Removal of malachite green using carboxymethyl cellulose-g-polyacrylamide/montmorillonite nanocomposite hydrogel

Carbon Nanotubes Hybrid Hydrogels for Environmental Remediation: Evaluation of Adsorption Efficiency under Electric Field

The performance of Carbon Nanotubes hybrid hydrogels for environmental remediation was investigated using Methylene Blue (MB), Rhodamine B (RD), and Bengal Rose (BR) as model contaminating dyes. An acrylate hydrogel network with incorporated CNT was synthesized by photo-polymerization without any preliminary derivatization of CNT surface. Thermodynamics, isothermal and kinetic studies showed favorable sorption processes with the application of an external 12 V electric field found to be able to influence the amount of adsorbed dyes: stronger interactions with cationic MB molecules (qexp and qexp12 of 19.72 and 33.45 mg g⁻¹, respectively) and reduced affinity for anionic RD (qexp and qexp12 of 28.93 and 13.06 mg g⁻¹, respectively) and neutral BR (qexp and qexp12 of 36.75 and 15.85 mg g⁻¹, respectively) molecules were recorded. The influence of pH variation on dyes adsorption was finally highlighted by reusability studies, with the negligible variation of adsorption capacity after five repeated sorption cycles claiming for the suitability of the proposed systems as effective sorbent for wastewater treatment.

Development of Arabic gum-based AgTiO2 nanocomposite hydrogel as high efficient adsorbent of cationic dye methylene blue from water

The chemically crosslinked silver titanium dioxide embedded Arabic gum grafted polyacrylamide-polyacrylonitrile nanocomposite AgTiO₂@AG-g-P(AM-co-AN)was successfully synthesized and investigated by ATR-IR, XRD, and SEM. The synthesis optimization parameters of AG-g-P(AM-co-AN)were 5% AG, 1/0.5 AM/AN monomer molar ratio, 0.5 mg MBA cross-linker, and AgTiO₂ content (1%) gives AgTiO₂@AG-g-P(AM-co-AN) nanocomposite. While adsorption studies for AgTiO₂@AG-g-P(AM-co-AN) exhabited the maximum adsorption capacity (104.50 ± 3.02 mg/g) at concentration (150 mg/L), MB concentration (15 mg/L) and pH (8.0). The adsorption nonlinear kinetics models were used. Pseudo-second order governs the adsorption process, and the Langmuir model is more suited than Freundlich and Temkin.

Preparation of clinoptilolite/starch/CoFe2O4 magnetic nanocomposite powder and its elimination properties for cationic dyes from water and wastewater

A new magnetic nanocomposite clinoptilolite (CLT)/Starch/CoFe₂O₄ was synthesized using co-precipitation method. The prepared magnetic composite powder was utilized for decontamination of methylene blue dye (MBD), methyl violet dye (MVD), and crystal violet dye (CVD) from water media. The BET analysis showed that CLT modification using starch and CoFe₂O₄ nanoparticles improved its specific surface and the amount of specific surface area for CLT, CoFe₂O_4, and CLT/Starch/CoFe₂O₄ powder was reported to be 18.82 m².g^-1, 151.4 m².g^-1, and 104.75 m².g^-1, respectively. Experimental results showed that pH 9 had a vital role in the adsorption process of all three types. Langmuir and Redlich-Petersen isotherm models were well fitted with experimental data. Also, the maximum adsorption capacity of CVD, MBD, and MVD to the desired composite was determined as 32.84 mg.g^-1, 31.81 mg.g^-1, and 31.15 mg.g^-1, respectively. In addition, the kinetic data of the removal process followed a pseudo-first order (PFO) kinetic model. Negative thermodynamic parameters were indicated that the process is spontaneous and exothermic. Finally, ad(de)sorption experiments' results showed that the synthesized nanocomposite adsorbent has an excellent ability to adsorb cationic dyes after several consecutive cycles.

Mechanistic evaluation of metformin drug confiscation from liquid phase on itaconic acid/kaolin hydrogel nanocomposite

Herein, kaolin (K) was amended by a novel gemini surfactant to attain nano-kaolin (nK), which was subsequently employed as a cross-linker in the preparation of itaconic acid/kaolin hydrogel nanocomposite (IA/nK) via free radical polymerization route employing the sonochemical technique, which has been used for the first time to extract metformin (MF) from water solution. The aspects which affect sorption behavior of IA/nK on metformin (MF) were systematically investigated via batch experiments, in harmony with effect of sorbent dosage, contact time, pH, MF concentration, equilibrium curves, kinetic behavior, and thermodynamic parameters. BET studies of IA/nK exhibited S_BET of 106.42 m²g^-1, pore volume 0.281 cm³ g^-1, and a pore radius of 16.627 Å. Kinetic and isotherm modelling portrayed that pseudo-second order and Freundlich model appropriated adsorption data with maximum sorption capacity of 278.35 mg g^-1. Thermodynamic parameters ΔH^O (13.67 kJmol^-1) and ΔG^O (-7.648 kJmol^-1) revealed that sequestration of MF on IA/nK was endothermic, spontaneous, and dominated by physisorption. Molecular docking study along with X-ray photoelectron spectroscopy inferred electrostatic interaction and hydrogen bonding as main mechanism of MF removal. IA/nK demonstrated dose-reliant inhibition of both gram-positive and gram-negative bacterial strains. IA/nK demonstrated good regeneration properties, up to four cycles without considerable decrease in its efficacy. The admirable sorption capacity coupled with good reusability, and low toxicity substantiates IA/nK as promising adsorbent for MF confiscation.

Adsorption/desorption performance of Pb2+ and Cd2+ with super adsorption capacity of PASP/CMS hydrogel

Super-absorbent polyaspartic acid/carboxymethyl Salix psammophila powder (PASP/CMS) hydrogel was prepared by aqueous solution polymerization. PASP/CMS hydrogel was characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results showed that PASP/CMS hydrogel is prepared by graft copolymerization of the -COOH of polyaspartic acid (PASP) and the -CH₂OH of CMS. The surface of the hydrogel became dense from loose porosity, and Pb²⁺ and Cd²⁺ were adsorbed onto the surface of hydrogel. The crystallinity of CMS was destroyed by the addition of PASP. The initial concentration of Pb²⁺ and Cd²⁺, pH, adsorption time and adsorption temperature on the adsorption effect were studied through experiments. Results showed that hydrogel has a good removal effect on Pb(II) and Cd(II) ions. Pseudo-second-order kinetics and Langmuir isotherm models are represented in the process, which are spontaneous, exothermic and decreased in randomness, and it is a single layer chemical adsorption. At the same time, the effect of desorption experimental parameters (HNO₃ initial concentration, desorption time, and desorption temperature) on the experiment was studied and optimized.

Application of adsorption process for effective removal of emerging contaminants from water and wastewater

Emerging pollutants in the marine ecosystem, as well as their possible impact on live species, have become a rising cause of worry. A traditional wastewater treatment plants alone are not successful in eliminating such massive contaminant groups and therefore additional water treatment is required which is to be cost effective. Since standard primary and secondary treatment plants are unsuccessful at eliminating or degrading these harmful chemicals, a cost-effective tertiary treatment approach is proposed. Adsorption is a successful approach for Contaminants removal globally, because it is low installation expense, high performance and has easy operational design. Emerging pollutants have been removed from wastewaters using various adsorbents like activated carbons, improved bio chars, Nano adsorbents, hybrid adsorbents, and others. The purpose of this paper is to review the source of contaminants and the concept of adsorption when separating emerging contaminants. The present study aims to examine the adsorption mechanism as an effective approach for treating emerging contaminants. Then, the analysis of natural and man-made adsorbents for the separation of contaminants is examined along with its comparison. Also, future view on emerging contaminants and adsorbents in modern generation has been discussed.

Crystal violet dye sorption over acrylamide/graphene oxide bonded sodium alginate nanocomposite hydrogel

The synthesis of acrylamide bonded sodium alginate (AM-SA) hydrogel and acrylamide/graphene oxide bonded sodium alginate (AM-GO-SA) nanocomposite hydrogel was successfully performed using the free radical method. The AM-SA and AM-GO-SA hydrogels were applied as composited adsorbents in crystal violet (CV) dye removal. The adsorption process experiments were performed discontinuously and the acquired data showed that the efficiency is more dependent on pH than other factors. The C-O, CO, and CC groups were detected in the produced hydrogels. The amount of surface area was computed to be 44.689 m²/g, 0.0392 m²/g, and 6.983 m²/g for GO, AM-SA, and AM-GO-SA nanocomposite hydrogel, respectively. The results showed that the experimental data follow the Redlich-Peterson isotherm model. Also, the maximum adsorption capacity of monolayer for CV dye adsorption was determined using AM-SA hydrogel and AM-GO-SA nanocomposite hydrogel 62.07 mg/g and 100.30 mg/g, respectively. In addition, the parameters R_L, n, and E showed that the processes of adsorption of CV dye using both types of adsorbents are physical and desirable. Thermodynamically, the CV elimination was exothermic and spontaneous. Besides, thermodynamic results showed that the adsorption process is better proceeding at low temperatures. The experimental data followed a pseudo- second- order (PSO) kinetic model. Also, the Elovich model showed that AM-GO-SA nanocomposite hydrogel has more ability to absorb CV dye. Therefore, according to the obtained results, it can be stated that the produced hydrogels are efficient and viable composited adsorbent in removing CV dye from aqueous solution.

Adsorption of Crystal Violet Dye Using Activated Carbon of Lemon Wood and Activated Carbon/Fe3O4 Magnetic Nanocomposite from Aqueous Solutions: A Kinetic, Equilibrium and Thermodynamic Study

Activated carbon prepared from lemon (Citrus limon) wood (ACL) and ACL/Fe₃O₄ magnetic nanocomposite were effectively used to remove the cationic dye of crystal violet (CV) from aqueous solutions. The results showed that Fe₃O₄ nanoparticles were successfully placed in the structure of ACL and the produced nanocomposites showed superior magnetic properties. It was found that pH was the most effective parameter in the CV dye adsorption and pH of 9 gave the maximum adsorption efficiency of 93.5% and 98.3% for ACL and ACL/Fe₃O₄, respectively. The Dubinin–Radushkevich (D-R) and Langmuir models were selected to investigate the CV dye adsorption equilibrium behavior for ACL and ACL/Fe₃O₄, respectively. A maximum adsorption capacity of 23.6 and 35.3 mg/g was obtained for ACL and ACL/Fe₃O₄, respectively indicating superior adsorption capacity of Fe₃O₄ nanoparticles. The kinetic data of the adsorption process followed the pseudo-second order (PSO) kinetic model, indicating that chemical mechanisms may have an effect on the CV dye adsorption. The negative values obtained for Gibb’s free energy parameter (−20 < ΔG < 0 kJ/mol) showed that the adsorption process using both types of the adsorbents was physical. Moreover, the CV dye adsorption enthalpy (ΔH) values of −45.4 for ACL and −56.9 kJ/mol for ACL/Fe₃O₄ were obtained indicating that the adsorption process was exothermic. Overall, ACL and ACL/Fe₃O₄ magnetic nanocomposites provide a novel and effective type of adsorbents to remove CV dye from the aqueous solutions.

A Review on the Synthesis, Characterization, and Modeling of Polymer Grafting

A critical review on the synthesis, characterization, and modeling of polymer grafting is presented. Although the motivation stemmed from grafting synthetic polymers onto lignocellulosic biopolymers, a comprehensive overview is also provided on the chemical grafting, characterization, and processing of grafted materials of different types, including synthetic backbones. Although polymer grafting has been studied for many decades—and so has the modeling of polymer branching and crosslinking for that matter, thereby reaching a good level of understanding in order to describe existing branching/crosslinking systems—polymer grafting has remained behind in modeling efforts. Areas of opportunity for further study are suggested within this review.

Instantaneous Adsorption of Synthetic Dyes from an Aqueous Environment Using Kaolinite Nanotubes: Equilibrium and Thermodynamic Studies

Innovative kaolinite nanotubes (KNTs) are synthesized utilizing a simple technique involving a sonication-induced exfoliation process, followed by chemical scrolling reactions. The KNTs as a material have high reactivity and promising surface area to be used in the purification of water from cationic dyes (safranin (SF) and malachite green (MG)) and anionic dyes (methyl orange (MO) and Congo red (CR)). The kinetic studies of the four dyes SF, MG, CR, and MO show an equilibration time interval of 240 min. The SF, MG, CR, and MO dyes' uptake reactions are in agreement with the kinetic behavior of the pseudo-first-order model and the equilibrium properties of the Langmuir model. Such modeling results, in addition to the Gaussian energies from the Dubinin-Radushkevich (D-R) model (SF (1.01 kJ/mol), MG (1.08 kJ/mol), CR (1.11 kJ/mol), and MO (1.65 kJ/mol)), hypothesize monolayer adsorption of the four dyes by physical reactions. The KNTs show theoretical q max values of 431.6, 489.9, 626.2, and 675.5 (mg/g) for SF, MG, CR, and MO, respectively. The thermodynamic examination of SF, MG, CR, and MO adsorption reactions using KNTs verifies their adsorption by exothermic and spontaneous reactions. The KNT adsorbents achieve promising adsorption results in the presence of different coexisting ions and show significant recyclability properties. Therefore, the production of KNTs from kaolinite shows a strong effect on inducing the textural, physicochemical, and adsorption properties of clay layers as well as their affinity for different species of synthetic dyes.

Magnetic methacrylated gelatin-g-polyelectrolyte for methylene blue sorption

The presence of organic dyes in wastewater is a problem of growing interest due to its effect on the environment and human health. The aim of this work was to obtain magnetic hydrogels of methacrylated gelatin-g-polyelectrolyte to be used for the removal of methylene blue (MB) used as a model contaminant dye. Grafted gelatins with two degrees of functionalization (48% and 76%) were obtained and subsequently crosslinked using 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) and sodium 4-vinylbenzenesulfonate (SSNa) monomers. Magnetic nanoparticles were formed by an in situ precipitation method to easily remove the hydrogel from the adsorption medium. Our data show that the hydrogel with a low degree of methacrylation displayed a high degree of swelling and decreased stiffness due to its less connected polymer network. MB adsorption experiments showed that neither the low degree of methacrylation nor the presence of the aromatic group in the PSSNa polyelectrolyte generated an increase in the adsorption capacity of the hydrogel. However, a significant increase in the adsorption capacity was observed when dry hydrogels were combined compared to that of previously swollen hydrogel. The experimental data were non-linearly fitted to the pseudo-first and pseudo-second order models and in both cases, the highest q_e values were obtained for the GelMA-HF/PAMPS and GelMA-LF/PAMPS hydrogels. The Freundlich isotherm model was the one with the best correlation with the data (r² > 0.9700). Higher k_f values were obtained for the GelMA-HF/PAMPS and GelMA-LF/PAMPS hydrogels at 20 °C. The results obtained from this study demonstrated that magnetic polyelectrolyte-grafted gelatins are an efficient option for the removal of contaminant dyes from aqueous solutions.

Magnetic methacrylated gelatin grafted with anionic polyelectrolytes hydrogels removes methylene blue efficiently and easily separate with a magnet.

Innovative bactericidal adsorbents containing modified xanthan gum/montmorillonite nanocomposites for wastewater treatment

Herein, we reported the preparation of novel antibacterial nanocomposites based on biodegradable polymers. The nanocomposites were applied as capable adsorbent for removing of malachite green (MG) dye, as well as inhibiting of E. coli and S. aureus growth as the most common pollutants for water. The grafted xanthan gum with poly(vinylimidazole) (XG-g-PVI) nanocomposites were synthesized in the presence of different Montmorillonite (MMT) nanoclays concentrations (1%, 3% and 5%). The prepared modified XG nanocomposites were detected through XRD, SEM-EDX, FTIR and TEM. The maximum adsorption MG capacity was determined as 99.99% (909.1 mg/g) in basic medium at 30 °C for 90 min. The adsorption isotherm for removal of MG dye was studied against different models like Langmuir, Freundlich, Temkin, FloryHuggins isotherm models, however, the adsorption results were good fitted with Langmuir isotherm model (R² = 0.9942). Additionally, various adsorption kinetic models: pseudo-first order, second order, pseudo-second order, and intra-particle diffusion models were studied for adsorption mechanism of MG dye on top of prepared nanocomposite surface. Finally, the antibacterial activity outcomes displayed that the prepared XG-g-PVI/MMT nanocomposites had excellent inhibition growth for bacteria and the antibacterial activity increased abruptly with the increased of MMT nanoclay concentrations.

Adsorption and desorption of malachite green by using chitosan-deep eutectic solvents beads

Chitosan-deep eutectic solvent (DES) beads were prepared from chitosan and DESs. The DESs used were choline chloride-urea (DES A) and choline chloride-glycerol (DES B). Both chitosan-DES beads were used to remove malachite green (MG) dye from an aqueous solution. The optimum pH for chitosan-DES A was recorded at pH 8.0 while optimum pH for chitosan-DES B was pH 9.0. The maximum adsorption capacity obtained for chitosan-DES A and chitosan-DES B were 6.54 mg/g and 8.64 mg/g, respectively. The optimum conditions for both chitosan-DES beads to remove MG were 0.08 g of adsorbent and 20 min of agitation time. Five kinetic models were applied to analyse the data and the results showed that the pseudo-second-order and intraparticle diffusion model fitted best with R² > 0.999. For the adsorption capacity, results show that the Freundlich and Langmuir adsorption isotherms fitted well with chitosan-DES A and chitosan-DES B, respectively. The maximum adsorption capacities (q_max) obtained from chitosan-DES A and chitosan-DES B were 1.43 mg/g and 17.86 mg/g, respectively. Desorption indicated good performance in practical applications.