Rita Farida Yunus, Environmental Science and Engineering, National University of Singapore, Blk E2, #05-05, Division of Environmental Science & Engineering, 5 Engineering Drive 2, NUS, Singapore, 117576, Singapore, Yuming Zheng, Division of Environmental Science and Engineering, National University of Singapore, 10 kent ridge, Singapore, Singapore, K.G.Nadeeshani Nanayakkara, Division of Environmental Science & Engineering, National University of Singapore, 10 Kent Ridge Cresent, Singapore, 119260, Singapore, and J. Paul Chen, Environmental Science and Engineering, Natioanl University of Singapore, Singapore, Singapore.
Dye-containing wastewater from colorants manufacturing industries presents serious problems to the water environments due to its greater toxicity, carcinogenicity, mutagenicity, and poor biodegradability. Electrochemical technologies appear to be promising, since these technologies are low cost and able to provide full decolourization of dyes. In this study, an efficient electrochemical technology for the removal of Rhodamine 6G, a fluorescent-rigid dye, by using RuO2 coated titanium mesh as dimensionally stable anode was developed and studied. Our results show that, the decolourisation process is favorable under acidic conditions (pH 2 – 4) in the presence of 0.1 – 0.2 M of NaCl as electrolyte salt and the applied current of 1.0 – 1.9 A, and full decolourisation of dye-containing wastewater can be achieved within 5 min under the optimum condition. The simultaneous electrochemical oxidation and coagulation are involved in the removal of dye. Total organic carbon (TOC) analysis reveals, under the optimum conditions (pH 2, 1.9 A, and in the presence of 0.2 M NaCl), the electrochemical process significantly reduces the organic content (~ 95 % of TOC removal) in the wastewater within 5 min. Above 55% of the TOC is removed by forming solid foam products via an electrocoagulation process, and another ~ 40 % of TOC is mineralized by electrochemical oxidation. FTIR and GC/MS spectroscopy were used to analyze the solid foam products and intermediate products to probe the removal mechanism of the electrochemical process.