Photo-degradation ibuprofen by UV/HO process: response surface analysis and degradation mechanism.

The removal of ibuprofen (IBP) in aqueous solution using UV/HO process was evaluated. The response surface methodology (RSM) and Box-Behnken design were employed to investigate the effects of process parameters on IBP removal, including the initial IBP concentration, HO dosage, UV light intensity, and initial pH value of solution. The RSM model developed herein fits well with the experiments, and provides a good insight into the OH radical irritated degradation mechanisms and kinetics. High resolution accurate mass spectrometry coupled with liquid chromatography was used to identify the degradation intermediates. A total of 23 degradation products were identified, including mono-hydroxylated products and dihydroxylated products. A series of OH radical-initiated reactions, including hydroxylation, dihydroxylation, decarboxylation, demethylation, ring break, lead to the final mineralization of IBP to CO and HO. UV/HO technology could be a promising technology for IBP removal in aqueous solution.