TiO2-SiO2/GAC particles for enhanced electrocatalytic removal of acid orange 7 (AO7) dyeing wastewater in a three-dimensional electrochemical reactor

In this work, granular activated carbon (GAC) supported TiO2-SiO2 oxide (TiO2-SiO2/GAC) was prepared and packed in a three-dimensional electrochemical reactor (3DER) for the removal of acid orange 7 (AO7) dyeing wastewater. The characteristics and the electrocatalytic performance of the prepared TiO2-SiO2/GAC were investigated to verify the feasibility of TiO2-SiO2/GAC application as particle electrodes. Results show that the TiO2-SiO2/GAC could significantly improve the AO7 removal efficiency, extend service life of particle electrodes, and enhance the stability of 3DER system. Orthogonal array was designed to optimize the operation parameters of 3DER, which was determined as electric field intensity 1 V/cm, filling amount of TiO2-SiO2/GAC particles 200 g/L, electrolytic concentration (Na2SO4) 0.07 mol/L, pH 3, treatment time 120 min. Under the optimal condition, the AO7 decolorization rate and COD removal efficiency are 83.20% and 48.95% respectively. The possible intermediates generated in 3DER during AO7 decomposition were identified and the biodegradability of the effluent was also estimated. Results suggest that the 3DER with TiO2-SiO2/GAC particle electrodes could be an alternative for the pretreatment of dyeing wastewater before biological treatment. (C) 2017 Elsevier B.V. All rights reserved.