太阳光/Fe(Ⅱ)/柠檬酸/激活过硫酸盐对污水二级出水中罗红霉素的降解效能

Degradation of roxithromycin in secondary effluent by persulfate activated by the combination of sunlight, Fe(Ⅱ) and citric acid

本文以柠檬酸作为Fe(Ⅱ)的螯合剂,引入模拟太阳光强化Fe(Ⅱ)/柠檬酸/螯合物活化过硫酸盐(PS)氧化降解污水处理厂二级出水中的罗红霉素,探讨了该体系对罗红霉素的降解效果、影响因素、活性物种的贡献和降解路径.结果表明,太阳光/Fe(Ⅱ)/柠檬酸/PS体系能有效降解罗红霉素,在Fe(Ⅱ)浓度为0.25 mmol·L^(-1),PS为4 mmol·L^(-1),Fe(Ⅱ)/柠檬酸物质的量比为1∶2,反应60 min时,罗红霉素的去除率可达到92%以上.淬灭实验表明,·OH是反应体系的主要活性物种,其对罗红霉素降解的贡献为78.3%—86.4%,而SO4·-的作用相对较弱,其贡献仅为7.3%—12.5%.基于高效液相色谱高分辨质谱鉴别出8种罗红霉素的降解产物,它们主要是由罗红霉素的肟侧链断裂(—C_(4)H_(8)O_(2))、脱克拉定糖(—C_(8)H_(14)O_(3))和脱羟胺(—NH_(2)OH)形成的,其中DP679(C_(33)H_(63)O_(12)N_(2))和DP749(C_(37)H_(69)O_(13)N_(2))是最主要的降解产物.

In this study,citric acid was used as the chelating agent of Fe(Ⅱ),and simulated sunligh was introduced to enhance the degradation of roxithromycin in secondary wastewater by persulfate(PS) activated by Fe(Ⅱ)-citrate chelate complex.The removal efficiency,impact factors contribution of active species and degradation pathway of roxithromycin were examined.The results showed that sunlight/Fe(Ⅱ)/citrate/PS system can degrade roxithromycin effectively.When Fe(Ⅱ) concentration was 0.25 mmol·L^(-1),PS concentration was 4 mmol·L^(-1),molar ratio of Fe(Ⅱ)citrate was 1∶2,and reaction time was 60 min,the removal efficiency of roxithromycin reached higher than 92%.Quenching experiments showed that·OH was the principal active species in the reaction system,and its contribution to the degradation of roxithromycin was 78.3%—86.4%;In contrast,S O;played a minor role in the degradation of roxithromycin,with the contribution of only7.3%—12.5%.Eight degradation products (DPs) of roxithromycin were identified using high performance liquid chromatography and high resolution mass spectrometry.They were mainly formed by the cleavage of C_(4)H_(8)O_(2) from the oxime side chain,cleavage of cladinose (C_(8)H_(14)O_(3)) and hydroxylamine (NH_(2)OH).DP679 (C_(33)H_(63)O_(12)N_(2)) and DP749 (C_(37)H_(69)O_(13)N_(2)) were the primary degradation products.