MacKeown Henry, von Gunten Urs, Criquet Justine
Univ. Lille, CNRS, UMR 8516 - LASIRE, Laboratory of Advanced Spectroscopy for Interactions, Reactivity and Environment, Lille F-59000, France.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, Duebendorf 8600, Switzerland; Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich 8092, Switzerland; School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland.
Water Res. 2022 Jun 15;217:118417. doi: 10.1016/j.watres.2022.118417. Epub 2022 Apr 7.
Iodine is a naturally-occurring halogen in natural waters generally present in concentrations between 0.5 and 100 µg L. During oxidative drinking water treatment, iodine-containing disinfection by-products (I-DBPs) can be formed. The formation of I-DBPs was mostly associated to taste and odor issues in the produced tap water but has become a potential health problem more recently due to the generally more toxic character of I-DBPs compared to their chlorinated and brominated analogues. This paper is a systematic and critical review on the reactivity of iodide and on the most common intermediate reactive iodine species HOI. The first step of oxidation of I to HOI is rapid for most oxidants (apparent second-order rate constant, k > 10 Ms at pH 7). The reactivity of hypoiodous acid with inorganic and organic compounds appears to be intermediate between chlorine and bromine. The life times of HOI during oxidative treatment determines the extent of the formation of I-DBPs. Based on this assessment, chloramine, chlorine dioxide and permanganate are of the highest concern when treating iodide-containing waters. The conditions for the formation of iodo-organic compounds are also critically reviewed. From an evaluation of I-DBPs in more than 650 drinking waters, it can be concluded that one third show low levels of I-THMs (<1 µg L), and 18% exhibit concentrations > 10 µg L. The most frequently detected I-THM is CHClI followed by CHBrClI. More polar I-DBPs, iodoacetic acid in particular, have been reviewed as well. Finally, the transformation of iodide to iodate, a safe iodine-derived end-product, has been proposed to mitigate the formation of I-DBPs in drinking water processes. For this purpose a pre-oxidation step with either ozone or ferrate(VI) to completely oxidize iodide to iodate is an efficient process. Activated carbon has also been shown to be efficient in reducing I-DBPs during drinking water oxidation.
碘是天然水体中天然存在的卤族元素，其浓度通常在0.5至100微克/升之间。在饮用水的氧化处理过程中，会形成含碘消毒副产物（I-DBPs）。I-DBPs的形成主要与所生产的自来水中的味道和气味问题有关，但最近已成为一个潜在的健康问题，因为与氯化和溴化类似物相比，I-DBPs通常具有更高的毒性。本文是对碘化物反应性以及最常见的中间活性碘物种HOI的系统且批判性的综述。对于大多数氧化剂而言，I氧化为HOI的第一步很快（在pH 7时的表观二级速率常数，k>10 M⁻¹s⁻¹）。次碘酸与无机和有机化合物的反应性似乎介于氯和溴之间。氧化处理过程中HOI的寿命决定了I-DBPs的形成程度。基于此评估，在处理含碘水体时，氯胺、二氧化氯和高锰酸盐是最受关注的。对碘有机化合物的形成条件也进行了批判性综述。通过对650多种饮用水中的I-DBPs进行评估，可以得出结论，三分之一的饮用水中I-THMs含量较低（<1微克/升），18%的饮用水中I-THMs浓度>10微克/升。最常检测到的I-THM是CHClI，其次是CHBrClI。还对极性更强的I-DBPs，特别是碘乙酸进行了综述。最后，有人提出将碘化物转化为碘酸盐（一种安全的碘衍生终产物）以减少饮用水处理过程中I-DBPs的形成。为此，用臭氧或高铁酸盐（VI）进行预氧化步骤以将碘化物完全氧化为碘酸盐是一种有效的方法。活性炭也已被证明在饮用水氧化过程中能有效减少I-DBPs。
