Copper Nanoparticles Supported by Starch‐Grafted Poly(N,N‐dimethyl acrylamide) Hydrogel as a Novel Heterogeneous Catalyst for Efficient Reduction of 4‐Nitrophenol

A novel starch‐grafted poly( N , N ‐dimethyl acrylamide) hydrogel or starch‐ g ‐PDMAA hydrogel was successfully synthesized by grafting of the hydroxyl groups on the starch with N , N ‐dimethyl acrylamide (DMAA), ethylene glycol dimethacrylate (EGDMA) as a crosslinker, and ceric ammonium nitrate (CAN) as an initiator. Additionally, copper nanoparticle‐supported starch‐grafted poly( N , N ‐dimethyl acrylamide) or CuNPs/starch‐ g ‐PDMAA composite was prepared by the reduction reaction of copper ions (Cu 2+ ) loaded in the starch‐ g ‐PDMAA hydrogel network using sodium borohydride (NaBH 4 ) as the reducing agent and then characterized by various techniques such as scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDS), Fourier transform‐infrared (FTIR) spectroscopy, X‐ray powder diffractometer (XRD), and thermogravimetric analysis (TGA). To study the catalytic activity, the CuNPs/starch‐ g ‐PDMAA composite was also utilized to reduce 4‐nitrophenol (4‐NP) in the presence of NaBH 4 . The kinetics of the reaction were investigated by UV–visible spectroscopy, and various parameters such as the initial amount of NaBH 4 , the catalyst dosage, and the reaction temperature were also studied. It was found that E a , ΔH, # and ΔS # were 24.76 kJ mol −1 , 21.74 kJ mol −1 , and −183.47 J mol −1 K −1 , respectively. The supported CuNPs could act as an alternative heterogeneous catalyst for reducing 4‐NP, as the most common environmental pollutant. Starch‐ g ‐PDMAA hydrogel can be effectively used to support the preparation of copper nanoparticles, with a great potential application.