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In this study, a novel eco-friendly sorbent, hexamethylenetetramine (HMTA) functionalized calcium alginate (AG) immobilized graphene oxide (GO) composite (AG-GO-HMTA) and hexamethylenetetramine functionalized calcium alginate composite (AG-HMTA) were prepared. Adsorption factors including pH impact, contact time, initial dye concentration, dosage, selectivity and reusability on methylene blue (MB) removal from water were investigated. The prepared sorbents were characterized using structural (e.g. XRD, FT-IR, EDAX), thermal (e.g. TGA, DTG), and morphological (e.g. SEM, BET) analysis techniques. The equilibrium adsorption data was described by the Langmuir and Freundlich isotherms, and the adsorption kinetic and thermodynamic parameters were investigated. The field studies and regeneration of the beads were investigated. AG-GO HMTA displays a well-defined porous structure and this desired morphology arising from high quality dispersion of HMTA within the AG-GO matrix. The highest adsorption capacities were observed at pH ∼ 5, meanwhile the adsorption of MB dye molecules, positively charged, onto the beads became faster due to strong electrostatic interactions. When the value of dosage is 0.01 g, the equilibrium concentration (mg/g) are maximum at 103, 110, 164, 168 mg/g for AG, AG-GO, AG-HMTA and AG-GO-HMTA, respectively. The present work shows that pseudo first order could describe the MB adsorption onto AG while it couldn't describe the MB adsorption onto the functionalized sorbents due to the hybrid materials complicity. [ABSTRACT FROM AUTHOR]

In this study, ex-situ crosslinked gellan gum (GG)/bacterial cellulose (BC) hydrogels have been investigated as good absorbents for the removal of safranin and crystal violet dye pollutants. The preparation involves a cost-effective and easy-to-perform crosslinking procedure, using citric acid (CA) as a green crosslinker. The physicochemical and mechanical properties of the crosslinked hydrogels were examined by FTIR, TGA, SEM, XRD, and unconfined compression analyses. The swelling capacity of the hydrogels as a function of pH was investigated. CA depicted to improve structural stability as a crosslinker. The dye removal capacity of the hydrogels as good adsorbents was explored and showed higher efficiency in the removal of safranin dye as compared to crystal violet with optimum adsorption capacities obtained as 17.57 and 13.49 mg/g, respectively. Adsorption kinetics and isotherm models as well as thermodynamics examined. Results showed the adsorption process well fitted the pseudo 2nd-order kinetic and Langmuir-Freundlich models while temperature dependence study depicted to be exothermic. Furthermore, no significant loss of removal efficiency of the hydrogel adsorbent was observed even after five adsorption-desorption cycles. Based on the revealed results, the prepared hydrogel may serve as an effective adsorbent for the removal of dyes from the aqueous phase. [Display omitted] • Eco-friendly crosslinked gellan gum/bacterial cellulose (GB) hydrogels were produced. • Swelling, structural, morphological, and mechanical properties of the hydrogels were evaluated. • The hydrogel as adsorbents demonstrated good dye adsorption performance and reusable property. • Adsorption kinetics and thermodynamics of the hydrogel adsorbents were investigated. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DES) are renowned for their effectiveness in deconstructing lignocellulose and extracting lignin, yet the challenges lie in lignin condensation and the disposal of the DES remnants after pretreatment. To overcome these issues, this work proposed a holistic strategy utilizing deep eutectic solvent (DES)-driven lignocellulose deconstruction to upgrade lignocellulose into nitrogen-doped carbon dots (CDs) and iron-decorated porous carbons, serving as photocatalysts and adsorbents, respectively. These nitrogen-doped CDs via the choline chloride/FeCl 3 DES pretreatment exhibited abundant nitrogen/oxygen functional groups, enhancing photocatalytic activities and facilitating effective charge separation and transfer. The photocatalytic efficiency of the CDs on dyes reached 97 % under acidic conditions primarily, and free radical quenching experiments indicated that singlet oxygen was the dominant oxidant species. Moreover, the adsorption capabilities of Fe-decorated porous carbons for Congo red reached 2432.3 mg·g -1 , surpassing most existing carbon materials. The adsorption mechanism was due to a synergistic effect including physical adsorption, coordination, hydrogen bonding, electrostatic, and π-π interactions. This study proposed a synergetic conversion of DES and lignocellulose into functional carbon materials for wastewater remediation, which inspired the development of a green and cost-effective biorefinery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

This study investigates graphene oxide (GO) modified poly(vinylidene fluoride) (PVDF) membranes focusing on their dye rejection efficiency and their antifouling properties against bovine serum albumin (BSA). These membranes were prepared by modifying commercial PVDF membrane with a thin layer of GO nanosheets and chitosan (CS) using vacuum filtration. The synergistic physicochemical properties of the GO-CS/PVDF membranes were analyzed by XRD, FTIR, Raman, and XPS spectroscopy. The surface morphologies were observed by SEM and AFM microscopy, and WCA measurements. The deposition of GO and CS in the presence of citric acid resulted in a decrease in pore size and an increase in hydrophilicity. Modified membranes showed enhanced rejection of RB and MB, with rates increasing from 13.0 to 96.0 % and 28.3 to 69.1 %, respectively. Antifouling studies using BSA on selected membranes outperformed pristine membranes, which had higher irreversible fouling due to pore blockage. GO-CS/PVDF membranes exhibited higher flux recovery and lower irreversible fouling due to increased hydrophilicity, which prevents tight cake layer formation. Minimal detachment of the GO-CS layer during the long-term stability test is confirmed by minor fluctuations in dye flux and rejection. In summary, enhancing PVDF membranes with GO and CS augments dye rejection rates and bolsters antifouling properties., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Two novel chitosan-based adsorbents, sulfamic acid-chitosan-epichlorohydrin-Fe 2 O 3 (HK-1) and sulfanilic acid-chitosan-epichlorohydrin-Fe 2 O 3 (HK-2), were successfully synthesized and characterized by XRD, TGA, DSC, BET, and SEM techniques. The ability of the synthesized adsorbents for removing cationic Methyl Green (MG) and anionic Eosin Yellow (EY) from aqueous solutions was investigated at different solution pHs, adsorbent dosages, and contact times. The results showed a removal efficiency of 93.5 % and 96.8 % for adsorbing cationic MG respectively by HK-1 and HK-2 at pH = 8. The removal efficiency for adsorbing anionic EY by HK-1 and HK-2 was respectively 90.8 % and 94.6 % at pH = 3. The results also showed that >50 % of MG was adsorbed within the first 30 min of contact with HK-1 and HK-2, but it took about 75 and 45 min to adsorb 50 % of EY respectively by HK-1 and HK-2. DFT calculations confirmed the spontaneous adsorption of EY and MG on the surface of HK-1 and HK-2. These promising results suggest that HK-1 and HK-2 can be used to remove other cationic and anionic dyes from aqueous solutions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Layered double hydroxides (LDH) are great adsorbents for anionic pollutants, but are in a powder form that leads to challenges in solid-liquid separation, low hydraulic conductivity, and handling. Herein, novel bionanocomposite films containing chitosan (Cs), tannic acid (TA), and LDH were fabricated and applied for the removal of reactive blue 4 (RB4). A response surface methodology with Box–Behnken design was applied to study the effect of operating parameters (TA%: 0–20, LDH%: 0–20, pH: 5–9, adsorbent dosage: 0.5–1.5 g L−1, time: 30–90 min) on RB4 dye removal (DR%). A quadratic regression equation was successfully developed to predict the response (R2: 0.95). The obtained optimized condition was TA%: 10, LDH%: 20, pH: 5, adsorbent dosage: 1.5 g L−1, and time: 71 min that resulted in DR%: 98.2. The best-fitted adsorption isotherm and kinetic models were linear Langmuir and nonlinear pseudo-second-order models, respectively. The maximum capacity of adsorption for the optimized film was 406 mg g−1. The obtained thermodynamic parameters implied that the process of adsorption was exothermic and spontaneous. The reusability studies showed that the DR% was decreased from 93% for the first cycle to 69%, 57%, and 56% for the second, third and fourth cycle, respectively. [Display omitted] • Chitosan/tannic acid@ ZnFe layered double hydroxide film was synthesized. • The Cs/TA@LDH film was applied for color removal of reactive blue 4 dye. • A Box–Behnken design was used to optimize film composition and adsorption conditions. • The optimal percentages of TA and LDH in Cs/TA@LDH were 10% and 20%, respectively. • The maximum adsorption capacity of the fabricated adsorbent was 406 mg g−1. [ABSTRACT FROM AUTHOR]

The ongoing challenge of water scarcity persists alongside a concerning rise in water pollution driven by population expansion and industrial development. As a result, urgent measures are imperative to address the pressing need for a clean and sustainable water supply. In this study, a sustainable and green approach was utilized to prepare four chitosan-based sponges from a chemically modified chitosan with different alkyl chains in aqueous medium and at room temperature. The resulting sponges displayed excellent stability in water with outstanding dye removal efficiency. The adsorption capacity was associated with the alkyl chain length incorporated to the polymer backbone. All sponges displayed a high adsorption capacity of methyl orange (MO) ranges between 238 and 380 mg g−1, while a low capacity were obtained for methylene blue (MB) and Rhodamine B (RB). Competitive adsorption experiments were conducted on binary and ternary mixtures to assess the selective removal of MO from a mixture of dyes in which the separation factor was found to be ranging between 1.6 and 32. The adsorption kinetics isotherms of all sponges followed the pseudo-second-order, and the Langmuir model was found to be more suitable than the Freundlich for the adsorption of MO on the sponges. The chitosan-based sponges showed stable performance, robustness and reusability over 5 adsorption-desorption cycles, indicating their great potential for water treatment applications. • Synthesis and fabrication of chitosan-based sponges with different alkyl chain lengths. • High adsorption capacity and removal efficiency of methyl orange exceeding 380 mg g−1. • Selective adsorption of anionic dyes in binary and ternary mixtures. • Fine-tuning initial adsorption rate and capacity by controlling alkyl chain length. [ABSTRACT FROM AUTHOR]

A superabsorbent hydrogel was prepared by the free-radical copolymerization of natural rubber (NR) latex with poly(acrylic acid) (PAA) at NR loadings up to 50 wt%. An NR/PAA hydrogel containing 40 wt% of NR (NR-40) had a water absorption capacity of 214 g/g (21,400 %) of its dry weight. The compressive modulus increased 512 % and sample integrity was improved due to the physical entanglement of NR chains. NR-40 hydrogel removed 97 % of methylene blue (MB) from the aqueous solution in 1 h (at initial concentrations of 10–1000 mg/L) and produced a maximum removal of 1191 mg MB/g of hydrogel at an initial MB concentration of 4500 mg/L. The adsorption of MB was an endothermic process. Fourier transform infrared spectroscopy indicated that hydrogen bonding and electrostatic interaction drove the process. After the in-situ incorporation of ZnO into NR-40, absorbed energy from sunlight generated active species that could photocatalytically degrade adsorbed MB in the hydrogel matrix. The scavenger tests indicated that superoxide radical anions and hydroxyl radicals were the main species for this process. The hydrogel composite material showed good stability and could be regenerated and reused over 10 cycles, degrading >80 % of the adsorbed dye. This novel natural-based hydrogel provides double functions of adsorption and photodegradation of toxic dyes without the requirement of chemicals and a separation process. • Natural rubber (NR) was used to prepare hydrogel with poly(acrylic acid) (PAA). • The hydrogel containing 40 wt% of NR had a water absorption capacity of 214 g/g. • NR-40 hydrogel removed 97 % of methylene blue (MB) in 1 h up to 1191 mg/g. • ZnO incorporation added photocatalytic degradability of adsorbed MB under sunlight. • The material had good stability and could be regenerated and reused over 10 cycles. [ABSTRACT FROM AUTHOR]

The effective removal of toxic dyes from aqueous solution is of great significance for environmental protection. Herein, an eco-friendly sugarcane cellulose (SBC)/sodium carboxymethylcellulose (CMC-Na) adsorbent reinforced with carbon nitride (g-C 3 N 4) was successfully prepared via a facile sol-gel method. The resulting gel-like adsorbent or composite hydrogel was comprehensively characterized with FTIR, SEM, EDS, TGA analysis. The adsorption behaviors of the adsorbent in the removal of methylene blue (MB) were systematically investigated. Results showed the pseudo-second-order kinetic model and Langmuir model described adsorption process accurately with the maximum adsorption capacity of 362.3 mg g−1, indicating that adsorption behavior is a monolayer chemical adsorption. Moreover, the composited hydrogel displayed excellent adsorption selectivity on MB/MO or MB/RhB mixed dyes. In addition, adsorbent showed great stability and reusability with almost no loss in adsorption capacity after 7 cycles. Due to the facile preparation process and outstanding mechanical properties, as well as high recyclability, g-C 3 N 4 @SBC/CMC has great potential in wastewater treatment. • Eco-friendly g-C 3 N 4 @SBC/CMC was prepared using a facile sol–gel method. • Hydrogel eliminated the self-aggregation and recovery problems of g-C 3 N 4. • g-C 3 N 4 @SBC/CMC showed high selectivity and excellent reusability for dye MB removal. • Composite hydrogel exhibited excellent mechanical and environmental stability. [ABSTRACT FROM AUTHOR]

Chitosan (Ch, a natural polymer) and kaolin (K, a natural mineral) composite (Ch-K) was produced with the help of two crosslinkers, epichlorohydrin and tripolyphosphate, and then moulded into uniform beads in tripolyphosphate solution. The synthesis was proved by the analyses involving FT-IR and SEM-EDX. The beads were then used as the natural adsorbent for removal of the auramine O (AO), a frequently-used industrial dye, in aqueous solutions. Adsorbent performance of the Ch-K composite for AO dye molecules was optimized: 500 mg L−1 at pH 7.5 at 25 °C. The Langmuir model found 0.118 mol kg−1 for the maximum adsorption capacity of the Ch-K and the D-R isotherm model showed that the nature of the adsorption process was physical. Kinetics of the adsorption could be explained by using both IPD (intraparticle diffusion) and PSO (pseudo second order) models. Thermodynamic parameters demonstrated that the behaviour of the adsorption was an endothermic and spontaneous. The activity of the composite adsorbent was recovered (88%) after the five sequential adsorption/desorption cycles. Supported by experimental findings, the results obtained from in silico modeling at M06-2X/6–31+G (d,p) level helped hypothesise a mechanism for the formation of the Ch-K composite, and shed some light onto the adsorption behaviour of AO dye by assuming several favourable intermolecular interactions. • Efficient adsorption of Auramine O using newly synthesized natural chitosan/kaolin composite • Spontaneous and endothermic process with favourable adsorption at relatively high temperature. • DFT-based composite formation and adsorption mechanism, supported by experimental data. [ABSTRACT FROM AUTHOR]

In this study, the laccase obtained from Trametes versicolor was immobilized onto the chitosan(CTS)/halloysite (HNT) beads. In the immobilization step, the effects of chitosan (1–3% w/v), halloysite (0–2% w/v), glutaraldehyde (0.5–1.5% v/v) and enzyme concentrations (1–3%) on loading and immobilization efficiency were investigated. SEM, FT-IR, XRD, TGA and XPS analyses were performed to examine the structure of beads. In addition, the effects of parameters such as pH (4–10), temperature (25–55 °C), storage life on the activity of free and immobilized laccase were also investigated. The activities of free and immobilized laccase preserved 23% and 56% of its initial activity at the end of 59 days of storage. The effects of mediators such as 2.2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 1-Hydroxybenzotriazole hydrate (HBT), 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) and violuric acid (VLA) on the dye removal efficiency were investigated. Reusability of the CTS/HNT/Lac in the presence of HBT and VLA mediators, which enable the highest dye removal, was tested. After 15 cycles, 42% and 54% dye removal were achieved with the CTS/HNT/Lac in the medium containing HBT and VLA, and 42% and 49% of the activity is preserved, respectively. This study showed that CTS/HNT/Lac can be used repeatedly for Remazol Red RR dye removal. [Display omitted] [ABSTRACT FROM AUTHOR]

The development of composite films with enhanced antibacterial and dye decolorization properties for water treatment has attracted a great attention. In this study, nickel oxide/chitosan/polyvinyl alcohol nanocomposite films containing different weight percentage of NiO nanoparticles with a dual functionality, removal of toxic dye and antibacterial properties, were prepared. Methyl orange (MO) was selected as a target pollutant. Additionally, the antimicrobial activity of the films against two Gram positive bacteria (Staphylococcus aureus and Bacillus cereus) and two Gram negative bacteria (Escherichia coli and Salmonella Typhimurium) was studied. The prepared samples were characterized by XRD, HRTEM, FESEM, ATR-FTIR, UV–Vis spectroscopy, and dielectric measurements. The morphological examination proved that the nanocomposite film has more porous structure compared to the unmodified chitosan/PVA. The antimicrobial tests indicated that the modified chitosan/PVA films have higher activity than pure chitosan/PVA toward all the tested pathogenic bacteria. The impact of the NiO amount (0.5, 1.5, 3, and 5 wt%), contact time (0–150 min), and adsorbent dose (40, 80, and 100 mg) on the removal of MO was studied. Dye adsorption results proved that the incorporation of 5 wt% NiO led to more than 2 fold increase in the dye removal percentage in comparison with the unmodified PVA/chitosan film. [Display omitted] • Sensitization of chitosan/PVA films with different weight percentage of NiO NPs • Incorporation of NiO improved porosity, crystallinity, and optical properties • Enhancing the antibacterial activity of chitosan/PVA films due to the incorporation of the NiO • Employment of NiO/chitosan/PVA nanocomposites as dye adsorptive membranes [ABSTRACT FROM AUTHOR]

Building a model that can accurately anticipate and optimize the dynamics of dye removal and Gibbs free energy within the framework of an adsorption process is the main goal of this research. Furthermore, it has been determined that a correlation exists between the efficacy of dye removal and the behavior of Gibbs free energy throughout the process of adsorption. The study utilized a composite material consisting of chitosan-polyacrylamide/TiO 2 as an adsorbent to remove anionic dye from a mainly aqueous solution. The parameters have been analyzed using response surface methodology (RSM), artificial neural networks (ANN), and machine learning (ML) techniques in this particular context. The obtained F-value of 814.62 for the RSM model, which assesses dye removal efficiency, suggests that the model under examination is statistically significant. Furthermore, based on the RSM data, the proposed model demonstrates a significant level of accuracy in predicting the performance of the TiO 2 /chitosan-polyacrylamide composite as an adsorbent during the dye removal adsorption process. The ANN model achieved a high level of accuracy, as evidenced by its R2 value of 0.999455. Through the utilization of neural networks and machine learning, the intended objective of forecasting dye removal efficiency and Gibbs free energy behavior in the adsorption process was effectively accomplished. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a new chitosan Schiff base with surface modification using citric acid was synthesized for efficient removal of pernicious dyes, namely Bismarck Brown R (BBR) and Rhodamine B (RhB), from wastewater. The physicochemical properties of the modified chitosan Schiff base were comprehensively investigated. Adsorption studies demonstrated that BBR adsorption occurred through monolayer formation, while RhB adsorption proceeded via multilayer formation on the heterogeneous surface. The synthesized adsorbent exhibited exceptional dye removal efficiency, with a Langmuir saturation capacity of 348 ± 11.0 mg.g−1 for BBR and 145 ± 18.44 mg.g−1 for RhB. Isotherm data fitting revealed consistency with the Langmuir isotherm model for BBR and the Freundlich isotherm model for RhB. Notably, the modified chitosan Schiff base showcased enhanced antibacterial properties, effectively inhibiting both gram-positive and gram-negative bacteria. The study's findings underscore the potential of this novel chitosan-based Schiff base as an efficient adsorbent for the removal of various dyes from wastewater, emphasizing its versatility and practical applicability in water treatment processes. [Display omitted] • A citric acid modified Chitosan SB was synthesized to remove BBR and RhB dyes from wastewater. • Langmuir saturation capacity was found to be 348 ± 11.0 mg/g for BBR and 145 ± 18.44 mg/g for RhB. • Pseudo second order kinetic model governs the rate of adsorption. • Antibacterial activity against gram positive and gram negative bacteria has been determined. [ABSTRACT FROM AUTHOR]

The Basil seeds mucilaginous polysaccharide exhibits remarkable physical and chemical properties like high water-absorbing capacity, emulsifying, and stabilizing properties. The metal-organic frameworks are one of the most promising precursors made of metal clusters and organic connectors for the fabrication of advanced adsorbents due to their unique properties. In this study, the bionanocomposite of magnetic zeolitic imidazolate framework-8 was successfully synthesized and applied to adsorb azo cationic and anionic dyes. The synthesized magnetite nanoparticles were pretreated with mucilage extracted from basil seeds to acquire negatively charged magnetite surface, followed by nucleation through attracting zinc cation, and then the growth of metal-organic frameworks which yields high-quality ZIF-8 crystals. The samples were characterized by Field Scanning Electron Microscopy, X-ray Diffraction, Fourier Transform Infrared Spectrometry, vibrating sample magnetometer, and Brunauer-Emmett-Teller surface area analysis. In the process of adsorption, influencing factors and recycling regeneration were discussed, and the adsorption mechanisms such as kinetics, isotherm, and thermodynamics were explored. The results of the adsorption process showed that maximum adsorption capacities were 9.09 and 13.21 mg/g for Methylene blue and Eriochrome Black T, respectively. The excellent reusability combined with its magnetic separation property makes the nanocomposite a promising adsorbent for the removal of cationic and anionic dyes. [ABSTRACT FROM AUTHOR]

In this research, a protein nanofiber membrane (P-COOH-CEW) was developed to treat the dye waste. Initially, polyacrylonitrile nanofiber membrane (PAN) was prepared by electrospinning, followed by heat treatment, alkaline treatment, and neutralization to obtain weak cation exchange nanofiber membrane (P-COOH). The P-COOH membrane was chemically coated with chicken egg white (CEW) proteins to obtain a 3D structure of complex protein nanofiber membrane (P-COOH-CEW). The composite prepared was characterized with Fourier Transform Infrared analysis (FTIR), Scanning Electron Microscopy (SEM), and thermogravimetric analysis (TGA). Further, the composite was evaluated by investigating the removal of Toluidine Blue O (TBO) from aqueous solutions in batch conditions. Different operating parameters - coupling of CEW, shaking rate, initial pH, contact time, temperature, and dye concentration were studied. From the results, maximum removal capacity and equilibrium association constant was determined to be 546.24 mg/g and 10.18 mg/mg, respectively at pH 10 and 298 K. The experimental data were well fitted to pseudo-second order model. Furthermore, desorption studies revealed that the adsorbed TBO can be completely eluted by using 50% ethanol or 50% glycerol in 1 M NaCl solution. Additionally, the reuse of P-COOH-CEW membrane reported to have 97.32% of removal efficiency after five consecutive adsorption/desorption cycles. • Waste CEW proteins were simply immobilized onto the acidic nanofiber membrane. • Egg white protein membrane is highly effective for removal of cationic TBO dye. [ABSTRACT FROM AUTHOR]

Water pollution caused by dyes has been a serious problem affecting human health and environment. The surface of polyacrylonitrile (PAN) nanofiber membranes was modified by mild hydrolysis and coupled with bovine serum albumin (BSA) obtained from the laboratory wastes, resulting in the synthesis of P-COOH and P-COOH-BSA nanofibers. The nanofibers with specific functional groups may enhance their potential applications toward the removal of ionic dyes in wastewater. Toluidine blue O (TBO) was applied as an example of cationic dye to evaluate the removal efficiency of P-COOH-BSA nanofiber. Results showed that the equilibrium dissociation constant and maximum removal capacity were 0.48 mg/mL and 434.78 mg/g, respectively, at pH 12, where the TBO removal can be explained based on Langmuir isotherm and pseudo-second-order model. Desorption studies have shown that TBO adsorbed on P-COOH-BSA protein membrane can be completely eluted with either 1 M NaCl or 50% glycerol. The results of repeated studies indicated that after five consecutive adsorption/desorption cycles, the removal efficiency of TBO can be maintained at ~97%. P-COOH-BSA has shown to be promising adsorbent in TBO dye removal from dye wastewater. • BSA protein from laboratory wastes was immobilized onto the nanofiber membrane. • 2D structure of P-COOH-BSA membrane is highly effective for TBO dye removal. • Low concentration of BSA protein capable of maximum adsorption amount of TBO dye. [ABSTRACT FROM AUTHOR]

A new approach of algal-polymer -sheets was performed by the embedding of two algal seaweeds (Ulva fasciata and Sargassum dentifolium) into cellulose acetate (CA) polymer forming two types of cellulose acetate; Ulva (CA-U) and Sargassum (CA-S) sheets. Afterward, the two sheets were characterized then subjected to 3-Rs evaluation (Removal, Recovery, and Reuse) of methylene blue dye (MB). Characterization data exhibited good properties for biosorption process. Algal biosorbents achieved more than twice biosorption capacity (Q max) after the embedding into the polymer sheet. Additionally, according to factorial design data, the contact time and the dose of biosorbents had positive effects on the biosorption in the two sheets. Freundlich, Langmuir, and pseudo-second order models displayed good represented data in the two sheets. Furthermore, the two sheets (CA-U, followed by CA-S sheet) were successfully given more than 98% adsorption of 273 mg/l MB concentration. Moreover, the recovery and reuse data proved that the two sheets can be performed in good behavior for more than three cycles. Unlabelled Image [ABSTRACT FROM AUTHOR]

Despite impressive progress of macromolecular encapsulation technique based on hyperbranched polymer (HP), the use of natural HP for guest encapsulation has rarely been reported. Herein, we present the simple synthesis of amphiphilic PGP-DC from natural peach gum polysaccharide (PGP) and demonstrate that the PGP-DC can be utilized as a robust host for encapsulation of dye molecules from water. The influences of initial dye concentration, dosage of PGP-DC, pH, ionic strength, and encapsulation mode on the encapsulation were systematically studied. The PGP-DC simultaneously exhibited fast encapsulation rate and superior encapsulation capability. Under optimal conditions, the encapsulation capacity of PGP-DC towards methylene blue (MB) (1 mM) can reach as high as 182.67 mg/g, which compares favorably to other separation techniques. Moreover, the MB-encapsulated PGP-DC could be well regenerated in acidic solution. Based on its simple synthetic process, excellent encapsulation performance and fine reusability, the PGP-DC holds great promise for using as a host for practical encapsulation applications. Unlabelled Image • Amphiphilic PGP-DC was synthesized from natural peach gum polysaccharide. • The use of PGP-DC as a host to encapsulate dye molecules from water was studied. • PGP-DC exhibited superior encapsulation capability towards dye molecules. • Encapsulation process was fast and could be completed within 2 min. • PGP-DC also showed good reusability. [ABSTRACT FROM AUTHOR]

Novel anionic adsorbent microbeads were fabricated based on surface functionalization of p -benzoquinone-carboxymethyl cellulose (CMC-PBQ) activated microbeads with iminodiacetic acid (IDA). The developed IDA@CMC-PBQ microbeads were characterized by FT-IR, TGA, SEM, XPS and zeta potential analysis tools. Ion exchange capacity measurements proved the successful generation of extra carboxylic groups on the surface of IDA@CMC-PBQ microbeads with a maximum value reached 3.984 m eq /g compared to 1.32 m eq /g for neat CMC microbeads. The fabricated microbeads were tested for the removal of cationic crystal violet (CV) dye from aqueous solutions under various adsorption conditions. The results clarified that the removal percent of CV dye was augmented and reached a maximum value of 91.56% with increasing IDA concentration up to 0.15 M. Moreover, the experimental data were well-fitted both Langmuir and Freundlich isotherms with a maximum adsorption capacity of 107.52 mg/g. while the adsorption process was obeyed the pseudo-second order kinetic model. The developed adsorbent displayed respectable reusability after five sequential cycles and exhibited higher adsorption ability towards cationic CV dye compared to cationic methylene blue (MB) and anionic methyl orange (MO) dyes. Therefore, IDA@CMC-PBQ adsorbent could be effectually used as a convenient and reusable adsorbent for removing cationic dyes from their aqueous solutions. Unlabelled Image • Functionalized microbeads based on carboxymethyl cellulose were developed. • Batch adsorption experiments were conducted for CV dye removal. • Results were verified by classical kinetics and isotherm studies. • The fabricated microbeads showed efficient adsorption with good reusability. [ABSTRACT FROM AUTHOR]

Herein, porous sodium alginate/graphite based hybrid hydrogel was fabricated as an effective adsorbent for organic pollutant. Sodium alginate was modified through graft polymerization of acrylic acid and subsequently loaded with graphite powder to enhance its adsorption capability. The synthesized sodium alginate cross-linked acrylic acid/graphite (NaA-cl-AAc/GP) hydrogel composite was utilized in the removal of malachite green (MG) dye from aqueous solution using batch adsorption experiments. The NaA-cl-AAc/GP hydrogel composite was characterized by infrared spectroscopy, Raman spectroscopy, thermo-gravimetric analysis, scanning electron microscopy, x-ray photoelectron spectroscopy and x-ray diffraction. Under optimized experimental conditions, a maximum adsorption capacity of 628.93 mg g−1 was attained for malachite green dye. Moreover, the adsorption process could be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. The hydrogel composite also showed 91% adsorption after three consecutive cycles of dye adsorption-desorption. Therefore, the NaA-cl-AAc/GP hydrogel composite is a potentially favourable material towards dye pollution remediation owing to its better swelling rate, environment friendliness, high adsorption potential and regeneration capability. • Cross-linked polymeric hydrogel network was synthesized successfully. • Graphite powder (GP) was incorporated into the NaA-cl-AAc hydrogel. • The adsorption of dye depends on pH. • NaA-cl-AAc/GP showed high adsorption capacity to malachite green dye. • The hydrogel composite can be regenerated and reused effectively. [ABSTRACT FROM AUTHOR]

We report here on the green synthesis method of hydrogel nanocomposite (Na-Ala/Chit-cl-polyAAm/CQDs) incorporated with carbon quantum dots for picric acid sensing and biebrich scharlet dye removal from industrial waste water. The nanocomposite precursor was derived from chitosan‑sodium alginate hybrid backbone and acrylamide monomer through the formation of semi-IPN matrix (Na-Ala/Chit-cl-polyAAm). The swelling percentage of semi-IPN can be controlled through process parameters such as reaction time, temperature, pH, water volume, acrylamide, N , N ′-methylenebisacrylamide and ammonium persulphate concentrations. Hydrogel nanocomposite displayed 99% quenching efficiency for the selective detection of picric acid and 96% dye removal efficiency was found to be observed for the removal of biebrich scarlet dye. The sorption was found to be favorable though Freundlich and Temkin adsorption isotherms along with the 2nd order kinetics. The devices were found to be recyclable and reusable up to six consecutive cycles indicating their applicability in textile industries for the treatment of effluents. Unlabelled Image [ABSTRACT FROM AUTHOR]

In the current article di-aldehyde alginate (DAA) crosslinking gelatin (Ge) hydrogel was prepared and investigated for stabilizing silver nanoparticles. DAA/Ge decorated silver nanoparticles hydrogel was characterized by IR, XRD, TGA, SEM and AFM. The outcomes demonstrate that silver nanoparticles with uniform sizes were homogenously distributed through DAA/Ge hydrogel. DAA/Ge decorated silver nanocomposite was examined for the rejection of methylene blue (MB) from aqueous solutions. Comparing with DAA/Ge hydrogel, the nanocomposite has high efficiency for removal of MB. The highest MB removal efficiency was observed at pH 7 and the adsorption process is well described by pseudo-second order and Langmuir adsorption model with adsorption capacity of 625 mg/g. Our results proved that the DAA/Ge/Ag nanocomposite could be used for removal of MB from decontaminated solutions. [ABSTRACT FROM AUTHOR]

In this study, a lignin-based hydrogel for wastewater treatment was prepared by incorporating kraft lignin (KL) into a poly (vinyl alcohol) (PVA) matrix. The underwater structural stability of the KL-PVA hydrogel was guaranteed through physicochemical crosslinking, involving freeze–thaw process and chemical crosslinking reaction. The KL-PVA hydrogel displayed superior compressive characteristics compared to the original PVA hydrogel. This improvement was attributed to the chemical crosslinking and the reinforcing effect of the incorporated KL microparticles. The incorporation of anionic KL microparticles into the PVA three-dimensional network structure enhanced the cationic methylene blue (MB) and crystal violet (CV) adsorption efficiency of the prepared KL-PVA hydrogel. The MB adsorption results were well explained by pseudo-2nd order kinetics model and Langmuir isotherm model. Electrostatic forces, hydrogen bonding and π-π stacking interactions were the main adsorption mechanisms between cationic dyes and KL surfaces, indicating the potential of KL-PVA hydrogel as an effective adsorption material. Moreover, regulating the molecular weight of PVA not only prevented lignin leakage from the KL-PVA hydrogel but also elevated the KL content within the hydrogel, consequently improving its dye removal performance. For KL-PVA hydrogel with high molecular weight PVA, the MB and CV adsorption capacities were 193.8 mg/g and 190.0 mg/g, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Chitosan (Ch)-diatomite (D) composite beads (Ch-D) were synthesized using epichlorohydrin and tripolyphosphate crosslinkers and then moulded into uniform beads in tripolyphosphate solution. FT-IR and SEM-EDX analyses showed that Ch-D composite adsorbent was successfully synthesized by functionalization of chitosan to Ch-D by hydrogen bonding and electrostatic interactions and improved adsorption capacity for removal of Allura red AC (AR) food dye. The removal rate of AR food dye was found to be 98 % at 25 °C, natural AR dye pH value, 24 h, and at the initial AR dye concentration of 200 mg L -1 . The maximum adsorption capacity was found to be 34.7 mg g -1 . It was observed that π-π interactions, hydrogen bonds, and electrostatic interactions between the functional groups containing oxygen and amine on the surface of the Ch-D composite and the functional groups of the anionic AR dye, and AR dye adsorption via complexation took place. In light of all this information, the Ch-D composite adsorbent is a promising potential material for the effective treatment of colored pollutants from wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A novel binary crosslinked material based on chitosan [chit-cl-Poly (AA-co-Am)] has been synthesized through crosslinking employing ceric ammonium nitrate (CAN) initiator under N 2 atmosphere for the effective removal of methyl orange dye as well as antibacterial studies. The synthesized adsorbent was characterized by FT-IR, SEM, XRD and TGA techniques. The effect of various process parameters such as pH, time, adsorption dose, and temperature on the removal of methyl orange was investigated. The isotherm data of the adsorption experiments obey the classical Freundlich adsorption isotherm while the kinetic data followed the pseudo-second-order kinetics. The antibacterial behavior of optimized samples was evaluated by the determination of maximum inhibitor growth of bacteria such as Escherichia coli (E. coli), Staphylococcus aureus and (S. aureus) Pseudomonas aeruginosa (P. aeruginos). The present study provides substantial evidence to prove beyond doubt that material based on chitosan [chit-cl-Poly (AA-co-Am)] seems to have the potential for effective removal of dyes from aqueous streams which can be extended to systems of significant importance. [ABSTRACT FROM AUTHOR]

A novel Fe(III) crosslinked poly (vinyl alcohol) (PVA)/chitin nanofiber composites were prepared for dye adsorption from water. The adsorbents were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis. The effects of Fe(III) content and chitin nanofibers (NFs) incorporation on the dye removal efficiency of adsorbents were investigated. The adsorption influencing parameters such as solution pH, contact time and initial dye concentration were optimized for maximum methyl orange (MO) adsorption. With loading of chitin NFs, the dye removal efficiency of PVA/Fe(III) adsorbents was noticeable increased. In addition, the dye removal efficiency did not show significant decline in alkaline solution in the presence of chitin NFs. Kinetics, isotherms and thermodynamics of dye adsorption process were also thoroughly studied. The adsorption data were better fitted with the pseudo-second-order kinetics and Freundlich isotherm model. PVA-chitin NFs-Fe(III) adsorbent exhibited a high maximum adsorption capacity of 810.4 mg/g for MO adsorption. Furthermore, reuse experiments revealed that the adsorption efficiency remained almost constant during five cycles of adsorption/desorption. At last, the possible mechanism for dye adsorption-desorption was proposed. The obtained results revealed that the developed bionanocomposites could be considered as promising recyclable adsorbents for wastewater treatment. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO)/polymer composites have received wide interests in adsorption of pollutants in water. However, the use of synthetic polymers and toxic cross-linking agents impacts the environment. Herein, a new GO/lignosulfonate aerogel (GLCA) cross-linked by chitosan was prepared without using any toxic chemicals. Characterizations by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction confirmed the three-dimensional porous structure and diverse functionalities of GLCA. The adsorption performance of GLCA to methylene blue (MB) was investigated by varying pH, dosage, contacting time, temperature and initial concentration. The obtained GLCA could capture MB molecules efficiently and over 99% MB could be removed from a MB solution (100 mg/L). The maximum adsorption capacity of MB onto GLCA was 1023.9 mg/g, higher than other reported GO/polymer composites and activated carbon. Adsorption thermodynamic analysis revealed the adsorption of MB on GLCA was spontaneous and endothermic. The interaction mechanisms involved electrostatic attraction, π-π interaction and hydrogen bond between GLCA and MB. Moreover, GLCA could be regenerated by washing with HCl solution and ethanol for multiple usage. Overall, this study indicated the GLCA could be an eco-friendly, cost-effective and recyclable adsorbent for the removal of dyes from water. • A three-dimensional graphene oxide/lignosulfonate aerogel was created. • The preparation process was feasible and eco-friendly. • The aerogel had an ultrahigh adsorption capacity (1023.9 mg/g) for methylene blue. • The aerogel showed excellent reusability during 5 cycles. [ABSTRACT FROM AUTHOR]

Abstract A novel adsorbent of chitosan/nanodiopside nanocomposite (CS-NDIO) was synthesized as a green composite for the removal of crystal violet (CV) and characterized by techniques like XRD, FT-IR, BET, and FESEM analysis. The influence of parameters like molar ratios of CS to NDIO, initial pH of the solution, dosage of adsorbent, initial concentration of CV and contact time was investigated and evaluated by central composite design (CCD; 5 levels and 4 factors). Also, Hybrid model of (ANN) model with genetic algorithm (GA) optimization was applied to the experimental data get through CCD. The optimized molar ratio of CS-NDIO was found: 20/80. Optimal parameter choice for maximum CV adsorption process using CCD and ANN-GA were as follows: pH = 7.50 and 7.499, adsorbent mass: 0.0077 and 0.0077 g, CV concentration: 20.000 and 20.002 mg/L, and contact time: 25.00 and 25.00 min, respectively. The evaluation adsorption equilibrium and kinetic data were fitted with the Langmuir monolayer isotherm model (q max : 104.66 mg g−1 and R2: 0.9937) and pseudo-second order kinetics mechanism (R2: 0.9978). Thermodynamic parameters (R2: 0.9180, ΔH°: −74.93 kJ mol−1, ΔG°: −12.89 kJ mol−1, and ΔS°: 0.93 kJ mol−1 K−1) were calculated and indicating adsorption to be an exothermic and spontaneous process. [ABSTRACT FROM AUTHOR]

Abstract The alginate beads have been widely used for dye removal. However, most of the systems described in literature refer to one type of dyes and the adsorbents of cationic ones are dominant. In this study, the composite alginate beads were prepared and characterized. The system was obtained by encapsulation of polyamidoamine – functionalized halloysite nanotubes in alginate (Alg/Hal_PAMAM beads). The adsorptive properties of the beads towards model dyes – cationic methyl green (MG) and anionic sunset yellow FCF (SY) - were investigated with reference to pH, adsorbent dose, time, dye concentration and temperature. The adsorption capacities were improved compared to pure alginate beads. The kinetic data were best correlated to the pseudo-second-order model. The intraparticle diffusion model showed two (MG) or one (SY) adsorptive steps of mass transport. The Freundlich isotherm model was suitable for describing the adsorption process thus the composite beads were characterized by heterogeneous sites. The thermodynamic parameters indicated the spontaneous and endothermic nature of the adsorption process. It was also found that the process was favorable. Additionally, the beads could be reused with satisfactory removal efficiency in several cycles. Therefore, Alg/Hal_PAMAM beads could be considered as promising material for simultaneous removal of cationic and anionic dyes. Graphical abstract Unlabelled Image Highlights • Alginate/PAMAM dendrimer-halloysite beads were produced and characterized. • The material studied was capable of adsorption of model cationic and anionic dyes. • The composite alginate beads could be easily regenerated and reused several times. [ABSTRACT FROM AUTHOR]

According to the widespread use of polyaluminum chloride (PAC) in wastewater treatment and residual aluminum left in treated water, there is an urgent need to use environmentally friendly natural coagulants with conventional chemical coagulants to reduce their consumption. In this investigation, chitosan (CS) nanoparticles prepared as natural coagulant by ion gelation were applied to remove anionic dyes from aqueous solutions. For the characterization of the synthesized CS nanoparticles, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and zeta analyzer were used. The effects of different parameters, including pH, initial concentration of dye in addition to CS nanoparticles, and PAC dosages on adsorption efficiency were studied via response surface methodology (RSM) to determine the optimum conditions for maximum color removal. Results of the tests indicate that the use of CS nanoparticles and PAC with an interval of 30 s effectively increases the efficiency of color removal. The usage of PAC (80 mg/L) and CS nanoparticles (150 mL/L) at pH = 6.6 reaches the maximum color removal efficiency of 92 %. Accordingly, the use of CS nanoparticles as coagulant aid reduced the amount of needed PAC and enhanced the color removal efficiency. Furthermore, the exclusive effect of CS nanoparticles in the adsorption of dye revealed that the adsorption followed the Langmuir type II model, with an adsorption capacity of 1100 mg/g. The resulting data from the kinetic study indicated that the pseudo-second-order type II model was the most suitable model to describe the adsorption process of dye on CS nanoparticles. Based on the results, the CS nanoparticles have adequate potential to reduce the amount of needed PAC dosage for the treatment of water contaminated with anionic dyes. [ABSTRACT FROM AUTHOR]

Agar based hybrid biosorbents were synthesized by free radical copolymerization of acrylamide, NN′-methylenebisacrylamide (NN′MBAAm) on the agar backbone in presence of free radical initiator (ceric ammonium nitrate (CAN)) via oxidation, grafting and crosslinking reactions. The resultant hybrid materials have been characterized by FTIR spectroscopy, elemental analysis, thermal analysis (TGA/DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) taking agar as a reference. The swelling responses of hybrid materials have been extensively studied with various pH, time, temperature and ionic strength [NaCl] of the solution. These hybrid materials have been utilized for selective removal of heavy metal ions (Fe(III), Cr(III), Ni(II) and Mn(II)) and dye (methylene blue) through adsorption mechanism by formation of complex between the functional groups of biosorbent and metal ions & dye. These hybrid materials showed excellent results with their potential applications for environmental remediation from the textile effluents and heavy metal ions contaminated water bodies. [ABSTRACT FROM AUTHOR]

Lignin is a complex natural polymer and it is one of the main constituent of the lignocellulosic biomass. Moreover, it is a bio-renewable material and it is available in large amounts as by-product from the forest industry. Lignin-based hydrogels with high swelling capabilities were prepared by crosslinking poly (methyl vinyl ether co-maleic acid) and different technical lignins in ammonium and sodium hydroxide solutions. The produced hydrogels showed a wide range of water absorption capacities varying from 13 to 130 g of water per 1 g of sample. It was observed that the higher the water uptake the poorer mechanical performance, as evaluated in terms of storage and loss modulus (G′ and G″, respectively) of the materials. Methylene blue (MB) was used as a model dye to evaluate the adsorption and release capabilities of the lignin hydrogels. Results suggested that these hydrogels showed a high MB removal efficiency, which ranged from 12 to 96%. On the contrary, the percentages of MB released depended on the negative surface charge of the hydrogels, showing values which ranged from 0.06 to 0.35%. Thus, these materials have potential to be used as adsorbents for the removal of organic dyes from waste water. [ABSTRACT FROM AUTHOR]

In this work, an environmentally friendly gum ghatti-crosslinked-polyacrylamide (Gg-cl-PAAM) hydrogel was synthesized from gum ghatti (Gg) and acrylamide (AAM) using a microwave-assisted grafting technique, and tested for use in water purification applications as an adsorbent and flocculent. The Gg-cl-PAAM was characterized using SEM, FTIR, and TGA, and displayed pH responsive swelling behavior, with maximum swelling (2117%) observed in solution with neutral pH. The flocculation characteristics of Gg-cl-PAAM were tested in clay solutions as a function of pH, temperature, and the polymer mass loading, showing that the best performance is obtained at neutral pH at 40 °C. The adsorption capacities of Gg-cl-PAAM for the removal different dyes such as brilliant green (BG), rhodamine B (RhB), congo red (CR), and methyl orange (MO) were tested, revealing that the adsorption of all dyes followed the Langmuir isotherm model, with q m values of 523.62 mg g −1 for BG, 421.60 mg g −1 for RhB, 179.09 mg g −1 for CR, and 173.69 mg g −1 for MO. Finally, the environmentally friendly nature of Gg-cl-PAAM was examined using the soil-burial composting method, which demonstrated 93% degradation of the Gg-cl-PAAM hydrogel within 60 days. [ABSTRACT FROM AUTHOR]

In the present study, new composite beads based on carboxymethyl cellulose (CMC)/k-carrageenan (kC)/activated montmorillonite (AMMT) were prepared for adsorptive removal of cationic methylene blue (MB) as a dye model. The structure and morphology of the composite beads were investigated by FT-IR and SEM, while the thermal properties were tested using TGA. Factors affecting the removal percent of MB such as CMC/kC/AMMT ratios, initial MB concentration, pH medium, adsorbent dosage, solution temperature, and agitation speed were also explored. Results demonstrated that MB removal (%) exceeded 92% after 120 min using CMC/kC/AMMT (1:1:0.4 ratio) compared to 69% in case of free AMMT beads. Moreover, data obtained from isotherm studies were fitted well to Langmuir model (R 2 = 0.999), and the kinetics of adsorption followed pseudo-second order model. Finally, the composite beads showed good reusability for MB dye removal with high efficiency. Results obtained from this study suggest that the prepared composite beads could be applied effectively for removing cationic dyes from aqueous solutions. [ABSTRACT FROM AUTHOR]

The pure chitosan nanofibrous membranes with average fiber diameter of 86 ± 18, 114 ± 17,164 ± 28 nm were successfully prepared by electrospinning. Batch adsorption experiments of using chitosan nanofibrous membranes as adsorbent to remove acid blue-113 were conducted. The adsorption capacity of 1377 mg/g was achieved by the chitosan nanofibrous membrane with average fiber diameter of 86 nm, which was superior to the chitosan microscale sample with the adsorption capacity of 412 mg/g. The average fiber diameter and the corresponding equilibrium adsorption capacity of pure chitosan nanofibrous membranes fitted well with linear relationship in our test range. The results also showed that the adsorption followed with pseudo second-order kinetics model, and the adsorption behavior was accordance with the Langmuir isotherm model. The pure chitosan nanofibrous membrane showed promise and feasibility as an effective adsorbent for dye removal. [ABSTRACT FROM AUTHOR]

A novel superadsorbent anionic hydrogel was synthesized by grafting of poly (3-sulfopropyl methacrylate), P(SPMA), onto carboxymethyl cellulose (CMC). CMC-g-P(SPMA) superadsorbent hydrogel was applied as an efficient and sustainable adsorbent to remove methylene blue (MB) from waste water. Batch adsorption experiments showed that the solution pH had an obvious effect on the adsorption capacity with an optimal sorption pH at 6. The CMC-g-P(SPMA) hydrogel had rapid adsorption kinetics for MB and the adsorption equilibrium reached within 40 min. The adsorption kinetics were more accurately described by pseudo second-order model and the Langmuir-fitted adsorption isotherms revealed a maximum capacity of 1675 mg/g. The current anionic hydrogel is reusable as the adsorption capacity remained at 89% level after five adsorption-desorption cycles. CMC-g-P(SPMA) hydrogel was presented as a sustainable promising adsorbent with high adsorption capacity and good regenerability for effective cationic dyes removal. [ABSTRACT FROM AUTHOR]

Cellulose nanofibers decorated with SiO 2 nanoparticles (SiO 2 -CNF) were prepared by the extraction of cellulose nanofibers from Yucca leaves, followed by modification with SiO 2 nanoparticles, and used as efficient materials for the removal of both anionic and cationic dyes from the aqueous solution. Prepared nanostructures were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction powder (XRD), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and transmission electron microscopy (TEM) analysis. The adsorption capacity of the nanostructures was investigated for the removal of both cationic (Methylene Blue, MB, and Crystal Violet, CV) and anionic (Eriochrome Black-T, EB) dyes. The kinetics of adsorption were investigated using some well-known models, including intraparticular diffusion (IPD), pseudo-first-order (PFO), pseudo-second-order (PSO), and Elovich. The adsorption isotherms were also explored using the Langmuir, Freundlich, Temkin, and Redlich-Peterson models. The obtained results revealed that the adsorption processes follow PSO kinetic and Langmuir isotherm models. Thermodynamic parameters of the adsorption were measured at different temperatures, indicating the feasibility and spontaneity of the adsorption. The pH and salt effects on adsorption were also explored. Finally, according to the reusability tests, the prepared adsorbents showed high recoverability without considerable loss in adsorption efficiency after five repeated runs. • Green adsorbents based on cellulose nanofibers were reported for the removal of dyes. • Cationic and anionic dyes were adsorbed rapidly. • Some known adsorption kinetic and isotherm models were studied. • Adsorbents were recycled and reused for five runs without considerable loss in efficiency. [ABSTRACT FROM AUTHOR]

The growing concern for the environment has resulted in renewed interest in bio-based resources. This study aims to produce a hydrogel adsorbent from cellulose and examine its adsorption performance. In pursuit of this goal, we report a simple one-pot synthesis of cellulose acetate sulfate (CAS), followed by the formation of CAS hydrogels and their subsequent adsorption performances. The CAS includes both hydrophilic and hydrophobic functional groups, enable the formation of a single-component hydrogel through intermolecular interactions in deionized water. The thermal reversibility of CAS hydrogels makes them easily processable into various shapes. The durability of the CAS hydrogel adsorbents can be improved by introducing divalent cations (e.g., Ca2+), which create ionically crosslinked hydrogels. The ionically a crosslinked CAS hydrogel adsorbent exhibits a maximum adsorption capacity of 245 mg/g for methylene blue (MB) at 23 °C and a pH of 7. The adsorption behavior of MB on the CAS hydrogel follows both the pseudo-second-order model and the Langmuir adsorption isotherm model. Furthermore, the CAS hydrogel adsorbent maintains a 70 % removal ratio after five cycles. The simplicity of synthesis and hydrogel formation opens up new possibilities for producing and utilizing cellulose-based hydrogels as adsorbents for aqueous contaminants. [Display omitted] • Cellulose acetate sulfate (CAS) hydrogels were prepared without the needs for crosslinking agents or supplementary polymers • The CAS hydrogels were processed into various shape via extrusion or molding • Double crosslinking was performed to enhance the durability of the CAS hydrogel adsorbents • Adsorption kinetics and isotherm of the CAS hydrogel adsorbent were investigated [ABSTRACT FROM AUTHOR]

The limited usage of chitosan as a dye adsorbent is attributed to its compact structure and low swelling ability, despite its exceptional properties. The present study aimed to prepare novel chitosan/pyrazole Schiff base (ChS) adsorbents enriched with greenly synthesized zinc oxide nanoparticles. The preparation of ZnO-NPs was carried out through a green approach using the Coriandrum sativum extract. The presence of ZnO-NPs at the nanoscale was validated through TEM, DLS and XRD analyses. FTIR and 1H NMR confirmed the successful preparation of the Schiff base and its ZnO-NPs adsorbents. The incorporation of ZnO-NPs improved the thermal, swelling and antimicrobial properties of the chitosan Schiff base. In addition, a significant improvement in the adsorption of Maxilon Blue dye from its aqueous solution by the Schiff base/ZnO-NPs adsorbent was achived. The prepared ChS/ZnO-NPs adsorbent has the potential to be used as an alternative to conventional adsorbents for the removal of dyes from wastewater. • Green ZnO nanoparticles (ZnO-NPs) were prepared using Coriandrum sativum extract. • Chitosan Schiff base (ChS) containing a pyrazole moiety was synthesized. • ChS was incorporated with varying amounts of ZnO-NPs. • ZnO-NPs incorporation led to enhanced thermal, biological, and swelling properties. • The prepared ChS/ZnO-NPs adsorbent efficiently removed MB dye from its solution. [ABSTRACT FROM AUTHOR]

A composite of Typha latifolia activated carbon (TLAC) (a novel, low cost absorbent) and chitosan (TLAC/Chitosan composite) was prepared. The composite was characterised using IR spectra, XRD, FESEM and Pore size studies. Its effectivity was tested for the removal of crystal violet dye from aqueous solutions. The effect of pH, dose rate and initial dye concentration was evaluated. The adsorption isotherm, kinetics and thermodynamic parameters were studied. Langmuir and Freundlich isotherm models were found fit effectively for the dye adsorption data in the present study. The adsorption followed pseudo-second order kinetics. The evaluated thermodynamic parameters show a spontaneous and exothermic reaction. Overall, this study indicates TLAC/Chitosan composite as an effective adsorbent for the removal of crystal violet dye from aqueous solutions. [ABSTRACT FROM AUTHOR]

Hybrid lignin (HL) particles were synthesized by compounding lignosulfonate and carboxylated chitosan through a simple ionic cross-linking method, and modifying by polyvinylpolyamine. Due to the synergistic effect of recombination and modification, the material exhibits excellent adsorption performance for anionic dyes in water. The structural characteristics and adsorptive behavior were systematically investigated. The pseudo-second-order kinetic model and the Langmuir model were revealed to well describe the sorption procedure of HL for anionic dyes. The results exhibited that the sorption capacities of HL on sodium indigo disulfonate and tartrazine were 1099.01 mg/g and 436.68 mg/g, respectively. Simultaneously, the adsorbent behaved no significant adsorption capacity loss after five adsorption-desorption cycles, indicating its superb stability and recyclability. Additionally, the HL exhibited excellent selective adsorption of anionic dyes form binary dye adsorption systems. The interaction forces between adsorbent and dye molecules, such as hydrogen bonding, π-π stacking, electrostatic attraction and cation bonding bridge, are discussed in detail. The facile preparation process and superior dyes removal performance of HL were considered a potential adsorbent to remove anionic dyes from wastewater. • A simple one-step ion-crosslinked method to prepare hybrid lignin particles • The hybrid lignin can selectively adsorb anionic dyes from binary dye mixtures. • The composites exhibit excellent anionic dyes removal performance. • The multiple adsorption mechanisms of dyes were further revealed. [ABSTRACT FROM AUTHOR]

Nowadays, a big challenge is developing a sustainable and effective method for removing contaminants like dyes from aqueous solutions. In this regard, Zr-based metal-organic framework (UiO-66-NH 2) and sawdust as the ideal adsorbents were used. Due to their low separation in adsorption processes, embedding into alginate and obtaining composite beads are suggested as a suitable strategy. The achieved Ca-alginate/citric acid (CA)-sawdust/UiO-66-NH 2 hydrogel beads were used to compare cationic and anionic dyes removal. This sorbent indicated an excellent selectivity for removing methylene blue versus methyl orange in a binary system. pH = 6, adsorbent amount = 80 mg, methylene blue concentration = 10 mg/L, and contact time = 420 min were achieved as optimal parameters on methylene blue adsorption with an adsorption capacity of about 26 mg/g. The removal process of methylene blue followed linear Freundlich isotherm and nonlinear pseudo-2nd-order kinetic models. The regeneration test demonstrated methylene blue removal efficiency higher than about 89 % after 9 cycles. According to the outcomes, methylene blue could be attached to the adsorbent surface through the electrostatic, hydrogen bonding, and π-π interactions of the aromatic rings. These results confirm the potential of Ca-alginate/CA-sawdust/UiO-66-NH 2 hydrogel beads as a selective bio-sorbent for cationic dye removal. [ABSTRACT FROM AUTHOR]

GO/HEC/PGDE/Fe 3 O 4 materials were successfully fabricated using environmentally-friendly hydroxyethyl cellulose (HEC), poly(ethylene glycol) diglycidyl ether (PGDE), graphene oxide (GO) and magnetic Fe 3 O 4. Systematic investigations were completed to explore the influences of GO content in GO/HEC/PGDE/Fe 3 O 4 and adsorption conditions on the adsorptions of cationic dyes (methylene blue (MB), crystal violet (CV)) and anionic dye acid blue 25 (AB-25). The increase of GO content can remarkably improve the adsorption capacity of GO/HEC/PGDE/Fe 3 O 4 for the dyes. The three kinetic, four isothermic and three thermodynamic models were investigated to reveal the adsorption behaviors of the dyes. The formation of HEC/PGDE/Fe 3 O 4 and adsorption mechanisms of the dyes by GO/HEC/PGDE/Fe 3 O 4 were suggested. The GO/HEC/PGDE/Fe 3 O 4 endowed with easy-fabrication, eco-friendly feature, efficient adsorption capacity of anionic/cationic dyes, convenient separation and reusability has potential applications in wastewater purification industry. • Develop novel eco-friendly adsorbent for cationic/anionic dyes removal. • Easy-fabrication and efficient adsorption capacity of dyes for the adsorbent. • Kinetic, thermodynamic and isothermic investigations for the adsorbent. • The adsorbent is easy recovery and shows high recycling performance. • Possible adsorption mechanism is proposed. [ABSTRACT FROM AUTHOR]

In this work, a class of bio-based hydrogels (LN-NH-SA hydrogel) were prepared from aminated lignin and sodium alginate. The physical and chemical properties of the LN-NH-SA hydrogel were fully characterized using field emission scanning electron microscopy, thermogravimetric analysis, fourier transform infrared spectroscopy, N 2 adsorption–desorption isotherms, and other techniques. LN-NH-SA hydrogels were tested for the adsorption of dyes (methyl orange and methylene blue). The LN-NH-SA@3 hydrogel showed better adsorption efficiency for MB with a maximum adsorption capacity of 388.81 mg·g−1, a bio-based adsorbent with a high adsorption capacity. The adsorption process followed the pseudo-second-order model and fitted to the Freundlich isotherm equation. More importantly, LN-NH-SA@3 hydrogel maintained 87.64 % adsorption efficiency after 5 cycles. Overall, the proposed hydrogel with environmentally friendly and low cost is promising for the absorption of dye contamination. • LN-NH-SA hydrogel is produced by chemical cross-linking and ionic cross-linking. • LN-NH-SA@3 hydrogel is capable of adsorbing both anionic and cationic dyes. • The maximum adsorption capacity toward methylene blue is 388.8 mg/g. • LN-NH-SA@3 hydrogel exhibit excellent stability and adsorption rate is 87.64 % after five cycles. [ABSTRACT FROM AUTHOR]

Ionogels are a category of hybrid material containing ionic liquid stabilized by polymeric network. These composites have some applications in solid-state, energy storage devices and environmental studies. In this research, chitosan (CS), ethyl pyridinium iodide ionic liquid (IL), and ionogel (IG) consisting of chitosan and ionic liquid were used in the preparation of a SnO nanoplate (SnO-IL, SnO-CS and SnO-IG). For the preparation of the ethyl pyridinium iodide, a mixture of pyridine and iodoethane (1: 2 molar ratio) was refluxed for 24 hours. The ionogel was formed using ethyl pyridinium iodide ionic liquid in chitosan that was dissolved in acetic acid (1 % v /v). By increasing NH 3 ∙H 2 O, the pH of the ionogel reached 7‐8. Then, the resultant IG was mixed with SnO in an ultrasonic bath for 1 h. The microstructure of the ionogel was involved as assembled unit via π-π, electrostatic and hydrogen bonding interactions to be three-dimensional networks. The intercalated ionic liquid and chitosan influenced the stability of the SnO nanoplates and improved band gap values. When chitosan was contained as the interlayer space of the SnO nanostructure, the resulting biocomposite formed a well-ordered flower-like SnO structure. These hybrid material structures were characterized by FT-IR, XRD, SEM, TGA, DSC, BET, and DRS techniques. The changes in the band gap values for photocatalysis applications were investigated. In the case of SnO, SnO-IL, SnO-CS, and SnO-IG, the band gap energy was 3.9, 3.6, 3.2, and 2.8 eV, respectively. The dye removal efficiency of SnO-IG was 98.5, 98.8, 97.9, and 98.4 % via the second-order kinetic model for Reactive Red 141, Reactive Red 195, Reactive Red 198, and Reactive Yellow 18, respectively. The maximum adsorption capacity of SnO-IG was 540.5, 584.7, 1501.5, and 1100.1 mg/g for Red 141, Red 195, Red 198, and Yellow 18 dyes, respectively. Also, an acceptable result (96.47 % dye removal) was obtained with the prepared SnO-IG biocomposite for dye removal from textile wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

The presence of multiple pollutants in wastewater, often with complex interactions, poses a significant challenge for conventional membranes to effectively remove multiple pollutants simultaneously. Herein, a lignin microparticles-reinforced cellulose filter paper (FP@AL-LS-DA) was fabricated via an aldol condensation between lignin and cellulose filter paper and cross-linking with dopamine hydrochloride (DA), which showed desired rejection of oil-in-water emulsions and dyes. Characterizations revealed that the addition of lignin and DA effectively narrowed the pore size (from 4.45 μm to 2.01 μm) and enhanced the rigidity and stability of the cellulose filter paper, thus making it not easily damaged in the water environment and showing excellent tolerance to strong acid and high-salt environments. The oil-in-water emulsions removal efficiency was higher than 99 % even after ten times usage, and the oil flux was kept stable at 52.54 L·m−2·h−1, indicating that FP@AL-LS-DA had outstanding reusability and stability. Remarkably, FP@AL-LS-DA showed excellent removal efficiency (>99 %) for complex pollutants containing dyes and oil-in-water emulsions. In this work, we demonstrate a lignin microparticles-reinforced cellulose filter paper that is simple to prepare and can efficiently separate oil-in-water emulsions and remove dyes. • Lignin microparticles filled the large pore of cellulose filter paper. • Excellent treatment capability for complex wastewater with oil-in-water emulsions and dyes. • Removal of anionic/cationic dyes via membrane adsorption. • Stable oil flux and excellent reusability. [ABSTRACT FROM AUTHOR]

A novel adsorbent was prepared via crosslinking graft copolymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA) onto carboxymethyl cellulose (CMC) backbone. Ethylene glycol dimethacrylate and potassium persulphate were used as crosslinker and initiator, respectively. CMC- g -PDMAEMA hydrogel was used to remove methyl orange (MO) from aqueous solutions. The adsorption kinetics and isotherms were found to follow Pseudo-second-order kinetic model and Langmuir model, respectively. The high maximum adsorption capacity (1825 mg/g) implied that CMC- g -PDMAEMA can be used as promising adsorbent for the synthetic dyes removal from wastewater. [ABSTRACT FROM AUTHOR]

Abstract: Removal of a basic dye (Methylene Blue) from aqueous solution was investigated using a cross-linked succinyl-chitosan (SCCS) as sorbent. The chemical structures of chitosan and its derivatives were testified by FT-IR. X-ray diffraction, DTG analysis and swelling measurements were conducted to clarify the characteristics of the chemically modified chitosan. The effect of process parameters, such as pH of the initial solution, and concentrations of dyes on the extent of Methylene Blue (MB) adsorption was investigated. The Langmuir isotherm model was used to fit the equilibrium experimental data, giving a maximum sorption capacity of 289.02mg/g at 298K. Kinetic studies showed that the kinetic data were well described by the pseudo-second-order kinetic model. Thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°) were determined to be −25.32kJmol−1, −6.76kJmol−1 and −62.36Jmol−1 K−1, respectively, which leads to a conclusion that the adsorption process is spontaneous and exothermic. [Copyright &y& Elsevier]