In-Situ Dosage of Fe2+ Catalyst Using Natural Pyrite for Thiamphenicol Mineralization by Photoelectro-Fenton Process

The degradation of the antibiotic thiamphenicol has been studied by photoelectro-Fenton (PEF) process with UVA light using pyrite particles as catalyst source. Pyrite is a sulfide mineral that naturally acidifies the reaction medium and releases Fe2+, thus promoting the effective generation of [rad]OH from Fenton s reaction. The assays were made in an IrO2/air-diffusion cell, which yielded similar results to a boron-doped diamond (BDD)/air-diffusion one at a lower cost. In dark conditions, electro-Fenton (EF) process showed an analogous ability for drug removal, but mineralization was much poorer because of the large persistence of highly stable by-products. Their photolysis explained the higher performance of PEF. Conventional homogeneous PEF directly using dissolved Fe2+ exhibited a lower mineralization power. This suggests the occurrence of heterogeneous Fenton s reaction over the pyrite surface. The effect of current density and drug content on pyrite-catalyzed PEF performance was examined. The drug heteroatoms were gradually converted into SO4 2−, Cl− and NO3 − ions. Nine aromatic derivatives and two dichloroaliphatic amines were identified by GC-MS, and five short-chain carboxylic acids were detected by ion-exclusion HPLC. A reaction route for thiamphenicol mineralization by PEF process with continuous H2O2 and Fe2+ supply on site is proposed. © 2020 Elsevier Ltd