Isotherm Model Research Articles

Synthesis of novel magnesium ferrite Schiff base chitosan nanocomposite for efficient removal of pb(II) ions from aqueous media

In this study, a novel MgFe2O4-Schiff base-chitosan nanocomposite was synthesized using a straightforward crosslinking method. The synthesis involved integrating MgFe2O4 nanoparticles with modified chitosan through a Schiff base formed by the reaction between terephthalaldehyde and aminopyrazine. A comprehensive characterization was performed, including X-ray diffraction analysis, which verified the crystalline structure and the successful incorporation of MgFe2O nanoparticles into the chitosan-Schiff base matrix. Scanning electron microscopy revealed a distinct surface morphology, characterized by a rough, non-uniform alignment resulting from the strong interactions between the nanoparticles and the Schiff base-chitosan matrix. Additionally, energy-dispersive X-ray analysis verified the elemental composition of the nanocomposite, revealing distinct peaks corresponding to carbon, nitrogen, oxygen, magnesium, and iron. The nanocomposite exhibited outstanding performance as a nanoadsorbent for the efficient removal of Pb(II) ions from aqueous media through electrostatic attraction and complexation mechanisms, achieving a maximum adsorption capacity of 290.7 mg g-1. The adsorption process was determined to be spontaneous, endothermic, and chemically driven, aligning well with the Langmuir isotherm model and pseudo-second-order kinetics. The optimal conditions for maximum Pb(II) ions removal were determined to be a pH of 5.5, a contact time of 100 min, and a temperature of 328 K. Furthermore, the nanocomposite demonstrated excellent recyclability, retaining over 94.8% of its initial removal efficiency after five consecutive adsorption-desorption cycles. This study highlights the nanocomposite’s potential as an eco-friendly, cost-effective, and highly efficient material for practical applications in water treatment, addressing the urgent need for sustainable solutions to heavy metal contamination.

Synthesis of a Novel Supermagnetic Fe3O4 Nanoparticles and their Congo Red Dye Removal, Cytotoxic, Antioxidant, and Antimicrobial Activities

Abstract Plantago lanceolata is a traditional medicinal plant that has attracted significant interest from researchers due to the use of its physiologically active components, particularly polyphenolics (flavonoids, hydroxycinnamic acids), in various fields. The aim of this study is to synthesize iron oxide (PLE@FeNPs) nanoparticles using a green synthesis approach with Plantago lanceolata (P. lanceolata) leaf extracts, characterize them, evaluate their in vitro effects, and assess their use in the removal of Congo red (CR) from wastewater. We carried out the physicochemical characterization of the nanoparticles using UV–Vis, FT-IR, and XRD spectroscopies; TEM and SEM microscopy; and Zetasizer particle size analysis. While the distinct peaks in XRD confirm the crystalline structure, TEM has determined an average particle size (8 nm) for PLE@NPs with deformed spherical nanoparticles. The FT-IR spectra showed that bioactive compounds from P. lanceolata were involved in the participation of PLE@FeNPs. EDX confirmed the presence of iron in the designed PLE@FeNPs. The antibacterial, antioxidant, and anticancer analyses of the studied PLE@FeNPs revealed significant activities. We investigated the adsorption kinetics of CR on PLE@FeNPs, taking into account initial dye concentration, different pH levels, adsorbent dosages, and temperature. At optimal conditions (concentration, 50 ppm; dosage, 15 mg; pH, 8), the degradation of CR dye in sunlight was found to be 99%. The small size of PLE@NPs (8 nm) and the more negative zeta potential (− 12.2 mV) support this situation. The equilibrium data demonstrated a good fit to the Langmuir isotherm model, outperforming the Freundlich isotherm model. The results showed that the pseudo-second-order kinetic model accurately described the kinetic data. PLE@NPs exhibited significant antioxidant, antimicrobial, and anticancer activities. This situation suggests that the nanocomposition of PLE@NPs obtained through the green route may have improved efficiency due to various synergistic effects. Overall, these results pave the way for further applications in dye removal and biological applications of environmentally friendly PLE@FeNPs. Graphical Abstract

A comprehensive study on pomegranate (Punicagranatum) peels as a low-cost biosorbent: adsorption mechanisms, application, regeneration, and cost analysis.

This study investigates the potential of utilizing pomegranate peel, a waste material, as an environmentally friendly adsorbent for the removal of methylene blue (MB) from wastewater. The novelty of this study lies in producing a competitive adsorbent (96% removal in a reasonably short contact time), very low cost, from a biowaste material and in providing cost analysis, regeneration method, application, and a mechanism based on a set of results that are in harmony with each other. Characterization of the purified pomegranate (Punicagranatum) peels (PP) inferred remarkable acidic sites. The MB removal was observed to increase with increasing dosages of adsorbent, contact time (93-94% removal took place in the first 30-40min), agitation speed (the amount of MB removed increased with increasing agitation speed up to 160 rpm), pH (increasing solution pH up to pH 8.0, the removal efficiency of MB by PP increased), and MB initial concentrations. The experimental results of MB adsorption on PP were best fitted to the Temkin isotherm model and the kinetic studies showed that the adsorption rate was best fitted to the pseudo-second-order (PSO) model showing a correlation coefficient R2 of 0.969-0.991. Thermodynamic investigations demonstrated that the removal of MB dye utilizing PP may be due to a spontaneous, electrostatic, chemical, and exothermic interaction with a heterogeneous adsorption mechanism. Adsorption is anticipated to begin with attraction between cationic MB and negatively charged active functional groups on adsorbent's surface, soon to be followed by multisite chemical interaction. The results (up to 96% removal) show that pomegranate peels could be used as a potential eco-friendly, cost-effective, and efficient biosorbent for dye removal from wastewaters. With an average removal effectiveness of 86.8%, PP were successfully utilized to remove MB from MB-spiked actual river water samples.

Cost-effective adsorption of cationic dyes using ZnO nanorods supported by orange peel-derived carbon

Abstract Here, porous carbon (PC) and ZnO nanorods@PC (ZnO-NR@PC) composite derived from orange peel (OP) have been synthesized via a simple carbonization process. The prepared materials have been characterized by XRD, FT-IR, TEM, and BET analysis. The adsorptive properties of the prepared PC and ZnO-NR@PC composite have been investigated toward methylene blue (MB) and crystal violet (CV) cationic dyes from their aqueous solutions. The adsorption studies concluded that the maximum adsorption efficiency was achieved after 90 min in the basic conditions (pH = 10). Langmuir, Freundlich, Dubinin–Radushkevich (D-R), and Temkin non-linear isotherm models were applied to fit the experimental data. The adsorption of MB and CV dyes by the OP is fitted with the Freundlich model, and the adsorption of both dyes by the PC and the ZnO-NR@PC composite fitted with the Langmuir model. The estimated maximum adsorption capacity estimated from the adsorption of MB and CV by the ZnO-NR@PC composite was 74.45 and 74.89 mg/g, respectively. The calculated adsorption free energy from D-R and Temkin models indicates the adsorption of MB, and CV dye molecules by the OP, PC, and ZnO-NR@PC composite may be physical. The kinetic studies revealed the adsorption of MB and CV dyes onto the OP, PC and ZnO-NR@PC composite fitted with the pseudo-second-order model. On the otherhand, the thermodynamic studies confirmed the adsorption of MB, and CV dyes onto ZnO-NR@PC composite is an endothermic and spontaneous process. Furthermore, the prepared materials displayed high adsorption stability with an overall removal efficiency of about 90% after five cycles. The mechanism of MB and CV dyes by the ZnO-NR@PC composite is proposed to be controlled by electrostatic bonding, π-π interactions, and ion exchange. The results indicated the potential ability of OP-derived porous carbons as adsorbents for cationic dyes from aqueous media.

Temperature Dependence Evaluation of CO2 Adsorption on Eagle Ford Shale using Isothermal Models: A Comparative Study

This study investigates the CO2 adsorption capacity of the Eagle Ford (EF) shale under varying temperatures, utilizing six isothermal adsorption models: Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Sips, Toth, and Brunauer-Emmett-Teller (BET). The shale sample was characterized through Total Organic Carbon (TOC) analysis, X-ray diffraction (XRD), BET surface area analysis, and Field Emission Scanning Electron Microscopy (FESEM) to assess its organic content, mineral composition, pore structure and elemental composition. CO2 adsorption experiments were conducted using a volumetric method at pressures up to 12 MPa and temperatures of 35°C, 55°C, and 70°C. The results revealed that the adsorption capacity increased with pressure but decreased with rising temperature, which is consistent with the exothermic nature of CO2 adsorption. Among the models, Freundlich and Sips provided the best fit for most temperature conditions, highlighting the heterogeneous nature of the shale surface, while the Langmuir, Toth, and D-R models performed well but with slight deviations. The BET model exhibited the poorest fit. Overall, the findings suggest that the EF shale has significant potential for CO2 storage, especially at lower temperatures, with Freundlich and Sips models being the most reliable for predicting adsorption behavior in EF shale formations.

Versatile waste wood-chitosan composites for 2,4-D and paraquat adsorption: Isotherm modelling and thermodynamic evaluation.

2,4-dichlorophenoxy acetic acid (2,4-D) and 1,1-dimethyl-4,4-bipiridinium chloride (paraquat) are among the most widely used herbicides and are known to be toxic. Fabrication of green adsorbents which are capable of removing both herbicides remains a challenge. Here, we fabricate a novel adsorbent from tropical waste wood and use a facile, chitosan-mediated N-heteroatom functionalization technique to augment surface nitrogen and improve specific surface area. The addition of 20wt% chitosan to the waste wood feedstock prior to activation, increased specific surface area by 300m2/g (∼25%) and nitrogen content by 7-fold. This functionalized material removed 69% of 2,4-D and 82% of paraquat at initial concentrations of 4ppm and 40ppm from model solutions at pH 7. It also removed 39% 2,4-D and 93% paraquat from binary mixtures demonstrating its versatility. 2,4-D adsorption increased with chitosan addition suggesting synergistic effects between protonated amine functions and the anionic herbicide form. Paraquat adsorption was negatively correlated with chitosan addition, implying antagonistic interaction between protonated amine functions and quaternary nitrogen atoms on herbicide molecules. Adsorption of both herbicides was spontaneous, entropically favored and exothermic with ΔG °: 19.2kJ/mol and -28.8kJ/mol; ΔS °: 7.42 and 28.6J/Kmol and ΔH °: 17.0kJ/mol and -20.1kJ/mol for 2,4-D and paraquat respectively. Chitosan addition therefore provides a facile and green alternative for N-heteroatom functionalization, and these nitrogen-doped materials are promising candidates for the removal of multiple herbicides from aqueous systems.

Application and regeneration of magnetic material MgAlLDH@Fe3O4 humic acid with removal capacity for malachite green

Malachite green (MG), a dye in wastewater, pollutes the natural environment, and it is difficult to eliminate dyes from aquatic systems. MgAlLDH-magnetite humic acid (Mg3Al@M2HA) was prepared for MG adsorption via coprecipitation and hydrothermal methods. The adsorption was performed using the batch adsorption method at the pH of the point of zero charge (8.33), with an optimum contact time of 120 min and a maximum concentration of 100 mg/L of MG. Furthermore, the pseudo-second-order and Langmuir models were better fitted to the kinetic and isotherm models, respectively. The maximum monolayer adsorption capacity for MG on Mg3Al@M2HA at 313 K was 113.6 mg/g. The calculated thermodynamic parameters (Δ H = 18.524 kJ/mol, Δ S = 0.076 J/Kmol, Δ G = − 4.586 to − 6.111 kJ/mol) implied that the MG adsorption was spontaneous, endothermic, and had degrees of randomness in the temperature range of 303–323 K. Moreover, the ΔH was less than 40 kJ/mol, confirming that the combination of MG with Mg3Al@M2HAwas due to the physisorption with electrostatic interaction, hydrogen bonding, and π–π interaction. Recycling experiments showed that the MG removal rate was 82.55 % after 5 cycles. This study provides new insights into Mg3Al@M2HA and its potential applications for MG adsorption.

Adsorption and catalytic degradation by CoFe2O4 coated on metal–organic framework for the removal of 4-nitrophenol and 2,4-dichlorophenol

4-nitrophenol (4-NP) and 2,4-dichlorophenol (2,4-DCP) contaminated wastewater have attracted attention for their genotoxic and carcinogenic hazards. The magnetic MIL-101/CFO was constructed by synergistically integrating porous/hydrophilic/π-conjugated MIL-101(Cr) and CoFe2O4. The nanocomposites markedly accelerated the catalytic reaction activity. The BET characterizations reveal the nanocomposites had a larger specific surface area and pore volume in comparison to the individual CoFe2O4. The composite was employed to evaluate the adsorption and peroxymonosulfate (PMS)-activated ability of 4-NP and 2,4-DCP elimination. The adsorption equilibrium could be achieved within 60 min, following the pseudo-second-order kinetic model and the Langmuir isotherm model. The nanocomposites (0.2 g·L−1) achieved exceeding 96 % decomposition efficiencies toward 4-NP and 2,4-DCP (0.1 g·L−1) after 15 min by PMS (5.29 mM) activation. Notably, the reaction system displayed effective catalytic performance across pH 5 − 10 and resistance to the existence of saline ions and humic acid. According to the free radical quenching experiments and electron paramagnetic resonance, the non-radical route dominant by 1O2 and little of HO• and SO4•− were affirmed to participate the reaction. The recyclable MIL-101/CFO/PMS system approached high adsorptive and catalytic ability for phenolics remediation in the environmental application.

Construction of Fe and g-C3N4 codoped magnetic bamboo charcoal for enhanced catalytic degradation of tetracycline: Mechanism, degradation pathway, and ecological toxicity.

The well-designed bamboo charcoal (BC) composite Fe-g-C3N4/BC with multi-active sites of FeOx, FeNx, and g-C3N4, was fabricated in-situ by calcining Fe-melamine loaded bamboo charcoal (Fe-Me-BC) under nitrogen atmosphere. The as-synthesized Fe-g-C3N4/BC(550) exhibited a mesoporous structure with a large specific surface area of 108.23m2/g. The adsorption of tetracycline (TCL) on Fe-g-C3N4/BC(550) was calculated following the Langmuir isotherm model, and showed a maximum adsorption capacity of 19.92mg/g. Furthermore, the pseudo-second-order kinetic model showed a good fit for the TCL adsorption process on Fe-g-C3N4/BC(550). The Fe-g-C3N4/BC(550)/H2O2 system exhibited excellent photo-Fenton catalytic performance in degrading TCL with a degradation efficiency reaching up to 98.9% within 5min under visible-light. The effects of initial pH value and coexisting anions on TCL degradation were determined. As narrow band gap semiconductors, g-C3N4, Fe3O4, and Fe2O3 in the Fe-g-C3N4/BC exhibited good visible-light-driven photocatalytic activity. Moreover, photogenerated electrons could further activate H2O2 to produce high concentrations of ∙OH radicals. This outstanding photo-Fenton catalytic performance can be ascribed to the synergistic effect of g-C3N4/Fe3O4-Fe2O3/FexN multi-active sites as well as the excellent adsorption ability and conductivity provided by bamboo charcoal. This work presents a convenient approach for constructing economical catalysts for environmental remediation through g-C3N4 and Fe-N codoped BC.

Abatement of methylene blue and diazinon pesticide from synthetic solutions using magnetic biochar from pistachio shells modified with MOF-808.

This study develops a magnetic composite from pistachio shell biochar (PSBC/CoFe₂O₄) modified with MOF-808 for removing methylene blue (MB) dye and diazinon (DA) pesticide from water. The composite, with a surface area of 151.53m2/g and magnetic saturation of 19.653 emu/g, allowed easy separation from solutions. Key adsorption factors such as pH, temperature, contact time, adsorbent dosage, and initial pollutant concentration were optimized. Maximum removal efficiencies of 99.32% for MB and 99.14% for DA were achieved at adsorbent dosages of 1g/L for MB and 1.5g/L for DA, initial concentrations of 5mg/L, temperatures of 55°C, contact times of 60min for MB and 80min for DA, and pH levels of 9 for MB and 6 for DA. Thermodynamic analysis confirmed that the adsorption process is spontaneous and endothermic, with enthalpy values of 55.091kJ/mol for MB and 42.028kJ/mol for DA, while entropy values indicated increased randomness during adsorption. Kinetic studies revealed that adsorption involved both physical and chemical interactions, with intraparticle diffusion not being the rate-limiting step. The Freundlich isotherm model provided the best fit (R2=0.971 for MB and 0.988 for DA), highlighting heterogeneous surface interactions. The composite showed higher adsorption capacities for MB (31.44mg/g) than for DA (21.49mg/g) and exhibited excellent regeneration potential, performing better in deionized water due to the inhibitory effects of salts in non-deionized water.

Hydrophilic magnetic chitosan/gelatin hydrogel with enhanced fuel dehydration characteristics: Modeling, kinetic, isotherm and thermodynamic study.

In this research, a nanocomposite of Fe3O4/chitosan/gelatin was prepared and used as a magnetic recyclable dewatering agent to improve the quality of fuel. Prepared materials were characterized by XRD, FT-IR, VSM, BET and FESEM techniques. Effective factors on water uptake i.e., initial water content, time, percentage of Fe3O4 and adsorbent dosage were optimized with Box-Behnken design and results showed that all parameters are significant. The performances of three magnetic composites including crosslinked chitosan, functionalized chitosan and chitosan/gelatin showed that magnetic chitosan/gelatin with 13% of Fe3O4 content has a removal percentage of 99.2-97.3% besides the efficiencies were 35.8-43.8% and 79.5-89% using crosslinked chitosan, functionalized chitosan as adsorbents. Results from the kinetic study showed that pseudo - second-order model can better describe water uptake moreover, the adsorption process followed the Langmuir isotherm model. Magnetic chitosan/gelatin composite shows a maximum water removal efficiency of 97.3% at an initial water concentration of 2500mgL-1 after 40min. The thermodynamic study showed that adsorption is a spontaneous process with higher feasibility at higher temperatures. Moreover, the adsorbent shows a good efficiency of 93.7% after 6 recycling. These results confirmed good performances of the prepared hydrogel in dehydration to improve the quality of fuel.

Enhanced extraction of methylene blue by dodecyl-methyl imidazolium dodecyl sulfate GUMBOS - magnetic alginate beads.

In this study, dodecyl-methyl imidazolium dodecyl sulfonate ([C12MIm][DS]) GUMBOS were synthesized and incorporated into alginate with γ-Fe2O3 to fabricate magnetic adsorbent beads ([C₁₂MIm][DS]-beads) for methylene blue (MB) removal. Characterization via ESI-MS, FT-IR, SEM, BET, and TGA confirmed their structure and properties. The beads achieved a maximum adsorption capacity of 4.5mg/g at pH 10 with an initial MB concentration of 500mg/L, following pseudo-first-order kinetics and the Langmuir isotherm model. Thermodynamic studies confirmed the process was exothermic. Even after six recycling cycles, the beads retained similar morphology and an MB removal percentage of 57.6%. The beads demonstrated high adsorption efficiency (70%) in the presence of Cu2⁺, ibuprofen, and malachite green, comparable to MB removal alone. These results highlight the potential of [C12MIm][DS]-beads as effective adsorbents for water remediation applications.

Deciphering adsorption behaviour and mechanisms of enhanced phosphate removal via optimized cetyltrimethylammonium bromide-modified nanofibrillated cellulose.

To combat the persistent environmental issues resulting from eutrophication, it is necessary to scavenge excess phosphorous levels from aquatic ecosystems. In response, a cationic adsorbent was prepared by modifying agrowaste-derived natural biomacromolecule; nanofibrillated cellulose (NFC) using cetyltrimethylammonium bromide (CTAB) surfactant. Comprehensive characterization through XRD, FTIR, HR-SEM, SEM-EDX, BET and XPS demonstrated that quaternizing NFC significantly improved its surface chemistry by introducing substantial quaternary ammonium groups. This modification imparted positive ζ potential across broad pH range, underscoring a strong affinity for negatively charged phosphate ions. Enhanced roughness and improved spatial dispersion led to nearly threefold increase in phosphate removal efficiency compared to pristine NFC, attributable to a higher number of available active sites. The adsorption process followed pseudo-second-order kinetic and Sips isotherm model, with a maximum adsorption capacity of 21.78 mg P/g, reaching equilibrium within 120 min. Besides, the prepared adsorbent demonstrated pH-dependent adsorption and displayed stable adsorption capacity particularly at weakly acidic or neutral pH conditions. Furthermore, it exhibited excellent retention capacity with only 12.61 % desorption rates over three cycles. Both XPS and FTIR results revealed that electrostatic adsorption (based on Lewis acid-base principle) and hydrogen bonding were primary adsorption mechanism.

Synergistic mechanisms for efficient and safe antibiotic removal: Effective adsorption and photocatalytic degradation using aerogels

To tackle the issues of low adsorption capacity, poor regeneration efficiency, and limited recoverability in wastewater treatment adsorbents, we innovatively developed a low-cost Fe(III)-SA gel ball aerogel (FA) through a simple chemical crosslinking method. FA aerogel exhibits exceptional adsorption performance for a wide range of antibiotics, including norfloxacin (NOR), ciprofloxacin (CIP), and tetracycline hydrochloride (TC), showcasing its broad applicability. Remarkably, FA achieved a maximum NOR adsorption capacity of 338.4 mg/g (Langmuir isotherm model, pH 7.0, 298 K, m/V=0.1 g/L). Furthermore, under the synergistic effect of photocatalysis, FA demonstrated a breakthrough by removing 97 % of NOR (30 mg/L, 50 mL) within just 150 min. Notably, FA displayed innovative regeneration capabilities, successfully completing 10 continuous and stable NOR removal cycles without loss of performance. The DFT calculations alongside experimental evidence were employed to elucidate the NOR degradation pathway, while electron density distribution and Fukui function analysis confirming the proposed degradation pathways through HPLC-MS results. Moreover, plant stress and zone of inhibition tests verified that the degradation intermediates were significantly less toxic, ensuring the safety of the regeneration process. This research introduces an innovative approach for designing superior adsorbents and provides critical insights into efficient and sustainable adsorbent regeneration.

Zn2+ adsorption in ferric-silicates microstructures in sulfidic tailings mediated through mineral weathering by Acidithiobacillus species.

Heavy metals released from metallic sulfidic tailings pose significant environmental threats by contaminating surface and groundwater in mining areas. Sustainable rehabilitation methods are essential to remove or stabilize these metals, improving the quality of acid mine drainage and minimizing pollution. This study examines the adsorption capacity of zinc ions (Zn2+) by different iron-silicate mineral groups under natural weathering and bacteria-regulated weathered conditions. Batch experiments revealed that all tested mineral groups exhibit limited adsorption Zn2+ on iron-silicate surfaces, with adsorption behavior aligning with Langmuir and Freundlich isotherm models. Among the mineral groups, pristine iron-muscovite (2.58 mg/g) and iron-chlorite (4.52 mg/g) demonstrated the highest Zn2+adsorption capacity, primarily due to favorable ion exchange properties and surface characteristics. Acidic conditions induced by pyrite oxidation and the experimental growth medium slightly reduced Zn2+ adsorption in samples without microbial inoculation. In contrast, the addition of Acidithiobacillus species modestly enhanced Zn2+ adsorption, likely through microbial alteration of silicate surface properties and the formation of secondary iron-silicate aggregates with high adsorption potential. The dominant adsorption mechanisms included electrostatic attractions, surface complexation and coprecipitation. It is recommended to elevate pH levels and thus enhance metal ion adsorption through the incorporation of alkaline additives such as zeolites or bauxite residue to optimize Zn2+ immobilization in sulfidic tailings. This study highlights the importance of both microbial and clay mineral selection in designing effective strategies for stabilizing Zn2+ in metallic sulfidic tailings.

Direct conversion of resin button waste into adsorbent for efficient removal of dyes and heavy metals from aqueous solution

An eco-friendly and cost-effective solution was developed to solve the problem of resource waste and environmental pollution caused by dye wastewater and unsaturated polyester resin-based resin buttons. In this study, solvent degradation was utilized to directly convert waste resin buttons into selective adsorbents, and the degradation products showed good adsorption performance for methylene blue and Pb(II), with adsorption capacities up to 808.9mg/g and 380.5mg/g, and a removal rate of about 99%, respectively. The adsorption experiments showed that the kinetics of the adsorption process closely followed a quasi second-order model (R²＞0.999), and the interaction between the degradation products and the pollutants was governed by chemisorption. In addition, the adsorption process fits well with the Langmuir isotherm model (R² > 0.991), indicating that the adsorption process mainly involves uniform monolayer adsorption. Mechanistic analysis revealed that both electrostatic interactions and hydrogen bonding play important roles in the adsorption process. Notably, the material showed good cyclic stability for Pb(II), with the retention rate of the original adsorption capacity close to 98% after five cycles, while the results indicated that external factors such as pH, salinity and surfactant had a significant effect on the adsorption behavior. This “waste to treasure” recycling strategy not only provides an effective method for selective adsorption of water pollutants, but also improves the practical application of thermosetting resin recycling.

Preparation of Mg/Al-LDH@HC composite with low concentration hydrochloric acid modified for phosphate removal from aqueous solution: Synthesis, adsorption performance and mechanism.

With high microporosity, good dispersibility, excellent specific surface area and large content surface functional group, hydrochar demonstrates significant advantages and strong affinity towards pollutants in water. Modification method plays a significant role for anion adsorption by modified hydrochar, layered double hydroxide (LDH) modified hydrocarbons (Mg/Al-LDH@HC-HCl) have been synthesized through a one-step hydrothermal approach and activated with hydrochloric acid in this paper. The physical and chemical characteristics of the hydrochar, both before and after modification, are analyzed using BET, SEM-EDS, TEM, XRD, FTIR, and XPS to explore the phosphate adsorption mechanisms. The adsorption behavior of the composite follows the pseudo-second-order kinetic model and the Langmuir isotherm model, achieving a substantial adsorption capacity of 143.03mg/g. Multiple mechanisms are leveraged within the absorption process, including pore filling, electrostatic attraction, ligand exchange, metal complexation on inner and outer surfaces, and ion exchange. An approximate 70% phosphate removal efficiency is retained by modified Mg/Al-LDH@HC-HCl after a comprehensive 5-cycle desorption using NaOH as the eluent, demonstrating the remarkable regenerability of synthesized hydrochar composite.

Aging-mediated selective adsorption of antibiotics by tire wear particles: Hydrophobic and electrostatic interactions effects.

Tire wear particles (TWPs), as a prevalent form of microplastic pollution in aquatic environments, have been shown to adsorb antibiotics, potentially exacerbating their toxic effects. This study provides a comprehensive analysis of the adsorption of ofloxacin (OFL), ciprofloxacin (CIP), sulfadiazine (SDZ), and tetracycline (TC) on TWPs that have undergone various aging processes, including cyclic freeze-thaw and ozone aging. We observed a significant increase in the specific surface area (SBET) of TWPs after aging, from an initial 2.81±0.29 to 6.63±0.16m2/g for ozone-aged TWPs. This enhancement in surface area and pore volume led to a respective 1.36-fold and 28-fold increase in adsorption capacity for OFL and CIP, highlighting the substantial impact of aging on TWPs' adsorptive properties. Conversely, the adsorption of SDZ and TC was reduced post-aging, suggesting a complex interaction between antibiotic physicochemical properties and TWPs' surface characteristics. The pseudo-second-order model, indicating chemisorption interactions, effectively described the adsorption kinetics, with the Freundlich isotherm model capturing the adsorption behavior more accurately than the Langmuir model. Our findings underscore the critical role of hydrophobic and electrostatic interactions in the adsorption process, particularly for SDZ and TC. This study's results offer crucial insights into the environmental implications of TWPs, emphasizing the need for further research on their role in the transport and fate of antibiotics in aquatic ecosystems.

Experimental and theoretical investigation of allylated chitosan and acrylic acid-based smart polymer hydrogel for the removal of brilliant green from aqueous media.

Smart polymer hydrogels with superior dye adsorption (brilliant green) characteristics were synthesized via free-radical polymerization by grafting acrylic acid segments onto allylated chitosan and inducing crosslinking with a trimethylolpropane triacrylate crosslinker. The synthesized adsorbents were characterized for their chemical structure (FT-IR and 1H NMR), thermal stability (TG/DTG), and morphological features (SEM). The adsorption capacity for brilliant green (934mg/g) and water uptake (712g/g) were determined using spectrophotometric and gravimetric methods, respectively. The interaction between the synthesized adsorbent and brilliant green, including potential dye orientation on the adsorbent and hydrogen bond formation was analyzed using Density Functional Theory. The maximum adsorption of brilliant green (934mg/g) and water uptake was achieved by optimizing the monomer feed compositions. Adsorption studies revealed that dye uptake followed Fickian diffusion and the Langmuir isotherm model, with pseudo-second-order kinetics. Thermodynamic analysis demonstrated that the adsorption process was spontaneous and exothermic, as evidenced by changes in free energy, enthalpy, and entropy under varying temperatures. Theoretical investigations confirmed the excellent affinity of the synthesized adsorbent toward brilliant green. Furthermore, reusability studies showed that the adsorbent retained its dye-holding capability over 20 adsorption-desorption cycles, highlighting its potential for sustainable and efficient dye removal applications.

Mechanism of removal of Sb from printing and dyeing wastewater by a novel titanium-manganese binary oxide.

Antimony (Sb) is a toxic heavy metal that endangers both the environment and human health. In response to the growing need for efficient Sb removal from printing and dyeing wastewater (PDW), this study introduces a novel titanium-manganese binary oxide adsorbent (T2M1BO) synthesized via precipitation. Experimental results show that T2M1BO exhibited higher absorption efficiency for Sb(III) compared to Sb(V), with maximum adsorption capacities recorded at 323.19mg/g for Sb(III) and 273.65mg/g for Sb(V) at pH 5. The findings emphasize the synergistic interaction between titanium and manganese oxides, which enhances the adsorption of antimony. Adsorption followed a pseudo-second-order kinetic model, consistent with the Freundlich isotherm model. While Sb(V) adsorption involved surface metal hydroxyl group replacement and inner-sphere complex formation, Sb(III) removal required a more complex approach, incorporating adsorption and oxidation processes. The straightforward synthesis, high efficiency, and recyclability of T2M1BO position it as a cpromising candidate for antimony removal in recyclability wastewater treatment.