Electrocatalytic Oxidation of Orange 122 in Wastewater by Using Three-Dimensional Electrochemical Reactor (3DER)

Abstract

The effect of different catalysts on the oxidation of Orange 122 in wastewater is investigated by using an electrocatalytic system. For this study, TiO2/AC, V2O5/TiO2/AC and WO3/TiO2/AC (over activated carbon) catalysts were prepared by a sol–gel method in aqueous solution. The oxidation process was optimised by investigating the effects of differemnt paperemeter, for example, time, voltage, suspension’s pH, dye concentration, the amount of supporting electrolyte (NaCl) and the type of catalysts used. Optimum values for these parameters were found as 120 min., 15 volt, 6.5, 250 mgL-1 and 800 mgL-1 respectively. All experiments were carried out at room temperature and in the stability of constatant. During the experiment, samples were taken prediocally and the residual dye concentration present in aqueous wastewater samples was analysed to evaluate the efficiency of different catslysts. The results obtained show that after 30 minutes only 30% colour was removed in the absence of activated carbon and this value increased to 60% in the presence of activated carbon. However, the percentage removal increased to 98% in the presence of cataysts TiO2/AC, V2O5/TiO2/AC and WO3/TiO2/AC under the same experimental conditions. In addition, when used as the working electrode in a three-dimensional photoelectrochemical reactor, for all catalyst reacting, the pseudo-first-order rate constants were obtained amoung 1,12 10-2 min-1 and 3,97 10-2 min-1 with the individual use of the composite in electrocatalysis. .The high degradation efficiency of this system is attributed to the synergistic combination of different chemical processess ocurring simultaneously, for example, adsoption, electrocatalytic and electrochemical oxidations.