Chitosan was combined with zeolites into composite membranes reinforced with glutaraldehyde crosslinking. The zeolite loading in the composite membranes was varied in the range 10-50 %, and the resulting membrane loading was varied at around 50 wt. %. The zeolite-loaded membranes showed better mechanical properties. The elimination of trace metal cations, Cr, As, Cd and Pb, by the chitosan-zeolite composite membranes was examined through the evacuation permeation process (EPP). In the permeability at each applied pressure, the selectivity of the composite membranes to the Cr ion was shown in the order of Cr > As > Cd > Pb at pH 5.5. It was noticed that the composite membrane with 20 wt. % zeolite loading showed the highest performance in the adsorption selectivity to the Cr cations. These results reveal the potential ability of the composite membrane to purify wastewater by removal of trace metal ions.
Cellulose was chemically extracted from tea residue and then a cellulose-based hydrogel was fabricated as an adsorbent to remove methylene blue from aqueous solutions. In this study, the cellulose-based hydrogel was prepared based on the copolymerization of acrylic acid (AA) on cellulose materials, with the addition of N,N'-methylene bis-acrylamide (MBA) as crosslinking agent, assisted by ammonium persulfate (APS) as initiator. The adsorption of the methylene blue (MB) solution onto the cross-linked cellulose-based hydrogel was studied by the static adsorption method under different conditions of pH, contact time, adsorbent dosage and initial methylene blue concentration. The results showed that for 50 mg/L of methylene blue solution as the initial concentration, the optimum pH was 10 and the adsorption efficiency was up to 98.89%. The analysis of the adsorption equilibrium isotherm strongly indicated that the adsorption by the hydrogel material was best fitted by the Langmuir model, with the maximum adsorption capacity of 41.67 mg/g. Furthermore, the cellulose-based hydrogel maintained high reusability and efficiency in methylene blue adsorption after desorption.
In this study, the N,N-dimethyl acetamide (DMAc) solution with different lithium chloride concentrations of 3 wt%, 5 wt%, and 7 wt% by phase inversion in ethanol vapor to produce chitin hydrogels for plant growth. The chitin hydrogel prepared with a higher concentration of lithium chloride showed improvements in elastic and mechanical properties. The tensile strength was enhanced from 275.8 to 434 kPa for the chitin hydrogel with 3% and 7% of LiCl. While the reduction in water content suggested forming a denser hydrogel structure at higher LiCl concentrations; the water contact angle (WCA) value indicated that chitin-derived hydrogels are hydrophilic. Moreover, the bio-degradation experiment indicated the degradable percent of the chitin hydrogel placed in 10 mg/L of aqueous lysozyme solutions at 37 • C increases during 7 to 28 days from 4.72 wt% to 5.45 wt%. The obtained hydrogel was suitable for the growth and development on rosemary plants. The condition CE15 with the hydrogel of 85 wt% chitin-derived hydrogel and 15 wt% cellulose as best medium planting with the largest effect on the height, the crown's diameters and the number of level-one branches of the rosemary plants.
Chitosan and zeolite were composited by incorporation of zeolite into chitosan membranes in varying amounts from 50 to 100wt% of chitosan and glutaraldehyde was used to crosslinking.The zeolite loading in the chitosan membranes was varied in the range of 10%-30%, showing high mechanical properties even in the high zeolite loading. Potential adsorption targeted to waste elimination of heavy metal cations was carried out by using the chitosanzeolite composite membranes. In the permeation experiment, the selectivity of the composite membranes to especially chromium (Cr) was observed in the order of Cr>As>Cd >Hg>Pb>Cu. It was noted that the composite membrane having zeolite loading with 30 wt.% showed the highest performance adsorption selectivity. These results reveal that the composite membranes had a potential avility to purify wastewater by removing heavy metal ions.
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