Chitosan-titanium oxide fibers supported zero-valent nanoparticles: Highly efficient and easily retrievable catalyst for the removal of organic pollutants

Different chitosan-titanium oxide (CS-TiO₂-x, with x = TiO₂ loadings of 1, 5, 10,15 and 20 wt%) nanocomposite fibers were prepared and kept separately in each salt solution of CuSO₄, CoNO₃, AgNO₃ and NiSO₄ to adsorb Cu²⁺, Co²⁺, Ag⁺, and Ni⁺ ions, respectively. The metal ions loaded onto CS-TiO₂ fibers were reduced to their respective zero-valent metal nanoparticles (ZV-MNPs) like Cu⁰, Co⁰, Ag⁰ and Ni⁰ by treating with NaBH₄. The CS-TiO₂ fibers templated with various ZV-MNPs were characterized and investigated for their catalytic efficiency. Among all prepared ZV-MNPs, Cu⁰ nanoparticles templated on CS-TiO₂-15 fibers exhibited high catalytic efficiency for the reduction of dyes (methyl orange (MO), congo red (CR), methylene blue (MB) and acridine orange (AO)) and nitrophenols (4-nitrohphenol (4-NP), 2-nitrophenol (2-NP), 3-nitrophenol (3-NP) and 2,6-dinitrophenol (2,6-DNP)). Besides the good catalytic activities of Cu/CS-TiO₂-15 fibers, it could be easily recovered by simply pulling the fiber from the reaction medium.