Photodegradation mechanism of sulfadiazine catalyzed by Fe(III), oxalate and algae under UV irradiation

Abstract

Photodegradation mechanism of sulfadiazine (SD) in a solution containing Fe(iii), oxalate and algae were investigated in this study. The results indicated that the degradation of SD was slow in a solution containing Fe(iii) or oxalate, whereas it was markedly enhanced when Fe(iii) and oxalate coexisted. The optimal pH for formation of·OH was 4; a higher or lower pH resulted in a decrease in formation of·OH. A moderate increase of oxalate concentration was beneficial to the formation of·OH and the degradation of SD, and the algae enhanced the degradation rate of SD in a solution containing Fe(iii) and oxalate. Also, the degradation rate of SD rapidly decreased at low initial concentrations but slowly decreased at high initial concentrations, and pseudo-first order kinetics described the degradation process of SD well. A possible reaction mechanism in solution containing Fe(iii), oxalate and algae was proposed, and attack by·OH was the main pathway of SD degradation in the photocatalytic reaction.