Decolorisation of real textile waste using electrochemical techniques: Effect of the chloride concentration

Abstract

The present paper presents the study of the decolorisation of real textile effluent by constant current electrolysis in a flow-cell using a Ti/Ru 0.3Ti 0.7O 2 DSA ® type electrode. The effect of increasing the chloride ion concentration on the efficiency of colour removal is discussed. Attempts to perform galvanostatic oxidation (40 and 60 mA cm −2) on the as-received effluent demonstrate that colour removal and total organic carbon (TOC) removal are limited. If the conductivity of the effluent is increased by adding 0.033 mol L −1 Na 2SO 4, little increase in the extent of colour/TOC removal is observed. However, when Na 2SO 4 is substituted, stepwise, with NaCl (while maintaining the ionic strength constant) appreciable colour/TOC removal is observed. The study of the effect of increasing the current density demonstrates that total colour removal is possible at high currents. The efficiencies of colour and TOC removal are discussed in terms of the Energy per order ( E EO/kW h m −3 order −1) and Energy consumption ( E C/kW h kg −1TOC), respectively. Finally, the extent of colour removal is compared to consent levels presented in the literature.