水中常见离子对Fe(Ⅱ)/PS降解碘海醇及碘代消毒副产物生成影响研究

Effect of common ions on iohexol degradation and the formation of iodinated trihalomethanes in a Fe(Ⅱ)/PS system

选取医学上常用的碘化X射线显影剂(ICM)的典型代表碘海醇(Iohexol),研究水中常见的7种无机阴离子(Cl^(-)、Br^(-)、I^(-)、PO_(4)^(3-)、HCO_(3)^(-)、SO_(4)^(2-)、NO_(3)^(-))在Fe^(2+)/PS体系中对其降解的影响。然后考查其中三种卤离子(Cl^(-)、Br^(-)、I^(-))对Fe^(2+)/PS预氧化后氯(胺)化顺序处理过程中碘代三卤甲烷(I^(-)THMs)和常规DBPs生成的影响。结果表明:除Cl^(-)外,其他6种阴离子(Br^(-)、I^(-)、PO_(4)^(3-)、HCO_(3)^(-)、SO_(4)^(2-)、NO_(3)^(-))对碘海醇的降解都是抑制作用,且碘海醇的降解率随着它们各自浓度的增加而降低。相同浓度下,这6种离子抑制作用的大小依次为:PO_(4)^(3-)>HCO_(3)->I^(-)>Br^(-)>SO_(4)^(2-)≈NO_(3)^(-)。低浓度的Cl^(-)(<10mM)会促进Fe^(2+)/PS体系对碘海醇的降解,而高浓度的氯离子则会抑制其降解。当体系存在3种卤离子时,经Fe^(2+)/PS体系预氧化后,氯化产生的DBPs浓度均高于氯胺化,而氯胺化产生的I^(-)THMs浓度均高于氯化。I^(-)THMs和DBPs浓度随着初始Cl^(-)浓度的增加而先减少后增加,随着初始Br^(-)和I^(-)浓度的增加而增加。

Iohexol,a commonly used iodinated X-ray contrast media in medical field,was selected to study the effect of seven common inorganic anions(Cl^(-),Br^(-),I^(-),PO_(4)^(3-),HCO_(3)^(-),SO_(4)^(2-),NO_(3)-)on its degradation in Fe^(2+)/PS system.Then the effect of three halide ions(Cl^(-),Br^(-),I^(-))on the formation of iodinated trihalomethanes(I^(-)THMs)and conventional DBPs during Fe^(2+)/PS pre-oxidation and subsequent chlor(am)ination were studied.The results verified that except for Cl^(-),the other 6anions(Br^(-),I^(-),PO_(4)^(3-),HCO_(3)^(-),SO_(4)^(2-),NO_(3)-)all inhibited the degradation of iohexol.and the degradation rate of iohexol dicreased with the increased of these anions respectively.At the same concentration,the inhibitory effects of these six ions were:PO_(4)^(3-)>HCO_(3)^(-)>I^(-)>Br^(-)>SO_(4)^(2-)≈NO_(3)-.Low concentration of Cl^(-)(<10 mM)promoted the degradation of iohexol in Fe^(2+)/PS system,while high Cl^(-)concentration inhibited its degradation.When there were three halide ions in water,after Fe^(2+)/PS pre-oxidation,the concentration of DBPs produced by chlorination was higher than that of chloramination,while the concentration of I^(-)THMs produced by chloramination was higher than that of chlorination.The concentration of I^(-)THMs and DBPs first decreased and then increased with the increased of the initial Cl^(-)concentration,and increased with the increased of the initial Br^(-)and I^(-)concentration.When Cl^(-)、Br^(-)and I^(-)existed in the system,the most I^(-)THMs that produced by subsequent chlor(am)ination were CHCl2I,CHBr2I,and CHI3respectively,and the most DBPs that produced by subsequent chlor(am)ination were CF,BF,and CF respectively.