Decolorization of the azo dye Reactive Violet 5 by UV-A-Fenton and Ultrasound-Fenton Processes

Abstract

The textile dye Reactive Violet 5 (RV5) is mutagenic and teratogenic as well as carcinogenic and must be degraded before the release of textile wastewater into the environment. The aim of this work was to assess UV-A LED and ultrasound (US) reactors in RV5 degradation. Different AOPs were tested, Fenton and UV-A-Fenton processes showed the highest RV5 degradation with 86.6 and 95.5%, respectively. The UV-A-Fenton operational conditions were optimized varying initial pH (3.0–7.0), H2O2 (2.0–16.0 mM) and Fe2+ (0.05–0.20 mM) concentrations. The best deduced operational conditions (pH = 3.0, [RV5] = 0.28 mM, [H2O2] = 4.0 mM, [Fe2+] = 0.15 mM) were applied to the US-Fenton process, achieving a RV5 removal of 95.7%. The lowest values of electric energy per order (EEO) = 11 kWh m−3 order−1 and specific applied energy (ESAE) = 38 kWh mol−1 order−1 were obtained with the treatment of RV5 aqueous solution by the UV-A-Fenton process. This work shows that textile dyes can be degraded by UV-A-Fenton and US-Fenton processes and the UV-A LED reactor presented the lowest operational costs.

Keywords

• electric energy per order
• Reactive Violet 5
• UV-A-Fenton
• US-Fenton