Comparative study on sulfamethoxazole degradation by Fenton and Fe(ii)-activated persulfate process

Abstract

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants, which are ubiquitous and pose the potential risk to ecosystem and human health. It is necessary to remove PPCPs from water and wastewater. In this study, sulfamethoxazole, a widely used antibiotic, was chosen as targeted pollutant. Fenton process and persulfate process were employed to remove sulfamethoxazole from aqueous solution. The results showed that Fenton process required less amount of Fe(II) and oxidant than persulfate process to achieve 100% removal of sulfamethoxazole in the water sample prepared with de-ionized water. The maximal mineralization reached 83% when hydrogen peroxide concentration was 1 mM and Fe(II) was 0.05 mM for Fenton process. The maximal mineralization for persulfate process was 60% with 4 mM of persulfate and 4 mM of Fe(II). The increase of Fe(II) concentration could increase the decomposition of hydrogen peroxide and persulfate, but did not increase the mineralization of sulfamethoxazole, indicating that the decomposition of hydrogen peroxide and persulfate was not positive correlation with the removal and mineralization of sulfamethoxazole. Five intermediate compounds were detected in Fenton process while eight intermediate compounds in persulfate process, suggesting that different degradation pathway occurred in the two processes. The wastewater components had negative effect on the degradation of sulfamethoxazole for both Fenton and persulfate processes. The removal efficiency of sulfamethoxazole was 52.5% and 52.3%, respectively, for Fenton and persulfate processes. Persulfate process could be an alternative for treating the real wastewater containing PPCPs.