Benzophenone-3 degradation via UV/H2O2 and UV/persulfate reactions

Abstract

The degradation of benzophenone-3 (BP3) in water via the UV/H2O2 and UV/persulfate (UV/PS) reactions was investigated. The degradation of BP3 exhibited pseudo-first-order kinetics in both reactions. The degradation efficiency of BP3 was higher in the UV/PS reaction than in the UV/H2O2 reaction. In both reactions, the observed rate constants (kobs) of BP3 degradation were highest at pH 6 and increased linearly with increasing dosage of H2O2 and persulfate. The second-order rate constants of BP3 with •OH (k•OH_BP3) and •SO4– (k•SO4−_BP3) were determined to be 1.09 (± 0.05) × 1010 and 1.67 (± 0.04) × 109 M-1 s-1, respectively. The kobs values of BP3 were affected by water components such as HCO3−, NO3−, Cl−, and Br− ions, as well as humic acid. Based on the identified transformation products (TPs), the degradation pathway of BP3 during both reactions was a hydroxylation reaction. The inhibition of bioluminescence in Vibrio fischeri due to BP3 and its TPs decreased more quickly in the UV/PS reaction than in the UV/H2O2 reaction. The results suggest that the UV/PS process is a better alternative to the UV/H2O2 process for removing BP3 and its toxicity in water.