Degradation of methylparaben by anodic oxidation, electro-Fenton, and photoelectro-Fenton using carbon felt-BDD cell

In this study, the comparative efficiency of different electrochemical advanced oxidation processes, such as anodic oxidation with electrogenerated H2O2 (AO- H2O2), electro-Fenton (EF), and its combination with UV irradiation (photoelectron-Fenton (PEF)), was investigated for the removal of methylparaben (MP) using a carbon felt cathode and a boron-doped diamond anode. The EF process achieved a higher MP removal efficiency than the AO-H2O2 process for all applied current densities. The total organic carbon (TOC) removal after 6 h of treatment at a current density of 10 mA cm-2 reached 75.0% and 91.9% for the AO- H2O2 and EF processes, respectively. The combination of EF and UV light improved the efficiency of the EF process. The PEF process achieved a TOC removal of 84.6% in only 2 h at 5 mA cm-2 and 96.8% after 6 h of treatment. Furthermore, based on identifying oxidation reaction intermediates and short-chain carboxylic acids generated during the treatment, a reaction pathway for methylparaben mineralization by hydroxyl radicals was proposed.