Chemical Adsorption Mechanism Research Articles

Utilization and value-adding of waste: Fabrication of porous material from chitosan for phosphate capture and energy storage

Efficient removal and recycling of phosphorus from complex water matrices using environmentally friendly and sustainable materials is essential yet challenging. To this end, a novel bio-based adsorbent (DX-FcA-CS) was developed by coupling oxidized dextran-crosslinked chitosan with ferrocene carboxylic acid (FcA). Detailed characterization revealed that the incorporation of FcA reduced the total pore area of DX-FcA-CS to 7.21 m2·g−1, one-third of ferrocene-free DX-CS (21.71 m2·g−1), while enhancing thermal stability and PO43− adsorption performance. Adsorption kinetics and isotherm studies demonstrated that the interaction between DX-FcA-CS and PO43− followed a pseudo-second-order kinetic model and Langmuir model, indicating chemical and monolayered adsorption mechanisms, respectively. Moreover, DX-FcA-CS exhibited excellent anti-interference properties against concentrated co-existing inorganic ions and humic acid, along with high recyclability. The maximum adsorption capacity reached 1285.35 mg·g−1 (∼428.45 mg P g−1), three times that of DX-CS and surpassing many other adsorbents. PO43−-loaded DX-FcA-CS could be further carbonized into electrode material due to its rich content of phosphorus and nitrogen, transforming waste into a valuable resource. These outstanding characteristics position DX-FcA-CS as a promising alternative for phosphate capture and recycling. Overall, this study presents a viable approach to designing environmentally friendly, recyclable, and cost-effective biomaterial for wastewater phosphate removal and value-added applications.

Quantum chemical DFT-based adsorption mechanism of Pb(II) on a modified biochar

Quantum chemical DFT-based adsorption mechanism of Pb(II) on a modified biochar

Adsorption Mechanisms of CO2 on Macroporous Ion-Exchange Resin Organic Amine Composite Materials by the Density Functional Theory.

The adsorption mechanisms of CO2 on macroporous cation exchange resin (MCER), D001 ion-exchange resin, and macroporous ion-exchange resin organic amine composite materials (MCER-DEA and D001-PEI) were studied by density functional theory (DFT). The adsorption energies and Mulliken atomic charges in the adsorption process were analyzed, indicating that CO2 on MCER and D001 were physisorbed. The adsorption heat of the adsorption process of MCER-DEA and D001-PEI was calculated by the Monte Carlo method, and it was found that the adsorption process of CO2 by MCER-DEA and D001-PEI was both physical adsorption and chemical adsorption. Besides, the chemical adsorption mechanism of CO2 by MCER-DEA and D001-PEI was investigated by analyzing the free energy barrier and the Gibbs free energy change of the involved chemical reactions and the results showed that the free energy barrier required for MCER-DEA to generate zwitterion was 26.23 kcal/mol, which is 1.74 times that of D001-PEI (15.04 kcal/mol); meanwhile, the free energy barriers of the deprotonation process of zwitterions in MCER-DEA and D001-PEI were 16.23 and 9.89 kcal/mol, respectively, indicating that D001-PEI chemically adsorbs CO2 and requires more energy than MCER-DEA chemical adsorption of CO2. D001-PEI is more conducive to the chemical adsorption of CO2. In addition, H2O molecules were incorporated on the polymer models to study the influence of humidity on the CO2 adsorption mechanism. The analysis revealed that the adsorption of CO2 slowed under humid conditions.

An analytical investigation into solute transport and sorption via intra-particle diffusion in the dual-porosity limit

We develop a mathematical model for adsorption based on averaging the flow around, and diffusion inside, adsorbent particles in a column. The model involves three coupled partial differential equations for the contaminant concentration both in the carrier fluid and within the particle as well as the adsorption rate. The adsorption rate is modelled using the Sips equation, which is suitable for describing both physical and chemical adsorption mechanisms. Non-dimensionalisation is used to determine the controlling parameter groups as well as to determine negligible terms and so reduce the system complexity. The inclusion of intra-particle diffusion introduces new dimensionless parameters to those found in standard works, including a form of internal Damköhler number and a new characteristic time scale. We provide a numerical method for the full model and show how in certain situations a travelling wave approach can be utilized to find analytical solutions. The model is validated against published experimental data for the removal of Mercury(II) and CO2. The results show excellent agreement with measurements of column outlet contaminant concentration and provide insights into the underlying chemical reactions.

Highly Selective Pb(II) Adsorption by DTPA-Functionalized Graphene Oxide/Carboxymethyl Cellulose Aerogel.

Graphene oxide (GO) exhibits a strong adsorption capacity for the removal of heavy metal ions from liquids, making it a topic of increasing interest among researchers. However, a significant challenge persists in the preparation of graphene oxide-based adsorbents that possess both high structural stability and excellent adsorption capacity. In this paper, a green and environmentally friendly ternary composite aerogel based on graphene was successfully synthesized. The adsorption capacity of graphene oxide was enhanced through diethylenetriaminepentaacetic acid modification, while the incorporation of composite carboxymethyl cellulose improved the structural stability of the composite aerogel in liquid. The composite aerogel demonstrates robust interactions between its components and features a multiscale porous structure. Adsorption tests conducted with Pb(II) revealed that the GO/DTPA/CMC (GDC) composite aerogel exhibits a favorable adsorption capacity. The study of adsorption kinetics and isotherms indicated that the adsorption process follows the quasi-secondary adsorption model and Freundlich adsorption model, suggesting a chemical multilayer adsorption mechanism, and the maximum adsorption capacity for Pb(II) ions was 521.917 mg/g based on the quasi-quadratic kinetic model fitting. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analyses, performed before and after adsorption, confirmed that the adsorption of Pb(II) primarily occurs through chelation, complexation, proton exchange, and electrostatic interactions between ions and active sites such as hydroxyl and carboxyl groups. This study presents an innovative strategy for simultaneously enhancing the adsorption properties of graphene oxide-based composite aerogels and ensuring solution stability.

Efficient removal of radioactive iodide from contaminated seawater by radiation-resistant Ag+-doping polypropylene nonwoven adsorbents

For the efficient removal of radioactive iodide ions from medium and low radioactive contaminated water, an Ag-doped adsorbent was designed via radiation grafting method and chemical modification and applied based on the solid–liquid adsorption method. The silver loading content in the adsorbents could be flexibly decided by adjusting the sulfhydryl content. SEM/EDS, ATR, XPS, and XRD characterization methods were used to determine the features of the new adsorbents. With the silver content 67.9 mg/g and 125.6 mg/g in the adsorbents PGM25%-Ag+ and PGM220%-Ag+ respectively, the maximum I− adsorption capacities were varied at 29.92 mg/g and 100.82 mg/g. In wide pH conditions (pH7-11), PGM25%-Ag+ was sufficient to achieve 131I removal efficiency of over 92 %, and the removal efficiency was almost unaffected in the coexistence of high concentration (10 mmol/L) of anions and complex real contaminated seawater, highlighting the applicability and selectivity of the adsorbent. The adsorption behavior conformed to the Langmuir isothermal model and pseudo-second-order kinetics model. XPS analysis confirmed that excellent adsorption capacity and selectivity were attributed to the chemical adsorption mechanism of ion exchange and complexation occurs between I− and Ag on the solid–liquid interface, where AgI precipitation formed. In addition, the Ag+-doping adsorbent withstood the harsh conditions of 200 kGy irradiation by observing the ATR structure, thermal stability, and 131I removal property. This study provides a feasible solution for the treatment of low and medium-radioactive contaminated seawater.

Eco-friendly methanolic Ajuga orientalis extract as corrosion inhibitor for aluminium in 1.0 M NaOH

The inhibitory impact of the methanolic Ajuga orientalis (MAO) extract on Al corrosion in 1.0 M NaOH solution was examined using weight loss with electrochemical polarisation and scanning electron microscopy (SEM) techniques. According to the findings, the extract was an effective inhibitor in basic condition, as well as inhibition effectiveness increased with concentration. Furthermore, temperature studies revealed a loss in efficiency followed by a rise when temperature rose, followed by an increase and a fall in the fundamental media when the temperature increased from 30 °C to 50 °C. Frumkin, Freundlich and El Awady isotherms were used to mimic the inhibitor's adsorption properties. For the inhibitory behaviour, physical and chemical adsorption mechanisms are proposed. The adsorption process's thermodynamic parameters (ΔH*, ΔS* and Ea) were determined and explained. The inhibitor was examined as a mixed-type (anodic and cathodic) inhibitor based on polarisation studies. The inhibitor, according to the SEM data, is partially coating the metal surface, providing it with a reasonable amount of protection. The findings from weight loss, electrochemical polarisation, SEM and quantum chemical calculations collectively demonstrate a strong consensus, indicating that the MAO extract exhibits high effectiveness as an inhibitor for aluminium in a basic solution.

Facile synthesis of lignin-based Fe-MOF for fast adsorption of methyl orange

To rapidly remove dyes from wastewater, iron-based metal–organic frameworks modified with phenolated lignin (NH2-MIL@L) were prepared by a one-step hydrothermal method. Analyses of the chemical structure and adsorption mechanism of the NH2-MIL@L proved the successful introduction of lignin and the enhancement of its adsorption sites. Compared with NH2-MIL-101-Fe without phenolated lignin, the modification with lignin increased the methyl orange (MO) adsorption rate of NH2-MIL@L. For the best adsorbent, NH2-MIL@L4, the MO adsorption efficiency in MO solution reached 95.09% within 5 min. NH2-MIL@L4 reached adsorption equilibrium within 90 min, exhibiting an MO adsorption capacity of 195.31 mg/g. The process followed pseudo-second-order kinetics and the Dubinin-Radushkevich model. MO adsorption efficiency of NH2-MIL@L4 was maintained at 89.87% after six adsorption-desorption cycles. In mixed solutions of MO and methylene blue (MB), NH2-MIL@L4 achieved an MO adsorption of 94.02% at 5 min and reached MO adsorption equilibrium within 15 min with an MO adsorption capacity of 438.6 mg/g, while the MB adsorption equilibrium was established at 90 min with an MB adsorption rate and capacity of 95.60% and 481.34 mg/g, respectively. NH2-MIL@L4 sustained its excellent adsorption efficiency after six adsorption-desorption cycles (91.2% for MO and 93.4% for MB). The process of MO adsorption by NH2-MIL@L4 followed the Temkin model and pseudo-second-order kinetics, while MB adsorption followed the Dubinin-Radushkevich model and pseudo-second-order kinetics. Electrostatic interactions, π-π interactions, hydrogen bonding, and synergistic interactions affected the MO adsorption process of NH2-MIL@L4.

Elimination of indigo carmine in water by Pinus patula biochar: Adsorption process optimization, kinetics and isotherms

The textile industry causes major pollution to water bodies due to the discharge of dye-containing wastewater, such as indigo carmine (IC). Biochar has been used to treat organic pollutants like dyes because of its pore structure and surface area, as well as the functional groups contained, low cost, and sustainability of this material. In this study, biochar derived from Pinus patula wood pellets was used to assess its efficiency in the elimination of IC in water. Under optimal conditions of pH, biochar dose, and particle size (3, 13.5 g/L, and 300–450 µm, respectively), a 99% removal of a 25 mg/L solution of IC was achieved. Furthermore, studies on dissolved organic carbon (DOC) revealed that Pinus patula biochar contributed to a 73.8% reduction in the organic matter present in water. The IC adsorptive process was described by the pseudo-second order kinetic and the Freundlich isotherm models. Chemical and physical adsorption mechanisms were associated with the uptake of IC by Pinus patula biochar. Hydrogen bonding, electrostatic attraction, π-π interactions, and pore-filling were regarded as the possible mechanisms involved in the adsorption system. Pinus patula wood pellets biochar was shown to be an efficient adsorbent to remove dyes from water.

Preparation of Chladophora‐Based Biochar and Its Adsorption Properties for Antibiotics

AbstractThe biochar prepared by Chladophora (CB) was used to adsorb the ibuprofen and ofloxacin in sewage. SEM showed that CB preserved the natural tubular structure and increased its specific surface area. According to the BET results, the specific surface area of CB was 296.831 m2 g‐1. The adsorption of ibuprofen and ofloxacin on biochar conformed to the pseudo second‐order kinetic model, indicating that their adsorption rate was controlled by the chemical adsorption mechanism. According to the adsorption isotherms study, the adsorption of ibuprofen on CB met the Dubin‐Radushkevich model, while it fitted well with the Freundlich model for ofloxacin adsorption, making their adsorption onto biochar relating to non‐uniform surface and adsorption layer, respectively. The pore filling and electrostatic interaction were considered the main mechanism for the adsorption of pharmaceuticals and personal care products on CB, whereas the π‐π electron donor acceptor (EDA) interaction and hydrogen bond would also partially contribute to the adsorption process.

Synthesis and characterization of surface-modified magnetic mesoporous silicate materials for phosphate adsorption.

The magnetic mesoporous silica material, Mag-MCM-41, was synthesized by coating magnetite (Fe3O4) nanoparticles with a mesoporous material called MCM-41. Mag-MCM-41 and modified nanomaterials Mag-MCM-41-NN and Mag-MCM-41-NN-Fe+3 which were modified with aminopropyl functional groups. In water and wastewater, phosphate anions are considered significant contaminants due to their detrimental impact on the environment. They promote the growth of algae, leading to eutrophication. The purpose of this study is to investigate the removal of phosphate anions from aqueous solutions using modified magnetic silica particles. The Mag-MCM-41 material exhibits hexagonal properties and belongs to the class of "mesoporous" materials. It has a surface area of 923 m2.g-1, which was determined through N2 adsorption-desorption isotherms, FTIR, TEM, BET, and SAXS analysis. Kinetic and adsorption isotherm studies were conducted using Mag-MCM-41, Mag-MCM-41-NN, and Mag-MCM-41-NN-Fe+3 adsorbents to examine the behavior of phosphate anions. The kinetic and adsorption isotherm studies of phosphate anions revealed that the adsorption process on Mag-MCM-41, Mag-MCM-41-NN, and Mag-MCM-41-NN-Fe+3 adsorbents followed the chemical adsorption mechanism. Phosphate adsorption on all adsorbents occurred in a monolayer, and the MCM-41-NN-Fe+3 adsorbent exhibited the highest maximum adsorption capacity (qm) value of 112.87 mg.g-1 compared to the other adsorbents.

Pyracantha fortuneana alcohol extracts as biodegradable corrosion inhibitors for copper in H2SO4 media

Compared with traditional copper corrosion inhibitors, Pyracantha fortuneana alcohol extracts are derived from natural plants, will not cause environmental pollution after use, and are in line with the concepts of green chemistry and sustainable development. In this study, Pyracantha fortuneana alcohol extracts (PFAE) were obtained by ethanol soaking extraction method. PFAE, a novel degradable green corrosion inhibitor, has been investigated by experiments and theoretical calculations for its anti-corrosion performance of copper in H2SO4 solution. Electrochemical experiments have demonstrated a pronounced increase in corrosion inhibition efficiency (η) as the concentration of PFAE rises. At a PFAE concentration of 600 mg/L, the inhibition efficiency can exceed 95 %. Additionally, the electrochemical method was used to investigate how the effect of soaked time on its anti-corrosion performance. After 4 h of immersion in a H2SO4 solution containing PFAE, the copper could still maintain more than 80 % of the anti-corrosion performance. The results of surface morphology analysis demonstrate that after adding PFAE, the roughness of the copper sample is significantly reduced. This provides intuitively evidence that PFAE can indeed proficiently inhibit copper corrosion within a sulfuric acid solution. According to the study of the adsorption model, it was found that the adsorption behavior of PFAE onto the copper surface adheres to the Langmuir monolayer adsorption model. Moreover, the findings indicate the coexistence of both physical and chemical adsorption mechanisms. The findings of molecular dynamics simulations (MD) and quantum chemistry (QC) calculations indicate that the six active components of PFAE can display strong anti-corrosion capability.

Single and multicomponent adsorption of amoxicillin, ciprofloxacin, and sulfamethoxazole on chitosan-carbon nanotubes hydrogel beads from aqueous solutions: Kinetics, isotherms, and thermodynamic parameters

The removal of antibiotics in water receiving bodies is an integral part in eradicating antimicrobial resistance which has become a major threat to public health. Solid-liquid adsorption has demonstrated to be an effective technique in the removal of antibiotics from aqueous environments. Herein, chitosan-carbon nanotube (chitosan-CNT) hydrogel beads were synthesised for the adsorption of amoxicillin (AMX), ciprofloxacin (CIP) and sulfamethoxazole (SMX) from aqueous solution. Adsorption kinetics, isotherms and thermodynamic parameters were systematically investigated at a solution pH of 7. Single adsorption kinetics findings suggest that experimental data for AMX, CIP and SMX was better fitted by the nonlinear pseudo-first order model with calculated maximum adsorption capacities of 23.1 mg.g−1, 23.7 mg.g−1 and 25.17 mg.g−1, respectively. Moreover, findings from the Weber-Morris kinetic model suggest that multiple processes were limiting the overall adsorption rate of AMX, CIP and SMX on chitosan-CNT. Adsorption isotherm results indicated that single adsorption experimental data was better fitted by the nonlinear Freundlich isotherm model, while binary and ternary system experimental data were better fitted by the nonlinear competitive extended Sips adsorption isotherm models. Moreover, results for binary and ternary adsorption showed that multicomponent adsorption systems exhibited both antagonistic and synergistic adsorption of AMX, CIP and SMX. From the thermodynamics fundings, it was evident that the adsorption of AMX, CIP and SMX from solution is an endothermic process governed by both physical and chemical adsorption mechanisms. Based on the findings of the current study, it was concluded that chitosan-CNT has potential as a green technology for the removal of antibiotics from solution.

Separator engineering toward suppressed shuttle effect and homogenized lithium deposition in lithium−sulfur batteries

Lithium−sulfur (Li−S) batteries are ideal energy storage devices due to their high energy density (2600 Wh kg−1), but polysulfide shuttling and lithium dendrite growth seriously preclude their practical application. Herein, a multifunctional layer composed of MnO, MnWO4 and carbon black (CB) is constructed to modify the polypropylene separator (MnO-MnWO4/CB@PP) of Li−S batteries. The MnO-MnWO4/CB layer possesses the ability to adsorb polysulfides through physical and chemical adsorption mechanisms, as well as catalyze their conversion. Results show that the adsorption-catalysis characteristic of MnO-MnWO4/CB enhances the capture capability for polysulfides to suppress its shuttling. Moreover, it acts as a buffer layer, facilitating the parallel electrodeposition of Li and inhibiting the growth of Li dendrite. As a result, the Li/Li symmetrical cell with MnO-MnWO4/CB@PP enables durable Li plating/stripping over 8000 h at 1.0 mA cm−2 with a capacity of 1.0 mAh cm−2. In addition, the Li−S battery with this modified separator demonstrates a competitive initial capacity of 1527.7 mAh g−1 at 0.2 C and a capacity retention of 80.8% after 1000 cycles at 2.0 C. This work presents an effective and straightforward approach for designing separator of Li−S battery.

Enhancement of Pb(ii) adsorptive removal by incorporation of UiO-66-COOH into the magnetic graphitic carbon nitride nanosheets.

Efficient elimination of Lead (Pb(ii)) from aqueous solutions has become a crucial area of focus in the wastewater treatment industry. In this study, novel mesoporous magnetic g-C3N4/Fe3O4/UiO-66-COOH was synthesized by combining the acid-functionalized metal-organic framework (MOF) of UiO-66-COOH via a facile novel solvothermal method with magnetic graphitic carbon nitride (g-C3N4/Fe3O4) sheets to enhance Pb(ii) adsorption in water. The study investigated various influential adsorption parameters, including pH, dosage, contact time, ion concentration, and temperature. The Langmuir model, which depicts monolayer adsorption on a uniform surface, was a more suitable fit for the adsorption isotherms. The kinetics conformed to the pseudo-second-order model, indicating a chemical adsorption mechanism. According to the Langmuir model, the adsorption capacity of g-C3N4/Fe3O4/UiO-66-COOH is expected to reach a maximum of 285.8 mg L-1. This value is 2.6 times higher than g-C3N4/Fe3O4 and 1.6 times higher than UiO-66-COOH. The enhanced adsorption capacity of g-C3N4/Fe3O4/UiO-66-COOH is attributed to its superior characteristics, such as abundant functional groups and high surface area which is 2.16 times higher than g-C3N4/Fe3O4. The adsorption thermodynamics indicated that the adsorption occurred spontaneously and was characterized as exothermic. g-C3N4/Fe3O4/UiO-66-COOH material exhibited good recyclability for up to five runs.

Mesoporous γ-AlOOH as an adsorbent for silica removal from aqueous solutions

Silica plays a crucial role in the formation of inorganic scaling. Therefore, we present a study on the effectiveness of γ-AlOOH (boehmite) as a silica removal adsorbent. Kinetic analysis reveals a combination of chemical and physical adsorption mechanisms, with the pseudo-second-order model suggesting significant chemisorption. The adsorption isotherm of silica followed Freundlich model in higher concentration region at over 50 mg/L and mesoporous effectively act on silica adsorption in tap water. This study proposes γ-AlOOH as a novel adsorbent to address issues related to silica in various industries.

3,4-Dimethoxy phenyl thiosemicarbazone as an effective corrosion inhibitor of copper under acidic solution: comprehensive experimental, characterization and theoretical investigations.

This study investigates the corrosion inhibition potential of 3,4-dimethoxy phenyl thiosemicarbazone (DMPTS) for copper in 1 M hydrochloric acid (HCl) solutions, aiming to disclose the mechanism behind its protective action. Through an integrative methodology encompassing electrochemical analyses-such as weight loss measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS)-we quantitatively evaluate the corrosion protection efficacy of DMPTS. It was determined that the optimal concentration of DMPTS markedly boosts the corrosion resistance of copper, achieving an impressive inhibition efficiency of up to 89% at 400 ppm. The formation of a protective layer on the copper surface, a critical aspect of DMPTS's inhibitory action, was characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). These techniques provided empirical evidence of surface morphology modifications and roughness changes, affirming the formation of a protective barrier against corrosion. A significant advancement in our study was the application of Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, which identified chemical adsorption as the definitive mechanism of corrosion inhibition by DMPTS. The ATR-FTIR results explicitly demonstrated the specific interactions between DMPTS molecules and the copper surface, indicative of a robust protective adsorbed layer formation. This mechanistic insight, crucial to understanding the inhibitory process, aligns with the protective efficacy observed in electrochemical and surface analyses. Theoretical support, provided by the Quantum Theory of Atoms in Molecules (QTAIM) and quantum chemical computations, further validated the strong molecular interaction between DMPTS and copper, corroborating the experimental findings. Collectively, this research not only confirms the superior corrosion inhibition performance of DMPTS in an acidic setting but also elucidates the chemical adsorption mechanism as the foundation of its action, offering valuable insights for the development of effective corrosion inhibitors in industrial applications.

Adsorption of acetochlor-contaminated water systems using novel P-doped biochar: Effects, application, and mechanism

Given the serious threat of acetochlor (ACT) to the aquatic ecological environment, designing wastewater treatment–oriented adsorbents for the sustainable remediation of actual ACT-contaminated water is a promising yet challenging strategy. Herein, a novel P-doped biochar (PBC-800) with a high adsorption capacity (51.34 mg g−1) and a rapid reaction rate (47.35 mg g−1 h−1) for ACT was prepared through pyrolyzing of rice straw biomass pre-impregnated with potassium dihydrogen phosphate (KH2PO4). Additionally, P-doped biochars synthesized at different pyrolysis temperatures exhibited significant variations in ACT adsorption performance, which was mainly ascribed to the distinction between hydrophilicity and sp2 conjugate C (ID/IG = 0.84–1.08). The adsorption behavior of ACT on PBC-800 followed the Elovich kinetics and Freundlich adsorption isotherm models. Thermodynamic calculations indicated that the adsorption of ACT by PBC-800 was a spontaneously disordered decreasing exothermic process. Besides, PBC-800 exhibited a powerful anti-interference for ACT adsorption within complex water matrices, highlighting its potential for various of practical applications. Through characterization analysis and further experiments, it was proved that the excellent adsorption performance of PBC-800 on ACT was ascribed to a combination of physical and chemical adsorption mechanisms, including 57.5% pore filling, 23.4% hydrophobic interaction, 12.7% π–π interaction, and 6.4% hydrogen bonding. Moreover, PBC-800 exerted a prominent adhesion impact upon Gram-positive and negative bacteria at 3 h. This study offers a new idea for the utilization of agricultural residues and provides insights into the mechanism of ACT adsorption through its derived biochar.

N-halamine modified poly(amidoxime) nanofibrous antibacterial adsorbents for the extraction of copper ions and dyes from aqueous medium

Wastewater with contaminants such as heavy ions, organic dyes, and bacteria is extremely damaging to the environment and human life. In this study, N-halamine modified poly(amidoxime) nanofibrous membranes (PAO-Cl) were prepared using amidoxime-modified polyacrylonitrile (PAN), followed by chlorination. The amidoxime conditions of PAN were investigated, and the micromorphologies of each sample were examined. The durability, water release properties, antibacterial activities, and adsorption properties of the Cu2+ ions and methyl orange(MO) were investigated. The results demonstrated that PAO and PAO-Cl exhibited an adsorption capacity toward Cu2+ ions and MO, respectively. Chlorination of PAO resulted in the loss of Cu2+ ion adsorption properties of PAO-Cl. Nevertheless, PAO-Cl presented a higher MO adsorption capacity than poly(amidoxime) nanofibrous membranes (PAO). When the pH value less than 4, the adsorption properties of PAO-Cl was significantly enhanced, and the adsorption process was optimal, as described by the pseudo-second-order kinetic and Langmuir models. For PAO-Cl, the chemical structure changes and adsorption mechanism toward MO were thoroughly studied. After 5 min of contact time, the chlorinated sample displayed excellent antimicrobial capacities against 100 % of S. aureus (6.2 log) and E. coli O157:H7 (6.0 log), making it a promising candidate for use in water disinfection fields.

Economical and eco‐friendly adsorbent derived from “Halodule uninervis” for effective removal of N‐nitrosodiphenylamine from wastewater: Equilibrium, reusability, and mechanism studies

AbstractN‐nitrosodiphenylamine (NDPhA) is soluble in water and highly toxic. Exposure to NDPhA even at low concentrations for a long period can cause several health effects. Hence the removal of NDPhA from aqueous samples using a widely abundant and economical adsorbent is highly challenging. In this study, a highly efficient, eco‐friendly, and low‐cost adsorbent was derived from the dead leaves of Halodule uninervis seagrass (SG) without any chemical modifications. The derived adsorbent was characterized and investigated for the removal of NDPhA from aqueous solutions. The effects of solution pH, contact time, adsorbent dosage, and adsorbate concentration were studied and optimized. The SG adsorbent showed a significant removal efficiency of 83% for NDPhA from wastewater solution using 1 g L−1 adsorbent. The maximum adsorption capacity for SG was found to be 64.84 mg g−1 at neutral pH and room temperature. The adsorption isotherm results fitted with the Langmuir model and followed pseudo‐second‐order kinetics. From the thermodynamic parameters, it has been found that the adsorption of NDPhA onto SG adsorbent is favorable, endothermic, and the chemical adsorption mechanism is predominant. This study indicated that SG adsorbent is reusable and can be easily regenerated and reused at least three times with a slight decrease in its removal efficiency.