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 (k(obs)) 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 center dot OH (k center dot(OH_BP3)) and center dot SO4- (k(center dot SO4_BP3)) were determined to be 1.09 (+/- 0.05) x 1010 and 1.67 (+/- 0.04) x 10(9) 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.