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) 及其有氧转化产物 (TP) 是高度极性的三碘苯甲酸衍生物，普遍存在于城市水循环中。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，我们假设与苯环结合的碘原子对吸附起着决定性作用，因为它们的原子半径大、电子数高且在芳香族系统中的对称定位。本研究的目的是调查在缺氧/厌氧堤岸过滤期间发生的（部分）脱碘是否会改善对含水层材料的吸附。在批量实验中测试了两种 ICM（碘普罗胺和泛影酸盐）和一种 ICM 前体/TP（5-氨基-2,4,6-三碘间苯二甲酸）的三、二、单和脱碘结构，使用两种含水层砂和一种含有机质和不含有机质的壤土。二、单和脱碘结构是通过三碘化初始化合物的（部分）脱碘作用产生的。结果表明，（部分）脱碘增加了对所有测试吸附剂的吸附，即使理论极性随着碘原子数量的减少而增加。褐煤颗粒对吸附有积极影响，而矿物成分会降低吸附。动力学测试显示脱碘衍生物的双相吸附。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、侧链特性和吸附剂材料的组成。我们的研究表明，由于（部分）脱碘，ICM 及其碘化 TP 在缺氧/厌氧堤岸过滤过程中对含水层材料的吸附潜力增加，因此通过吸附有效去除不需要完全脱碘。此外，它表明初始有氧（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。