Removal of Basic Blue 9 Dye by Hydrogen Peroxide Activated by Electrogenerated Fe²⁺/Fe³⁺ and Simultaneous Production of Hydrogen

Abstract

Electrochemical techniques were used to oxidize organic pollutants by Fenton process using a mix of H 2 O 2 and ferrous ions at a parallel plate reactor. The first stage was to build a micro scale reactor comprising two compartments, cathode and anode, separated by a membrane (Nafion-117). Each compartment has inlets and outlets to allow the flow of fluids (10 Lmin -1 ). The function of the reactor is to oxidize organic pollutants as well as to produce H 2 . Hydrogen is electrogenerated in the catholyte by the reduction of protons on a carbon steel cathode in acidic medium (0.05 M H 2 SO 4 ). At the same time, a mixture of Fe 2+ /Fe 3+ ions is produced in the anolyte (0.05 M Na 2 SO 4 , pH ≈ 2) by means of the oxidation of a sacrificial electrode made of stainless steel mesh. Fe 2+ /Fe 3+ ions interact with H 2 O 2 to generate strong oxidants which are responsible for oxidizing the organic matter and removing color. A voltage of 1 V was applied between the electrodes and remained constant, while the current observed was approximately 0.06 A. Under these conditions, the activation rate with different H2O2 concentrations (15, 20, 25, 30, 35, 40, 45 and 50 mM) was evaluated. The maximum activation rate (1.3 mM·min -1 ) was obtained using 30 mM H 2 O 2 . Under these conditions, the oxidation of a synthetic industrial effluent (0.615 mM BB9) was performed and the following results were obtained: 95% of this concentration was removed in 5 minutes and 15 mL of H 2 was electrogenerated in 30 minutes.