Electro-oxidation of methyl paraben on DSA®-Cl2: UV irradiation, mechanistic aspects and energy consumption

The electro-oxidation of methylparaben (MeP) was studied using a DSA®-Cl2 in simple electrolysis and hybrid process (electrolysis followed by UV light irradiation), aiming at evaluating the oxidation mechanism, the removal of organic matter and the energy consumption. Analysis of the results revealed that MeP removal is rapid in both processes. However, the formation of a solid byproduct of a polymeric nature, which is probably related to MeP oxidation products, has occurred. Irradiation of UV light in the solution improved the mineralization process by facilitating the degradation of byproducts, including the solid one. Using the hybrid process, mineralization increased by 40% with low additional energy costs. In addition, new aspects about the MeP electrooxidation mechanism were found. The use of the DSA®-Cl2 appears to favor oxidative coupling reactions, resulting in higher molecular weight products prior to aromatic ring breakdown and further mineralization.