Equilibrium Isotherms Research Articles

Efficient Phytoremediation of Methyl Red and Methylene Blue Dyes from Aqueous Solutions by Juncus effusus.

The contamination of water with dyes stemming from the discharge of industrial waste poses significant environmental risks and health concerns. In this study, the phytoremediation potential of the wetland plant Juncus effusus was investigated (as a function of plant biomass, pH, contact time, and initial dye concentration) for the removal of methylene blue and methyl red dyes from wastewater. The experimental adsorption capacities under the optimum conditions were found to be 1.421 and 1.038 mg g-1 plant wet weight for methylene blue and methyl red, respectively. Pseudo-first-order and pseudo-second-order models were employed to determine the kinetics of the phytoremediation adsorption process. The pseudo-second-order model was found to be the most suitable for both methylene blue and methyl red. The results were found to conform to the Freundlich equilibrium isotherm, with a correlation of R 2 ≥ 0.99 for removal of both dyes. Confirmation of dye uptake by the plant was determined by using Fourier transform infrared spectroscopy (FTIR). Additionally, direct analysis in real time-high-resolution mass spectrometry (DART-HRMS) analysis of plant roots is reported here for the first time as a means to investigate dye degradation by plant roots.

Freeze-drying synthesis of mesoporous magnetic grafted chitosan/calcium oxide nanoparticle for remazol brilliant blue dye removal: A statistical optimization

Herein, a mesoporous magnetic chitosan-salicylaldehyde/calcium oxide nanoparticle (CS-SL/CaO/Fe3O4) biocomposite adsorbent that was prepared via freeze-drying. The CS-SL/CaO/Fe3O4 was utilized for the adsorption of ramazol brilliant blue (RBB) dye from aqueous solution. The physicochemical properties of the CS-SL/CaO/Fe3O4 were evaluated using diverse characterization techniques, including BET, XRD, FTIR, FESEM-EDX, CHNS, and pHpzc. The three main factors for adsorption included the following A: CS-SL/CaO/Fe3O4 dosage (0.02–0.1 (g)/100 mL), B: pH (4–10), and C: Time (60–540 min). These factors were improved using statistical methods, specifically the Box-Behnken design (BBD). The optimal conditions for achieving maximum RBB removal (62.5 %) are listed: CS-SL/CaO/Fe3O4 dosage of 0.1 g/100 mL, a solution pH of 7, and a contact time of 540 min. The adsorption kinetics and equilibrium isotherms were well described by the pseudo first order (PFO) kinetic and Langmuir isotherm models, respectively. Thus, the CS-SL/CaO/Fe3O4 material has a maximum adsorption capacity (qmax) of 63.3 mg/g for RBB at 25 °C. The adsorption mechanism of RBB onto the CS-SL/CaO/Fe3O4 surface was attributed to electrostatic forces, n-π stacking, H-bonding, and Pi-Pi interactions. Thus, CS-SL/CaO/Fe3O4 represents a recoverable magnetic adsorbent with potential for capture of organic dyes from wastewater.

Rayleigh-Taylor instability in inhomogeneous relativistic classical and degenerate electron-ion magnetoplasmas

Abstract We study the Rayleigh-Taylor instability (RTI) of electrostatic plane wave perturbations in compressible relativistic magnetoplasma fluids with thermal ions under gravity in three different cases of when (i) electrons are in isothermal equilibrium, i.e., classical or nondegenerate, (ii) electrons are fully degenerate (with $T_e=0$), and (iii) electrons are partially degenerate or have finite temperature degeneracy (with $T_e\neq0$). While in the cases of (i) and (iii), we focus on the regimes where the particle's thermal energy is more or less than the rest mass energy, i.e., $\beta_e \equiv k_{\mathrm B}T_e/{m_ec^2}<1~\rm{or}~>1$, the case (ii) considers from weakly to ultra-relativistic degenerate regimes. A general expression of the growth rate of instability is obtained and analyzed in the three different cases relevant to laboratory and astrophysical plasmas, which generalize and advance the previous theory on RTI.

Biocomposite adsorbent (cross-linked chitosan + algae + montmorillonite) for methyl violet 2B dye removal: statistical modelling and optimisation

ABSTRACT Herein, a biocomposite of crosslinked chitosan polyethylene glycol diglycidyl ether (CS-PEDGE), montmorillonite (MMT), and food-grade algae (FGA) was successfully prepared by a hydrothermal technique. The resulting absorbent (CS-PEDGE/FGA/MMT) was assessed for its adsorption property with methyl violet 2B (MV 2B) a toxic cationic dye. The physicochemical properties of CS-EDGE/FGA/MMT were assessed via various analytical techniques, including BET, Elemental analysis, pHpzc, and spectroscopy (FTIR, XRD, SEM-EDX). The influence of three adsorption variables, namely adsorbent dose (A: 0.02–0.1 g/100 mL), solution pH (B: 4–10), and contact time (C: 10–420 min) on the rate of MV 2B dye removal was examined using the Box-Behnken design (RSM-BBD). The findings from the equilibrium isotherm and kinetic analyses suggest that the MV 2B dye adsorption onto the biocomposite surface follow the Freundlich model and pseudo-second-order kinetic models. The biocomposite adsorbent exhibits a maximum dye adsorption capacity (q max ) of 94.2 mg/g. The proposed MV 2B dye adsorption mechanism involves hydrogen bonding, n-π stacking, and electrostatic forces. This research demonstrates the unique structure and outstanding adsorption properties of CS-EDGE/FGA/MMT, which offers a viable solution for removal of detrimental MV 2B dyes from aqueous media.

Insight into Iron(III)-Tannate Biosorbent for Adsorption Desalination and Tertiary Treatment of Water Resources.

An innovative biosorbent-based water remediation unit could reduce the demand for freshwater while protecting the surface and groundwater sources by using saline water resources, such as brine, brackish water, and seawater for irrigation. Herein, for the first time, we introduce a simple, rapid, and cost-effective iron(III)-tannate biosorbent-based technology, which functions as a stand-alone fixed-bed filter system for the treatment of salinity, heavy-metal contaminants, and pathogens present in a variety of water resources. Our approach presents a streamlined, cost-efficient, energy-saving, and sustainable avenue for water treatment, distinct from current adsorption desalination or conventional membrane techniques supplemented with chemical and UV treatments for disinfection. The proof of feasibility for effective treatment of heavy metals, adsorption desalination, and cleansing of pathogens is demonstrated using synthetic water, brine, and field-collected seawater. The adsorption equilibrium and adsorption kinetic isotherm models, and mass transfer diffusion models confirmed the sorbent's function for sieving heavy-metal ions-silver (Ag+), cadmium (Cd2+), and lead (Pb2+)-from water. The maximum adsorption capacities (q m) of the sorbent for Ag+, Cd2+, and Pb2+ reach 96.25, 66.54, and 133.83 mg/g at neutral pH. The sorbent's affinity for heavy-metal-ion adsorption significantly increased, yielding q m of 116.57 mg/g for Ag+, 104.04 mg/g for Cd2+, and 165.66 mg/g for Pb2+, at pH 9, respectively, due to the sorbent's amphoteric nature. The pristine sorbents exhibit exceptional adsorption desalination efficacy (>70%) for removing salinity from brine and seawater, promoting heterogeneous adsorption. Fe(III)-TA's ability to disinfect seawater, with 67% efficacy over a very short contact time (∼15 min), confirms its remarkable antimicrobial properties for contact active mode pathogens cleansing. By preventing the release of salts, heavy-metal contaminants, and pathogens into the environment, our results proved that this novel multiplex biobased sorbent approach directly contributes to the water quality of surface and groundwater resources.

Biosorption of petroleum compounds from aqueous solutions using walnut shells

Herein, a walnut shell as a biosorbent was applied to remove petroleum compounds from the water medium. The characterization analyses of the walnut shells showed the macro-mesopore structure of the walnut shells, a specific surface area of 26 m2/g, and the presence of various functional groups (-OH, -COOH, -C = O). The CCD design showed that the walnut shell can remove 84.43% of petroleum compounds at pH = 3 (the optimum pH), adsorbent dosage: 2 g/L, and initial concentration of petroleum compounds: 550 mg/L. The study of kinetics and adsorption equilibrium indicated matching the experimental data with the pseudo-second-order kinetic model and Freundlich equilibrium isotherm, respectively. The maximum adsorption ability of walnut shell was 3038.29 mg/g at 45 °C. The ability to regenerate and reuse the walnut shell was investigated in 6 cycles, and the results showed a 21% decrease in adsorption ability after 6 cycles. The obtained data showed that the walnut shells could be a promising adsorbent with high adsorption ability toward petroleum components. Also, the walnut shell is a regenerable adsorbent, low-cost, and environmentally friendly, and can be effective in successive cycles. Therefore, this biosorbent can have a superb influence on wastewater treatment technology and possible applications at an industrial scale.

Efficient in situ synthetic routes of the polymeric composite containing clinoptilolite using ultrasonic assistance for sorption of some lanthanides

The ultrasound assistance synthesis strategy of the polymeric composite is based on free radical polymerization of polyallylamine hydrochloride (PAH) cationic polyelectrolyte, with vinyl sulfonic acid (VSA) anionic monomer with microporous crystalline alumino silicate clinoptilolite clay. The P(AH-co-VSA)/clinoptilolite polymeric composite was fully characterized by fourier transform infrared spectroscopy, energy dispersive X-ray, thermogravimetric analysis, and scanning electron microscope. FTIR demonstrated the presence of PAH and VSA, confirming the composition of the prepared composite. It was also used to map the energy-dispersive X-ray to affirm the interdependence of the clinoptilolite into the polymeric matrix. Consequently, the physicochemical characteristics of this copolymer may be adjusted using VSA and PAH suitable combinations. Batch experiments were applied and maximal sorption capacities for studied ions Nd3+, Ce3+, Y3+, Gd3+, and Eu3+ were 36.6, 50.2, 55.9, 57.2, and 57.7 mg/g, respectively. Sorption kinetics and equilibrium isotherm were conducted. Experimental isotherms of studied ions were successfully fit to pseudo-second-order model, langmuir isotherm model. The Dubinin–Radushkevich (D–R) isotherm was found to be applicable and suggesting that, the sorption occurs via a ion exchange reaction. The breakthrough data were measured in a fixed bed column, and variable process factors were examined, including bed depth, flow velocity, and initial metal ion concentration. The experimental work was then focused, for continuous investigations, on Ce3+, Eu3+, and Y3+ to represent light, intermediate, and heavy lanthanides respectively. The overall bed capacity and total metal ion adsorption increased when the flow rate increased. They reduced with rising initial metal ion concentration and bed depth, and reached 22.8, 31.4, and 28.5 mg/g for Ce3+, Eu3+, and Y3+ metal ions, respectively.

Investigation of the adsorptive capacity of a poly(vinyl alcohol)-based film for sodium diclofenac in aqueous media

Sodium diclofenac (DCF) has been detected in waters worldwide and is considered a micropollutant of emerging concern due to its potential toxicity in aquatic and terrestrial ecosystems. Traditional water treatment methods are unable to remove DCF completely from water, which makes adsorptive films a suitable alternative to address this challenge. In this context, the present study investigated the adsorptive capacities of a poly(vinyl alcohol)-based film for removing DCF from aqueous solutions. The effects of the initial DCF concentration and solution pH on the adsorption performance were evaluated, as well as kinetics and equilibrium isotherms. Regarding the results, DCF precipitation was observed within a pH range of 4.0-7.0, probably due to its limited solubility in acidic media. The optimal DCF concentration was found to be the lowest tested (2.5 mg L-1), yielding an equilibrium adsorption capacity (qe) of 0.511 mg g-1 and a DCF removal percentage (%R) of 23.4% within 90 min. Although the adsorption equilibrium was well described by the Redlich-Peterson isotherm despite the unusual behavior observed, pseudo-first and pseudo-second order kinetic models were satisfactory only at the initial concentration of 2.5 mg L⁻¹. Overall, the data set indicate that the film has a limited adsorption capacity, reaching saturation at low adsorbate concentrations. Nonetheless, these findings support further investigations at lower DCF concentrations to better understand the film’s adsorptive behavior under environmentally relevant conditions.

Synthesis of zeolite type A from metakaolin obtained by thermal treatment of kaolin: Textural and BB41 dye adsorption experimental design studies

ABSTRACT Algerian Kaolin was valorized firstly to synthesized zeolites A and then performed in Basic bleu 41 (BB41) dye from aqueous media. Kaolin was transformed by thermal treatment to Metakaolin (MK) at 700°C for 2 h. Zeolites A are synthesized from MK by hydrothermal crystallization according to optimal conditions (Temperature: 100°C, solid/liquid: 20 g/L, NaOH concentration: 2 mole/L, and time: 24 h). The structural characteristics of samples are determined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electronic microscopy (SEM), Energy dispersive spectroscopy (EDS), Thermogravimetric/Differential thermogravimetric analysis (TG/DTG) and Brunauer-Emmett-Teller (BET) method. Zeolites A are obtained with high crystalline percentages (98%) and the sizes of the crystallites (224–463 nm) are proportional to the dimensions of the lattice parameters a0. Zeolite A highlighted an uptake BB41 dye of 40% and a maximum capacity of 31.25 mg/g. Langmuir equilibrium isotherm and pseudo-second-order (PSO) models provided a good fit to the adsorption experimental data. The adsorption process is exothermic and within the limits of the energy barrier. The study of the impact of the influenced parameters pH, solid/liquid ratio, concentration, and temperature on the BB41 adsorption onto zeolite A by experiment design showed a strong dependence on pH.

A concurrent approach for determining binary isotherm and optimizing moving bed adsorber for solid amine adsorbent in the coexistence of CO2 and H2O

A concurrent approach, which allows for determining multi-component equilibrium isotherms and designing a multi-component adsorption process within a realistic amount of time and effort, is demonstrated for the first time in a moving bed process using an amine-impregnated solid adsorbent in the presence of CO2 and H2O. The proposed approach extracts measurement points for the binary isotherms from the temperature and partial pressure regions that exist in the optimized process from all potential combinations of CO2 partial pressure, H2O partial pressure, and temperature. At the extracted points, the equilibrium adsorption amounts were measured experimentally to obtain multi-component adsorption amount data, with which the binary isotherm parameters were determined by the Tikhonov regularization. The accuracy of the equilibrium isotherm was further improved iteratively by repeating the steps described above. The proposed approach enables us to determine the binary interactions parameters in the isotherm model reducing the multi-component measurement points only to 12, while obtaining the optimized process operation at the same time.

Alkali and alkaline earth ion exchange affinity in ETS-10 toward aqueous lithium separation

Continuous ion exchange is a more sustainable alternative to current methods for removing common impurities from lithium sources. In this work, we examine ion-adsorbent interactions for Mg2+ and Ca2+ with microporous titanosilicate ETS-10, an ion exchange solid with promising performance, using experimental and computational (density functional theory, DFT) methods. Ion exchange affinity for Mg2+ and Ca2+ using the Na+-form of ETS-10 are quantified from measured equilibrium isotherms, analyzed using a modified Langmuir isotherm accounting for overall stoichiometric desorption/adsorption in the cation exchange process. The equilibrium constant for ion exchange using Na-ETS-10 is greatest for Ca and decreases in order of Mg, K, and Li, respectively. These differences in ion exchange affinity are consistent with trends in DFT-derived ion exchange energies, which account for hydration and solvation of cations using a thermochemical cycle. These equilibrium constant values and ion exchange energies suggest that exchange of Ca2+, Mg2+, and K+ using Na-ETS-10 is more favorable than that of Li+. Indeed, competitive ion exchange of equimolar aqueous mixtures of Li+ and each of K+, Mg2+, or Ca2+ demonstrate selective uptake of the non-lithium cation into the solid, thereby concentrating Li+ in the aqueous solution while removing impurity cations.

Sustainable cost-effective chemically modified banana leaf powder for methyl blue dye removal: kinetics, isotherm, thermodynamics and artificial intelligence-based analysis

This study investigates cellulose-based adsorbents that are naturally occurring and have a unique, abundant supply for adsorbing organic dye. The effectiveness of chemically modified banana leaf powder (CMBLP) as a biodegradable and environmentally friendly adsorbent for extracting methyl blue (MB) dye from aqueous solutions was studied. Point-zero charge (pHpzc) analysis, scanning electron microscopy (SEM), X-ray energy dispersion (EDS), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the CMBLP. At pH 6.0, 100 mg/L of dye, 50 min of contact time, and 300 K temperature, the maximum removal values were obtained. Under ideal circumstances, CMBLP displays 77.13215% removal rate. Langmuir and Freundlich models, along with pseudo-first- and pseudo-second-order kinetics equations, were used to investigate the equilibrium isotherm and kinetics of CMBLP. The acquired experimental data fit pseudo-second-order kinetics (R2 = 0.9986 and 0.9984) and the Langmuir isotherm (R2 = 0.9996) better. Utilizing the Langmuir isotherm model, the maximum adsorption capacity (qmax) of CMBLP has been identified to be 118.24 mg/g. At a temperature of 300 K, the adsorbent was also able to adsorb the maximum amount of methyl blue (MB). The thermal properties of methyl blue (MB) dye adsorption validate the spontaneous and exothermic nature of the adsorption process. The majority of statistical and artificial intelligence-based model (like KNN, SVM, ANN and LSTM) validate the superiority of MB removal onto CMBLP and support our experimental findings.Graphical

The Ce-modified biochar for efficient removal of methylene blue dye: Kinetics, isotherms and reusability studies

Exploring modification methods for enhancing the adsorption performance of biochar-based adsorbents for effective removal of methylene blue (MB), biochar-loaded CeO2 nanoparticles (Ce/BC) were synthesized by pomelo peels through co-precipitation combined with the pyrolysis method. Ce/BC showed a higher specific surface area and disorder degree than that of BC. The 0.5Ce/BC (mass ratio of Ce(NO3)3·6H2O/BC = 0.5/1) showed the best performance to adsorption of MB solution at different reaction conditions (MB concentration, Ce/BC composites dosage, and initial pH). Adsorption kinetics and equilibrium isotherms were well-described with a pseudo-first-order equation and Langmuir model, respectively. In addition, the maximum adsorption capacity of 0.5Ce/BC for MB was 105.68 mg·g−1 at 328 K. The strong adsorption was attributed to multi-interactions including pore filling, π-π interactions, electrostatic interaction, and hydrogen bonding between the composites and MB. This work demonstrated that the modified pomelo peels biochar, as a green promising material with cost-effectiveness, exhibited a great potential for broad application prospectively to dyeing-contaminated wastewater treatment.

Preparation and Characterization of Materials for Low- to Intermediate-Temperature CO2 Adsorption

Global carbon dioxide emissions are rising and the use of fossil fuels in several sectors are the leading causes. As global population and economies continue to grow significantly, the most practical method of lowering such emissions is to capture CO2. Although other technologies are more developed, adsorption is very promising and has attracted much attention. To ensure this technology’s success, it is essential to have suitable CO2 adsorbent materials. In this work, several new hydrotalcites (HTs) with different initial concentrations of ion precursors were prepared for the first time by the co-precipitation method—it was possible to verify that the ion concentrations influence the characteristics of the materials. The prepared HTs were characterized by thermogravimetric analysis (TG), X-Ray diffraction (XRD), surface area measurements and temperature-programmed desorption of CO2 (TPD-CO2) to relate their CO2 capture capacity to their physicochemical properties; the CO2 adsorption equilibrium isotherms were determined at 35 and 300 °C for the prepared samples, as well as for some commercial materials: magnesium oxide, calcium oxide, aluminium oxide and Zeolite 13X. After determining which materials present the best CO2 adsorption capacity, these were submitted to adsorption-desorption cycles to study their stability. The main objective of the work was to prepare and study different CO2 adsorbents for processes that are carried out at low and intermediate temperatures. From the experimental results, it was possible to conclude that the Zeolite 13X showed the best capacity at 35 °C, 3.38 mmol·g−1 (@ pCO2 = 1 bar), and a prepared calcined HT (c-HT2) was the best at 300 °C, 0.97 mmol·g−1 (@ pCO2 = 1 bar). Moreover, it seems there is an optimum initial concentration of the ions’ solutions for the tested HTs, which depends on the final application—c-HT1 showed a better capacity at 35 °C and c-HT2 at 300 °C. From the adsorption-desorption cycles—performed at 35 and 300 °C with the best materials using a magnetic suspension microbalance at 1 bar of CO2 partial pressure —, a working cyclic capacity of 2.69 mmol∙g−1 was achieved by the Zeolite at 35 °C; in turn, c-HT2 showed a working cyclic capacity of 0.79 mmol∙g−1 at 300 °C.

Selective separation and recovery of rare-earth elements (REEs) from acidic solutions and coal fly ash leachate by novel TODGA-Impregnated organosilica media

Rare-earth elements (REEs) are essential in a wide range of applications including magnets and satellite technology, with demand driven by geopolitical factors. While multiple techniques exist for REE recovery including solvent extraction and selective precipitation, solid–liquid extraction offers key advantages in selectivity, scalability, and recyclability. N,N,N′,N′-tetraoctyl diglycolamide (TODGA) is a tridentate ligand widely used in solvent extraction, but the incorporation in a solid support to separate individual lanthanides from acid solutions remains largely unexplored. A novel TODGA-organosilica sorbent material was developed and tested to evaluate recovery of 17 elements (REEs and thorium) in terms of selectivity, kinetics, and equilibrium isotherms in 0.01 to 15.9 M nitric acid. Characterization of the new sorbent was performed before and after sorption using FTIR, XPS, and SSA techniques to help elucidate sorption mechanisms and limiting variables. REE adsorption increased from 1.26 mg g−1 to 10 mg g−1 with nitric acid concentrations of 0.01 M and 15.9 M, respectively. TODGA-organosilica exhibits high selectivity towards heavy REEs (Dy to Lu), with minimal sorption of lighter REEs (Ce to Gd). Batch adsorption experiments confirm pseudo-second-order kinetics and a Langmuir adsorption isotherm with TODGA binding to REEs in a 3:1 complex. A packed bed column study confirmed the high selectivity of TODGA-impregnated organosilica towards heavy REEs and a proof-of concept experiment with coal fly ash leachate shows high selectivity for REEs over Al, Fe, and Ca present in several orders of magnitude higher concentrations. Fractionation was observed where loading cycle effluent contained 84% light REEs while strip cycle effluent contained 80% heavy REEs. More than 90% of loaded REEs were successfully stripped with water as the stripping agent.

Using activated and modified adsorbent surfaces from banana peels to remove the green Janus dye:

In order for the process of removing pollutants, including dyes, from the aquatic environment to be effective, plant wastes such as banana peels were used as adsorbent surfaces by thermally activating them (ABP) and modifying them with iron oxide nanoparticles (MABP), which were characterized using Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) techniques. They were applied in the field of Janus green (JG) dye adsorption for the batch system and studied the effect of several factors (adsorbent weight, contact time, initial concentration, and temperature). Their data were analyzed kinetically using first- and second-order kinetic models and they were found to follow the second order. Their data were also analyzed through the equilibrium isotherms (Freundlich and Langmuir), and it was found to follow the Freundlich isotherm model. The thermodynamic functions for the dye adsorption process on both surfaces were calculated, through these functions, it was found that the dye adsorption process is spontaneous, easy, regular, and exothermic.

Improving the adsorption properties of low surface area hardwood biochar for the removal of Fe+ and PO₄3- from aqueous solution.

Biochar produced from wood residues may provide a new method and material for managing the environment, particularly in terms of carbon sequestration and contaminant remediation. Additionally, biochar produced from wood residues is free of chemical fertilizers, likewise in rice straw, wheat straw, corn straw, etc. This study investigated the removal of iron from aqueous solutions by a novel low-cost and eco-friendly biochar made from hardwood trees and modified by adding MgCl2 for effective phosphate removal. Optimal adsorption conditions were determined through studies of adsorption time, pH, and adsorbent dosage. Batch equilibrium isotherm and kinetic experiments and pre/post-adsorption characterizations using FESEM-EDS, XRD, and FTIR suggested that the presence of carboxyl group elements and colloidal and nano-sized MgO (periclase) particles on the biochar surface were the main adsorption sites for aqueous iron and phosphate respectively. In this study, the HW and MgO-HW biochar showed excellent Dubinin-Radushkevich isotherm (D-R) maximum adsorption capacities of 289.45 and 828.82mg/g for iron and phosphate. The kinetic study for iron and phosphate adsorption was described well by pseudo second-order model and pseudo second-order model respectively. The HW biochar and the prepared MgO-HW biochar exhibited commendable iron adsorption (98.25%) performance at 10 pH units and phosphate (96.22%) at pH 6 respectively. Thus, this research reveals a waste-to-wealth strategy by converting hardwood waste into mineral-biomass biochar with excellent Fe and P adsorption capabilities and environmental adaptability.

Adsorptive potential of apricot (Prunus Armeniaca) stone in the removal of Cr (VI) and Fe (II) ions from Aquatic Systems: Kinetic and isothermal investigations

Biogenic adsorbents have emerged as a promising alternative to the traditional remediation techniques of heavy-metals contaminated water treatment. Using apricot (Prunus Armeniaca) stone as a naturally derived adsorbent, the current study provides a comprehensive analysis of the kinetic and isothermal characteristics associated with Cr (VI) and Fe (II) ion adsorption. The results show that 0.5 mg of the adsorbent removed approximately 90 % of Cr (VI) and Fe (II) ions from 100 ppm solutions within 120 min at 298 K at 300 rpm stirring speed. Equilibrium was attained within 90 to 120 min, with a significant increase in the removal percentage observed in the first 30–40 min for both metals compared to the subsequent 80–90 min. The optimal pH conditions for adsorption were determined to be acidic (pH = 1.5) for Cr (VI) and neutral (pH = 7) for Fe (II). The adsorption kinetics followed a pseudo-second order model, while the isothermal equilibrium data best fit the Freundlich model over the Langmuir model. Moreover, the thermodynamic parameters, including ΔG°, ΔH°, and ΔS°, indicated that the sorption process is spontaneous, feasible, and endothermic. The response surface methodology (RSM) analysis showed a high level of accuracy in predicting the percent removal. These findings illustrate the effectiveness of apricot stone as a low-cost and environmentally conscious adsorbent, contributing to the development of sustainable water treatment technologies.

Valorization of Eggshell as Renewable Materials for Sustainable Biocomposite Adsorbents—An Overview

The production and buildup of eggshell waste represents a challenge and an opportunity. The challenge is that uncontrolled disposal of generated eggshell waste relates to a sustainability concern for the environment. The opportunity relates to utilization of this biomass resource via recycling for waste valorization, cleaner production, and development of a circular economy. This review explores the development of eggshell powder (ESP) from eggshell waste and a coverage of various ESP composite sorbents with an emphasis on their potential utility as adsorbent materials for model pollutants in solid–liquid systems. An overview of literature since 2014 outlines the development of eggshell powder (ESP) and ESP composite adsorbents for solid–liquid adsorption processes. The isolation and treatment of ESP in its pristine or modified forms by various thermal or chemical treatments, along with the preparation of ESP biocomposites is described. An overview of the physico-chemical characterization of ESP and its biocomposites include an assessment of the adsorption properties with various model pollutants (cations, anions, and organic dyes). A coverage of equilibrium and kinetic adsorption isotherm models is provided, along with relevant thermodynamic parameters that govern the adsorption process for ESP-based adsorbents. This review reveals that ESP biocomposite adsorbents represent an emerging class of sustainable materials with tailored properties via modular synthetic strategies. This review will serve to encourage the recycling and utilization of eggshell biomass waste and its valorization as potential adsorbent systems. The impact of such ESP biosorbents cover a diverse range of adsorption-based applications from environmental remediation to slow-release fertilizer carrier systems in agricultural production.

Synthesis of Multivalent Glycoside-Immobilized Carboxymethyl Cellulose Nanohydrogel Particles with Superadsorption Ability for Lectins.

Carboxymethyl cellulose (CMC) is a water-soluble cellulose derivative that is nontoxic, biocompatible, biodegradable, and nonallergenic. As developing an adsorbent material for carbohydrate-binding proteins is challenging, we aimed to synthesize CMC nanohydrogel particles (CMCGPs) with an extremely high lectin adsorption tendency in this study. CMCGPs were used as the backbone of an adsorption carrier that was synthesized by cross-linking CMC with ethylene glycol diglycidyl ether. A series of glycoside-immobilized CMCGPs were synthesized by binding two types of glycans (LacNAc and lactose) to the polyvalent carboxymethyl groups that are present on the CMCGP surface and act as reaction sites. These immobilized glycosides function as molecular recognition sites. Glycan moieties were incorporated into the CMCGP backbone at degrees of immobilization (DI) ranging from 8.7 to 21.0% by altering the reaction composition. LacNAc-CMCGP (3b) showed a 19.9% DI of LacNAc glycoside to the CMCGP carboxymethyl group; on average, its particle size swelled to 418 nm in phosphate-buffered saline, which is approximately 1.4 times its dry-state size. Analyzing the adsorbent properties of glyco-CMCGPs using a lectin-binding assay showed the high structural specificity of glyco-CMCGPs to lectins. The equilibrium isotherm data was explained by the Langmuir adsorption model. Notably, compound 3b adsorbed 1.95 ± 0.05 μg of wheat germ agglutinin (WGA) lectin per 1.0 μg-dry of 3b particles at an adsorption equilibrium time of a few minutes. Furthermore, solid-state 13C nuclear magnetic resonance analysis showed that WGA lectin retained its natural structure without denaturation after binding to LacNAc-CMCGP. These results were also supported by affinity purification experiments of WGA from raw wheat germ extract using LacNAc-CMCGP, demonstrating that glyco-CMCGP is capable of adsorbing and desorbing lectin while maintaining its biological activity. Thus, multivalent glycoside-immobilized CMCGPs that use woody biomass derivatives as the backbone are expected to be applied as biorefinery materials, which specifically and abundantly adsorb not just plant lectins but also pathogenic viruses and toxin proteins.