硫化亚铁活化过一硫酸盐降解碘帕醇:表面反应机理及途径解析

Degradation of iopamidol by FeS catalyzed peroxymonosulfate:Surface reaction mechanism and pathway

构建了非均相FeS/过一硫酸盐(PMS)体系,并与均相Fe(Ⅱ)/PMS体系对比降解非离子型碘代X射线造影剂—碘帕醇(Iopamidol,IPM)的效果.通过自由基淬灭、电子顺磁共振(EPR)和FeS反应前后的X射线衍射(XRD)、X射线光电子能谱(XPS)、傅里叶红外(FTIR)等表征,探究了FeS活化PMS降解IPM的机理.同时,通过密度泛函计算(DFT)、HPLC/MS/MS解析IPM的中间产物及降解途径,对IPM降解过程中碘代消毒副产物—碘仿(CHI3)的生成量进行分析,并进一步采用生态结构活性软件(ECOSAR)预测IPM及中间产物的生态毒性变化.最后考察了初始pH、HCO_(3)^(-)、Cl^(-)和腐殖酸(HA)对体系降解IPM的影响.结果表明,FeS/PMS体系非均相降解IPM的主要活性物种是SO_(4)·-、·OH和1O_(2),而Fe()/PMS体系主要是SO_(4)·-、·OH,FeS/PMS体系更有利于IPM的降解.FeS表面Fe(Ⅱ)活化PMS是形成活性物种的主要途径,S作为电子供体可促进Fe(Ⅲ)/Fe(Ⅱ)的循环再生.IPM的降解主要包括侧链酰胺水解及氧化、脱氢、脱碘和羟基加成,共生成10种中间产物.ECOSAR分析表明中间产物有一定的生态风险;但与PMS和Fe(Ⅱ)/PMS体系相比,FeS/PMS体系降解IPM过程中CHI3的生成量最小.FeS/PMS体系在初始pH范围(3.0~6.5)对IPM的降解率≥90.0%,HCO_(3)^(-)和Cl^(-)对FeS/PMS体系的影响较小,HA基本没有影响.研究表明,FeS可作为一种有效、安全的过硫酸盐活化剂用于碘代有机物IPM的控制.

The heterogeneous FeS/PMS system was established and compared with homogeneous Fe(II)/PMS system to degrade iopamidol(IPM),one of the non-ionic iodinated X-ray contrast medias.The IPM degradation mechanism under FeS activated PMS system was investigated by means of radical quenching experiment,electron paramagnetic resonance(EPR),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and Fourier infrared(FTIR)of FeS before and after reaction.The intermediate products and degradation pathway of IPM were analyzed by density functional calculations(DFT)and HPLC/MS/MS.The formation of iodoform(CHI_(3)),one of the iodine disinfection by-products,was determined.And the ecotoxicity of IPM were further predicted through ECOSAR.The results showed that the heterogeneous FeS/PMS system was more conductive to IPM degradation,which mainly due to the radical species of SO_(4)•−,·OH and 1O_(2),while SO_(4)•−,·OH were dominant in homogeneous Fe(II)/PMS system.The PMS activated by Fe(II)on the surface of FeS was the dominant way to form active species.And the sulfur species promoted the recycling of Fe(III)/Fe(II).IPM degradation pathway involved side chain amide hydrolysis and oxidation,dehydrogenation,deiodination and hydroxyl addition,and a total of 10 intermediates were formed.ECOSAR analysis showed that the intermediate products have certain ecological risk.However,compared with PMS and Fe(II)/PMS system,CHI3 formation in FeS/PMS system was the least.IPM degradation rate was≥90.0%in the initial pH range of 3.0~6.5.HCO_(3)-and Cl-had a little effect,while HA had no effect.The findings showed that FeS was an effective and safe persulfate activator for the control of iodinated organic compounds IPM.