Cobalt Catalyzed and UV Activated Peroxymonosulfate for Acetaminophen Degradation: Kinetics, Mechanism, and Toxicity

This study compared photochemical degradation of acetaminophen (ACT) by UV/peroxymonosulfate (PMS) and UV/PMS/Co 2+ . The results indicated that photolytic removal of ACT (15 mg/L) by UV was not efficient, with only 6.33 % of ACT degraded in 60 min. Adding 1 mM PMS significantly improved the removal efficiency of ACT (85.67 % in 60 min). Further adding 0.05 mM cobalt ions (Co 2+ ) to the UV/PMS system synergistically improved the degradation of ACT, with 100 % ACT degraded in 60 min. Moreover, the degradation of ACT increased with improving the concentration of PMS or Co 2+ . At PMS concentrations of 0.5, 1.0 and 2.0 mM, the degradation rate constants of the UV/PMS/Co 2+ system to ACT were 3.81 × 10 −2 , 5.41 × 10 −2 , and 7.64 × 10 −2 min −1 , respectively, at [ACT] 0 = 15 mg/L, [Co 2+ ] 0 = 0.05 mM, and [pH] 0 = 5.6. Three key degradation products (DPs), including N‐(3,4‐dihydroxyphenyl)acetamide, 4‐aminophenol, and hydroquinone, were detected. The toxicity of these DPs is in the order of: N‐(3,4‐dihydroxyphenyl)acetamide < ACT < hydroquinone < 4‐aminophenol. The present study suggests that the UV/PMS/Co 2+ system could be used for efficient degradation of aqueous environmental contaminants.