Chlorination is the most common method for disinfection of recreational water. However, it is also known to react with aqueous constituents to yield disinfection byproducts (DBPs). Reactions between free chlorine and common organic-N compounds, which mostly come from sweat and urine, in recreational waters can lead to the development of undesirable DBPs, including some that are sufficiently volatile to be transferred to the gas phase. A considerable body of anecdotal evidence is available to indicate that some of these compounds can function as irritants. However, relatively little information is available to describe the specific compounds responsible for this behavior. In this research, four model compounds (creatinine, urea, L-histidine and L-arginine) were selected as model organic-N compounds. At least four volatile DBPs were detected by membrane introduction mass spectrometry (MIMS) during the chlorination of model organic-N compounds. Trichloramine (NCl3), which can function as an irritant to eye and respiratory system irritation in indoor swimming pool applications, was observed to result from chlorination of all four model organic-N compounds. Also, time-course monitoring data suggest that trichloramine may persist for several days in the absence of measures taken to eliminate it from solution. In addition to trichloramine, dichloromenthlyamine (CH3NCl2) was detected in chlorination of creatinine, and cyanogen chloride (CNCl) and dichloroacetonitrile CNCHCl2) were identified in chlorination of L-histidine. Same volatile DBPs were also found in real recreational water samples. Given that the four DBPs identified in these experiments are volatile, it is reasonable to hypothesize that they could also affect air quality in recreational water settings. Additional experimentation has allowed for identification of reaction mechanisms to describe the formation of each of these four DBPs from chlorination of the four model compounds. Some aspects of these mechanisms can be generalized to other organic-N compounds. Dr. Jing Li is currently a postdoctoral research associate for the School of Civil Engineering at Purdue University. He conducts research on volatile byproduct formation resulting from chlorination organic-N precursors in recreational water and on photolysis of DBPs resulting from chlorination of swimming pool water under UV irradiation. Prior to his research work at Purdue, Dr. Ling was a research assistant for the Institute of Chemistry, Chinese Academy of Sciences, China. Dr. Li earned a Bachelor of Science in Chemistry from Zhengzhou University, Zhengzhou, China, a Bachelor of Liberal Arts in Demotics from Tsinghua University, Beijing, China and a Doctor of Philosophy in Physical Chemistry from the Institute of Chemistry, Beijing, China.
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