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A pH responsive monometallic‐clay nanocomposite hydrogel, sodium alginate‐cl‐poly (N‐hydroxy ethyl acrylamide‐co‐methacrylic acid) @ Au/ montmorillonite clay (SANCHG@Au/MMT) is synthesized in situ using sodium alginate (SA) as a polysaccharide. Two other nano composite hydrogels namely sodium alginate‐cl‐poly (N‐hydroxy ethyl acrylamide‐co‐methacrylic acid) @ Au (SANCHG@Au) and sodium alginate‐cl‐poly (N‐hydroxy ethyl acrylamide‐co‐methacrylic acid) @ montmorillonite clay (SANCHG@MMT) are also prepared. All the synthesized nano composite hydrogels are characterized using various techniques. Water swelling of the three hydrogels along with their textile dye adsorption properties is evaluated in congo red (CR), benzopurpurin (BP) and tartrazine (TZ) from their aqueous solutions. Among the three hydrogels the % water swelling of SANCHG@Au/MMT is superior (396% at pH = 8) and also the adsorption capacity over the other two. The dye adsorption property of SANCHG@Au/MMT is found to be pH sensitive. Adsorption follows both the Langmuir adsorption isotherm with Qmax values 512.19 mg.g−1 for CR at pH = 4, 476.09 mg.g−1 at pH = 4 for BP and 454.79 mg.g−1 at pH = 6 for TZ respectively and Dubinin–Radushkevich isotherm model. The kinetic data fit with pseudo second order kinetic model. Thermodynamic parameters like negative ∆G0 and positive ∆H0 values suggest that the adsorption process is spontaneous and endothermic in nature. [ABSTRACT FROM AUTHOR]

The objective of this study was to produce hydrophobic porous wood ceramics as adsorbents for CO2 through the resin treatment of pine. The prepared samples underwent analysis using various methods to determine their structure and properties. An orthogonal experimental approach was employed to obtain adsorbents with optimal preparation process. The highest adsorption capacity was determined to be 1.36 mmol/g at a temperature of 30 ℃ and a CO2 concentration of 15 vol%. The effect of temperature on the microstructure of wood ceramics was studied by characterization. Increasing temperatures adversely affected the adsorption capacity. Nevertheless, the hydrophobic nature of wood ceramics resulted in little impact of humidity on CO2 absorption. The CO2 adsorption kinetics of wood ceramics were analyzed using kinetic studies, which demonstrated that the kinetics can be accurately fitted by both the pseudo-first-order and Avrami models. The findings of the adsorption isotherm analysis showed that the Langmuir model fit was optimal. Following 30 cycles of adsorption-desorption in the presence of simulated gas, the CO2 sorption capacity of the wood ceramics was maintained at over 90%. In terms of CO2/N2 selectivity, the wood ceramics showed a clear preference for CO2, especially at 30 °C, where the CO2/N2 selectivity ratio reached 24.50. [ABSTRACT FROM AUTHOR]

This study explored cefuroxime sodium (CXM) adsorption on sepiolite-rich dolomite, assessing the impact of various conditions like pH, contact time, temperature, and initial CXM concentration. The research utilized data mining, kinetic and isotherm models, and analytical techniques such as FTIR, SEM, and EDX to understand the adsorption mechanism and behavior. Findings indicated that pH significantly influenced CXM adsorption, with the highest efficiency at pH 5. Additionally, the adsorption kinetics were consistent with a pseudo-first-order model, showing that adsorption was rapid and cooperative and reached equilibrium within 60 minutes, while the Freundlich isotherm model best described the adsorption isotherm. The adsorption mechanism was mainly governed by the electrostatic attraction, ion exchange, and pore-filling processes, influenced by the adsorbent's surface heterogeneity and texture characteristics, the adsorbate functional groups, and the bulk solution. Thermodynamic parameters revealed the adsorption to be spontaneous, exothermic, and entropy-driven, suggesting a predominantly physical process. While the presence of negative ΔG values showed that adsorption preferred low temperatures, the presence of a positive ΔS value showed increased randomness at the solid-liquid interface during adsorption. SEM and FTIR results confirmed the changes in the sepiolite-rich dolomite's surface properties and functional groups after CXM adsorption. EDX analysis revealed that CXM's adsorption involved the replacement of Ca2+ ions by CXM's functional groups. The study proved that sepiolite-rich dolomite can be a very effective and environmentally friendly adsorbent to remove CXM and treat bacterial infections from domestic waste or wastewater. [ABSTRACT FROM AUTHOR]

The presence of bound water in clay has a significant impact on the physical and chemical properties of clay, particularly its strength, permeability, and creep behavior. In this paper, the bound water in clay has been studied from the perspective of water potential. Initially, the adsorption isotherms of powders and consolidated samples for Na- and Ca-bentonite and illite were measured, and the bound water content was determined by subtracting the capillary water in the isotherms, with the capillary water being calculated by mercury intrusion porosimetry tests. The results indicated that bound water is independent of the void ratio and pore structure of clay, which is consistent with previous studies. Then, metadynamics was conducted to determine the adsorption free energy landscapes of the three clays, and the lowest suctions of the three clay minerals were determined to be −1.7 , −5.4 , and −2.1 GPa , respectively. Finally, through a comparison of the simulations and experiments in this study and in the literature, three important conclusions were drawn. Firstly, the lowest water potential for montmorillonite exhibits a linear relationship with the hydration free energy of exchangeable cations. Secondly, the critical water potential for tightly bound water is determined as the first inflection point in the relationship between water potential and water content, and the critical value of montmorillonite is found to be correlated to the valence of exchangeable cations. Lastly, the boundary between loosely bound water and capillary water is determined as the starting point of capillary water formation. Overall, this research highlights the importance of considering water potential as a key factor in understanding the behavior of bound water in clay. [ABSTRACT FROM AUTHOR]

The study aimed to determine the feasibility of using compost as a 'green adsorbent' for the removal of five anionic azo dyes belonging to the monoazo, disazo and trisazo classes: Direct Red 81 (DR-81), Direct Blue 74 (DB-74), Reactive Blue 81 (RB-81), Reactive Red 198 (RR-198) and Acid Black 194 (ABk-194) from aqueous solutions. The adsorption capacity of the compost was determined using a batch method with initial dye concentrations ranging from 1 to 1000 mg/L. The kinetics of dye removal followed a pseudo-second-order model, indicating chemisorption as the rate-limiting step. The monoazo dyes RB-81, RR-198 and ABk-194 with the smaller molecule size were adsorbed the fastest. The Langmuir and Sips models best fit the adsorption system with maximum adsorption capacities in the range of 12.64 mg/g (RR-198)—20.92 mg/g (ABk-194) and 12.57 mg/g (RR-198)—25.43 mg/g (ABk-194), respectively. The adsorption depended on the dye structure, especially on the ratio of the numbers of proton donors to proton acceptor locations in functional groups. The differences in the adsorption mechanism could be explained by thermodynamic properties such as dipole moments, HOMO–LUMO energy gap, polarizability, electron affinity, ionization potential, electronegativity and chemical hardness obtained by Density Functional Theory. [ABSTRACT FROM AUTHOR]

The purpose of this study is to determine how well activated carbon made from kluwak shell (Pangium edule Reinw) works as an adsorbent to remove Pb(II) and Cu(II) heavy metal ions from wastewater used in laboratories. Kluwak shell was selected as an agricultural waste material due to its high carbon content, which makes it a promising material for activated carbon that can lower Pb(II) and Cu(II) heavy metal levels. Finding the ideal contact time, pH, and adsorption capacity as well as the kinetics and adsorption isotherm model are the main goals of this study. Using 25% KOH for carbonization and chemical activation, Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), and Surface Area Analyzer (SAA) for characterization are some of the research methods used. FTIR results showed the presence of O-H, C-H, C = C and C-O functional groups, while SEM showed more open pores after activation. SAA analysis indicated an activated carbon surface area of 3.11 m²/g, pore volume of 0.006 cm³/g, and pore diameter of 4.08 nm, categorized as mesoporous. The optimum condition for adsorption of Pb(II) ions is at pH 5 with contact time of 10 minutes and adsorption capacity of 21.83 mg/g. As for Cu(II) ions, the optimum condition is at pH 4 with a contact time of 20 minutes and adsorption capacity of 10.82 mg/g. The adsorption of metal ions is in accordance with the Langmuir isotherm model and pseudo second-order kinetics. The adsorption effectiveness of Pb(II) and Cu(II) ions from laboratory wastewater was 1.69 mg/g and 1.73 mg/g. It is concluded that activated kluwak shell can be used as Pb(II) and Cu(II) metal adsorbent. [ABSTRACT FROM AUTHOR]

AbstractThe present study used low-cost, abundant, and nontoxic kaolin and kaolin-based PVA/alginate composite (KPA) as adsorbents to remove U(VI) and Sr(II) ions from aqueous solutions. The characterization of the adsorbents was performed by several techniques. The results showed that PVA/alginate enhanced the functional groups and changed the surface morphology. Adsorption isotherm parameters were determined through both linear and non-linear regression analyses, from which it was inferred that the Langmuir model provides a better fit than other ones. The uranium removal capacity of KPA significantly improved as compared to that of kaolin, reaching 104.17 mg/g under the conditions of 30 min, pH 4.0, 298 K, and a solid-to-liquid ratio of 1.2 g/L. The strontium removal capacity of kaolin was significantly high as compared to that of KPA, reaching 68.96 mg/g under the optimum conditions. Removal of the radionuclides on both adsorbents was better described by the pseudo-second-order kinetic model, showing the ions to be immobilized on the adsorbents through chemical adsorption. Kaolin was not affected by interfering metals for U(VI) and Sr(II) adsorption, but KPA composite was influenced by the other metals. The adsorbents display potential as candidates to remove uranium and strontium from wastewater. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are superior sorbents for water adsorption‐based applications. The unique step‐like water isotherm at a MOF‐specific relative pressure allows easy loading and regeneration over a small range of temperature and pressure conditions. With good hydrothermal stability and cyclic durability, it stands out over classical sorbents used in applications for humidity control, water harvesting, and adsorption‐based heating and cooling. These are easily regenerated at moderate temperatures using "waste" heat or solar heating. The isotherm thermodynamics and adsorption mechanisms are described, and the presence of MOFs in the water–air system is explained. Based on six selection criteria ≈40 reported MOFs and one COF are identified for potential application. Trends and approaches in further synthesis optimization and production scale‐up are highlighted. No‐MOF‐fits‐all, each MOF has its own specific step location matching only with a certain application type. Most applications are technically feasible and demonstrated on the bench‐scale or small pilot. Their maturity is benchmarked by their technology readiness level. Retrofitting existing applications with MOFs replacing classical desiccants may lead to rapid demonstration. Studies on techno‐economic analysis and life cycle analysis are required for a rational evaluation of the feasibility of promising applications. [ABSTRACT FROM AUTHOR]

There is a necessity for an eco‐friendly inhibitor technology to safeguard mild steel from corrosion. Redox‐active Oligoanilines, namely diamine‐capped trimer (DCTA) and tetramer (DCTAni) have been synthesized and incorporated into the polyurethane backbone derived from polyethylene glycols (PEG, Mw = 2050, 4000) and toluene diisocyanate (TDI). The four water‐soluble polyurethanes, resulting from PEG, TDI, and DCTA/DCTAni, were denoted as IH‐1, IH‐2, IH‐3, and IH‐4. The corresponding redox‐active polyurethanes were rationally characterized using FTIR, and UV–visible spectroscopies. Scanning electron microscopy (SEM) was employed to investigate the surface morphology. The electrochemical properties of these inhibitors were characterized by cyclic voltammetry (CV). All the inhibitors were studied for their corrosion inhibition efficiency using Tafel potentiodynamic polarization analysis and weight loss methods. These demonstrated high efficacy at a low concentration of 200–300 ppm. The absorptivity of polymers on the mild steel were confirmed by Langmuir adsorption isotherms with a well‐fitting (R2 = 99.9%). The SEM analysis showed the adsorption capacity of inhibitors as protective layers for the mild steel panels. Overall, this work paves the way for innovative ideas for producing more water‐soluble and electrochemically active polymer additives as excellent corrosive inhibitors for mild steel surfaces. [ABSTRACT FROM AUTHOR]

Two water‐stable indium metal‐organic frameworks, (NH2Me2)3[In3(BTB)4] ⋅ 12DMA ⋅ 4.5H2O (In‐MOF‐1) and (NH2Me2)9[In9O6(BTB)8(H2O)4(DMSO)4] ⋅ 27DMSO ⋅ 21H2O (In‐MOF‐2) (BTB=4,4′,4′′‐benzene‐1,3,5‐tribenzoate) with 3D interpenetrated structure has been constructed by regulating solvents. Structure analysis revealed that In‐MOF‐1 has a three‐dimensional (3D) structure with a single metal core, while In‐MOF‐2 features an octahedron cage constructed by three kinds of metal clusters to further form a 3D structure. The fluorescence investigations showed that In‐MOF‐1 and In‐MOF‐2 are potential MOF‐based fluorescent sensors to detect acetone and Fe3+ ions in EtOH or water with high sensitivity, excellent selectivity, recyclability and a low limit of detection. Moreover, the fluorescence mechanisms of In‐MOF‐1 and In‐MOF‐2 toward acetone and Fe3+ ions were further explained. In addition, In‐MOF‐2 has higher thermal and framework stability than In‐MOF‐1. The activated In‐MOF‐2 presents a high BET surface area of 998.82 m2g−1 and a pore size distribution of 8 to 16 Å. At the same time, In‐MOF‐2 exhibits high selective CO2 adsorption for CO2/CH4 and CO2/N2, respectively. Furthermore, the adsorption sites and adsorption isotherms were predicted using grand canonical Monte Carlo (GCMC) simulations, and the adsorption energy of the lowest‐energy adsorption configuration was calculated using molecular dynamics (MD) simulations. [ABSTRACT FROM AUTHOR]

AbstractTwo new quinoxaline derivatives namely (E)-3-(2-chlorostyryl)quinoxalin-2(1H)-one (CSQO) & (E)-3-(2-(thiophen-2-yl)vinyl)quinoxaline-2(1H)one (TVQO) were synthesized and identified through the following methods like infrared (IR) analysis, mass spectrometry,1H NMR and 13C NMR. Weight loss, electrochemical techniques [PDP&SIE], surface analytical techniques [SEM&UV-Visible], quantum chemical calculations [DFT], and MD simulations have all been used to examine the effectiveness of CSQO and TVQO in preventing the corrosion of mild steel. According to the findings of the experiments, the inhibitors CSQO and TVQO effectively suppress the corrosion of mild steel in 1 M HCl solution, with maximum corrosion inhibition of 97.0 and 95.5% at 10−3 M for CSQO and TVQO, respectively. Based on PDP investigations, CSQO and TVQO function as mixed-type inhibitors, and their adsorption on the MS surface follows the Langmuir adsorption isotherm and the mode of adsorption is chemisorption. Both surface investigations (SEM and UV-Visible) have validated the protective layer that developed on the metal surface. DFT calculations and MD simulations were used to study the association between inhibitor molecular structure [CSQO and TVQO] and inhibitory efficacy, and they closely match the experimental findings. [ABSTRACT FROM AUTHOR]

The present work aimed to highlight an efficient, readily accessible, and costeffective adsorbent derived from Dalbergia sissoo (DS) leaf powder for removing the environmentally hazardous dye "alizarin red S" (ARS) from hydrous medium. A variant of the adsorbent is activated via sulfuric acid and composited with magnetic iron oxide nanoparticles (DSMNC). Both adsorbents are thoroughly characterized using techniques such as Fourier transform infrared spectroscopy, point of zero charge, energy-dispersive X-ray spectroscopy, and scanning electron microscopy, which show that they have a porous structure rich in active sites. Different adsorption conditions are optimized with the maximum removal efficiency of 76.63% for DS and 97.89% for DSMNC. The study was highlighted via the application of various adsorption isotherms, including Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich, to adsorption data. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were utilized to investigate the kinetics and mechanism of adsorption. The Freundlich model and pseudo-second-order kinetics exhibited the best fit, suggesting a combination of physical interactions, as confirmed by the D-R and Temkin models. The dominant adsorbate-adsorbent interactive interactions responsible for ARS removal were hydrogen bonding, dispersion forces, and noncovalent aromatic ring adsorbent pi-interactions. Thermodynamic parameters extracted from adsorption data indicated that the removal of the mutagenic dye "ARS" was exothermic and spontaneous on both DS and DSMNC, with DSMNC exhibiting higher removal efficiency. [ABSTRACT FROM AUTHOR]

The application of low-cost biosorbent of bamboo in methylene blue (MB) removal treatment is limited by its poor adsorption performance. In this study, bamboo parenchyma cell (BP) was isolated from bamboo powder by facile method of water separation and then incorporated with natural non-toxic vermiculite (VE) to prepare bamboo parenchyma cell-vermiculite (VEBP) composites. Much more nanopores were formed and more active adsorbed sites were introduced by filling with VE in BP lumen, which is favorable for improving the MB adsorption capacity. The MB adsorption isotherm of VEBP was preferably fitted with Langmuir model, yielding the highest equilibrium MB adsorption capacity of approximately 422 mg/g. As-obtained adsorption capacity is much higher than that of BP and various kinds of biosorbents in previous researches. Besides, the adsorption kinetics was closer to the pseudo-second-order model, indicating the dominant chemisorption process. Thermodynamic parameters implied the endothermic and spontaneous as well as entropy-governed adsorption process. Based on the analysis of adsorption behavior together with characterizations of VEBP, it can be confirmed that the predominant mechanisms for MB adsorption may involve electrostatic attraction, ion exchange, hydrogen bonding, pore filling, complexation reaction, and π-π interactions. Furthermore, the VEBP exhibited excellent reusability with MB removal efficiency of more than 80% after five cycles. Therefore, this study successfully provides a facile method for preparation of bamboo-based adsorbent with efficient MB adsorption performance. [ABSTRACT FROM AUTHOR]

Abstract\nSTATEMENT OF NOVELTYRemoval of Cd(II) and Pb(II) from aqueous solutions is a challenging task and the search for novel adsorbents is underway. This study examined the efficiency of nanobiochar (NB) and rice husk (RH) in the adsorption and removal of Cd(II) and Pb(II) from water. The effect of various physicochemical parameters such as initial pH, initial Cd and Pb concentration, adsorbent dosage, and contact time were tested. SEM/EDX images confirmed the adsorption of Pb and Cd with surface physical and chemical changes. The maximum Pb removal was noted at pH 6 using NB (96%) and at pH 8 for RH (90%), and the maximum Cd removal by NB was recorded at 8 pH (91%) and by RH at pH 6 (87%). The decline in adsorption intensity at lower pH suggested protonation of the adsorbent surface causing cation-cation repulsion. Most of the adsorption occurred within the initial 60 min. A continuous gradual increase in the adsorption with time suggested multilayer formation. Of the three isotherms, the Freundlich model fits the present data best, implying an infinite surface coverage and indicating the potential for multilayer adsorption of Pb and Cd on the surfaces of RH and NB adsorbents. In conclusion, this study highlights the promising potential of NB as a cost-effective adsorbent for the removal of Cd and Pb ions from aqueous solutions.This study explores the effectiveness of utilizing low-cost natural and agricultural waste biomasses for removing Cd(II) and Pb(II) ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

To enhance the physical and chemical properties and stability of magnetic MOFs, and to improve their adsorption and reuse performance, an innovative modification strategy involving hybridization with three-dimensional (3D) terminal carboxyl hyperbranched polymers was employed. A novel polymer composite material, Fe3O4@MOF/HBPC, was synthesized and its morphological characteristics were analyzed. The adsorption properties of Fe3O4@MOF/HBPC were tested by removing Malachite Green (MG) from aqueous solutions. Various influencing factors, including dosage, pH, and temperature, as well as adsorption kinetics, isotherms, and thermodynamics were investigated. The results showed that the stretching vibration peaks of Fe3O4@MOF/HBPC appeared at 1708 cm−1, 1408 cm−1, 1278 cm−1, 1112 cm−1, and 543 cm−1, corresponding to the C＝O, –COO−, O–H, C–O, and Fe–O bands, respectively. Fe3O4@MOF/HBPC exhibited a negative charge and a spherical structure. The composite material contained the elements O, C, Fe, and N, and the assembly process had a minimal impact on the crystal structure. For MG removal, the optimal reaction conditions were a dosage of 20 mg and pH 6. The adsorption process followed a pseudo-first-order kinetic model and a Langmuir isotherm model, and it was found to be endothermic and spontaneous, involving both physical and chemical adsorption. Regarding recycling and reuse, Fe3O4@MOF/HBPC demonstrated a recycling efficiency of over 90.8%, with a removing efficiency of MG of above 87.5% after three cycles, indicating excellent stability and reusability. [ABSTRACT FROM AUTHOR]

ABSTRACT This study developed a green and efficient surface protection method for Cu–Ni alloys. A zinc dibenzyl dithiocarbamate film was prepared on the surface of electrodeposited Cu–Ni alloys using the self‐assembly method to improve the material's corrosion resistance in seawater. The influence of zinc dibenzyl dithiocarbamate concentration and self‐assembly time on the corrosion resistance of the self‐assembled films was investigated through electrochemical testing. The findings revealed that at a zinc dibenzyl dithiocarbamate concentration of 10 mmol/L and a self‐assembly time of 20 min, the self‐assembled film exhibited the most robust corrosion resistance, achieving a maximum corrosion inhibition efficiency of 97.70%. The self‐assembly and adsorption mechanism of zinc dibenzyl dithiocarbamate were explored using molecular dynamics simulations and adsorption isotherms. The protective effect of self‐assembled films was visually observed through salt spray testing. Zinc dibenzyl dithiocarbamate self‐assembled film technology has high application prospects in the field of marine anti‐corrosion. [ABSTRACT FROM AUTHOR]

To remove phosphate from water, a novel Fe-doped ZIF-8 was synthesized as a superior adsorbent. The Fe-doped ZIF-8 was fully characterized using different characterization techniques and it was found that the as-prepared Fe-doped ZIF-8 (denoted as ZIF-(2Zn:1Fe)) showed a polyhedral morphology with a large specific surface area of 157.64 m2/g and an average pore size of 3.055 nm. Analyses using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction showed that Fe atoms were successfully incorporated into the ZIF-8 skeleton. Batch experiments demonstrated that the molar ratio of Fe and Zn has effects on phosphate adsorption. The adsorption kinetics conformed to a pseudo-second-order model with a high correlation coefficient (R2 = 0.9983). The adsorption isotherm matched the Langmuir model (R2 = 0.9994) better than the Freundlich model (R2 = 0.7501), suggesting that the adsorption of phosphoric acid by ZIF-(2Zn:1Fe) can be classified as a chemisorption on a homogeneous surface. The adsorption amount was 38.60 mg/g. It was found that acidic environments favored the adsorption reaction and the best adsorption was achieved at an initial pH of 2. Inhibition of adsorption by common anions is NO3-> CO32-> SO42-> Cl-. Characterization results indicate that the main mechanism of adsorption is surface complexation interactions. [ABSTRACT FROM AUTHOR]

This study systematically investigates the optimization of synthesis parameters for ternary layered double hydroxide (LDH) to achieve a pure phase and high crystallinity. The [Co0.52+Al0.253+Fe0.253+(OH)2].(CO32−)0.125.mH2O$[{\mathrm{Co}}_{0.5}^{2 + }{\mathrm{Al}}_{0.25}^{3 + }{\mathrm{Fe}}_{0.25}^{3 + }({\mathrm{OH}})_2 ].({\mathrm{CO}}_3^{2 - })_{0.125}.{\mathrm{m}}{\mathrm{H}}_2{\mathrm{O}}$, LDH is synthesized using the coprecipitation method and applied for wastewater treatment. The ternary LDH is synthesized at 60 °C for 24 h and exhibited maximum crystallinity with a crystallite size of 4 nm. The crystallinity index (CI) is a quantitative indicator of crystallinity, which is calculated using the X‐ray diffraction (XRD) method. The influence of reaction time on the structural characteristics of this LDH was thoroughly investigated, mainly focusing on achieving well‐crystalline LDH. Experimental results revealed a direct correlation between reaction time and crystallinity. This study highlights the significant influence of controlled synthesis and reaction time on producing high crystalline ternary LDH. The role of different parameters, such as solution pH, adsorbent dosage, contact time, and dye concentration, has been investigated. The adsorption isotherm data is analyzed using different isotherm models, which shows this material having a significant adsorption capacity of 82.92 mg/g for Congo Red dye. [ABSTRACT FROM AUTHOR]

The current work was designed to eliminate reactive yellow 18 dye (RY‐18) via adsorption from water, and CO2 from the gas stream, using the tragacanth gum‐based Cr doped NiO N.P.s/Clay (GCNC) composite. The one‐pot synthesis approach was used to produce the adsorbent, and physical and chemical properties were assessed using techniques like XRD, FTIR, UV‐visible spectroscopy, SEM, DLS, Zeta Potential, and adsorption–desorption isotherm. The GCNC composite demonstrated an impressive adsorption potential and percentage removal of 398 mg/g and 91.28%, respectively. Temkin and intraparticle diffusion models with R2 values of 0.98401 and 0.99918 were the most effective at fitting the experimental adsorption model. The thermodynamics parameters, including the change in enthalpy (H), entropy (S), and Gibbs free energy (G), demonstrated the endothermic and spontaneous nature of the adsorption process. A positive H value indicates an endothermic process, while a negative G value indicates a spontaneous process. According to the isotherms fitting model, the capacity for adsorbing CO2 at 25 °C and 1 atm was 4.8 mmol/g. The significant correlation between the slope in the log‐linear plot of the isosteric heat of adsorption and CO2 adsorption performance indicates that the isosteric heat of adsorption can be used as a predictive tool for CO2 adsorption performance. These significant results underscore the potential of the GCNC composite to revolutionize the water treatment field and CO2 capture, offering hope for a more sustainable and cleaner future. [ABSTRACT FROM AUTHOR]

Green processes for synthesizing nanocomposites are a hot area of research today as traditional processes are expensive, inefficient, harmful for synthesizing organic and inorganic molecules, and unsuitable for large-scale operations. The present study investigates the capacity of green synthesized Calcium oxide nanoparticles (CaO NPs) for efficiently removing Rhodamine B. Chemical reduction was replaced with Mulberry (Morus nigera) leaf extract as an environmentally friendly reaction mechanism. CaO NPs are characterized by various analytical techniques including EDX, BET, SEM, FTIR, TGA, Zeta Potential, Point of Zero Charge (PZC), and XRD. Maximum adsorption of Rhodamine B by CaO NPs is revealed at an initial concentration of Rhodamine B of 80 ppm, a temperature of 343 K, and contact time of 60 min, 0.4 g of adsorbent at a pH value of 7. Maximum removal of Rhodamine B by CaO NPs was found to be 98.2% which is promising with this small amount of adsorbent (0.4 g). Diverse Kinetic and adsorption isotherms are employed in this study to determine the requirement and significance of the adsorption process. Various adsorption isotherms such as Freundlich, Temkin, Dubinin–Radushkevich (D–R), and Langmuir models have been employed. Among the kinetic adsorption isotherms Elovich, Intraparticle kinetic model, pseudo 1st order, and pseudo 2nd order models were applied. The current study investigates the thorough understanding of the Rhodamine B adsorption process including the mechanism of adsorption using condition optimization, characterization, and model applications. The proposed adsorbent can be employed for the green removal of Rhodamine B from wastewater of industry with maximum efficiency and favorable regeneration properties. [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]

AbstractIn this study, copper-bismuth oxide/iron oxide (CuBi2O4@Fe3O4) nanocomposites were prepared by microwave-assisted synthesis and used as adsorbents for the adsorptive removal of cadmium from textile wastewater. The pH/volume of buffer solution, mixing type/period and adsorbent dosage were optimized univariately to enhance the removal efficiency of the adsorbent and determined as 1.5 mL of pH 8.0 buffer solution, vortexing for 60s, and 30 mg of CuBi2O4@Fe3O4 nanocomposite material. Following the determination of the optimum parameters, equilibrium adsorption studies were performed at five different initial concentrations of cadmium within the range of 0.50 − 10 mg L−1 in textile wastewater. A matrix-matching calibration strategy was utilized for the accurate and precise quantification of cadmium in the wastewater matrix with a R2 value of 0.9961. The percent removal efficiencies were calculated within the range of 77.2 − 81.5% for the adsorptive removal of cadmium ions from textile wastewater in the equilibrium adsorption experiments. Furthermore, the Langmuir, Freundlich, and Sips adsorption isotherm models were employed for modeling the equilibrium data, and the results showed that all the models fitted well with the experimental data with R2 values higher than 0.99. The simple and efficient batch adsorption process developed was successfully utilized to remove cadmium ions from textile wastewater. [ABSTRACT FROM AUTHOR]

The corrosion inhibition action of Phalaris canariensis extract on 316 L stainless steel in the H2O-35 (wt%) LiCl mixture at different temperatures has been evaluated with the aid of weight loss, potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy tests. These studies were complemented by Fourier Transformed Infrared spectroscopy, FTIR, gas/mass chromatography analytical techniques and detailed scanning electronic microscopy studies. Results have indicated that Phalaris canariensis extract is an efficient inhibitor, with an efficiency that increases with its concentration, but it decreases as the temperature increases. Phalaris canariensis extract is physically adsorbed onto stainless steel according to a Temkin type of adsorption isotherm. Phalaris canariensis extract affected both anodic and cathodic electrochemical reactions with a stronger effect on the anodic ones, acting, thus, as a mixed type of inhibitor. Main compounds contained in the Phalaris canariensis extract were palmitic and oleic acids, responsible for its inhibitory properties. [ABSTRACT FROM AUTHOR]

Phosphonic acid (PA) self‐assembled monolayers (SAMs) were deposited onto Pt/Al2O3 catalysts to modify the support to enable control over CO2 adsorption and CO2 hydrogenation activity. Significant differences in catalytic activity toward CO2 hydrogenation (reverse water‐gas shift, RWGS) were observed after coating Al2O3 with PAs, suggesting that the reaction was mediated by CO2 adsorption on the support. Amine‐functionalized PAs were found to outperform their alkyl counterparts in terms of activity, however there was little effect of amine location in the SAM (i. e., spacing between the amine functional group and phosphonate attachment group). One amine‐PA and one alkyl‐PA, aminopropyl phosphonic acid (C3NH2PA) and methyl phosphonic acid (C1PA), respectively, were investigated in more detail. The C3NH2PA‐modified catalyst was found to bind CO2 as a combination of carbamate and bicarbonate. Additionally, at 30 °C, both PAs were found to reduce CO2 adsorption uptake by approximately 50 % compared to unmodified 5 %Pt/Al2O3. CO2 adsorption enthalpy was measured for the catalysts and found to be strongly correlated with hydrogenation activity, with the trend in binding enthalpy and CO2 hydrogen rate trending as uncoated >C3NH2PA>C1PA. PA SAMs were found to have weaker effects on CO binding and CO selectivity, consistent with selective modification of the Al2O3 support by the PAs. [ABSTRACT FROM AUTHOR]

Rapid industrialization has led to significant environmental challenges, including the disposal of effluents with high zinc ion concentrations. This study investigates the use of hydroxyapatite nanoparticles as an adsorbent for Zn (II) ions from aqueous solutions at neutral pH. These nanoparticles are characterized by their high purity, mesoporous structure, and a specific surface area of 60.97 ± .40 m2 g−1. Their thermal stability was confirmed by thermogravimetric analysis, and zeta potential measurements indicated a surface charge close to the isoelectric point. Adsorption experiments showed that the kinetics fit well with the pseudo‐second‐order model, with a rate constant of 2.58 ± .49 min−1 mg−1 and a determination coefficient (R2) of 1.00. Isotherm analyses using Redlich–Peterson, Langmuir, and Freundlich models revealed the highest adsorption capacity and best fitting with the Redlich–Peterson model, showing maximum capacities of 30.36 mg g−1 (linear fitting) and 32.11 mg g−1 (nonlinear fitting). These fits achieved R2 values of .9949 and .9923, respectively, suggesting efficient and reliable adsorption profiles. This research highlights the potential of hydroxyapatite nanoparticles for effective zinc ion removal, supporting their application in sustainable industrial practices and environmental remediation. [ABSTRACT FROM AUTHOR]

Phosphonic acid (PA) self‐assembled monolayers (SAMs) were deposited onto Pt/Al2O3 catalysts to modify the support to enable control over CO2 adsorption and CO2 hydrogenation activity. Significant differences in catalytic activity toward CO2 hydrogenation (reverse water‐gas shift, RWGS) were observed after coating Al2O3 with PAs, suggesting that the reaction was mediated by CO2 adsorption on the support. Amine‐functionalized PAs were found to outperform their alkyl counterparts in terms of activity, however there was little effect of amine location in the SAM (i. e., spacing between the amine functional group and phosphonate attachment group). One amine‐PA and one alkyl‐PA, aminopropyl phosphonic acid (C3NH2PA) and methyl phosphonic acid (C1PA), respectively, were investigated in more detail. The C3NH2PA‐modified catalyst was found to bind CO2 as a combination of carbamate and bicarbonate. Additionally, at 30 °C, both PAs were found to reduce CO2 adsorption uptake by approximately 50 % compared to unmodified 5 %Pt/Al2O3. CO2 adsorption enthalpy was measured for the catalysts and found to be strongly correlated with hydrogenation activity, with the trend in binding enthalpy and CO2 hydrogen rate trending as uncoated >C3NH2PA>C1PA. PA SAMs were found to have weaker effects on CO binding and CO selectivity, consistent with selective modification of the Al2O3 support by the PAs. [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]

This study investigates the removal efficiency of Cu2+ from wastewater using a composite hydrogel made of carbon nanotubes (CNTs), sodium alginate (SA), and polyacrylic acid (PAA) prepared by free radical polymerization. The CNTs@SA/PAA hydrogel's structure and properties were characterized using SEM, TEM, FTIR, XRD, rheology, DSC, EDS, elemental mapping analysis, and swelling. The adsorption performance for Cu2+ was tested in batch adsorption experiments, considering the pH, dosage, initial concentration, and contact time. The optimal conditions for Cu2+ removal were pH 5.0, an adsorbent dosage of 500 mg/L, and a contact time of 360 min. The adsorption followed pseudo-second order kinetics. Isotherm analyses (Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Sips, Toth, and Khan) revealed that the Freundlich isotherm best described the adsorption, with a maximum capacity of 358.52 mg/g. A thermodynamic analysis indicated that physical adsorption was the main interaction, with the spontaneity of the process also demonstrated. This study highlights the high efficiency and environmental friendliness of CNT@SA/PAA composites for Cu2+ removal from wastewater, offering a promising approach for water treatment. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSIn this study, the ability of live mycelia of Schizophyllum commune to remove heavy metals from aqueous solution was investigated. The influence of various experimental parameters, such as pH, temperature, and contact time on the biosorption process was investigated. The maximum biosorption capacity using live biomass was found as 81.5, 90.71, 70.18, and 66.18 mg/g for Pb(II), Sr(II), Zn(II), and Cd(II), respectively, at optimized conditions. The biosorption process reaches equilibrium between 180 and 240 min for the tested metal ions. The experimental data were used to study biosorption isotherm and kinetics models. The thermodynamic parameters, ΔG°, ΔH°, and ΔS°, showed that the biosorption process was endothermic and spontaneous at 303–343 K. SEM images revealed that the presence of metal ions altered the morphology of fungal hyphae. The presence of Pb(II), Sr(II), Zn(II), and Cd(II)on the fungal mycelia was confirmed using SEM-EDX. FTIR spectroscopy of biomass showed the involvement of functional groups like, -CH, amino acid, fatty acid, carboxyl group, and alkane and alkyl groups in adsorption of heavy metal ions. The adsorption capacity of S. commune for removal of heavy metals under the optimized conditions was Sr(II) > Pb(II) > Zn(II) > Cd(II). Thus, the study demonstrated an application of Schizophyllum commune for efficient removal of heavy metals from metal-contaminated water or industrial effluents.The maximum biosorption capacity were 81.5, 90.71, 70.18, and 66.18 mg/g for Pb(II), Sr(II), Zn(II), and Cd(II), respectively.Optimum conditions for the maximum adsorption were pH 4–5, temperature 60–70 °C, and contact time of 180–240 min.The biosorption process was endothermic and spontaneous at 303–343 K and fitted Langmuir isotherm model and pseudo-second-order kinetics.The functional groups including -CH, amino acid, fatty acid, carboxyl group, and alkane and alkyl groups were responsible for the adsorption of metal ions.The maximum biosorption capacity were 81.5, 90.71, 70.18, and 66.18 mg/g for Pb(II), Sr(II), Zn(II), and Cd(II), respectively.Optimum conditions for the maximum adsorption were pH 4–5, temperature 60–70 °C, and contact time of 180–240 min.The biosorption process was endothermic and spontaneous at 303–343 K and fitted Langmuir isotherm model and pseudo-second-order kinetics.The functional groups including -CH, amino acid, fatty acid, carboxyl group, and alkane and alkyl groups were responsible for the adsorption of metal ions. [ABSTRACT FROM AUTHOR]

Phosphorus in wastewater from pressed vegetables is a significant contributor to water pollution, emphasizing the importance of its removal and recycling for ecological management. In this study, an improved method of coprecipitation pyrolysis of Mg(OH)2 and FeCl3•6H2O was used to successfully synthesize iron-magnesium biochar composite (FeMg@BC2) from corn cob. Compared with iron-modified biochar (Fe@BC), magnesium-modified biochar (Mg@BC), and iron–magnesium-modified biochar (FeMg@BC1) prepared by traditional coprecipitation methods, the improved iron–magnesium biochar had higher yield, specific surface area, and crystallinity. The study investigated the impact of modified biochar dosage, initial solution pH, and coexisting ions on the adsorption capabilities of modified biochar for phosphate removal. The results demonstrated that the addition of 1.0 g/L FeMg@BC2 was highly effective in removing phosphate from simulated wastewater when the phosphate concentration was 80 mg/L, achieving a removal rate exceeding 95%. Using an adsorption isotherm model, the maximum phosphate adsorption capacities of Fe@BC, Mg@BC, FeMg@BC1, and FeMg@BC2 were estimated to be 40.76, 46.97, 96.78, and 107.97 mg/g, respectively. Particularly, FeMg@BC2 exhibited superior phosphate adsorption capacity, and its adsorption mechanism mainly included electrostatic attraction, surface precipitation, and ligand exchange. The desorption test of phosphorus-loaded modified biochar revealed that the desorption rates of FeMg@BC2 from simulated wastewater and pressed vegetable wastewater using a 0.5M NaOH solution were 92.2% and 84.8%, respectively. After three cycles of adsorption in pressed vegetable wastewater, the phosphorus removal efficiency of FeMg@BC2 at 1.0 g/L remained about 50%. Therefore, the utilization of FeMg@BC2 for phosphorus recovery from pressed vegetable wastewater showed promising potential. [ABSTRACT FROM AUTHOR]

A simple strategy is presented for the preparation of Prussian blue-modified g-C3N4. PB/g-C3N4 is synthesized as an efficient adsorbent for the adsorption of U (VI), and the effects of various conditions on the adsorption of U (VI) are investigated. Static adsorption experiments reveal that the adsorption of U (VI) by PB/g-C3N4 conforms to the Langmuir adsorption isotherm and pseudo-second-order adsorption model. The composition and morphology of the materials are characterized by XRD, FT-IR, XPS, SEM, and BET. This study demonstrates that PB/g-C3N4 is a promising material for uranium-containing wastewater treatment, with the advantages of low cost, environmental friendliness, and facile synthesis. [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]

Rational utilization of fly ash, a widely emitted solid waste, was explored by investigating the effects of various factors on the types and properties of zeolites prepared from fly ash. Additionally, the mechanism for adsorption of ammonium nitrogen onto NaP zeolite synthesized via a one-step hydrothermal method was explored. The characterization studies included scanning electron microscopy (SEM), X-ray diffraction (XRD), and adsorption of ammonium nitrogen from wastewater. The effects of the crystallization time, solid‒liquid ratio, alkali concentration, and crystallization temperature on the performance of the fly ash-derived zeolites were systematically investigated. Adsorption isotherms and kinetic models were employed to analyze the adsorption behavior and mechanisms. The results indicated that the optimal conditions for the zeolite synthesis included a 24-hour crystallization time, a solid‒liquid ratio of 1:10, an alkali concentration of 3 mol/L, and a crystallization temperature of 150°C. Under these conditions, the zeolite exhibited intense diffraction peaks, a large surface area, a regular morphology, and an ammonia-nitrogen adsorption rate of 73.01%. An orthogonal test revealed that the alkali concentration had the most significant impact on the zeolite synthesis, with a range value of 14.28. The isothermal adsorption data for ammonia-nitrogen were consistent with the Freundlich model, while the kinetic studies showed that pseudosecond-order kinetics governed the process. [ABSTRACT FROM AUTHOR]

Molecular hydrogen ($\hbox {H}_{2}$ H 2 ) is a renewable energy carrier, however, its practical applications are limited due to the challenges of developing safe and efficient $\hbox {H}_{2}$ H 2 storage devices. Metal Organic Frameworks (MOFs) containing at least two different metal ions in their structures are called as mixed-metal MOFs (MM-MOFs) and they could adsorb $\hbox {H}_{2}$ H 2 in higher amounts compared to structures containing single metal nodes. We theoretically examined the $\hbox {H}_{2}$ H 2 storage capacities of 26 MM-MOFs having various physical and chemical properties applying Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) simulations. $\hbox {H}_{2}$ H 2 adsorption isotherms were calculated using a five-site anisotropic $\hbox {H}_{2}$ H 2 model. QIXSOG, YOMVIG, OSOYUR, Cu-Mg-BTC, Fe-Mg-BTC, and Cr-Mg-BTC were selected as top-performing MM-MOFs maximising $\hbox {H}_{2}$ H 2 adsorption gravimetrically and volumetrically at near-ambient conditions (233 K and 100 bar), approaching the DOE targets. YOMVIG has the largest $\hbox {H}_{2}$ H 2 adsorption enthalpy, calculated as $-9.93\, \hbox {kJ/mol}$ − 9.93 kJ/mol at 233 K and 100 bar. DFT simulations have been conducted to analyse preferable $\hbox {H}_{2}$ H 2 adsorption sites as well as identify guest-host interactions. Electron density difference analysis showed that adsorbed $\hbox {H}_{2}$ H 2 molecules in the OSOYUR, Cr-Mg-BTC, Cu-Mg-BTC, and Fe-Mg-BTC are polarised. Our study challenges existing literature by identifying promising MM-MOFs as potential next-generation hydrogen storage adsorbents at near-ambient conditions. [ABSTRACT FROM AUTHOR]

The use of magnetic nanomaterials (MNPs) as adsorbents to eliminate pollution causing dyes from water has attracted substantial attention in recent years because they can be easily isolated and reused. In this work, core–shell Fe3O4@SiO2 MNPs in which magnetic Fe3O4 NPs as a core enclosed with a thick SiO2 shell were successfully synthesized by chemical co–precipitation followed by hydrolysis and condensation of alkoxysilanes in a mixture of ammonia, ethanol and water. The formation of core–shell Fe3O4@SiO2 MNPs has been characterized by TEM, TEM-EDS, XRD, FT-IR and VSM. TEM characterization revealed that several Fe3O4 NPs (around 10 nm) aggregated to form a Fe3O4 magnetic core and surrounded by an uniform SiO2 shell of 40-50 nm thickness to obtain Fe3O4@SiO2 magnetic core–shell NPs. As synthesized core–shell NPs were employed as adsorbent for elimination of two cationic toxic dyes, crystal violet (CV) and malachite green (MG) from aqueous solutions. Further, different adsorption parameters such as pH, adsorbent dosage and contact times of the dyes were found to enhance the adsorption of cationic dyes. At neutral pH 7 the cationic dyes could be speedily removed from aqueous solution with high efficiency. It has been observed that 0.35 g of adsorbent dosage is sufficient for 95% of dye removal efficiency. The contact time is optimised for 20 min for both the dyes. The Langmuir model adsorption isotherm is best suitable which indicates that the cationic dyes adsorption behaviour of Fe3O4@SiO2 is a homogeneous monolayer chemisorption process. The adsorptive binding of CV/MG with Fe3O4@SiO2 was directed through electrostatic interactions. Moreover, the magnetic adsorbents could be easily reused and regenerated with almost no adsorption capability is significantly reduced up to 5 cycles. So, the Fe3O4@SiO2 is an efficient and reusable adsorbent for rapid and removal of cationic dyes from the aqueous solution. [ABSTRACT FROM AUTHOR]

Well shut-in time significantly affects the production performance of shale-gas-well. However, interaction between shale powders and fracking fluid on methane desorption has been rarely reported. In this work, based on the volume method following Boyle's law under higher pressure, the experimental setup was conducted to obtain the adsorption and desorption isotherms to explore the effect of different shut-in times (including 0, 1, 3, 5, 10, and 30 days) on methane desorption. We fitted the methane adsorption and desorption isotherms by the Freundlich model, and the results show that the interaction can obviously impact desorption isotherm, desorption efficiency and adsorbed phase methane content. The inflection points of the constant k and n reduction curves, desorption efficiency reduction curve and adsorbed gas content reduction curve all occur when the interaction time is to 10 days, indicating that 10 days is the best value for the interaction between slick water and gas shale. The results provide an essential supplement that can help elucidate the impact of shut-in time on gas-shale-well production performance experimentally. [ABSTRACT FROM AUTHOR]

Water contamination is a major health issue that can be addressed by using carbonaceous materials to adsorb and filter pollutants, yet adsorption mechanisms need to be better understood to improve the adsorption efficiency. Here we review the models that are used to study the mechanisms of adsorption of drugs, dyes and metal ions on carbonaceous materials, with emphasis on classical and advanced isotherms. We discuss the fitting frequency, lignocellulosic and fossil fuel-derived adsorbents, biomass composition, activating agents, surface functions, the carbonization temperature, the medium temperature effect and the use of several isotherms to explain the same mechanism. The adsorption capacity can reach up to 2651 mg of contaminant per g of lignocellulosic materials and 1274 mg of contaminant per g of fossil materials. Isotherm validation commonly depends on several parameters. The adsorption on lignocellulosic carbonaceous materials is best described by the Langmuir isotherm. In contrast, adsorption on fossil materials is best described by the Redlich-Peterson isotherm. Advanced and classical isotherms are in good agreement in 44% of reports. [ABSTRACT FROM AUTHOR]

The corrosion inhibition effects of Drimia maritima (L.) Stearn sin. Urginea maritima (L.) Backer on three different materials, i.e., as-cast Al-7 wt.% Si alloy, SAE 1020 low carbon steel, and commercially pure Al samples, into a stagnant and naturally aerated 0.5 M NaCl solution are evaluated. For this purpose, both the potentiodynamic polarization curves and electrochemical impedance spectroscopy with an equivalent circuit are utilized. It is found that inhibition effect increases up to certain minor Drimia maritima content. Adsorption isotherms (e.g., Langmuir and Temkin) indicate that all three examined materials comprise physical adsorption mechanisms. Al-Si alloys attained inhibition efficiencies of about 96% at 25 °C with 1250 ppm of Drimia maritima and ~43% with 625 ppm at 45 °C. On the other hand, the cp. Al and SAE 1020 samples attain ~89% and 68% with 1250 ppm and 500 ppm at 25 °C, respectively. This clearly indicates that the dosage of Drimia maritima green inhibitor into NaCl solution possesses certain susceptibility for each distinctive material examined. Impedance parameters obtained by using CNLS (complex non-linear least squares simulations) are correlated and discussed. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, cadmium ions were effectively removed from domestic wastewaters using an adsorptive treatment strategy based on γ-AlOOH nanoflowers. A novel, rapid, and simple procedure was developed for the synthesis of the nanoflowers. Characterization studies were performed using X-ray powder diffraction patterns and scanning electron microscope images. The synthesized nanoflowers were utilized as adsorbent in the batch adsorption experiments. The influential parameters of the adsorption process were optimized, and a flame atomic absorption spectrophotometry (FAAS) system was used to determine maximum percent removal of cadmium ions. Matrix-matched calibration strategy, in which the calibration plot was developed in wastewater medium, was utilized for the accurate and precise quantification of cadmium in the effluent samples. The percentage removal efficiency values were calculated between 84 and 98% for different concentrations of cadmium ions in the wastewater samples. Equilibrium data was fitted to the four different linearization methods of the Langmuir isotherm model, as well as the Freundlich isotherm model and Elovich isotherm model. The best fitting was achieved for the Langmuir model with a high R2 value of 0.9956 and maximum adsorption capacity was calculated as 6.23 mg/g. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Metal-organic frameworks (MOFs) have emerged as a class of highly promising materials for wastewater dye removal due to their unique properties. However, the existing body of research has primarily concentrated on the removal of organic dyes. To address this gap and contribute to advancements in water treatment technologies, this study investigates the efficacy of a zirconiumterephthalate-based MOF for the adsorptive removal of hematite, an inorganic dye, from aqueous environments. This investigation explored the influence of key parameters, including initial dye concentration, pH, adsorbent dosage, and adsorption temperature, on the adsorption capacity of NH2-UiO-66 for hematite. The findings revealed that elevated temperatures and initial dye concentrations promoted hematite adsorption onto NH2-UiO-66. Furthermore, the analysis of experimental data demonstrated concordance with the theoretical predictions of both the linearized Freundlich and Langmuir isotherm models. The study of kinetic models reveals that the pseudo-first-order model can adequately describe experimentally obtained data. The adsorption thermodynamic parameter ΔG0 was found to be approximately -3.70, -3.94, and -4.19 kJ.mol-1 at 298, 313, and 328 K, respectively. Furthermore, the ΔH0 and ΔS0 parameters were 5.15 kJ.mol-1 and 54.3 J.mol-1, respectively, indicating an endothermic adsorption mechanism. Further investigation found that the regeneration effectiveness is greater than 92% even after three adsorption cycles. [ABSTRACT FROM AUTHOR]

Nanosorbent NiFe2O4@g-C3N4 was produced via green and ultrasonication methods to remove oxytetracycline (OTC) from aqueous solutions. The prepared material was analyzed using powder x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The adsorption capacity of the NiFe2O4@g-C3N4 nanosorbent for OTC decontamination was studied using a batch experiment under various parameters. The adsorption capacity was notably increased to 1634 mg g−1 under fixed experimental conditions. The kinetic and isothermal analyses were conducted using several optimal pH and temperature models. The adsorption kinetics graphs aligned with the pseudo-second-order model, suggesting chemical adsorption via electrostatic interactions. The adsorption isotherm curves aligned more closely with the Langmuir model than the Temkin and Freundlich models, suggesting a monolayer adsorption mechanism. The adsorption mechanism was clearly elucidated using FTIR investigations. The results of the study indicate that NiFe2O4@g-C3N4 nanosorbent is a promising candidate for specific elimination of OTC on many different levels for the treatment of wastewater. [ABSTRACT FROM AUTHOR]

The textile industry's waste often contains excessive amounts of crystal violet (CV), leading to environmental concerns. Graphene oxide has been studied as a promising adsorbent for removing crystal violet, a cationic dye, from aqueous solutions. The study involved a comprehensive analysis of various experimental parameters, including initial concentration, pH, adsorbent mass, contact time, and temperature. Graphene oxide underwent thorough analysis using Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and specific surface area determination via the Brunauer–Emmett–Teller (BET) method. Energy‐dispersive X‐ray spectroscopy (EDS) was also employed. This study aimed to optimize the synthesis yield of graphene oxide from graphite using the Hummers method and response surface methodology (RSM), achieving a yield of 106.14% with 5 g of KMnO4 and 1 g of NaNO3 for 8 hours. The graphene oxide was analyzed via FTIR, XRD, SEM, BET, pHpzc, and EDS. Optimal conditions for maximal adsorption included 0.016 g of graphene oxide, 18 minutes of contact time, pH 10, and a temperature of 25°C, resulting in a 97.38% reduction in crystal violet with a monolayer adsorption capacity of 470.78 mg/g. Kinetic data were best fitted by the pseudosecond‐order model, and the Langmuir isotherm accurately depicted adsorption. Thermodynamic analysis indicated spontaneous (ΔG° < 0) and exothermic (ΔH° < 0) crystal violet adsorption. Density functional theory (DFT) explored interactions between graphene oxide and crystal violet, supporting experimental findings and confirming graphene oxide's efficacy as an adsorbent for crystal violet removal from aqueous solutions. [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]

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]

Activated carbon was prepared at 300 °C and 600 °C, characterized by SEM, EDX and XRD, and was then used as an adsorbent for the removal of acidic dyes; acid yellow 25 and acid red 4. The activated carbon prepared at high temperature (600 °C) due to its high carbon contents and surface area was subsequently used as adsorbent for the selected dyes adsorption using batch adsorption approaches to estimate different adsorption parameters. For the estimation of kinetics and equilibrium parameters a number of kinetics and isotherm models were employed. Dyes were adsorbed on activated carbon surface at a high rate for the first 15 min, after which it began to diffuse into the micro pores and thus the process became steady. The rate constant was estimated for first and second order kinetics models. The maximum adsorption capacities recorded were 526.32 mg g−1 for acid red 4 and 555.55 mg g−1 for acid yellow 25. The enthalpy change values recorded were; 19.44 kJ mol−1 for acid yellow 25 adsorption and 16 kJ mol−1 for acid red 4 adsorption, meant that the process is endothermic. The negative values of Gibbs free energy change (−393.28, −1,515.48, −2,634.68 J mol−1) of acid red 4 and acid yellow 25 (−251.72, −1,058.06, −2,367.84 J mol−1) at tested temperatures, confirmed the feasibility and spontaneity of the adsorption processes. The adsorption of dyes on the carbon surface was diffusion-controlled process, as demonstrated by the linear graph of intraparticle diffusion model. [ABSTRACT FROM AUTHOR]

We report the effect of Feynman–Hibbs corrections on the intermolecular potential to take into account the quantum effects of hydrogen at low temperature and high density for vapor–liquid equilibria (VLE) and confinement into carbon nanotubes. Density against temperature, pressure against temperature and isochoric curves are displayed for VLE, while adsorption isotherms for different pore sizes and different temperatures are showcased to see the effect under confinement. Besides, 5 different models for hydrogen are employed; one atomistic and 4 coarse-grained models, covering both classical and quantum approximations. For the case of VLE we observed that the quantum corrected models lead to more accurate and reliable results in good agreement with the experimental data. The adsorption isotherms produced with the different models showed that the difference between quantum and classical approximations are significant for maximum confinement (smallest pore) and lowest temperature (77K). As we increase both the temperature and the pore size, the difference between the different models become less noticeable. [Display omitted] • Cryogenic hydrogen behavior. • Adsorption into carbon nanotubes. • Molecular modelling of hydrogen. • Quantum effects on cryogenic hydrogen. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are promising materials for processes such as carbon dioxide (CO2) capture or its storage. In this work, the adsorption of CO2 and nitrogen (N2) in Co3(ndc)3(dabco) MOF (ndc: 2,6-naphthalenedicarboxylate; dabco: 1,4-diazabicyclo[2.2.2]octane) is reported for the first time over the temperature range of 273–323 K and up to 35 bar. The adsorption isotherms are successfully described using the Langmuir isotherm model. The heats of adsorption for CO2 and N2, determined through the Clausius–Clapeyron equation, are 20–27 kJ/mol and 10–11 kJ/mol, respectively. The impact of using pressure and/or temperature swings on the CO2 working capacity is evaluated. If a flue gas with 15% CO2 is fed at 6 bar and 303 K and regenerated at 1 bar and 373 K, 1.58 moles of CO2 can be captured per kg of MOF. The analysis of the multicomponent adsorption of typical flue gas streams (15% CO2 balanced with N2), using the ideal adsorbed solution theory (IAST), shows that at 1 bar and 303 K, the CO2/N2 selectivity is 11.5. In summary, this work reports essential data for the design of adsorption-based processes for CO2 capture using a Co3(ndc)3(dabco) MOF, such as pressure swing adsorption (PSA). [ABSTRACT FROM AUTHOR]