Eco-friendly and biodegradable sodium alginate/quaternized chitosan hydrogel for controlled release of urea and its antimicrobial activity.

Hydrogels could be employed in agriculture for efficient management of water and controlled-release urea (CRU). This study aimed to synthesize a superabsorbent hydrogel for CRU by cross-linking sodium alginate (Alg) and N-(2-hydroxy-3-trimethyl ammonium) propyl chitosan chloride (HTACC). The hydrogel structure was characterized by various techniques, and the urea loading and releasing behaviors of the synthetic hydrogels were investigated. The results revealed that the maximum urea loading ranged between 107 and 200%, and that the urea loading kinetics fitted with Langmuir model followed by the Freundlich model. The urea release behavior reached equilibrium after 30 days and urea releasing kinetics fitted with the zero-order and Higuchi models. The synthesized hydrogels exerted significant antimicrobial activities and molecular docking showed their binding affinity toward glucosamine-6-phosphate synthase, ß-lactamase II, TraR binding site and nucleoside diphosphate kinase. In conclusion, these Alg/HTACC hydrogels showed swelling, urea release, and antimicrobial properties suitable to meet the plant requirements and produce economic and environmental benefits.

Synthesis and characterization of diphenylamine grafted onto sodium alginate for metal removal.

A novel grafting polymer was synthesized via grafting of diphenylamine (DPA) onto sodium alginate (NaAlg) as a new adsorbent for Cobalt (Co2+) from aqueous solutions. Optimization of sodium alginate grafted by diphenylamine (NaAlg-g-DPA) was addressed in the current study by several parameters including; initiator and monomer concentrations, contact time of polymerization, as well as polymerization temperature. In addition, the structural and chemical characteristics of NaAlg-g-DPA were explored using different modalities later. The results showed that sodium alginate grafted by diphenylamine (NaAlg-g-DPA) is suitable for adsorbent to removal Co2+ ion. The parameters for the adsorption of Co(II) ions by NaAlg-g-DPA were also determined. It was shown that the samples of NaAlg-g-DPA had given good correlation with Temkins isotherm model and their kinetics followed pseudo-second-order model. It was also observed that the adsorption capacity seemed to be dependent on pH value in solution which showed better results at basic pH. The findings from this research show that NaAlg-g-DPA has capability to remove Co (II) from aqueous solutions.

Photocatalytic degradation of malachite green dye using chitosan supported ZnO and Ce-ZnO nano-flowers under visible light.

Two types of chitosan-based composites (chitosan/ZnO and chitosan/Ce-ZnO composites) were synthesized under microwave irradiation and characterized as advanced catalysts of enhanced photocatalytic activity under the visible light. The morphological investigation reflected the formation of ZnO and Ce doped ZnO at stunning micro flowers of nano limps. Additionally, the optical studies reflected a reduction in the bandgap of ZnO from 3.3 eV to 2.85 eV and 2.5 eV after supporting it onto chitosan chains and after doping it with cerium, respectively. The synthetic composites were applied in photocatalytic removal of malachite green dye under a visible light source. The synthetic CH/ZnO and CH/Ce-ZnO showed enhancement in the photocatalytic removal of M.G by 54% and 87%, respectively, as compared to the pure ZnO. The synthetic composites are of high stability and can be reused for five photocatalytic degradation cycles at stunning removal percentages. The main oxidizing radicals during the removal of M.G by CH/ZnO are the generated electron-hole pairs as well as the hydroxyl radicals. The effective species in CH/Ce-ZnO photocatalytic system are the photogenerated hydroxyl radicals followed by the electron-hole pairs.

Synthesis, characterization and antimicrobial activity of Schiff bases modified chitosan-graft-poly(acrylonitrile).

Graft copolymerization of chitosan (Ch) with acrylonitrile (AN) prepared by free radical polymerization using potassium persulfate (PPS) as initiator. Optimization of Graft copolymerization of acrylonitrile on to chitosan was performed by studying the main parameters that affecting the grafting process such as initiator and monomer concentrations, reaction time and temperature of the polymerization process to study their influence on percent grafting (G%), grafting efficiency (GE%) and percent homopolymer (H%). Modification of grafted chitosan was done by Schiff's base derivatives using different aldehydes. They are characterized by FT-IR, X-ray diffraction, thermal analysis and scanning electron microscope. Their antibacterial activities against Streptococcus pneumonia (RCMB 010010), Staphylococcus aureus (RCMB 010028), as Gram-positive bacteria and Escherichia coli (RCMB 010052) as Gram-negative bacteria and the antifungal activity against Aspergillus fumigatus (RCMB 02568), Candida albicans (RCMB 05036) and Geotricum candidum (RCMB 05097) were examined using the diffusion agar technique. The obtained data proved that modified chitosan by grafting show better antimicrobial activities than Chitosan. Also Schiff base derivatives showed better antimicrobial activities than grafted chitosan.