Iodinated trihalomethane formation during chloramination of iodate-containing waters in the presence of zero valent iron

Ying Xia; Yi-Li Lin; Bin Xu; Chen-Yan Hu; Ze-Chen Gao; Wen-Hai Chu; Nai-Yun Gao

doi:10.1016/j.watres.2017.07.059

Iodinated trihalomethane formation during chloramination of iodate-containing waters in the presence of zero valent iron

Water Res. 2017 Nov 1:124:219-226. doi: 10.1016/j.watres.2017.07.059. Epub 2017 Jul 24.

Authors

Ying Xia¹, Yi-Li Lin², Bin Xu³, Chen-Yan Hu⁴, Ze-Chen Gao¹, Wen-Hai Chu¹, Nai-Yun Gao¹

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, Institute of Disinfection By-product Control in Water Treatment, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
² Department of Safety, Health and Environmental Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung 824, Taiwan, ROC.
³ State Key Laboratory of Pollution Control and Resource Reuse, Institute of Disinfection By-product Control in Water Treatment, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. Electronic address: tjwenwu@tongji.edu.cn.
⁴ College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090, PR China.

PMID: 28759794
DOI: 10.1016/j.watres.2017.07.059

Abstract

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.

Keywords: Chloramination; Disinfection by-products (DBPs); Iodate (IO(3)(−)); Iodinated trihalomethanes (I-THMs); Zero valent iron (ZVI).

MeSH terms

Corrosion
Equipment Design
Iodates
Iodides / chemistry*
Iron
Trihalomethanes / chemistry*
Water Purification
Water Supply

Substances

Iodates
Iodides
Trihalomethanes
Iron