Removal of methyl orange from aqueous solution by electrochemical process using stainless steel/PbO2-TiO2 stable electrode

Abstract

Methyl orange (MO) belongs to the group of acid dyes with an azo chromophore. It is a toxic sub-stance that harms human health and the environment. Therefore, it is very necessary to treat MO before discharged into environment. In this paper, the sol–gel TiO2 nanoparticles were dopped into PbO2 layer on stainless steel (SS) substrate by the cyclic voltammetry method. The obtained SS/PbO2-TiO2 composite electrode was used to remove MO from the aqueous solution. The effects of current density, initial pH, degradation time, and MO concentration were investigated. The results by X-ray diffraction showed that the β-PbO2 co-existed with α-PbO2 in composite coating. TiO2 particles have been successfully doped into the PbO2 layer because of containing 0.3% Ti proven by energy dispersive X-ray spectroscopy examination. The optimal conditions for MO treatment were a current density of 1.75 mA cm–2, initial pH of 6, degradation time of 50 min, and MO concentration of 50 mg L–1. The decolorization efficiency reached 99.31%, indicating that the MO was almost completely removed in the aqueous solution by electrocatalytic oxidation method using the stable electrode SS/PbO2-TiO2 as the anode.