A Hybrid Approach: Indirect Electro-Oxidation Followed by In Situ Electrogeneration of H₂O₂ in Real Textile Effluent

A two-step treatment process has been investigated for effective textile effluent management. In step I, the effluent was decolorized via chlorine-mediated indirect electrooxidation (InDEO), while H₂O₂ was electrogenerated during step II in the decolorized textile effluent, by employing an H-type divided electrochemical cell. The native salts present within the decolorized textile effluent (9.4g/L Na₂SO₄ and 0.8g/L NaCl) were exploited as electrolytes for the catholyte, whereas 0.5N sulfuric acid was used as the anolyte for the in situ electrochemical generation of H₂O₂. During the cyclic voltammetry tests, O₂ reduction at the activated carbon felt cathode was observed around -0.86V versus saturated calomel electrode (SCE) at a scan rate of 100mV/s. Under optimized conditions (cathode potential of -0.9V vs. SCE and catholyte at pH 6) about 1.45±0.01mM H₂O₂ have been generated. The effluent containing H₂O₂ was subjected to Fenton reaction and the generation of OH^• radicals was confirmed by electron paramagnetic resonance spectroscopy. The results indicated a 59% reduction of the chemical oxygen demand, significant modifications of the functional groups were observed by Fourier transform IR spectroscopy. High performance LC analysis confirmed the degradation of the organic compounds during the oxidative treatment process. These findings suggest the application of this method for degradation of highly colored textile effluents.