Degradation of Enrofloxacin Antibiotic by Ultraviolet Activated Persulfate (Uv/Pds) Advanced Oxidation Process: Performance, Mechanism, Pathways

Enrofloxacin (ENR) is continually detected in natural water environment, becoming one threaten if treating untimely. Performance and mechanism of ENR degradation by ultraviolet (UV)/persulfate (PDS) technology was systematically investigated. Degradation efficiency by UV/PDS was 5.4 times of UV alone, due to the higher rate constant (kobs) of 5.848×10-2 min-1. Quencher experiments showed, ·SO4- and ·OH were the major free radicals generated by UV/PDS, and the corresponding contribution rate on degrading ENR was 65.2% and 17.2%. Moreover, ENR degradation efficiency of UV/PDS positively influenced by high PDS dosage (20 mg/L) and pH (9.0), but negatively affected by high ENR dose (15 mg/L). Results of electrical energy per order (EE/O) demonstrated, UV/PDS was less energy consumption and more economical. Results of response surface model (RSM) illustrated that ENR degradation efficiency was less negatively influenced, when inorganic ions like Cl-, HCO3- and NO3- was 7, 2 and 3 mM, respectively. Using density functional theory (DFT) and Fukui functions to analyze the possible active sites of ENR, meanwhile using intermediate products to study the pathways of ENR degradation by UV/PDS process. These results illustrated that C28 and C30 on piperazine ring of ENR was attacked by UV/PDS process, according to the substitution and de-alkylation.