Sulfamethazine removal by peracetic acid activation with sulfide-modified zero-valent iron: Efficiency, the role of sulfur species, and mechanisms

Sulfide-modified zero-valent iron (S-Fe 0 ) has been regarded as a promising method to enhance the catalytic activity of Fe 0 . Therefore, peracetic acid (PAA) firstly activated by S-Fe 0 was conducted to remove sulfamethazine (SMT) in this study. Only 13.1% SMT could be removed within 60 min in Fe 0 /PAA system while 86.5% SMT could be removed within 60 min in S-Fe 0 /PAA system at condition of [PAA] = 100 μΜ, [S-Fe 0 ] = 20 mg/L, [SMT] = 5 mg/L, pH = 4.0. The effect of S/Fe ratio, S-Fe 0 dosage, PAA concentration and initial pH on SMT removal were investigated. The characterization of S-Fe 0 such as SEM, XPS, contact angle and Tafel confirmed that the formation of sulfur species on Fe 0 surface could enhance the catalytic performance of Fe 0 . S 2− played the major role and SO 3 2- played the minor role in accelerating the conversion of Fe 3+ to Fe 2+ . • OH and R-O • exhibited 67.1% and 32.5% contribution for SMT removal in S-Fe 0 /PAA system, respectively. The possible degradation pathway of SMT was also proposed. Cl − and HCO 3 – had a negligible adverse effect on SMT removal in S-Fe 0 /PAA system indicating the good adaptability of inorganic ions. In addition, S-Fe 0 /PAA system had the good recycle ability of S-Fe 0 and showed a better performance in removing SMT in the natural fresh water. Therefore, this study notably showed the potential applicability of S-Fe 0 /PAA system in degrading SMT in natural fresh water.