Oxidative degradation of benzene rings using iron sulfide activated by hydrogen peroxide/ozone

Mineral pyrites-metal sulfides abundant in the earth's crust-exhibit oxidative ability when exposed to water. This oxidizing ability makes mineral pyrites suitable for the natural and enhanced remediation of environmentally hazardous materials. Herein, we evaluate the benzene ring degradation ability of iron bisulfide activated by H₂O₂ and O₃ and elucidate the corresponding reaction pathways. A set of control experiments was conducted to optimize the reaction conditions, i.e., the FeS₂/H₂O ratio under aerobic conditions and the H₂O₂ and/or O₃ dosages. Benzene ring was successfully decomposed to CO₂ via organic acids even by the simplest FeS₂/H₂O combination. This process was accelerated by the addition of both O₃ and H₂O₂. The extent of degradation to CO₂ increased in the presence of O₃, while oxalic acid generation increased in the presence of H₂O₂. The reaction proceeded via the radicals generated on FeS₂/H₂O, which is enhanced by O₃, and a Fenton-like reaction using the iron obtained from FeS₂ dissolution.