Green Synthesis of Cu Loaded Gel Membrane Biocomposite as a Highly Efficient and Recyclable Catalyst for 4‐Nitrophenol Reduction

The catalytic reduction of 4‐nitrophenol (4‐NP) is essential for addressing environmental pollution caused by toxic nitroaromatic compounds. While traditional transition metal nanoparticles often suffer from aggregation and recyclability issues, this study presents an eco‐friendly approach to fabricate a biocatalytic membrane. The biocomposites (Cu@O‐CP) consist of copper nanoparticles (Cu NPs) uniformly supported on a chitosan‐polyvinyl alcohol network crosslinked by oxidized sodium alginate (OSA). Characterization confirms the successful complexation between the gel membrane and Cu NPs. The optimized catalyst, Cu@O‐CP‐3 (with 0.5% OSA), possesses a mesoporous structure with the max specific surface area (2.5368 m 2 /g) and Cu loading content (15.1492%). In the reduction of 4‐NP, Cu@O‐CP‐3 demonstrates good catalytic performance with the apparent rate constant ( k ) of 0.01605 s −1 , the turnover frequency (TOF) of 8.21 h −1 , and a low activation energy ( E a ) of 31.07 kJ mol −1 . The catalytic efficiency is enhanced under acidic conditions due to facilitated proton transfer. Moreover, the catalyst exhibits excellent structural stability in various solvents and retains considerable activity over 5 cycles. This work highlights the potential of bio‐based gel membranes as sustainable and efficient platforms for heterogeneous catalysis in environmental remediation.