Late transition metal complexes bearing chitosan-2,6-pyridine dicarbamide as an intrinsic heterogeneous catalytic converter of 4-nitrophenol

Abstract

The quest for biopolymeric-based heterogeneous catalysts is rapidly increasing owing to added intrinsic recompense. In this study, Chitosan-2, 6-pyridine dicarbamide (CPDC) ligand, and its metal ion complexes [M-CPDC] were synthesized by direct combination method. The characterization of the complexes by FTIR suggested that the amide coordinated with the metal ion through the carbonyl of the amide group. The SEM micrograph of [M-CPDC] showed discrete particles in contrast to the rough surface of CPDC which suggests coordination. The XRD diffractogram of chitosan, CPDC, and [M-CPDC] revealed semi-crystalline, amorphous, and crystalline respectively. The [M-CPDC] were applied as heterogeneous catalysts for the reduction of toxic organic pollutants, 4-Nitrophenol to an environmentally friendly 4-Aminophenol. The synthesized catalysts lowered the activation energy (Ea) range of 0.84–1.30 kJmol−1. However, [CPDC-Ni] showed the highest activity (Ea = 0.84 kJmol−1). The synthesized catalysts displayed higher catalytic activities (reduction process within 60 s) than previously reported. The catalysts were reusable at least five times in the reduction of 4-Nitrophenol.

Keywords

• 2, 6-pyridinedicarbonyldichloride
• Chitosan
• 4-nitrophenol
• Heterogeneous catalyst
• Catalytic efficiency
• Rate constant