Ma Xiaoyan, Cheng Yongqing, Ge Yongjian, Wu Huadan, Li Qingsong, Gao Naiyun, Deng Jing
College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China.
College of Environmental Science and Engineering, Xiamen University of Technology, Xiamen 361024, China.
Ultrason Sonochem. 2018 Jan;40(Pt A):763-772. doi: 10.1016/j.ultsonch.2017.08.025. Epub 2017 Aug 24.
Commercial nanosized zero-valent copper (nZVC) was used as hydrogen peroxide (HO) activator in conjunction with ultrasonic irradiation (US) for the oxidative degradation of norfloxacin (NOR) in this study. Compared with silent degradation system, a significantly enhanced NOR removal was obtained in sono-advanced Fenton process, which involved a synergistic effect between sonolysis and Fenton-like reaction. Almost complete removal of NOR was achieved at 30min when the operating conditions were 0.25g/L nZVC and 10mM HO with ultrasound power of 240W at 20kHz. The released Cu during the nZVC dissolution was the predominant copper species to activate HO and yield hydroxyl radicals (OH) in US/nZVC/HO system. According to the radical quenching experiments and electron paramagnetic resonance technique, hydroxyl radicals in solution (OH) were verified as the primary reactive species, and superoxide anion radicals (O) were regarded as the mediator for the copper cycling by reduction of Cu to Cu. NOR removal efficiencies were improved in various degrees when increased nZVC dosage, ultrasound power, hydrogen-ion amount and HO concentration. Moreover, the inhibitory effect of different inorganic salts on NOR degradation followed the sequence of NaSO>NaNO≈no salt>NaCl>NaHCO. Finally, eleven intermediates were identified and five oxidation pathways were proposed, the cleavage of piperazine ring and transformation of quinolone group seemed to be the major pathway.
本研究采用商业纳米零价铜（nZVC）作为过氧化氢（HO）的活化剂，并结合超声辐照（US）对诺氟沙星（NOR）进行氧化降解。与无超声降解体系相比，超声强化芬顿过程中NOR的去除率显著提高，这涉及到超声空化和类芬顿反应之间的协同作用。当操作条件为0.25g/L nZVC、10mM HO、超声功率240W、频率20kHz时，30分钟内NOR几乎完全去除。nZVC溶解过程中释放的Cu是US/nZVC/HO体系中活化HO并产生羟基自由基（OH）的主要铜物种。通过自由基猝灭实验和电子顺磁共振技术验证了溶液中的羟基自由基（OH）是主要的活性物种，超氧阴离子自由基（O）被认为是通过将Cu还原为Cu实现铜循环的介质。增加nZVC用量、超声功率、氢离子量和HO浓度时，NOR去除效率均有不同程度提高。此外，不同无机盐对NOR降解的抑制作用顺序为：NaSO>NaNO≈无盐>NaCl>NaHCO。最后，鉴定出11种中间体并提出了五条氧化途径，哌嗪环的断裂和喹诺酮基团的转化似乎是主要途径。
