Electrochemical removal of crystal violet dye from simulated wastewater by stainless steel rotating cylinder anode: COD reduction and decolorization

Abstract

Crystal violet dye is a harmful organic pollutant when it exists in wastewater. It may potentially cause renal failure and respiratory issues in humans, while it is considered carcinogenic and mutagenic in aqua life. In this study, crystal violet dye was electrochemically removed from simulated wastewater using a stainless-steel rotating cylinder anode. Effects of anode rotation rate (250–500 rpm), applied current (400–750 mA), concentration of supporting electrolyte (0.3–0.6 M), and time (30–70 min) on chemical oxygen demand (COD) reduction and colour removal were studied. The experimental results were correlated by two quadratic regression models: one for COD reduction with R2 equals to 0.859, and one for colour removal with R2 equals to 0.934. Process optimization was conducted using the response surface methodology (RSM) with a rotatable central composite design CCD. The results showed that the optimum conditions for maximum COD reduction (86.89 %) and maximum colour removal (88 %) are as follows: anode rotation rate = 625 rpm, applied current = 658.568 mA, supporting electrolyte = 0.422 M and treatment time = 90 min. Generally, all the studied factors have a potential effect on the process efficiency.