Development of a horseradish peroxidase-Fenton-like system for the degradation of sulfamethazine under weak acid condition

Both horseradish peroxidase (HRP) and ferrous ion (Fe 2+ ) can degrade organic micropollutants (e.g., sulfamethazine) in the presence of hydrogen peroxide (H 2 O 2 ), but they have their own disadvantages, such as low degradation efficiency and low pH condition, respectively. In order to overcome the above shortcomings, this study is to develop a HRP-Fenton-like system for sulfamethazine (SMR) efficient degradation by analyzing the optimal reaction conditions, degradation mechanisms, and effect of ions. Results show that HRP and Fe 2+ achieve effective coupling by adding trace Fe 2+ (≤ 10 μmol/mL) to the HRP system at pH = 5, and the degradation rate of SMR increased by 20.7–42% depending on Fe 2+ concentration compared with single HRP treatment. Consumption of H 2 O 2 and quenching of hydroxyl radicals confirmed that HRP dominated SMR removal in the HRP-Fenton-like system. HPLC-MS analysis shows that SMR was degraded by C-S bond breaking, N-S bond breaking, hydroxyl substitution, and rearrangement. Furthermore, Cl − , HCO 3 − , and NO 3 − exhibit an acceptable negative effect, while SO 4 2− shows a positive effect on the degradation of SMR.