 was endothermic and spontaneous. In addition, the isosteric heat of adsorption does not depend on surface loading, so the adsorbent has an energetically homogeneous surface. [ABSTRACT FROM AUTHOR]

The development of efficient adsorbents for sustainable adsorption processes is required in environmental studies. Here, we propose using carbonized Ailanthus altissima leaves as a novel adsorbent, derived from invasive species that threaten biodiversity. Biochar was prepared by pyrolysis at 500 °C, activated with ZnCl2 and tested for the target adsorbates—active pharmaceutical ingredients (APIs). A range of characterization techniques were employed—FTIR, SEM, XPS and Raman spectroscopy—and the adsorption of representative APIs was analyzed. The adsorption kinetics revealed that the adsorbent reached equilibrium within a 3 h period. The adsorption capacities for the selected model substances ranged from 59 mg g−1 for atenolol to 112 mg g−1 for paracetamol, while the highest values were recorded for ketorolac and tetracycline at over 130 mg g−1. The excellent retention is ascribed to the developed surface area, the availability of oxygen surface functional groups and the aromatization of the biochar. The proposed biochar, which is obtained in a sustainable process, proves to be a highly efficient adsorbent for selected pharmaceuticals. [ABSTRACT FROM AUTHOR]

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In this work, zeolite imidazolate framework-7 (ZIF-7) nanoparticles are synthesized via a solvothermal method and rapid synthesis durations of 1 h and 3 h. The effect of the synthesis duration on the structural properties of ZIF-7 was characterized by XRD and FESEM analyses. Subsequently, CH4 single gas adsorption over ZIF-7 nanoparticles was examined using the volumetric method at room temperature and pressure ranging from 2 to 9 bar. The results showed that the synthesized ZIF-7 adsorbents were highly crystalline with a well-defined and homogeneous particle size distribution of 50–60 nm. It was found that increasing the synthesis duration from 1 h to 3 h did not amend the structure and morphology of the resultant samples significantly, mainly due to the short synthesis duration. Meanwhile, the CH4 adsorbed by ZIF-7 nanoparticles increased with rising pressure for both samples, and the ZIF-7 nanoparticles synthesized at 3 h showed a greater adsorption capacity than that of 1 h, mainly due to its higher crystallinity and well-developed pore structure. The ZIF-7 synthesized at 3 h demonstrated an adsorption capacity up to 2.2 mol/kg, which was higher than those values reported in the literature for micron-sized ZIF-7 samples. The CH4 gas adsorption behavior of ZIF-7 nanoparticles synthesized at 1 h and 3 h were well predicted by the Langmuir isotherm model, with coefficients of determination, R2, of 0.9994 and 0.9982, respectively. [ABSTRACT FROM AUTHOR]

Raw white clay was acidified with H2SO4 (2 M) and then activated in a furnace for 2 h at 150oC. The resulting acid-activated clay product was used as an adsorbent for the removal of radioactive substances such as Cs+, Sr2+ and Co2+ ions in aqueous solution. The specific surface area and the pore volume of acid-activated clay were three times higher compared to raw white clay. At 100 mg L- of initial concentration and 1.0 g of dosage, removal efficiencies of Cs+, Sr2+ and Co2+ ions showed 60.0%, 27.3%, and 88.1%, respectively. It was found that the Langmuir isotherm was described well to the adsorption behavior of Cs+, Sr2+ and Co2+ ions on acid-activated clay rather than Freundlich isotherm. The Langmuir isotherm constant (Q) for Cs+, Sr2+ and Co2+ ions was found to be 8.81, 3.78 and 10.20 mg g-1, respectively. Compared to the pseudo-first-order kinetic model, the pseudo-second-order kinetic model was more suitable for adsorption of Cs+, Sr2+ and Co2+ ions in water/acid-activated clay medium owing to the higher correlation coefficient (R2) and the more proximity value of the experimental value qe,exp and the calculated value qe,cal. [ABSTRACT FROM AUTHOR]

This study investigated the efficacy of utilizing eggshells and their pyrolyzed derivatives, within the temperature range of 400–800 °C, as adsorbents for ciprofloxacin (CIP) removal. Experimental data were analyzed using various machine learning (ML) algorithms, viz. linear regression, random forest, support vector machines, decision trees, and k-nearest neighbor to predict performance. Results demonstrated that pyrolyzed eggshells at 600 °C (PES-600) exhibited the highest CIP removal rate (86.06 ± 2.25%). Optimal performance was consistently observed at an initial CIP concentration of 125 mg/L, with the order of PES-600 > PES-500 > PES-400 > PES-700 > eggshells > PES-800. Adsorption capacity peaked at pH 5 (5.84 ± 0.1 mg/g), attributed to interactions including hydrogen bonding, π–π interaction, and ion exchange. Scanning electron microscope images revealed that PES-600 had the highest number of pores, resulting in a smoother surface post-adsorption. Langmuir isotherm model fitting was best for ES, PES-700, and PES-800, while Freundlich isotherm was suitable for PES-400, PES-500, and PES-600. PES-600 showed the best fit with the pseudo-second-order kinetic model. Characterization analysis highlighted the significance of functional groups like C = O, C = C, and –CH groups in aromatic rings. ML algorithms demonstrated remarkable performance with an accuracy level of 90.28%. In conclusion, pyrolyzed eggshells can effectively remove ciprofloxacin (CIP) from wastewater, with optimal performance predicted by the random forest machine learning algorithm when considering real environmental factors. [ABSTRACT FROM AUTHOR]

Dependence on reclaimed wastewater and biosolids for agronomic use in semi-arid and arid regions is progressively increasing across the globe. The impact of contamination of treated water with residues of recalcitrant pharmaceuticals on the ecosystem is now one of the major environmental concerns. Common sunflower, Helianthus annuus (H. annuus), has been reported to remove one of the recalcitrant pharmaceuticals, carbamazepine (CBZ). However, it's potential to tolerate CBZ is not yet characterized. For this, the plant cell suspension system of H. annuus (6.67 g DWL-1) was used as a model system and within 6 h of exposure to CBZ (15 ppm), 39.47 ± 6.8% was found to be removed with initial removal rate of 0.987 ± 0.17 mg L −1 h−1. The adsorption equilibrium data was fitted with the Freundlich isotherm and the removal kinetics of CBZ onto plant cells of H. annuus was correlated well with Elovich kinetics. Also, no significant change in the viability and antioxidant levels (Ascorbate peroxidase and Glutathione peroxidase) was observed in the plant cells exposed to higher concentrations of CBZ (15 ppm), demonstrating high tolerance. The finding strongly indicates that in-vitro system of H. annuus holds significant promise as a robust platform for investigating the intricate mechanisms underlying its tolerance to CBZ. [ABSTRACT FROM AUTHOR]

In this study, anthocyanin was extracted from saffron tepals utilizing the ultrasound‐assisted extraction method. The adsorbents of raw bentonite (RB), acid activation of bentonite (AA) thermal activation of bentonite (TA), and acid and thermal activation of bentonite (ATA) were employed to separate anthocyanin from solution. The influence of the operating parameters was evaluated. The isotherm study demonstrated that anthocyanin adsorption on adsorbents could be fitted better by the Langmuir equation than the Freundlich equation. A good agreement between the predicted consequences of the pseudo‐second‐order model and empirical data was provided. Thermodynamic parameters indicated that anthocyanin was adsorbed in an exothermic and physical process. Findings presented that the best adsorption performance of anthocyanin related to ATA with 2.25 mg/g adsorption capacity which was more than 1.55, 1.75, 1.88 mg/g for RB, AA, and TA, respectively. It was due mainly to the increased surface area by both thermal and acid activation of raw bentonite. [ABSTRACT FROM AUTHOR]

Research efforts are focusing on investigating cost-effective and ecologically friendly ways to create nanoparticles as a result of promising developments in green technology (NPs). This experiment focused on the effectiveness of using biochar (TWB) made from coffee waste to extract levofloxacin (LEV) from water. The conclusive results of the trials showed that TWB is an effective adsorbent for removing LEV from liquid solutions. The TWB produced through biological processes underwent comprehensive analysis using techniques such as X-ray diffractometry (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller surface area measurement (BET), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. The bioengineered TWB's exceptional crystalline properties, which closely resemble the monoclinic structure of bulk TWB, were confirmed by the XRD analysis. Based on the scanning electron microscopy (SEM) data, the synthesis of TWB Nanoparticles resulted in the formation of spherical particles with an approximate diameter of 40 nm, accompanied by a substantial surface area of 285.55 m²/g. The Pseudo-Second-Order model, which best captured Levofloxacin's adsorption characteristics, was evaluated on the TWB, and the results showed that external mass transfer was the main determinant of response rate. It was also found that the adsorption process was endothermic and spontaneous. The system was optimized using the Box–Behnken design (BBD) methodology. The achieved removal capacity of 1119.19 mg/g utilizing the tested adsorbent was determined to be reasonable when compared to the performance of other previously used adsorbents when evaluating the effectiveness of eliminating LEV. The process of LEV adsorption onto TWB involves a number of different mechanisms, such as ion exchange, π-π interactions, electrostatic pore filling, and hydrogen bonding. Following extensive testing in connection with a real-world sample, the adsorbent demonstrated remarkable efficacy, and it maintained good performance even after undergoing three further regeneration cycles. By adjusting the annealing temperature, we controlled the synthesis of TWB nanoparticles across a range of sizes in order to maximize their antibacterial capabilities. This research utilized a pair of Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and a pair of Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) to evaluate the antibacterial efficacy of TWB. Highlights: Green synthesis of biochar via using tea waste. Adsorption studies of harmful pesticides Levofloxacin (LEV). The adsorbents exhibited good reusability for four adsorption/desorption cycles. Adsorption fit with pseudo second order kinetics and Langmuir isotherm model. The adsorption fitted to pseudo-second-order kinetically. This system will provide helpful guidance for coloured effluent treatment. Optimized the results by using Box-Behnken design. [ABSTRACT FROM AUTHOR]

AbstractIn this study, carbofuran (CF) was eliminated from wastewater using pomegranate peel nano adsorbent (PPNA). Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) before and after adsorption were used to assess the process efficiency. BET demonstrated that the PPNA has a specific surface area of 356.5 m2/g. The PPNA was tested under some environmental factors, such as contact time, concentration, adsorbent dose, temperature, and pH. Experimental work was done within the range of 10–50 mg/l initial concentration and the best biosorption capacities were found at 30 min contact time, 0.7 g adsorbent dose, 25 °C, and pH 2. The Freundlich isotherm was the best-fitting isotherm model. The pseudo-second-order model provided the best fit to the process kinetics and indicated that the intra-particle diffusion stage is the rate-limiting step for the process. The study of thermodynamics showed that carbofuran adsorption on PPNA was physisorption (ΔG = −3.2334 kJ/mol) and spontaneous at high temperatures (ΔH = 22.2058 kJ/mol, ΔS = 85.0355 J/mol K). Design of a single-stage batch adsorber for the adsorption of CF from aqueous liquors using PPNA was also done. [ABSTRACT FROM AUTHOR]

Removal of dye contamination from wastewater is crucial for protecting human health and the environment, and adsorption is considered an effective removal method. In addition, agricultural residues are attractive for use as adsorbents for the adsorption due to their renewability. Therefore, the present work aimed to develop silica xerogel from rice husk (agricultural residue in rice production) into an adsorbent for dye wastewater treatment. In the xerogel synthesis, a non-toxic organic acid (citric acid) was used instead of a toxic inorganic acid for leaching and precipitation steps to lower the environmental impact of the process. It was found that the obtained silica xerogel has physical properties such as a surface area and pore volume, comparable with silica xerogels in other literature. When applying it in the dye (methylene blue) wastewater treatment, the obtained silica xerogel showed better adsorption capacity than unprocessed silica at all studied conditions, i.e. various times, pH and initial concentration. The maximum adsorption capacity of the xerogel and unprocessed silica were 103.45 and 61.78 mg/g, respectively. This indicates the benefit of silica xerogel with low environmental impact when applied in dye wastewater treatment. The adsorption isotherms and kinetic for both types of silica were also conducted. It was found that the adsorption process of methylene blue on the silica fitted the Langmuir adsorption isotherm and followed the pseudo-second-order kinetic model. This provides valuable information for optimizing the operating parameters for best performance in a given situation. [ABSTRACT FROM AUTHOR]

Lentil shell (LS) on modification with sulfuric acid (LSAC), formaldehyde (LSFM), and on calcination (LSCL) were used for the adsorption of methylene blue dye in the present study. The sulfuric acid treated LS adsorbent has shown maximum adsorption. The batch adsorption experiments were studied with the effect of adsorbent dose (10–60 mg), pH (4–10), dye concentration (10–80 mg/L), contact time (10–60 minutes), and temperature (303–333 K). The maximum removal of methylene blue was found at pH 10 with adsorption time 60 minutes. The maximum adsorption capacity is measured for LSAC, LSCL, LSFM, and LS untreated (LSUN) are 49.56, 45.79, 42.24, and 42.09 mg/g respectively for 60 mg adsorbent dose with 60 mg/L of initial methylene blue dye concentration. The biosorbents were characterized with Fourier Transform Infrared spectra, Scanning Electron Microscopy, Transmission Electron Microscopy, BET-N2 adsorption, and Energy Dispersive X-ray analysis. The adsorption isotherm was studied at the temperature of 303, 313, 323, and 333 K. It was found that the higher temperature suitable for maximum adsorption. Langmuir model and Freundlich model were studied from the obtained results for adsorption mechanism. The pseudo second order kinetic model was found suitable for the present adsorption study in comparison with pseudo first order model and intraparticle diffusion model. The data obtained from the present work showed that LS could be employed as an efficient adsorbent for the adsorption of the dye. [ABSTRACT FROM AUTHOR]

To investigate chlorine adsorption from water onto resins, some batch adsorption tests were considered. The mechanisms and characteristic parameters of the adsorption process were analyzed using isotherm models which revealed the following order (based on the coefficient of determination): Flory–Huggins (0.99) > Fowler‐Guggenheim (0.98) >, and Langmuir (0.38).The experimental data were examined using two kinetic models, including first‐ and second‐order ones with R2 value of 0.88, 0.1 respectively. According to the adsorption isotherm study, the Flory–Huggins isotherm model better fit adsorption on the surface of resin, as compared to other models. Assessing the thermodynamic parameters found out that the adsorption of Cl onto resins became an exothermic and spontaneous process. The results were then obtained. Similarly, the results of the experiment were provided via the computational fluid dynamics evaluation. Moreover, the results obtained by computational fluid dynamics were compared with the experimental data, and their accuracy was proved. Subsequently, the effects of changing the design and operating parameters, including flow rate (3, 6, 10 L min−1) and bed height (10, 20, 40 cm) on the performance of this tower were studied. The results showed that by reducing the adsorbent, the adsorbed Cl increased and a longer bed was required for adsorption, which was not cost‐effective. The amount of adsorption decreased as the flow rate increased, indicating that there was little contact between the Cl and the adsorbent. [ABSTRACT FROM AUTHOR]

The adsorption of cationic water-soluble polymers onto negatively charged porous wood pulp fibers is an essential aspect of papermaking. Adsorption data can be displayed as a direct plot of the amount adsorbed, Γ, versus the amount of polymer added or as an isotherm plot showing the amount adsorbed versus the residual unadsorbed polymer. In either data presentation, the analysis is more transparent if the units of each axis are the same (e.g., mg/g or meq/g), giving dimensionless slopes. Values for Γmax, ΓI, fI, and Γme can be extracted from many isotherms where: Γmax is the maximum capacity of the fibers to adsorb polymer; ΓI is the y-axis isotherm intercept and gives the maximum dose that can be fully adsorbed; fI is the slope of the direct plot at ΓI, and fI is the mass fraction of the added polymer that can access interior (pore) surfaces; and, Γme is the saturated amount of polymer adsorbed on exterior surfaces. Additionally, the molecular weight distribution of the adsorbing polymer in conjunction with the adsorption isotherm can be used to estimate the molecular weight distributions of adsorbed polymer on interior and exterior fiber surfaces as functions of the polymer dose. [ABSTRACT FROM AUTHOR]

According to environmental concerns related to water pollution, this study aims to develop a novel hydrogel bead as a biocompatible and efficient adsorbent by integrating bacterial cellulose-activated carbon (BCAC) and montmorillonite (MT) in alginate hydrogel (ALG). The ionotropic gelation method was applied to the fabrication of BCAC/MT/ALG hydrogel beads. The BCAC/MT/ALG hydrogel bead exhibited significantly higher tensile strength, Young's modulus, and thermal stability, with ~1.4 times higher adsorption uptake of methylene blue (MB) from aqueous solution as compared to the pristine ALG bead. The textural properties, including specific surface area and porosity, were beneficial to accommodate the size of cationic MB as the target molecule. This resulted in a remarkable MB adsorption uptake of 678.2 mg/g at pH 7 and 30 °C. The adsorption isotherm showed the best fit for the nonlinear Redlich-Peterson isotherm model. Experimental adsorption data were well-described by the pseudo-second order kinetic model, with R2 values reaching 0.997. In addition, the adsorbent bead demonstrated easy regeneration with high reusability with approximately 75% of MB removal after being used for six cycles. Therefore, BCAC/MT/ALG bead represents an eco-friendly, cost-effective, and highly efficient adsorbent for MB removal from water and could potentially be used for removal of a wide range of cationic dye pollutants from wastewater. [ABSTRACT FROM AUTHOR]

The adsorption isotherms and intraparticle mass transfer coefficients of a novel adsorbent with various VOCs at different temperatures during the desorption process are investigated. Firstly, the adsorption isotherms of an HCP-5 adsorbent with o-xylene and ethyl acetate systems were determined at temperatures ranging from 30 to 160 °C, and the data were fitted using the Langmuir adsorption isotherm equation. Subsequently, a mathematical model for the fixed-bed desorption breakthrough of VOCs was established. By combining with fixed-bed desorption breakthrough experiments, the intraparticle mass transfer coefficients of o-xylene and ethyl acetate during the desorption process at different temperatures were obtained through the least squares method. This study revealed that the intraparticle mass transfer coefficients of o-xylene and ethyl acetate during the desorption process were basically equal. The intraparticle mass transfer coefficients increased and then decreased with temperature during the desorption process. Compared with the adsorption process, the contribution of surface diffusion inside the adsorbent pores to intraparticle mass transfer decreased during the desorption process, leading to a significant decrease in the intraparticle mass transfer coefficients, which were approximately one-twentieth of those during the adsorption process. [ABSTRACT FROM AUTHOR]

Abstract Ternary bio-adsorbent was synthesized by using sisal fiber as a base with the integration of conductive polymer; polyaniline (PANI), supported with zero-valent iron nanoparticles by chemical activation with potassium hydroxide. The activation temperature impact on adsorption properties of Sisal fiber composite activated carbon was studied. The activation temperatures had a major effect on adsorption process as 100% removal efficiency was attained at 800 °C activated temperature. Scanning electron microscopy (SEM) was used for surface analysis of the adsorbent. Adsorption isotherms (Langmuir, Freundlich and Temkin) were examined and the negative values of $$1/n_{F}$$ 1 / n F demonstrated that the adsorption data does not match with Freundlich model for chemisorption. The pseudo second order and Elovich kinetics correlation coefficients for the retention of Fe and Cd to solid-phase interface at SF-800/NP/PANI (C) offered a better correlation for the bio-adsorption of Fe and Cd than pseudo first order kinetic. However, the pseudo second order kinetic attained a surpassing interaction for the bio-adsorption of Fe (0.989) than Cd (0.966); while the Elovich kinetic attained a surpassing interaction for the bio-adsorption of Cd (0.975) than Fe (0.945). The recovery and recycling stability of the bio-adsorbent composites were studied.

Abstract This research focuses on the utilization of nano glauconite clay as an environmentally friendly sorbent for the removal of cationic dyes, particularly Methylene Blue (MB), from polluted water. The glauconite clay was sourced from the El Gidida region of Egypt and subjected to grinding in a laboratory-type ball mill to ensure homogeneity and increase the active sites available for the adsorption process. The resulting ball milled nano clay (BMNC) was characterized using techniques such as X-ray fluorescence (XRF), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The concentration of MB dye was monitored using UV–Vis spectroscopy to assess the adsorption capacity of BMNC under various conditions including pH, time, dose, and temperature. The optimal conditions for the adsorption process were determined to be a pH range of 7–8, a contact time of 60 min, and a dose of 200 ppm, resulting in an adsorption capacity of 128 mg/g. This process demonstrated both low cost and high speed. The adsorption mechanism of MB on the BMNC surface was evaluated through kinetics, adsorption isotherms, and thermodynamics. The experimental data indicated an endothermic, spontaneous, and thermodynamically favourable adsorption process, which was further supported by simulated modelling results using Forcite program. The in-silico data aligned well with the experimental findings. Additionally, the study assessed the interference of salts, metal ions, and other dyes on MB adsorption onto BMNC, showing promising results. These findings strongly support the effectiveness of our sorbent substrate under challenging conditions.

Mining, particularly gold mining, is a lucrative industry. However, it poses significant environmental risks, such as releasing heavy metal elements into the soil and water. After gold mines are exhausted, whether they are small or large scale, the excavated sites often need to be repaired. This situation has led to a global concern regarding the presence of heavy metals from mining activities, which are known to be carcinogenic and harmful to living organisms. The concentration of heavy metals in these areas often surpasses safety limits, necessitating advanced treatment methods for their removal, especially lead (Pb) compounds from gold mining waste. One effective treatment method is the adsorption process. This study examined POFA's inherent capacity to remove lead from water contaminated by gold mining without modification. This method was preferred due to its high efficiency and cost-effective option for removing heavy metal compounds. According to the experiment's results, the largest adsorption capacity of 0.816 mg/g was followed by the greatest removal efficiency of 91.837%. The isotherm analysis found that the Langmuir model provided an outstanding fit for the experimental data. Thus, this relationship suggested that on the surface of the POFA, a monolayer and an adsorption process suitable for physical adsorption took place.

This study investigates the synthesis and characterization of Al2O3 nanoparticles derived from multilayered packaging (MLP) waste, specifically postconsumer coffee capsules, and evaluates their efficacy in fluoride adsorption from aqueous solutions. The nanoparticles were synthesized using a facile thermal degradation technique followed by leaching and precipitation processes. Characterization techniques, including inductively coupled plasma‐mass spectroscopy, XRF, Fourier transform infrared spectroscopy, X‐ray diffraction, and transmission electron microscope, confirmed the formation of γ‐Al2O3 nanoparticles with a cubic crystal structure. The adsorption process was found to be endothermic and spontaneous, with a maximum adsorption capacity of 9.60 mg/g. Kinetic studies revealed that the pseudo‐second order model best described the adsorption process, indicating a complex multistep mechanism involving both physisorption in the initial rapid adsorption and chemisorption in the latter slower phase. The Freundlich–Langmuir isotherm provided the best fit for equilibrium data suggesting a complex adsorption mechanism involving both homogeneous and heterogeneous surface interactions. The presence of competing anions, particularly carbonate and phosphate, significantly affected the adsorption efficiency. This research demonstrates the potential of upcycling MLP waste into valuable adsorbents for wastewater treatment applications, offering both environmental and economic benefits. [ABSTRACT FROM AUTHOR]

Abstract Concrete durability is greatly influenced by the transport rate of aggressive chemicals. Moisture diffusion plays a key role in the long-term performance of cementitious materials, as it facilitates the entry of aggressive chemicals into concrete. The pore size distribution plays a critical role in determining moisture diffusivity. However, the characteristics of the concrete pore structure have not been included comprehensively in the material models so far. In this paper, a theoretical model was developed to obtain the pore size volume fractions for each diffusion mechanism including Molecular, Knudsen and Surface diffusions. An effective moisture diffusivity in concrete was then obtained using the weighted average based on the diffusion mechanisms and pore size volume fractions. The model’s validity was demonstrated by comparing model predictions with available experimental data. The findings of this study provide valuable insights into the behavior of the concrete pore structure and its impact on moisture diffusivity.

Abstract Cd(II) is a potentially toxic heavy metal having carcinogenic activity. It is becoming widespread in the soil and groundwater by various natural and anthropological activities. This is inviting its immediate removal. The present study is aimed at developing a Cd(II) resistant strain isolated from contaminated water body and testing its potency in biological remediation of Cd(II) from aqueous environment. The developed resistant strain was characterized by SEM, FESEM, TEM, EDAX, FT-IR, Raman Spectral, XRD and XPS analysis. The results depict considerable morphological changes had taken place on the cell surface and interaction of Cd(II) with the surface exposed functional groups along with intracellular accumulation. Molecular contribution of critical cell wall component has been evaluated. The developed resistant strain had undergone Cd(II) biosorption study by employing adsorption isotherms and kinetic modeling. Langmuir model best fitted the Cd(II) biosorption data compared to the Freundlich one. Cd(II) biosorption by the strain followed a pseudo second order kinetics. The physical parameters affecting biosorption were also optimized by employing response surface methodology using central composite design. The results depict remarkable removal capacity 75.682 ± 0.002% of Cd(II) by the developed resistant strain from contaminated aqueous medium using 500 ppm of Cd(II). Quantitatively, biosorption for Cd(II) by the newly developed resistant strain has been increased significantly (p

Abstract The environmental impact of wastewater discharged from the textile dyeing industry has a significant challenge and influence on aquatic ecosystems and human health if not properly managed. This study aimed to develop a novel cross-linked chitosan composite, denoted as chitosan/fly ash/polyvinyl alcohol (Ch/FA/PVA), as a bio-adsorbent for removing Congo Red (CR) textile dye from industrial wastewater. The synthesis involved the incorporation of FA into the chitosan matrix at various ratios to optimize the process. A specifically tailored composite, Ch/FA0.75/PVA, exhibited superior performance with a remarkable 99.7% CR removal under optimum conditions: adsorbent dose (0.9 g/l), contact time (50 min), and dye concentration (40 mg/l). The characterization of Ch/FA0.75/PVA through SEM–EDX, BET, FTIR, and pHzpc confirmed its suitability for adsorption. Employing Box–Behnken design and analysis of variance (ANOVA) facilitated the optimization of key adsorption variables. The Freundlich model described the adsorption equilibrium, indicating a maximum adsorption capacity of 263.15 mg/g for CR dye. The pseudo-second-order model demonstrated favorable kinetics. The study was scaled up to the practical application of Ch/FA0.75/PVA in a pilot plant for industrial wastewater treatment, revealing substantial removal percentages for dye, color, COD, BOD5 and TDS. This comprehensive approach highlights the promising efficacy of Ch/FA0.75/PVA in addressing environmental concerns associated with textile dye wastewater.

Abstract In this study, Delonix regia seed pods (DRSPs) as a locally available material were refluxed in 90% H2SO4 to yield a novel D. regia seed pods biochar-sulfur oxide (DRB-SO). FTIR, BET, BJH, SEM, EDX, XRD, DSC and TGA were applied to investigate the characterizations of the prepared DRB-SO. Various adsorption parameters like pH effect, dye concentration effect, adsorbent dose, reaction time isotherm and kinetic study were carried out to explain the process of adsorption of methyl orange (MO) and methyl red (MR) onto DRB-SO. Langmuir's adsorption model perfectly explained the adsorption process onto the surface of DRB-SO as a monolayer. The maximum adsorption efficiency of DRB-SO was (98%) and (99.6%) for MO and MR respectively which attained after 150 min with an adsorbent dose of 0.75 g/L. The pseudo-second-order kinetic model best explained the process of adsorption of MO and MR dyes by DRB-SO. The highest observed adsorption amount was as high as 144.9 mg/g for MO dye and 285.7 mg/g for MR dye, comparable with other reported materials based on activated carbon materials. All of the outcomes signposted a prodigious perspective of the fabricated biochar composite material in wastewater treatment. Using the regenerating DRB-SO through an acid–base regeneration process, six cycles of adsorption/desorption were examined. Over the course of the cycles, there was a minor decrease in the adsorption and desorption processes. Also, it was revealed what the most plausible mechanism was for DRB-SO to absorb the ions of the MO and MR dyes.

In this study, the hydrogen storage properties of various synthetic zeolites, including Zeolite Y (FAU), Mordenite (MOR), ZSM-12 (MTW), and MCM-22 (MWW) are determined at 77 K and atmospheric pressure. The structures of the zeolites are characterized by XRD, ICP-OES, FE-SEM, TGA and N 2 adsorption-desorption isotherms. The results show that H-MCM-22 zeolite has the highest hydrogen storage capacity at 1.0 bar with 1.19 wt%, followed by H-MOR zeolite with 1.05 wt%, H–Y zeolite with 0.75 wt% and H-ZSM-12 zeolite with 0.60 wt%. The hydrogen adsorption data on FAU, MOR, MTW, and MWW at 77 K obey the Sips isotherm model. The experimental data show that the ultra-micropore volume of the zeolite is effective in hydrogen adsorption at low-pressure ranges. In addition, increasing the aluminum content of the zeolite increases the hydrogen adsorption capacity of the zeolite at atmospheric pressure. Therefore, zeolites with channel sizes close to the kinetic diameter of a hydrogen molecule, large cage volumes, and high aluminum content are potential candidates for energy storage applications. [Display omitted] • ZSM-12 and MCM-22 were synthesized and characterized. • The H 2 adsorption capacities of four zeolites were determined at 77 K and 1.0 bar. • The experimental data were analyzed using the Langmuir, Freundlich, and Sips isotherms. [ABSTRACT FROM AUTHOR]

Concrete durability is greatly influenced by the transport rate of aggressive chemicals. Moisture diffusion plays a key role in the long-term performance of cementitious materials, as it facilitates the entry of aggressive chemicals into concrete. The pore size distribution plays a critical role in determining moisture diffusivity. However, the characteristics of the concrete pore structure have not been included comprehensively in the material models so far. In this paper, a theoretical model was developed to obtain the pore size volume fractions for each diffusion mechanism including Molecular, Knudsen and Surface diffusions. An effective moisture diffusivity in concrete was then obtained using the weighted average based on the diffusion mechanisms and pore size volume fractions. The model's validity was demonstrated by comparing model predictions with available experimental data. The findings of this study provide valuable insights into the behavior of the concrete pore structure and its impact on moisture diffusivity. [ABSTRACT FROM AUTHOR]

Deliquescent salts are well known for their high-water vapor adsorption capacity, but they form crystalline hydrates and dissolve in adsorbed water; therefore, they cannot be used in most water vapor adsorption applications. To counter this issue, we fabricated solid polymer desiccants comprising polyacrylic acid (PAA) and sodium chloride (NaCl), which were able to capture water vapors from humidity in large quantities and avoid the dissolution of NaCl by keeping it intact inside the polymer matrix. Polymer desiccants, i.e., super-porous hydrogels (SPHs), were synthesized using gas-blowing and foaming techniques to create a porous structure. Due to dense capillary channels, the polymer matrix alone (i.e., without NaCl salt) could capture a high amount of water vapors (0.82 gw/gads). Introducing NaCl salt in the polymer matrix drastically improved desiccant performance (3.1 gw/gads). Further, the polymer matrix avoided salt dissolution in the adsorbed water and kept it intact within the polymer matrix. Adsorption isotherm was found to be type-III isotherm and best explained using GAB and FHH isotherm models, suggesting that the high desiccant performance of synthesized solid polymeric adsorbents was due to the presence of dense capillary channels in the polymer structure and the presence of NaCl salt within the polymer matrix. The adsorption kinetics followed the linear driving force (LDF) model and the case-II type diffusion mechanism. The desorption performance and kinetics of water release from fully hydrated desiccant samples after capturing water vapors were studied at different temperatures, suggesting that the water release rate depends highly on desorption temperature. Furthermore, the synthesized desiccants exhibited good cyclic performance for six adsorption cycles with a little loss in the desiccant performance. [ABSTRACT FROM AUTHOR]

In recent years, with the development of China's industry, the pollution problem of heavy metal wastewater in the country has become increasingly serious. In this paper, peanut shells modified with zinc chloride were selected as an adsorbent for the adsorption of Ag+ , and the optimal conditions for this adsorption were investigated. The results showed that the best adsorption effect was achieved at pH 4.0, an initial concentration of 250 μg/mL of Ag+ , a dosage of 0.10 g of peanut shell, a contact time of 40 min, and a temperature of 20°C. The prepared materials were also characterized by scanning electron microscopy and an X-ray diffraction analyzer. It was found that the skeleton did not change after the peanut shell treatment: the pores became larger; and the peanut shells had good adsorption capacity for Ag+ after being modified with zinc chloride. The kinetic, thermodynamic, and isothermal properties of the adsorption process were analyzed, showing that the adsorption conforms to the quasisecond-order kinetic equation and to the Freundlich adsorption isotherm. By this method, the heavy metal Ag+ in wastewater can be absorbed at low cost and with high efficiency, providing protection to the environment. [ABSTRACT FROM AUTHOR]

Exploration has been made into 2-nitro-4-methylsulfonyltoluene (NMST) adsorption on coconut activated carbon from acetic acid. The results demonstrate that the adsorption of NMST on activated carbon augments with its concentration in acetic acid. NMST adsorption on activated carbon is also improved with temperature. Though NMST adsorption on per gram of carbon will decrease with carbon dosage, more NMST will be adsorbed. The kinetic study depicts that NMST adsorption on activated carbon is in good agreement with the pseudo-second-order kinetic equation. Both of the Langmuir and Freundlich equilibrium isotherm models are well fit for the experimental results, with R2 = 0.9994 and 0.9979, respectively. The adsorption thermodynamic parameters (ΔH, ΔG, ΔS) calculated with Van't Hoff equations indicate that NMST adsorption on carbon is spontaneous and endothermic. [ABSTRACT FROM AUTHOR]

The method of isotherm simulation by approximating mathematical expressions that are valid for a small experimental section of the isotherm over the entire range of equilibrium concentrations is an important and useful tool in adsorption practice. Nine adsorption equilibrium systems of activated carbon (AC)–derivatives of aniline and phenol were examined. The adsorbent used was activated carbon obtained from fruit pits. The results of isothermal adsorption of aromatic substances with relatively small molecules on a microporous carbon adsorbent indicate the simultaneous adequacy of the Freundlich and Langmuir models to the experimental data in moderate concentration ranges ((0.1–100)n mg/dm3, where n = 1, 2, 3, 4, 5). Thus, the results of adsorption from the aqueous phase do not demonstrate the energy differences of the AC surface that are incorporated into the theoretical classical model isotherms. The isotherm reflects the adsorption process on both homogeneous and heterogeneous surfaces simultaneously. This may be due to the displacement nature of adsorption from the aqueous phase, where initial surface screening by water molecules occurs during adsorbent wetting, leading to the leveling of its energetic heterogeneity. In the next stage—displacement of some water molecules by the organic adsorbate—the energetic differences of the adsorption sites are not as clearly manifested as in gas-phase adsorption. Therefore, theorizing the nature of the AC surface based on the best model simulation of experimental isotherms using classical equations becomes questionable. Three-parameter equations (Langmuir–Freundlich, Redlich–Peterson) demonstrated a finer simulation of the experiment compared to the classical two-parameter models. The study emphasizes that the mathematical description of the isotherm is a convenient method for the efficient storage and use of information about the adsorption properties of the system. It serves to compare the effectiveness of new materials with commercial analogs and to predict the performance of real purification systems under dynamic conditions. [ABSTRACT FROM AUTHOR]

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This research work aimed to study the kinetics and isotherms of adsorption of mixture of four pesticides (atrazine, chlorothalanil, β-endosulfan, and α-endosulfan) from aqueous solution on activated carbon (AC) and biochar (BCH) under the effect of ultrasonic media. The optimized pH, sonication time, solution initial concentration, adsorbent dose, adsorbent particle size, solution temperatures, and sonication power (US-power) for the maximum adsorption rate were found to be 7, 60 min, 10 µg Lˉ1, 200 µg Lˉ1, 20 µm, 288, and 80 W, respectively. Pesticides adsorption was enhanced by increasing pH to 7, while slight decreases were noted when pH increases from 7 to 9. The adsorption equilibrium data were well described by the Langmuir isotherm model having a significant correlation coefficient value of 0.9999. The kinetics model of pseudo-second order was perceived to best describe the adsorptions data. Negative values of standard Gibb's free energy (ΔG) were observed for thermodynamics analysis, signifying the process's spontaneity. The positive value observed for enthalpy change (ΔH) shows that the reaction's nature is endothermic with randomness intensifying due to positive entropy change. The adsorbents' high adsorptions efficiency designates its appropriateness for the remediation of pesticides from synthesized aqueous solutions and water-containing bodies. No previous ultrasonic-assisted adsorption study on AC and BCH has been recorded for the pesticides in reference, which shows the significance and novelty of the current research study. [ABSTRACT FROM AUTHOR]

Cd(II) is a potentially toxic heavy metal having carcinogenic activity. It is becoming widespread in the soil and groundwater by various natural and anthropological activities. This is inviting its immediate removal. The present study is aimed at developing a Cd(II) resistant strain isolated from contaminated water body and testing its potency in biological remediation of Cd(II) from aqueous environment. The developed resistant strain was characterized by SEM, FESEM, TEM, EDAX, FT-IR, Raman Spectral, XRD and XPS analysis. The results depict considerable morphological changes had taken place on the cell surface and interaction of Cd(II) with the surface exposed functional groups along with intracellular accumulation. Molecular contribution of critical cell wall component has been evaluated. The developed resistant strain had undergone Cd(II) biosorption study by employing adsorption isotherms and kinetic modeling. Langmuir model best fitted the Cd(II) biosorption data compared to the Freundlich one. Cd(II) biosorption by the strain followed a pseudo second order kinetics. The physical parameters affecting biosorption were also optimized by employing response surface methodology using central composite design. The results depict remarkable removal capacity 75.682 ± 0.002% of Cd(II) by the developed resistant strain from contaminated aqueous medium using 500 ppm of Cd(II). Quantitatively, biosorption for Cd(II) by the newly developed resistant strain has been increased significantly (p < 0.0001) from 4.36 ppm (non-resistant strain) to 378.41 ppm (resistant strain). It has also shown quite effective desorption capacity 87.527 ± 0.023% at the first desorption cycle and can be reused effectively as a successful Cd(II) desorbent up to five cycles. The results suggest that the strain has considerable withstanding capacity of Cd(II) stress and can be employed effectively in the Cd(II) bioremediation from wastewater. [ABSTRACT FROM AUTHOR]

A laboratory experiment was carried out to study the ability of soil to adsorption of Zinc added from three sources: nano-Zinc oxide (ZnnO), nano-chelated Zinc (Znn-DTPA), and nano-organic Zinc (Znn-HA), with several concentrations ranging from 0-160 mg Zn kg-1. Zinc was added for each concentration at an amount of 20 ml per 1 gm of soil. As for the ordinary sources, Zinc was added from the ordinary sources, Zinc oxide, ZnO, chelated Zinc, Zn-DTPA, and ordinary organic Zinc, Zn-HA, in several concentrations, ranging from 0-500 mg Zn kg-1. Each concentration was added at 20 ml per 1 gm of soil and two repetitions for each source. The adsorption capacity of the soil and the binding energy of the adsorbed Zinc, and to estimate the thermodynamic parameters for the adsorption of nano-Zinc in desert soils, and Freundlich equations were used to study and evaluate the adsorption process. The thermodynamic parameters Kº, ΔGº, ΔHº, and ΔSº were calculated based on the results of the adsorption experiment. The results of the experiment indicate that both equations succeeded in describing the adsorption of nano and ordinary Zinc depending on the value of the determination coefficient of (R² ), which ranged between (0.959 - 0.971) and (0.884 - 0.985) for each of the Langmuir and Freundlich equations respectively. As for the thermodynamic equilibrium constant Kº, it decreased with the increase in the reaction temperature for three sources: Znn-DTPA, ZnO, and Zn-HA, while it increased with the other three sources. The negative ΔGº values for all sources of nano and ordinary Zinc parameters spontaneity of the reaction at both temperatures 25°C - 45°C. [ABSTRACT FROM AUTHOR]

Background. The cinder of industrial molybdenum product (IPM), obtained at JSC Almalyk Mining and Metallurgical Combine, based on a charge with kaolin, is processed by soda leaching in 6-7 stages. Purpose: to study the textural and sorption properties of IPM samples based on kaolin and organic binders. Methodology. Using the calorimetric method of adsorption of water and nitrogen vapors on the surface of the cinder, by constructing adsorption isotherms, using the Langmuir equation, the sorption characteristics of the materials were obtained. Originality. It has been established that the IPM cinder, based on organic binders, is characterized by a porous structure. It is more efficient in processing, compared to kaolin cinder. Findings. The sorption of water vapor and nitrogen on granules of IPM cinder based on kaolin and organic binders was studied. [ABSTRACT FROM AUTHOR]

Sodium alginate and alginate silver nanoparticles were utilized as adsorbents to eliminate Fe (II) ions from aqueous solutions. Biosorption capacity was established through the use of serial bioadsorption experiments. The effect of different investigated factors in bioadsorption included contact time, pH, adsorbent dosage, and various metal ion concentrations. Alginate silver nanoparticles were more effective than sodium alginate in removing Fe (II) from an aqueous solution. The removal efficiency of Fe (II) by nanoparticles was 80%, while by alginate was 54%. The optimal conditions for bioadsorption of Fe (II) were pH 4, contact time 150, and an adsorbent dose 0.01 g. Adsorption isotherm was fitted to Langmuir isotherm (R2 = 0.995) rather than Freundlich isotherm. Also, UV and FT-IR before and after Fe (II) adsorption were performed to confirm the bioadsorption process. [ABSTRACT FROM AUTHOR]

This work mainly studied the adsorption mechanism of chitosan biochar(CB) on cationic dyes gentian violet(GV) and malachite green(MG) in aqueous solution. The adsorption behavior of cationic dyes GV and MG on biochar was analyzed by adsorption isotherm. In the single system, the adsorption equilibrium experiment found that the Langmuir model can describe the adsorption behavior of CB adsorption GV and MG, indicating that it is mono-layer adsorption. In the binary system, the extended-Langmuir model and Langmuir-Freundlich model can describe the adsorption behavior of CB adsorbing GV and MG, indicating that there is an interaction between GV and MG, that is, the adsorption of dye molecules on the adsorption site depends on the presence of dye molecules on other adsorption sites, and multi-layer adsorption occurs. In the binary systemsynergistic effect" occurs when the dye concentration is low, and "antagonistic effect" occurs when the concentration is high. [ABSTRACT FROM AUTHOR]

The environmental impact of wastewater discharged from the textile dyeing industry has a significant challenge and influence on aquatic ecosystems and human health if not properly managed. This study aimed to develop a novel cross-linked chitosan composite, denoted as chitosan/fly ash/polyvinyl alcohol (Ch/FA/PVA), as a bio-adsorbent for removing Congo Red (CR) textile dye from industrial wastewater. The synthesis involved the incorporation of FA into the chitosan matrix at various ratios to optimize the process. A specifically tailored composite, Ch/FA0.75/PVA, exhibited superior performance with a remarkable 99.7% CR removal under optimum conditions: adsorbent dose (0.9 g/l), contact time (50 min), and dye concentration (40 mg/l). The characterization of Ch/FA0.75/PVA through SEM–EDX, BET, FTIR, and pHzpc confirmed its suitability for adsorption. Employing Box–Behnken design and analysis of variance (ANOVA) facilitated the optimization of key adsorption variables. The Freundlich model described the adsorption equilibrium, indicating a maximum adsorption capacity of 263.15 mg/g for CR dye. The pseudo-second-order model demonstrated favorable kinetics. The study was scaled up to the practical application of Ch/FA0.75/PVA in a pilot plant for industrial wastewater treatment, revealing substantial removal percentages for dye, color, COD, BOD5 and TDS. This comprehensive approach highlights the promising efficacy of Ch/FA0.75/PVA in addressing environmental concerns associated with textile dye wastewater. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of ultrasound (US) processing on the physical and powder flow properties of nixtamalized corn flour (NCF) and its influence on the quality parameters of tortillas such as texture, yield, and the presence of amylose-lipid complexes. Nixtamalized corn flour modified by ultrasound (NCFMU) exhibited lower lipid content (3.35%), higher WAI, and higher WSI, as well as higher enthalpy of gelatinization (6.92 J·g− 1) and minimum setback viscosity (2934cP). Also, US processing improved the moisture content corresponding to minimum integral entropy (MIE) of adsorption and reduced caking (138.77 N), cohesiveness index (18.03 N·m·g− 1), and the speed flow dependency values of NCFMU. SEM analysis revealed a rough surface of starch granules in NCFMU. Tortillas prepared from NCFMU exhibited higher values of tensile (2.51 N) and cutting force (23.75 N), as well as flour yield (1.52 kg of tortillas made per kg of flour), than those prepared from NCF. DSC and RVA analyses revealed the formation of amylose-lipid complexes in tortillas prepared from NCFMU. This study provides valuable information on the conditions of US for its employment as an easy, novel, and suitable strategy for obtaining NCF with improved pasting and thermal properties, most desirable moisture-storage conditions, and flow powder behavior, while a better tortilla product is obtained. The effects provided by US could be useful for its application in improvements of NCF with limited functionality, such as those obtained from maize varieties not suitable for the tortilla industry. [ABSTRACT FROM AUTHOR]

(CoFe2O4)1-x/(Mg0.9Ni0.1O)x nanocomposites, with weight fraction x = 0, 0.1, 0.2, 0.4, 0.8 and 1, have been synthesized by co-precipitation method followed by high-speed ball milling technique. The structural and optical properties of the prepared samples have been studied. XRD analysis confirmed the formation of the two pure phases CoFe2O4 and Mg0.9Ni0.1O, without the formation of any impurities or minor phases in the nanocomposites. Transmission electron microscopy (TEM) followed by high-resolution TEM (HRTEM) and SAED were used to study the morphology, crystallinity and lattice spacing, respectively. TEM micrographs revealed the co-existence of spherical particles for both pure phases and their nanocomposites. The second-order kinetic model was employed to investigate the adsorption efficiency of the nanocomposites for removing malachite green (MG) dye from the solution. Among the prepared samples, superior adsorption performance was revealed by (CoFe2O4)0.2/(Mg0.9Ni0.1O)0.8 and Mg0.9Ni0.1O. (CoFe2O4)0.2/(Mg0.9Ni0.1O)0.8 nanocomposites were chosen as the best candidate among all samples as they possess magnetic properties which makes them easily removed from the solution after the adsorption process. Different adsorption isotherms (Langmuir, Freundlich, and Temkin isotherms) were used to determine the adsorption isotherm, and the results are consistent with the Langmuir theoretical model. The adsorption was further investigated by varying adsorbent concentration, pH of MG solution and reaction temperature. [ABSTRACT FROM AUTHOR]