Cu(Ⅱ)催化NaOCl氧化碘帕醇的效果和过程解析

The performance and process analysis of copper ion activated chlorine system in the removal of Iopamidol

本文研究Cu(Ⅱ)催化NaOCl氧化非离子型碘代X射线造影剂—碘帕醇(IPM),对IPM降解过程中Cu的回收和形态进行解析,考察Cu(Ⅱ)、NaOCl浓度和卤素离子对IPM降解效果及碘代消毒副产物-碘仿的生成影响;采用XRD、XPS分析Cu(Ⅱ)反应后的产物晶型和形态变化,结合循环伏安曲线和计时电流表征Cu(Ⅲ)的生成,推测Cu(Ⅱ)催化NaOCl氧化IPM的机理.利用HPLC/MS/MS分析中间产物,推测IPM的降解路径.结果表明,与Co(Ⅱ)、Fe(Ⅱ)、Mn(Ⅱ)相比,Cu(Ⅱ)显著提高了NaOCl的分解率和IPM的氧化效果,25℃、pH=6.71,500r/min,NaOCl和Cu(Ⅱ)浓度分别为0.5和0.05mmol/L,60min,8.0mg/L IPM的降解率达到77.51%;HO·、活性氯自由基和Cu(Ⅲ)都有助于Cu(Ⅱ)/NaOCl氧化IPM,且Cu(Ⅲ)的贡献随pH值升高而增大.NaOCl浓度在0.1~2.5mmol/L范围增加,IPM降解率增加;Cu(Ⅱ)浓度在0.005~0.5mmol/L存在适宜值.HPLC/MS/MS共检测出13种产物,IPM的降解途径主要包括:侧链酰胺键水解和氧化,碘取代、羟基加成.Cl^(−)、Br^(−)和I^(−)(1~5mmol/L)在影响IPM氧化效果的同时,Br^(-)显著促进了CHI_(3)的生成,生成量达到48.28μg/L.

A Cu(Ⅱ)--activated NaOCl system was established to oxidize iopamidol(IPM),one of the typical non-ionic iodine X-ray contrast agents.The effects of Cu(Ⅱ)and NaOCl concentrations,halide ions on the IPM oxidation,and the formation of iodine disinfection by-products(Iodoform,CHI_(3))were examined.In addition,the crystallographic and morphological changes of Cu(Ⅱ)after the reaction were analyzed to explore its recovery and recycling.Combined with the cyclic voltammetry curves and chronoamperometry,the formation of Cu(Ⅲ)was confirmed,and the mechanism of Cu(Ⅱ)-activated NaOCl for oxidizing IPM was speculated.The results showed that compared with that of Co(Ⅱ),Fe(Ⅱ),and Mn(Ⅱ),Cu(Ⅱ)significantly improved NaOCl decomposition and IPM degradation,with IPM removal reaching 77.51%in 60min under the experimental condition of 25℃,initial pH=6.71,500r/min,NaOCl and Cu(Ⅱ)concentrations of 0.5 and 0.05mmol/L,respectively.HO·,reactive chlorine radicals,and Cu(Ⅲ)all contributed to IPM degradation.Meanwhile,the contribution of Cu(Ⅲ)increased with pH value.IPM removal increased with NaOCl concentration in the range of 0.1~2.5mmol/L.There was an optimum value for Cu(Ⅱ)concentration between 0.005 and 0.5mmol/L.A total of 13 intermediates were detected through HPLC/MS/MS analysis,degradation of IPM mainly followed hydrolysis and oxidation of side-chain amide bonds,iodine substitution,and hydroxyl addition.Cl^(−),Br^(−),and I^(−)(1~5mmol/L)not only affected the IPM removal but also the formation of CHI_(3),with the maximum CHI_(3)formation of 48.28μg/L in the Cu(Ⅱ)/NaOCl/Br−system.