Destruction of phenicol antibiotics using the UV/H2O2 process: Kinetics, byproducts, toxicity evaluation and trichloromethane formation potential

Phenicol antibiotics (PABs) degradation by UV/H 2 O 2 is important because we need to determine the reduction in toxicity and disinfection byproducts for post-chlorine. In this study, the degradation of PABs, including florfenicol (FLO), chloramphenicol (CAP) and thiamphenicol (THA), was examined. The pseudo-first order degradation rate constants of PABs were 3 times higher in ultrapure water (UW) than that in synthetic wastewater (SW) for these conditions: [PABs] 0  = 1 μM, [H 2 O 2 ] = 0.1 mM, and I 0  = 1.985 × 10 −6  E L −1  s −1 . Fulvic acid (FA) and HCO 3 – inhibited PABs degradation, Cl − and NO 3 – concentrations of up to 5 mM and 10 mM had a negligible impact. The impact of water matrix on PABs degradation was successfully predicted using pseudo-steady-state kinetic model. The degradation of PABs was triggered via hydroxylation and/or hydrogen abstraction. The treatment of PABs via UV/H 2 O 2 could decrease their antimicrobial properties, while the byproducts of FLO and THA showed higher acute toxicity in Vibrio fischeri . In addition, two identification products (TP-276 and TP-354) of FLO had higher ecotoxicity toxicity (using ECOSAR) in fish, daphnid and green algae. The trichloromethane formation potential (TCMFP) for PABs with post-chlorination in UW and SW can be reduced after UV/H 2 O 2 compared to UV, and is related to the corresponding decrease of dissolved organic carbon (DOC).