Iodide (I⁻) and iodinated X-ray contrast media (ICM) are the primary iodine sources for the formation of iodinated disinfection byproducts (I-DBPs), and iodate (IO₃⁻) is believed to be a desired sink of iodine in water. This study found that highly cytotoxic iodinated trihalomethanes (I-THMs) also can be generated from iodate-containing waters (without any other iodine sources) in the presence of zero valent iron (ZVI) during chloramination, which could be a big issue in the wide usage of iron pipes. The effect of major factors including ZVI dosage, NH₂Cl and IO₃⁻ concentrations, initial pH, Br⁻/IO₃⁻ molar ratio, phosphate concentration, iron corrosion scales (goethite and hematite) on the formation of I-THMs were investigated. Formation of I-THMs from IO₃⁻ increased with the increase of ZVI dosage, IO₃⁻ and NH₂Cl concentrations. Chloramines can also remarkably accelerate the reduction of IO₃⁻ by ZVI. Peak I-THM formation was found at pH 8. As the Br⁻/IO₃⁻ molar ratio increased from 0 to 20, I-THM formation considerably enhanced, especially for the bromine-incorporated species. Goethite and hematite enhanced the formation of I-THMs in the presence of ZVI. Additionally, a significant suppression on I-THM formation was observed with the addition of phosphate. Considering that a large number of water distribution networks contain unlined cast iron pipes, transformation of IO₃⁻ in the presence of ZVI during chloramination may contribute to the formation of I-THMs in such systems.

中文翻译：

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零价铁存在下含碘酸盐水氯化过程中碘化三卤甲烷的形成

碘化物（I ^- ）和碘化的X-射线造影介质（ICM）是主要的碘源碘化消毒副产物的形成（I-消毒副产物），和碘酸盐（IO ₃ ^- ）被认为是在碘的期望沉水。这项研究发现，在氯化过程中存在零价铁（ZVI）的情况下，含碘酸盐的水（无其他碘源）也可能产生具有高细胞毒性的碘代三卤甲烷（I-THM）。铁管的广泛使用。的主要因素，包括ZVI剂量，NH效果₂ Cl和IO ₃ ^-浓度，初始pH值，溴^- / IO ₃ ^-研究了摩尔比，磷酸盐浓度，铁腐蚀垢（针铁矿和赤铁矿）对I-THMs形成的影响。从IO I-三卤甲烷的形成₃ ^-增加了与ZVI剂量，IO的增加₃ ^-和NH ₂氯浓度。氯胺也可以显着地加速IO的还原₃ ^-由ZVI。峰I-THM形成被发现在pH 8作为溴^- / IO ₃ ^-当摩尔比从0增加到20时，I-THM的形成显着增强，特别是对于结合溴的物质。在ZVI的存在下，针铁矿和赤铁矿会增强I-THM的形成。另外，通过添加磷酸盐观察到对I-THM形成的显着抑制。考虑到大量的水分配网络的包含无衬里的铸铁管，IO的变换₃ ^-在ZVI的氯胺期间存在可有助于在这种系统中的形成I-三卤甲烷的。