Decomposition of sulfadiazine in a sonochemical Fe0-catalyzed persulfate system: Parameters optimizing and interferences of wastewater matrix

Effective decomposition of antibiotic sulfadiazine (SD) in a Fe 0 -catalyzed sonochemical Fenton like system (Sono-FL) was demonstrated. By using the response surface methodology (RSM), an optimized experimental condition of pH 7.00, 0.94   mM Fe 0 , 1.90   mM persulfate (PS) and 20   W ultrasound (US) power was concluded, which could reach the predicted SD degradation efficiency of 90%. Afterwards, effects of wastewater matrix (five inorganic anions and two chelating agents) on the SD degradation were investigated in the system, respectively. It was found that the SD degradation could be inhibited by SO 4 2− , NO 3 − , HCO 3 − /CO 3 2− and H 2 PO 4 − to different extents. Cl − would lead to an enhancement with a low dosage (5   mM), but an inhibition with a high dosage (100   mM). Unexpectedly, chlorinated organic intermediates were also found as SD decomposed. Appropriate dosages of oxalic acid (OxA) or EDTA could benefit the SD degradation in the Sono-FL system, while excessive chelating agents would play as competitive pollutants. It was summarized that inorganic anions would mainly react with SO 4 − and/or OH to form sub-radicals of less oxidative potential. OxA and EDTA would not only participate in complexing dissolution of Fe 0 but also provide additional oxidants such as H 2 O 2 and [Fe IV O] 2+ , through the electron transfer reactions caused by the iron-ligands species.