Magnetic alginate-carboxymethyl cellulose to immobilize copper nanoparticles as a green and sustainable catalyst for 4-nitrophenol reduction

In the present work, sustainable green catalysts with high activity, and excellent stability were prepared and thoroughly characterized by XRD, FT-IR, BET, VSM, SEM, EDX, HR-TEM, and TGA techniques. The combined sodium alginate (SA) and carboxymethyl cellulose (CMC) biopolymers were functionalized with Fe3O4 nanoparticles to immobilize copper nanoparticles to form Fe3O4@SA-CMC-CuNP nanocomposites in batch experiments. Furthermore, the Fe3O4@SA-CMC-CuNP nanocomposites were utilized as the heterogeneous catalyst for 4-nitrophenol (4NP) reduction to 4-aminophenol (4-AP) in the presence of NaBH4, and the progress of the catalytic reaction was monitored using UV-visible spectrophotometry. The Fe3O4@SA-CMC-CuNP nanocomposite exhibited much higher catalytic activity for the 4-nitrophenol reduction reaction than individual components Fe3O4 and Fe3O4@SA-CMC. The effect of parameters such as the amount of catalyst was evaluated and 30 mg of the catalyst amount with a 95.0% reduction of 4nitrophenol for 1.5 min was obtained. The effect of reaction temperature was also investigated to find out the activation energy. The analyses of kinetics and thermodynamics were carried out to understand the catalytic behavior. Furthermore, the catalyst can be separated from the reaction system through the usage of a magnet and recycled up to five times without any loss of activity. Therefore, the development of sustainable green catalyst biopolymer-based nanocomposites is promising for new catalysts in the future for treating organic wastewater.