UV/过硫酸盐降解水中氧氟沙星的动力学和机理

研究了UV/过硫酸盐(peroxydisulfate,PDS)降解水中氧氟沙星(ofloxacin,OFL)的动力学和机理。考察了OFL和PDS初始浓度、pH、腐殖酸、富里酸对OFL降解作用的影响。结果表明,UV/PDS体系降解OFL的过程符合准一级反应动力学方程,OFL的降解速率随OFL初始浓度的增加而减小,随PDS初始浓度的增加而增大;酸性和碱性条件均抑制了OFL的降解,且碱性条件的抑制作用更为显著。腐殖酸和富里酸也不同程度地抑制了OFL的降解。经液相色谱-高分辨质谱联用仪(UPLC-MS)分析,得到了UV/PDS降解OFL的4种产物,推测主要的降解途径是脱甲基和开环作用。对比可知,UV/PDS降解OFL的反应速率(0.622 3 min~(-1))较相同条件下UV/H_2O_2降解OFL反应速率(0.518 4 min~(-1))快,由此可以预见,UV/PDS高级氧化技术在水处理中具有广阔的应用前景。

Degradation kinetics and mechanisms of ofloxacin in water by UV/PDS

This work investigated the degradation kinetics and mechanisms of ofloxacin (OFL) in aqueous solution by the UV/Peroxydisulfate (PDS) technology, and inspected the effect of initial concentration of OFL and PDS, pH value, humic acid and fulvic acid. The results showed that OFL could be rapidly degraded by UV/PDS, the degradation process obeyed to the pseudo-first-order kinetic equation. The degradation rate of OFL decreased with the increase of OFL concentration, but increased with the increase of PDS concentration. Both the acidic and basic environments inhibited the degradation of OFL, and the inhibition effect was more obvious in basic condition. The existence of humic acid and fulvic acid also inhibited the degradation of OFL in varying degree. Four degradation products of OFL were determined by ultra-performance liquid chromatography-high resolution mass spectrometry. The degradation pathways mainly encompassed demethylation and ring openings. By comparison, it was obvious that the degradation rate of OFL by UV/PDS (0.6223 min-1) was faster than that by UV/H2O2 (0.5184 min-1), which indicated that UV/PDS advanced oxidation technology was promising in water treatment.