UV/PAA降解氟甲喹污染水体的机制研究——pH影响、pH等组分相关性评价和脱氟性能分析

Study on the treatment of flumequine polluted water by UV/PAA system:Effect of different pH,correlation evaluation of components such as pH and evaluation of defluoridation performance

氟喹诺酮类抗生素应用广泛,基于其存在的环境生态风险,该类药物受到人们的重点关注.本研究采用紫外光活化过氧乙酸(UV/PAA)并用于不同pH氟甲喹(FLU)污染水体的降解.结果发现,在过氧乙酸(PAA)投加量为2 mg·L^(-1)时,UV/PAA对FLU具有优异的降解活性,此时FLU的反应速率常数比单独UV降解和单独PAA降解分别提升7.09和7.27倍.酸性环境有利于FLU的降解,酸性实验条件下FLU的降解率均可以达到80.0%以上,·OH在其中起主要作用;随着pH升高,FLU的降解率逐渐降低.FLU在体系中会发生脱氟降解;经过组分相关性分析发现,pH与FLU的降解速率常数k(|r|=0.96>0.5)、·OH浓度(|r|=0.91>0.5)和脱氟量(|r|=0.95>0.5)都呈显著负相关;而降解速率常数k、·OH浓度和脱氟性能两两之间具有显著的正相关关系.UV/PAA对FLU的矿化效果良好,反应30 min内FLU的荧光特征峰基本消失.经LC-MS/MS技术鉴定,FLU可能的降解途径包括:喹诺酮环开环、脱氟和脱羰等反应,降解途径有利于毒性的降低.UV/PAA降解FLU的效果会受到自然水体中常见共存物质的影响,其中,NO3-和NO2-对反应有协同促进作用.最后,UV/PAA在实际水体中对FLU表现出优异的降解性能,证明了UV/PAA技术具有实际运用于氟喹诺酮类药物污染修复的前景.

Fluoroquinolones are widely used in the world.Because of its ecological risk,these kind of drugs have been paid more attention.In this study,UV activated peracetic acid(UV/PAA)was used to degrade flumequine(FLU)contaminated solution at different pH.When the dosage of peracetic acid(PAA)was 2 mg·L^(-1),UV/PAA showed excellent degradation activity for FLU,and the reaction rate constant of FLU was increased by 7.09 and 7.27 times compared with UV degradation alone and PAA degradation alone,respectively.The low pH environment is conducive to the degradation of FLU.The degradation rate of FLU can reach more than 80.0% under the acid experimental conditions,and the hydroxyl radical plays the main role.With the increase of pH,the degradation rate of FLU decreased gradually.FLU degrades in the system by defluorination.Components and passes through correlation analysis found that pH and the degradation rate constant k on FLU(|r|=0.96>0.5),concentration of•OH(|r|=0.91>0.5)and defluorization quantity(|r|=0.95>0.5)were significantly negative correlation relationship;however,there was a significant correlation between the reaction rate constant k,•OH concentration and defluorination performance.UV/PAA had a good effect on the mineralization of FLU,and the fluorescence characteristic peak of FLU disappeared within 30 minutes of reaction.According to LC-MS/MS technology,the possible degradation pathways of FLU included:Quinolone ring opening,defluorination and decarbonylation reactions,and the degradation pathways were conducive to the reduction of toxicity.The effect of UV/PAA on the degradation of FLU was affected by the common coexisting substances in natural water bodies,among which NO3-and NO_(2)-promoted the reaction.Finally,UV/PAA showed excellent degradation performance to FLU in actual water,which proved the prospect of UV/PAA technology in practical application of fluoroquinolone drug pollution remediation.