Simultaneous electrodeposition of multicomponent of Mn–Co–Ni oxides electrodes for phenol removal by anodic oxidation

Abstract

Electrodeposition of metal oxides on graphite electrodes can improve their ability to remove organic substances. In this work, multicomponent oxides of Mn, Co, and Ni were electrochemically deposited on both the anode and cathode of graphite electrodes to enhance their performance in removing phenol. Formation of the deposit was achieved within 2 h in current densities of 20, 25, 30, and 35 mA/cm2 for better composite properties. The deposited layer was characterized by testing the surface structure, morphology, composition, and roughness. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and Atomic force microscopy (AFM) techniques facilitated these tests. The composite electrodes have synthesized with a metal salts concentration, i.e., Co(NO3)2, Ni(NO3)2, and MnCl2 of 0.1 M with a mixing ratio of 1:1:1. The results exhibited a remarkable formation of the deposit on both the anode and cathode of our electrochemical cell. An amorphous skin of Mn–Co–Ni oxide was constituted on the anode, while a crystalline film of Mn–Co–Ni oxide accumulated on the cathode. The effectiveness of composite electrodes was examined at current densities of 40, 60, and 80 mA/cm2, pH values of 3, 4 and 5, and NaCl concentration of 1, 1.5, and 2 g/l with an electrolysis time of 1 h. The results show that the removal efficiency of phenol increases with the increase in current densities and NaCl concentration, while it decreases with increasing of alkalinity. The highest removal occurs at the pH, current density and NaCl concentration of 3, 80 mA/cm2, and 2 g/l. The highest obtained removal efficiency is 99.68% which reflects a tremendously high performance of our multicomponent composite for phenol removal and reducing electrolysis time compared to previous studies.