Search

This review embarks on a comprehensive journey, exploring the application of lignocellulosic biomass materials as highly effective adsorbents for the removal of textile dyes (cationic and anionic dyes) from wastewater. A literature review and analysis were conducted to identify existing gaps in previous research on the use of lignocellulosic biomass for dye removal. This study investigates the factors and challenges associated with dye removal methods and signifies their uses. The study delves into the pivotal role of several parameters influencing adsorption, such as contact time, pH, concentration, and temperature. It then critically examines the adsorption isotherms, unveiling the equilibrium relationship between adsorbent and dye and shedding light on the mechanisms of their interaction. The adsorption process kinetics are thoroughly investigated, and a detailed examination of the adsorbed rate of dye molecules onto lignocellulosic biomass materials is carried out. This includes a lively discussion of the pseudo-first, pseudo-second, and intra-particle diffusion models. The thermodynamic aspects of the adsorption process are also addressed, elucidating the feasibility and spontaneity of the removal process under various temperature conditions. The paper then dives into desorption studies, providing insights into the regeneration potential of lignocellulosic biomass materials for sustainable reusability. The environmental impact and cost-effectiveness of employing lignocellulosic biomass materials in textiles including Congo Red, Reactive Black 5, Direct Yellow 12, Crystal Violet, Malachite Green, Acid Yellow 99, and others dyes from wastewater treatment are discussed, emphasizing the significance of eco-friendly solutions. In summary, this review brings together a wealth of diverse studies and findings to present a comprehensive overview of lignocellulosic biomass materials as adsorbents for textile cationic and anionic dye removal, encompassing various aspects from influential parameters to kinetics, adsorption isotherms, desorption, and thermodynamics studies. Its scope and other considerations are also discussed along with its benefits. The collective knowledge synthesized in this paper is intended to contribute to the advancement of sustainable and efficient water treatment technologies in the textile industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel multifunctional hydrogel (AGP/PEC) was prepared by microwave-assisted method. • Mefenamic acid (MFA) removal was optimised via central composite design in RSM. • Langmuir isotherm and PSO kinetic models appropriately described the equilibrium data. • The AGP/PEC exhibited high removal efficiency of 93.45% and Q m of 103.43 mg MFA/g. • H-bonding, electrostatic, π − π and n − π interactions majorly governed the MFA uptake. Pharmaceuticals and personal care products (PPCPs) are an emerging class of perilous pollutants due to their potential inimical impacts on ecosystems necessitating their abatement. Herein, an environmentally-affable and multifunctional acacia gum phthalate/ pectin hydrogel (AGP/PEC) was innovatively synthesised by microwave-assisted free-radical polymerisation for subsequent mefenamic acid (MFA) decontamination from synthetic wastewater. The physicochemical characteristics of AGP/PEC was studied through FTIR, XRD, BET, TEM, SEM-EDX and XPS characterisation techniques showing the existence of –OH and –COOH functionalities, rough surface with good surface area (18.95 m2/g) and porosity that contributed to high MFA uptake (93.45%) via hydrogen-bonding, electrostatic, pore-filling, π−π, and n−π interactions. The independent and interactive influences of operative variables on the adsorption capacity of AGP/PEC was statistically evaluated via central composite design of response surface methodology. The most-effective MFA uptake was attained at optimal operating conditions: initial solution pH (5.9), dosage (0.4 g/L), and time (28.5 min). Langmuir isotherm with Q m = 103.43 mg MFA/g and pseudo-second order kinetic models best-correlated the corresponding data. The Q m increased with temperature specifying an endothermic process, which was authenticated by positive Δ H⁰ (= 7.75 kJ/mol). The parameter, b T = 0.16 kJ/mol and E D = 2.12 kJ/mol, calculated from Temkin and Dubinin−Radushkevich isotherm models, respectively specified physisorption. The better adsorptive competence in real water along with an excellent reusable potential (87.1%) up to fifth cycle designated AGP/PEC as a potent adsorbent for practical purposes. These findings accentuated that AGP/PEC could be gainfully implemented as green and advanced multifunctional adsorbent material for removing residual MFA from wastewater. [ABSTRACT FROM AUTHOR]

The increasing usage of phosphate fertilizers for agricultural purposes has led to an augmented level of phosphorus in watercourses negatively impacting the ecosystems and water quality warranting its amputation from polluted water. This article describes the preparation of a novel natural deep eutectic solvent (NADES) functionalized-celite/polyethylene glycol hydrogel nanocomposite (NADES-Cel/PEG HNC) for adsorptive phosphate removal from water. The XRD, FTIR, SEM coupled with EDX spectroscopy, TEM, BET analysis, and pH pzc measurement were used to characterise the prepared material. Central composite design (CCD) in response surface methodology (RSM) was used for experimental design to analyse the individual and combined impact of five operational parameters on equilibrium adsorption capacity (Q e), and evaluate the optimal operating conditions by numerical optimization, which were obtained as: contact time (60 min), adsorbent dosage (1.0 g/L), initial [PO 4 3−] (80 mg/L), initial solution pH (3.5), and temperature (304 K). The adsorption process was best explicated via Langmuir adsorption isotherm with a noteworthy saturation capacity, Q m of 111.80 mg PO 4 3−/g at 298 K, and was favourable (S* = 0.99), feasible (Δ G° = −7.02 kJ/mol), exothermic (Δ H° = −8.39 kJ/mol) and physical in nature. The uptake mechanism largely involved H–bonding, electrostatic interaction, n-π interaction and pore-filling. Uptake kinetics of PO 4 3− was best explicated by pseudo-second order model, and the rate-determining step involved both intraparticle and liquid film diffusion mechanisms. The admirable performance of NADES-Cel/PEG HNC was signified by its competent adsorption efficacy and effectual reusability. The pertinence of the hydrogel nanocomposite for treatment of real wastewater was tested. Hence, NADES-Cel/PEG HNC might prove to be a pragmatic adsorbent for decontamination of PO 4 3− from an aqueous environment. [Display omitted] • Innovative fructose & glycine based-NADES was designed for celite functionalization. • Novel hydrogel nanocomposite was devised from NADES-celite and polyethylene glycol. • Operating variables for PO 4 3− uptake by NADES-Cel/PEG were optimized by CCD of RSM. • Hydrogel nanocomposite exhibited high Q m (111.8 mgPO 4 3−/g) with good reusability. • H–bonding, pore-filling, electrostatic & n-π interaction mediated the PO 4 3− removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • meso -phenylboronic acid calix[4]pyrrole was synthesized using deep eutectic solvents. • Paracetamol was adsorbed with maximum saturation capacity of 479.30 mg g−1 at 298 K. • Adsorption of paracetamol ensued via concurrent physisorption and chemisorption. • Salting out effect enhanced paracetamol confiscation in presence of different ions. • Mechanism involved hydrogen bonding, π-π, n-π, anion-π and cation-π interactions. It is critical to design an ecological and economically benign adsorbent for the decontamination of micropollutants from the aquatic realm. Supramolecular functional materials have garnered remarkable attention in recent times owing to their various potential applications. A supramolecular meso -phenylboronic acid functionalized calix[4]pyrrole (m PBA-C4P) was fabricated via a green synthetic approach utilizing a deep eutectic mixture of N,Ń- dimethylurea and L-(+)-tartaric acid, which was subsequently applied as an advanced adsorbent for paracetamol (PC) removal from aqueous phase. The characterization of m PBA-C4P was accomplished with NMR (1H and 13C), FTIR, high-resolution mass spectrometry (HRMS), SEM-EDX, Brunauer-Emmet-Teller (BET) analysis, and elemental mapping. The m PBA-C4P unveiled a commendable adsorption characteristics adsorbing > 92% PC within 20 min from simulated water having 30 mg L−1 PC concentration. The isotherm modeling inferred the Freundlich model to appropriate the equilibrium data, with high Langmuir adsorption capacity (479.30 mg g−1 at 298 K). The Δ H° (–53.98 kJ mol−1) along with a drop in adsorption capacity with temperature implied the process to be exothermic. The kinetics was in accord with the pseudo-second order model specifying chemisorption mechanism. However, the b t (2.56 kJ mol−1) and E (1.08 kJ mol−1) implied physical adsorption, suggesting, thereby, that the adsorption of PC occurred via concurrent physisorption and chemisorption. The m PBA-C4P maintained a decent removal rate after five consecutive adsorption–desorption cycles speculating its good reusability and practicality. Salting out effect was responsible for the enhancement in PC confiscation in presence of different ions. Based on FTIR spectral data, pH , isotherm, kinetic, thermodynamic and ionic studies, the proposed mechanism governing the uptake of PC by m PBA-C4P involved hydrogen bonding, π-π, n-π, anion-π and cation-π interactions, respectively. These findings indicated that m PBA-C4P could be weighed as a potentially superior adsorbent for alleviating paracetamol-laden waters. [ABSTRACT FROM AUTHOR]

The adsorption of acridine orange and Cr6+ ion onto plaster of paris reinforced glutamic acid-grafted-polyacrylamide hydrogel nanocomposite modified with riboflavin, Glu- g -PAM/POP/Rb HNC was studied. The Glu-g-PAM/POP/Rb HNC was physico-chemically characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, transmission electron microscopy and Brunauer-Emmett-Teller analysis. The specific surface area, pore volume and pore diameter were 15.48 m2/g, 0.015 cm3/g and 4.23 nm, respectively. Adsorption process was strategized by response surface methodology (RSM) based on a 3-level 5-factor (initial solution pH, contact time, adsorbent dose, initial adsorbate concentration and temperature) central composite design (CCD), and validity of the estimated parameters was statistically evaluated using analysis of variance (ANOVA). The optimized operating variables were: pH (AO = 10; Cr6+ = 4.15), contact time (AO = 60 min; Cr6+ = 59 min), adsorbent dose (0.8 g/L), initial adsorbate concentration (60 mg/L) and temperature (298 K). Isotherm results were coincident with Langmuir isotherm model. The experimental kinetic adsorption data was congruous with pseudo-second order model, with the uptake rate controlled by both intraparticle and liquid film diffusions. The relatively high Langmuir saturation capacity of 202.63 mg AO/g and 143.68 mg Cr6+/g, supported by the decent recyclability up to four times affirmed the promising performance of the adsorbent. The efficacy of the adsorbent for simultaneous removal of AO and Cr6+ from bi-component system was assessed. The possible adsorption mechanism mainly involved hydrogen bonding, van der Waals forces, electrostatic and π-π interactions. Adsorption of AO and Cr6+ onto Glu- g -PAM/POP/Rb HNC was feasible and exothermic as revealed by the thermodynamic parameters. The findings demonstrated superior adsorbent efficacy for the seizure of pollutants, particularly AO and Cr6+ from aqueous solution. • Novel Glu-g-PAM/POP/Rb HNC was prepared by graft co-polymerization technique. • Acridine orange and Cr+6 sequestration was optimized using RSM. • Langmuir isotherm model appropriately described the equilibrium data. • Langmuir saturation capacity Q m was 202.63 mg AO/g and 143.68 mg Cr+6/g. • H-bonding, electrostatic, and π-π interactions majorly governed the adsorption. [ABSTRACT FROM AUTHOR]

A cost-efficient kaolinite-cellulose/cobalt oxide green nanocomposite (Kao-Cel/Co 3 O 4 NC) was successfully synthesized, and utilized as a promising material for removing Pb2+ and Cd2+ from aqueous solution. The fabricated nanocomposite has been characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy-energy dispersive X-ray, high-resolution transmission electron microscopy, and Brunauer-Emmett-Teller analysis. The batch methodology was exploited for optimization of process parameters and the optimized conditions were found to be adsorbent dosage (2.0 g/L), extraction time (50 min), initial concentration (60 mg/L), and initial solution pH (6). Kao-Cel/Co 3 O 4 NC displayed excellent adsorption properties and achieved maximum saturation capacity (Q m) of 293.68 mg Pb2+/g and 267.85 mg Cd2+/g, with an equilibration time of 50 min at 323 K. The Langmuir model best expressed the isotherm data recommending the adsorption onto energetically homogeneous NC surface, while the compatibility of kinetics data with pseudo-second-order model revealed the dependency of adsorption rate on adsorption capacity, and probable involvement of chemisorption in the rate-controlling step. Electrostatic interaction and ion exchange mechanism were responsible for the uptake of Pb2+ and Cd2+ by Kao-Cel/Co 3 O 4 NC as demonstrated by Fourier transform infrared spectroscopy and pH studies. Thermodynamic parameters confirmed the physical, spontaneous, and endothermic sequestration processes. Real water investigation specified that the present adsorbent could be effectively used for liquid phase decontamination of Pb2+ and Cd2+. The nanocomposite exhibited high reusability, which could be utilized efficiently for five runs with sustainable results. In summary, this study portrayed the present nanocomposite as an emerging material for the adsorption of heavy metal ions particularly Pb2+ and Cd2+. [ABSTRACT FROM AUTHOR]

In the present work, a cost-effective Indian jujube seeds derived activated carbon (IJSAC) prepared via o -phosphoric acid chemical activation, is studied for the sequestration of acriflavine (AF) and Victoria blue B (VB) from the aquatic environment. The activated carbon is characterized by Fourier transform infrared spectroscopy, N 2 -adsorption/desorption isotherm, scanning electron microscopy techniques and point of zero-charge measurement. The specific surface area (S BET) of 571 m2/g with a pore radius of 22.45 Å specifies mesoporous nature of the IJSAC. The implication of operational conditions on the adsorption of both dyes onto IJSAC assessed by batch methodology, establish the optimal conditions as dosage (1.5 and 2.5 g/L), contact time (60 min), pH (8 and 10), and initial concentration (130 and 140 mg/L) for AF and VB uptake, respectively. The Freundlich adsorption isotherm model (R 2 = 0.99) appropriates the equilibrium data suggesting multilayer adsorption onto heterogeneous surface sites, while pseudo-second order (R 2 = 0.95–0.99) is the best fit kinetic model. The liquid film and intraparticle diffusion modelling demonstrate that the adsorption process of these dyes is governed by both the steps. Maximum Langmuir adsorption capacity is 113.6 mg/g for acriflavine and 92.78 mg/g for Victoria blue B. Thermodynamic studies indicate endothermic and spontaneous adsorption of dyes. The adsorption mechanism for the uptake of AF and VB by IJSAC most probably involves hydrogen bonding, electrostatic and π-π interactions. Based on its high adsorption capacity, relatively faster kinetics, and reusability, IJSAC can be perceived as a proficient and effective adsorbent for cationic dyes removal from the liquid waste. [ABSTRACT FROM AUTHOR]

Herein, a functionalized green hydrogel nanocomposite based on carboxymethylated gum tragacanth and nanobentonite (GTBCH) was designed via free-radical polymerization approach for the elimination of Aspartame (AS) from wastewater. The GTBCH fabrication was validated by Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques. Central composite design (CCD) was efficaciously applied to determine the quadratic polynomial approach for predicting the adsorption capacity (q e) of AS. The optimum sequestration conditions were dosage (0.8 g L‒1), agitation time (35 min) initial AS concentration (60 mg L−1), pH (6) and temperature (308 K). The CCD results revealed that dosage of GTBCH and initial concentration have greater impact on q e followed by pH, time, and temperature. The significant adsorption capacity (392.04 mg g−1), calculated from Langmuir model, could be attributed to the stronger interactions prevalent between AS and GTBCH. Diffusion investigations depicted the uptake of AS via surface adsorption, liquid film and intraparticle diffusion, respectively. Ionic strength and real water have minor effect on the adsorption capacity demonstrating electrostatic interaction has least impact in adsorption process. The pHzpc, FTIR and XPS investigations revealed hydrogen bonding, n-π and van der Waals interactions as the principal removal mechanisms. Robust design, high adsorption capacity, eco-friendly facets along with excellent reusability indicated the GTBCH as a competent adsorbent for AS decontamination from wastewater. [Display omitted] • Green hydrogel nanocomposite was fabricated for the adsorption of aspartame. • Central composite design showed dosage and concentration have key role on adsorption. • The nanocomposite exhibited excellent saturation capacity of 392.04 mg g−1. • Aspartame uptake was via surface adsorption, liquid film and intraparticle diffusion. • Hydrogen bonding, n-π and van der Waals interactions were mechanisms of removal. [ABSTRACT FROM AUTHOR]

Water, being the crucial feature of our planet, the contamination of which is a grave matter of concern globally. Elimination of tenacious pollutants from the aquatic phase is indispensable for the sustainability of this planet. Adsorptive sequestration of pollutants is a highly cherished way owing to its design simplicity, economic feasibility and, higher efficacy than various reported treatment methods. Amidst the ample range of adsorbents employed for an environmental cause, clay-hydrogel nanocomposites (CHN) are emerging as an enticing materials platform for wastewater treatment owing to their high sorption capacity, affinity, environmental viability, tailorable physiochemical characteristics, and better reusability. The presence of various functional groups in the polymer chain –OH, –COOH, –NH 2 along with the adsorptive potential of clays validate them as a hot spot sorbent. This review initially summarizes the synthetic methodologies of various clay-hydrogel nanocomposites and then their utilization in the seizure of pollutants from the aquatic realm. The removal mechanism which governs the uptake of pollutant on the clay-hydrogel nanocomposites has been thoroughly reviewed which illustrated that electrostatic interaction, hydrogen bonding, and complexation are the prime ways to sequester dyes and metals on CHN. Discussion on isotherm and kinetic models along with thermodynamic study is also provided. Regeneration efficiency of CHN was also discussed demonstrating HCl to be potent desorbing agent than various acids and organic solvents. Finally, the future perspective for the advancement of CHN in the direction of modern technological facets is also detailed out. [Display omitted] • Clay hydrogel nanocomposites for adsorption of pollutants is appraised. • Mechanism governing the seizure of pollutants on CHN is discussed. • Impact of clay on adsorption capacity and mechanical strength is provided. • Influence of Kinetics, Isotherm, and thermodynamics on adsorption is assessed. [ABSTRACT FROM AUTHOR]

• PAAm/nB hydrogel nanocomposite was prepared via sonochemical method. • PAAm/nB efficiently scavenges Pb2+ and Cd2+ with Q m of 138.33 and 200.41 mg/g, respectively. • Pseudo-second order and Freundlich isotherm models appropriately describe the kinetics and equilibrium data, respectively. • Both intra-particle and liquid film models govern the adsorption mechanism. Clay-hydrogel nanocomposites are suitable material for mitigating the pollution/environmental impact because of their high adsorption capacity. In this study, the synthesis of polyacrylamide/bentonite hydrogel nanocomposite was assisted by ultrasound through successful incorporation of nanobentonite as filler and cross-linker into polyacrylamide framework. The adsorbent was characterized by FTIR, XRD, BET, SEM-EDX, and TEM in order to observe structural changes and sorption interactions. The effect of adsorbent dose, contact time, initial metal ion concentration and pH on the sequestration of Pb2+ and Cd2+ was analyzed. The adsorbent removed more than 95% Pb2+ and Cd2+ within first 20 min, which corresponds to relatively high pseudo-first order rate constant, k 1 (0.240 for Pb2+ and 0.253 1/min for Cd2+) and pseudo-second order rate constant, k 2 (0.031 for Pb2+ and 0.033 g/mg/min for Cd2+). The isotherm and kinetics modeling data were best described by Freundlich isotherm over the entire concentration range and pseudo-second order rate equation, respectively. The thermodynamic studies implied spontaneous and endothermic nature of adsorption process. The maximum adsorption capacity (138.33 for Pb2+ and 200.41 mg/g for Cd2+) determined using Langmuir model along with a good regeneration potential depicts that polyacrylamide/bentonite hydrogel nanocomposite could be used effectively for Pb2+ and Cd2+ uptake from aqueous solution. [ABSTRACT FROM AUTHOR]