Decomposition of sulfadiazine in a sonochemical Fe-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 20W 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 SO42-, NO3-, HCO3-/CO32- and H2PO4- 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 SO4 center dot- and/or (OH)-O-center dot to form sub-radicals of less oxidative potential. OxA and EDTA would not only participate in cornplexing dissolution of Fe-0 but also provide additional oxidants such as H2O2 and [(FeO)-O-IV](2+), through the electron transfer reactions caused by the iron-ligands species. (C) 2015 Elsevier B.V. All rights reserved.