Improvement of dye electrochemical treatment by combination with ultrasound technique

Abstract

AbstractBACKGROUND: Currently, the combination of conventional physicochemical techniques appears to be an attractive option to apply to wastewater treatment. In this work, a hybrid technique, called sonoelectrochemistry as a result of the combination of electrochemical and ultrasound technology, was undertaken in order to increase the efficiency of textile wastewater remediation.RESULTS: Results have demonstrated the superiority of the sonoelectrochemical process over each treatment alone. Although in the sonoelectrochemical treatment, the decolourisation rate of di‐azo dyes was lower than mono‐azo or diphenylnaphthylmethane dyes, in all cases a first‐order kinetic behaviour was detected. In addition, the influence of inert electrolyte concentration (Na2SO4) was assayed. On the other hand, colour removal was considerably faster than the decrease in chemical oxygen demand (COD), which was attributed to the ease of chromophore destruction. Hence, for example for Lissamine Green B the efficiency of sonoelectrochemical decolourisation was 95% compared with 60% of COD removal after 1 h treatment. Additionally, a flow system with total reflux by the electrochemical and the sonoelectrochemical treatment was considered and a similar behaviour to previous experiments was found.CONCLUSIONS: Based on the results obtained, the feasibility of this hybrid technique was demonstrated. Furthermore, an efficient flow system was devised for dye decolourisation, which could be extrapolated to develop a continuous process. Copyright © 2009 Society of Chemical Industry