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 FeO nanoparticles to immobilize copper nanoparticles to form FeO@SA-CMC-CuNP nanocomposites in batch experiments. Furthermore, the FeO@SA-CMC-CuNP nanocomposites were utilized as the heterogeneous catalyst for 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) in the presence of NaBH, and the progress of the catalytic reaction was monitored using UV-visible spectrophotometry. The FeO@SA-CMC-CuNP nanocomposite exhibited much higher catalytic activity for the 4-nitrophenol reduction reaction than individual components FeO and FeO@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 4-nitrophenol 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.