Aminophenols formation from nitrophenols using agar biopolymer hydrogel supported CuO nanoparticles catalyst

In this article, copper (II) oxide (CuO) nanomaterial was synthesized by a quick microwave heating method from the basic pH copper sulfate solution and mixed with agar (AG) biopolymer powder aqueous suspension to make the AG-CuO nanocomposite hydrogel. The mixture was subjected to hydrogel formation by using the thermal treatment at 85 degrees C followed by cooling to 25 degrees degrees C. The spontaneous turning of the hot AG-CuO fluid to a soft hydrogel was confirmed. The synthetic steps for the AG-CuO hydrogel were verified by different techniques such as FESEM, EDX, TGA and XRD. The AG-CuO hydrogel was utilized as catalyst in the reduction of three different nitroarenes of 4-nitrophenol (4-NP), 2,6-dinitrophenol (2,6-DNP) and 2-nitrophenol (2-NP) to corresponding aminophenols by using sodium borohydride. The AG-CuO was able to reduce the nitroarenes in the increasing rate order of 4-NP > 2-NP > 2,6-DNP. The AG-CuO hydrogel catalyst showed good and easy recyclability as revealed by five times use in the same reduction reaction while keeping the high catalytic activity. The data provided in this article by using AG-CuO hybrid hydrogel suggest that it could be an efficient material for the other water-based chemical reduction reactions.