Studies on Electrochemical Treatment of Reactive Black 5 Dye and Urea Solutions using Indigenously Developed and Commercial Electrodes

Abstract

The present study aims at removal of organic model pollutants Reactive Black-5 (RB- newline5) dye and urea from aqueous solutions using advanced electrochemical oxidation newlinetechnology. In this context, mixed metal oxide (MMO) electrodes, popularly known as newlinedimensionally stable anodes (DSA), were indigenously developed using the standard newlinethermal decomposition technique in three phases by involving catalytic coatings newlinecomprising of single to quinary metal oxide combinations over Ti substrate. These anodes newlinewere prepared specifically catering to selective catalytic organics oxidation, high service newlinelife and stability, efficient process economics in terms of energy efficacy as well as newlineaffordability in view of practical implementation. Initial studies were directed towards newlinedeciding favourable operating parameters affecting electrooxidation like pH, current newlinedensity and electrolyte concentration employing Taguchi L27 array design and its newlineanalysis via MINITAB 17 statistical software. Extended electrooxidation of synthetic newlinesolutions containing 1000 mg/L RB-5 dye and 300 mg/L urea was independently newlineconducted under acidic pH and using NaCl electrolyte in both batch and continuous newlinereactor operation modes. Amongst all DSAs tested for RB-5, quinary-DSAs performed newlinebest in terms of higher COD, TOC and colour abatements. Hence, quinary-DSAs were newlinefurther adopted for investigating batch electrooxidation of urea solutions in terms of TN newlineabatement. The electrochemical treatment performance of quinary-DSAs was further newlinecompared with that of commercial Boron Doped Diamond (Si/BDD) electrodes with two newlinedifferent boron doping levels of 100 ppm and 10000 ppm boron (B) respectively. Further, newlineusing the acquired data on COD, TOC, colour and TN removal, overall treatment efficacy newlineof various anodes was also assessed in terms of associated electrochemical process newlineparameters such as current efficiency (CE), mineralization current efficiency (MCE), newlinespecific energy consumption, electrochemical oxidation index (EOI), kinetics of pollutant newlinedegradati