Effective Electro-Fenton Degradation of Reactive Black 5 Dye using Modified Electrode with Cu-Zeolites

Abstract

The electrocatalytic production of hydroxyl radical (HO•) on the surface of zeolite modified electrode (ME) employing Cu-Zeolites (ZSM5 and β) with different theoretical ionic exchange (15 and 100%) was investigated (ME/Cu-Zeolites). The i-E characteristic of ME/Cu-ZSM-5 presented the faradic process associated to redox couple Cu2+/Cu+. On the other hand, voltammetric studies showed that in presence of H2O2, the cathodic peak current of ME/Cu-Zeolites increases followed by a decrease in the corresponding anodic current. This suggested that hydroxyl radical was produced by a cooperative effect of the acidic properties of zeolite and copper that acts as a redox mediator on the electrode surface via an electrocatalytic mechanism. Experiments of degradation using azo dye Reactive Black 5 as probe molecule exhibited that the concentration of azo dye decreased in the time, this confirms the formation of hydroxyl radical on the surface of modified electrode; kinetics parameters demonstrated that the ME/Cu- β with 15% of ionic exchange presented the highest catalytic activity.