Chitosan coated cotton cloth supported zero-valent nanoparticles: Simple but economically viable, efficient and easily retrievable catalysts

A simple, economically viable and fast method has been utilized for the preparation of highly active metal nanoparticles (MNPs) in coating layer of chitosan (CH) over cellulose microfibers of cotton cloth (CC). 2 wt% of CH solution was used for the coating of CC strips (CC-CH), and were kept in aqueous solutions of metal salts to adsorb metal ions. The CC-CH templated with metal ions were then treated with aqueous solution of NaBH₄ to reduce the metal ions into zero-valent metal nanoparticles (M⁰). The CC-CH strips loaded with M⁰ were characterized by XRD, XPS, ATR-FTIR, FE-SEM and TGA, which indicates the successful synthesis of MNPs by this method. The M⁰/CC-CH strips were used as an efficient catalyst for the model reduction reaction of nitrophenol and toxic organic dyes. Among all the prepaped samples, Fe/CC-CH showed good catalytic activity for 4-NP and Rh-B dye reduction in the presence of NaBH₄ with rate constants of 0.2937 min^-1 and 0.3804 min^-1, respectively. Moreover Fe/CC-CH has good catalytic reduction ability for MO and MB having rate constants equal to 0.1698 and 0.2802 min^-1, respectively. Beside the good catalytic ability, it could be easily recoverable as compared to other available techniques. The recovery was completed by simply pulling the strip from the reaction matrix after completion of the reaction and can be used several times.