Combined oxidative degradation of ammonia and phenol by homogeneous UV/S2O8 2- process

Utilization of UV in peroxydisulfate (S2O8 2-) activation exhibits a potential for removing contaminants in wastewater. In this study, the oxidative degradation of aqueous ammonia (NH3/NH4 +) or/and phenol by UV/S2O8 2- process was investigated, including the kinetic model of ammonia removal, the effect of pH on degradation efficiency and TOC removal, and influence of S2O8 2- concentrations on contaminants removal. The results revealed that the kinetic model of ammonia removal conforms to pseudo-first-order. Strong alkaline conditions and high dosage of S2O8 2- were profited to ammonia degradation, and the removal percent was up to 95.98% (e.g. 50 mM S2O8 2- at pH 12). The near-neutral environment was conducive to phenol removal, and its maximal removal percent was 96.28% in 30 min at pH 8. In the combined oxidation system of ammonia and phenol, the ammonia removal quickly reached 40.90% in 30 min and got its maximum of 55.20% after 8 h, while the phenol degradation had almost no obvious decline. This study enriches our understanding of the oxidation kinetic of ammonia under UV, and provides new insights for combined oxidation of ammonia and phenol.