Electro-Fenton, solar photoelectro-Fenton and UVA photoelectro-Fenton: Degradation of Erythrosine B dye solution.

The treatment of Erythrosine B, selected as a model compound, has been comparatively studied by electrochemical advanced oxidation processes (EAOPs) such as electro-Fenton, UVA photoelectro-Fenton and solar photoelectro-Fenton at constant current density. Experiments are performed in a one-compartment cell with a BDD anode, and a commercial carbon felt cathode at pH = 3, treating a volume of 0.3 L in each test. The irradiation plays a crucial role in the increasing of hydroxyl radical production and in the recover of iron catalyst. A faster colour and COD removal degradation are achieved under the light application. UVA photoelectro-Fenton and solar photoelectro-Fenton processes allow degrading COD entirely in 90 min, while a conventional electro-Fenton does not reach 90% COD removal after 2 h. Energy consumptions are a substantial factor in process selection. Photo electro-Fenton with a UVA-100 W lamp has one of the best removal performance, but it becomes not suitable for application due to high energy demand, up to 515.6 kWh m, and the UVA system requires the main fraction of this energy. Possible alternatives are proposed to contain costs: the first is the reduction of UVA lamp power to 25 W, maintaining a high-performance removal with an E decreasing to 187.9 kWh m. Nevertheless, the lowest and competitive energy demands is obtained working with a solar photoelectro-Fenton system, where energy consumption are only related to the electrochemical process (20.9 kWh m), and removal is complete.