Bartels Yuki, Jekel Martin, Putschew Anke
Technische Universität Berlin, Faculty III Process Sciences, Institute of Environmental Technology, Chair Water Quality Engineering, Strasse des 17. Juni 135, 10623 Berlin, Germany.
Technische Universität Berlin, Faculty III Process Sciences, Institute of Environmental Technology, Chair Water Quality Engineering, Strasse des 17. Juni 135, 10623 Berlin, Germany.
Chemosphere. 2023 Jun;326:138438. doi: 10.1016/j.chemosphere.2023.138438. Epub 2023 Mar 20.
Iodinated X-ray contrast media (ICM) as well as their aerobic transformation products (TPs), are highly polar triiodobenzoic acid derivatives, ubiquitously found in the urban water cycle. Based on their polarity, their sorption affinity to sediment and soil is negligible. However, we hypothesize that the iodine atoms bound to the benzene ring play a decisive role for sorption, due to their large atom radius, high electron number and symmetrical positioning within the aromatic system. The aim of this study is to investigate, if the (partial) deiodination, occurring during anoxic/anaerobic bank filtration, improves the sorption to aquifer material. Tri, di, mono and deiodinated structures of two ICMs (iopromide and diatrizoate) and one precursor/TP of ICM (5-amino-2,4,6-triiodoisophtalic acid) were tested in batch experiments, using two aquifer sands and a loam soil with and without organic matter. The di, mono and deiodinated structures were produced by (partial) deiodination of the triiodinated initial compounds. The results demonstrated that the (partial) deiodination increases the sorption to all tested sorbents, even though the theoretical polarity increases with decreasing number of iodine atoms. Whereas lignite particles positively affected the sorption, mineral components decreased it. Kinetics tests show biphasic sorption for the deiodinated derivatives. We have concluded that iodine affects the sorption by sterical hindrance, repulsive forces, resonance and inductive effects, depending on the number and position of iodine, side chain characteristics and composition of the sorbent material. Our study has revealed an increased sorption potential of ICMs and their iodinated TPs to aquifer material during anoxic/anaerobic bank filtration as a result of (partial) deiodination, whereby a complete deiodination is not necessary for efficient removal by sorption. Furthermore, it suggests that the combination of an initial aerobic (side chain transformations) and a subsequent anoxic/anaerobic (deiodination) redox milieu supports the sorption potential.
碘化X射线造影剂（ICM）及其好氧转化产物（TPs）是高度极性的三碘苯甲酸衍生物，在城市水循环中普遍存在。基于它们的极性，它们对沉积物和土壤的吸附亲和力可以忽略不计。然而，我们推测，由于碘原子的原子半径大、电子数多且在芳香体系中对称定位，与苯环结合的碘原子对吸附起决定性作用。本研究的目的是调查在缺氧/厌氧岸边过滤过程中发生的（部分）脱碘是否能提高对含水层物质的吸附。在分批实验中，使用两种含水层砂和一种有或没有有机质的壤土，测试了两种ICM（碘普罗胺和泛影酸盐）以及一种ICM前体/TP（5-氨基-2,4,6-三碘间苯二甲酸）的三碘、二碘、单碘和脱碘结构。二碘、单碘和脱碘结构是通过三碘初始化合物的（部分）脱碘产生的。结果表明，（部分）脱碘增加了对所有测试吸附剂的吸附，尽管理论极性随着碘原子数目的减少而增加。褐煤颗粒对吸附有积极影响，而矿物成分则降低了吸附。动力学测试表明脱碘衍生物的吸附为双相吸附。我们得出结论，碘通过空间位阻、排斥力、共振和诱导效应影响吸附，这取决于碘的数量和位置、侧链特征以及吸附剂材料的组成。我们的研究表明，由于（部分）脱碘，ICM及其碘化TPs在缺氧/厌氧岸边过滤过程中对含水层物质的吸附潜力增加，因此对于通过吸附有效去除而言，完全脱碘并非必要。此外，这表明初始好氧（侧链转化）和随后的缺氧/厌氧（脱碘）氧化还原环境的组合支持吸附潜力。
