Electrochemical Oxidation of Synthetic Dyes in Simulated Wastewaters

Abstract

An electrochemical oxidation method for the degradation of synthetic reactive azodyes found in textile wastewaters is discussed. Four commercial synthetic dyes (black, blue, red and yellow) commonly used in dying operations were studied in single, binary and ternary mixtures. Low (100 mg/L) and high (500, 1,000 and 2,000 mg/L) initial dye concentrations were studied. The effect of various sodium chloride concentrations (as supporting electrolyte) on the effectiveness of electrochemical oxidation was examined. The effect of current intensity (1.5, 2.5 and 3.0 A) and pH (vales 3, 5, 7 and 10) was studied as well. The kinetics of the electrochemical oxidation for each dye were studied and compared. The conditions for effective dye degradation even from 2,000 mg/L initial concentration were established. The method was proved very effective even with binary and ternary mixtures of basic synthetic dyes. The Chemical Oxygen Demand (COD) and the Total Organic Carbon (TOC) were reduced by 60% and 25% respectively, meaning that the treated solutions were friendlier to the environment.