Kinetics of Acid Orange 7 oxidation by using carbon fiber and reticulated vitreous carbon in an electro-Fenton process

Abstract

In this study, a micro-scale parallel plate reactor was built to electrochemically generate hydrogen peroxide (H₂O₂) and to develop the Fenton reaction in situ, for the treatment of toxic organic pollutants. Two types of carbon materials were compared and used as cathodes: unidirectional carbon fiber (CF) and reticulated vitreous carbon (RVC). As anode, a stainless steel mesh was used. The results of H₂O₂ were experimentally compared by means of electrogeneration process. RVC cathode with dimensions of 2.5 × 1 × 5 cm (170 mA and variable voltage V = 2.0-2.7) and 180 min produced 5.3 mM H₂O₂, with an H₂O₂ production efficiency of 54%. Unidirectional carbon fiber cathode produced 7.5 mM of H₂O₂ (96% of H₂O₂ production efficiency) when a voltage of 1.8 V was applied during 180 min to a total area of 480 cm² of this material. Acid Orange 7 (AO7) was degraded to a concentration of 0.16 mM during the first 40 min of the process, which represented 95% of the initial concentration. Electrolysis process removed nearly 100% of the AO7 using both cathodes at the end of these experiments (180 min).

Keywords: Cost analysis; Electrochemical process; Oxidation kinetics; Reticulated vitreous carbon; Unidirectional carbon fiber.