Comparative study of 4-dimensional DSA on electrochemical treatability of a reactive dye

Abstract

Electrochemical oxidation is a continuously evolving advanced effluent abatement technology for complex and difficult organic wastewaters generated from various industries like dyes, tannery, pharmaceuticals, landfill leachates, etc. The removal and degradation of dyes from textile effluents to simpler compounds prior to their final discharge or reclamation has turned out to be a demanding issue. The present study attempts to treat synthetic Reactive Black 5 (RB-5) dye effluent by indirect electro-oxidation employing Dimensionally Stable Anode (DSA) type working electrodes. In this study, four different 4-dimensional (D) DSAs tested for RB-5 electrooxidation were indigenously prepared in the laboratory on titanium (Ti) substrate by thermal decomposition. Performance of these freshly fabricated electrodes viz. Ti/ZrO-RuO2-Sb2O5-SnO2, Ti/CeO-RuO2-Sb2O5-SnO2, Ti/CoO-RuO2-Sb2O5-SnO2 and Ti/AgO-RuO2-Sb2O5-SnO2 was investigated on percentage removal and decolourization of 500 mg/L of synthetic RB-5 dye solution. Laboratory scale batch reactor of 1 L capacity and a working volume of 500 mL was used under operating conditions of constant ionic strength at neutral pH, current density 50 mA/cm2, 8 mm interelectrode distance and 1 hr electrolysis duration for all experiments. NaCl served as supporting electrolyte to enhance solution conductivity. Colour, TOC and COD reduction were measured at regular periods of time by UV–Visible spectrophotometer, COD reactor and TOC analyser respectively. Surface morphology, coating formulation and microstructure of the best performing anode were explored using SEM-EDX and XRD. Maximum colour, COD and TOC reduction attained were 99%, 80% and 39% respectively employing Ti/ZrO-RuO2-Sb2O5-SnO2 electrode. Further detailed analysis was carried out for all tested anodes in terms of current efficiency (ICE), energy consumption (EC) and evaluation of kinetic rate constants.