Epoxy resin is used to repair old water distribution pipes. To cure the resin, 4,4’-methylendianiline (MDA), an aromatic amine, is used as a hardener. When the drying time during repairs is too short, MDA and the reaction products of MDA and chlorine may dissolve into tap water. Therefore, we investigated chemicals that were produced by the reaction of MDA or 4,4’-ethylendianiline (EDA), a hardener similar to MDA, and residual chlorine, and we also tried to establish a method for the examination of those chemicals in tap water.
We found that both MDA and EDA could produce various chemicals by reaction with residual chlorine at various concentrations. The chemicals identified with a molar ratio of 3 to 1,000 to residual chlorine and either MDA or EDA were p-benzoquinone, 2,4-dichloroaniline, 2,4,6-trichloroaniline. P-aminobenzyl chloride was also identified as a possible reaction chemical produced maximally at the molar ratio of 5. We conclude that detection of these chemicals in tap water is an effective method of confirming the dissolution of MDA and EDA.
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