Degradation of ciprofloxacin using UV-based advanced removal processes: Comparison of persulfate-based advanced oxidation and sulfite-based advanced reduction processes

摘要

In this study, the degradation of ciprofloxacin (CIP) in wastewater was investigated using UV-based sulfate radical advanced oxidation processes (SR-AOP) and UV-based advanced reduction processes (ARP). More specifically, a comparison of the UV-based persulfate advanced oxidation process (the UV/PS process) and the UV-based sulfite advanced reduction process (the UV/sulfite process) was made. Considering the UV-based SR-AOPs, the UV/PS process was much more efficient than the UV-based peroxymonosulfate advanced oxidation process (the UV/PMS process), with pseudo first order reaction rate constants (k_(obs)) of 0.752 and 0.145 min~(-1), respectively. For the UV-based ARPs, the UV/sulfite process was the most efficient, compared to the UV/sulfide and the UV/dithionite process (k_(obs) of 0.269,0.0157 and 0.0329 min~(-1) respectively). The optimal process parameters for both the UV/PS and the UV/sulfite process were determined and the contribution of the produced reactive species were identified. For the UV/PS process, maximal CIP degradation was found at pH 8, and both ・OH and ・SO_4~- were responsible for CIP degradation. For the UV/sulfite process, ・H and ・e_(aq)~- were responsible for CIP degradation, with ・e_(aq)~- being the predominant radical at pH 8.5. Although CIP degradation was much faster for the UV/PS process, the UV/sulfite process was determined to be much more efficient in the defluorination of CIP.