光助-二茂铁/H_2O_2非均相体系降解磺胺二甲基嘧啶

Photo-assisted Degradation of Sulfamethazine by Ferrocene-catalyzed Heterogeneous Fenton-like System

抗生素在废水和地表水中经常检出,因其可诱导细菌菌群的抗药性而备受关注,因而亟需发展新型高效的抗生素去除技术.本研究构建了基于二茂铁(Fc)的光助非均相氧化体系,并选取水体中广泛检出的磺胺二甲基嘧啶(SMZ)为模型化合物,研究了SMZ在该体系中的降解动力学、转化途径和产物.结果表明,相对于Fc、Fc+UV、H_2O_2、H_2O_2+UV、Fc+H_2O_2体系,SMZ在Fc+H_2O_2+UV体系中呈现更好的降解效率.自由基淬灭实验证实·OH是Fc+H_2O_2+UV体系中决定SMZ降解的最主要活性物种.电子自旋共振实验发现Fc+H_2O_2+UV体系中产生了超氧自由基阴离子,说明Fc在光照条件下可产生电子. H_2O_2接受电子后歧化产生·OH进而促进SMZ降解.采用轨道离子阱高分辨质谱对SMZ在Fc+H_2O_2+UV体系中的降解产物进行了鉴定,发现有SMZ的羟基化、脱SO_2和C—S、S—N及N—C键断裂的产物形成.水中常见溶解性组分,如DOM、Cl^-及Br^-,可淬灭·OH而抑制SMZ降解,但离子强度对SMZ在Fc+H_2O_2+UV体系中的降解无显著影响,说明该技术对于含有高盐度抗生素废水的处理仍具有较好的效果.

Antibiotics are acknowledged micropollutants in wastewaters and surface waters. They are of particular concern because they can trigger an increase in resistant bacteria. Therefore,novel and efficient technology for the removal of antibiotics is urgently needed.In this study,heterogeneous Fenton-like reaction based on ferrocene（ Fc） had been constructed,sulfamethazine（ SMZ） was selected as target compound due to its abundance in water. The degradation kinetics,transformation pathway,and degradation products of SMZ in this system were investigated. The results showed that Fc ＋ H2 O2＋ UV had better degradation efficiency for SMZ than did Fc,Fc ＋UV,H2 O2,and H2 O2＋ UV,Fc ＋ H2 O2 systems. Radical scavenger experiments confirmed that the photogenerated OH was largely responsible for the photolytic enhancement of SMZ in the Fc ＋ H2 O2＋ UV system. Additionally,the electron spin resonance technique revealed that photogenerated O-2 was found in the system,indicating that Fc can generate electrons under light conditions. H2 O2 underwent electron disproportionation to produce OH,which promoted the degradation of SMZ. The degradation products of SMZ in the Fc ＋ H2 O2＋ UV system were identified by LC/LTQ-Orbitrap MS. The hydroxylation of SMZ,the removal of SO2,and the products of breaking C—S,S—N,and N—C bonds were observed. Common soluble components（ such as DOM,Cl^-,and Br^-） in water can quench OH,thus inhibiting the photodegradation of SMZ. However,the ionic strength had no significant effect on the degradation of SMZ in the Fc ＋ H2 O2＋ UV system,which showed that this technique positively affected the treatment of wastewater containing highsalinity antibiotics.