Kinetic and mechanism study of UV/pre-magnetized-Fe0/oxalate for removing sulfamethazine.

In this study, UV irradiated photochemical reactions of oxalate (Ox) with premagnetized-Fe0 (pre- Fe0) as the catalyst was used to degrade sulfamethazine (SMT). Magnetic field promoted the release of iron ion from Fe0 thus enhanced SMT and Ox removal in UV/pre- Fe0/Ox process. X-ray photoelectron spectroscopy demonstrated that the presence of UV and Ox promoted the transformation of Fe3+ to Fe2+ on Fe0, which enhanced the surface bound •OH (•OHsurf) generation. Ox inhibited the formation of iron (hydro)xides and enhanced the hydroxylation of Fe0 surface. •OHsurf was mainly responsible for SMT removal (44%), while UV direct photolysis and •OH in the solution both caused around 28% SMT removal. The process with Ox exhibited much higher efficiency in SMT degradation than that added with H3PO4, citric acid and ethylenediaminetetraacetic acid, which greatly expanded the chelate-modified Fenton processes and their treatment efficiency.