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Water Supply Engineering
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Chlorine reacts with ammonia in water to form and release monochloramine (NH2Cl) dichloramine (NHCl2), and trichloramine (NCl3) and their distribution depends on the pH value of water.
Chemical Equilibrium for Acids and Bases
Published in Paul Mac Berthouex, Linfield C. Brown, Chemical Processes for Pollution Prevention and Control, 2017
Paul Mac Berthouex, Linfield C. Brown
Monochloramine may then react with more hypochlorous acid to form a dichloramine (NHCl2). Then the dichloramine may react with hypochlorous acid to form a trichloramine (NHCl3).
Indoor chlorine gas release in a natatorium: A case study
Published in Journal of Occupational and Environmental Hygiene, 2021
Benjamin N. Craig, Trent F. Parker, Qingsheng Wang, Michael D. Larrañaga
Chloramines include the inorganic compounds monochloramine (NH2Cl), dichloramine (NHCl2), and trichloramine (NCl3) (Jacobs et al. 2007). According to the CDC (2016), chloramines often off gas from pool water, particularly indoors, and when airborne irritate the skin, eyes, and respiratory tract similar to chlorine gas (Weng et al. 2011). Of the chloramines, trichloramine is the most volatile and is easily released into the air (Jacobs et al. 2007). When the free chlorine present within pool water contacts contaminants, including urine, saliva, sweat, and other organic materials, chloramines are formed and can spontaneously off gas into the air (Rodríguez et al. 2018). This is because these contaminants contain ammonia (NH3), which react with chlorine to generate chloramines. However, as there were likely no chloramines present in the pool water because of a lack of human activity in the newly filled and reopened pool, it is unlikely that chloramines would have interfered with the ORP readings. Thus, chloramines were excluded as a potential cause of the gas release.
Aqueous N-nitrosamines: Precursors, occurrence, oxidation processes, and role of inorganic ions
Published in Critical Reviews in Environmental Science and Technology, 2021
Tahereh Jasemizad, Peizhe Sun, Lokesh P. Padhye
Aqueous NDMA formation pathway was first suggested (Choi & Valentine, 2002b; Mitch & Sedlak, 2002) for chlorination of waters containing DMA and in the presence of ammonia. The proposed mechanism involved the generation of unsymmetrical dimethylhydrazine (UDMH) intermediate, with its subsequent oxidation to NDMA. Later, this pathway was revised by Schreiber and Mitch (2006), suggesting a nucleophilic substitution reaction between secondary amines and NHCl2, formed via disproportionation of NH2Cl, forming chlorinated UDMH (Cl-UDMH) and subsequent NDMA formation from oxidation of Cl-UDMH with dissolved oxygen. Although dichloramine is not intentionally applied for disinfection, it has been reported that the presence of NHCl2 could significantly enhance NDMA formation from DMA (Schreiber & Mitch, 2006) and tertiary amines, regardless of its relatively minor fraction (Mitch et al., 2005). At pH less than 8, dichloramine can be formed due to the self-decomposition of monochloramine (Valentine & Jafvert, 1988).
Temporal and spatial variations in the levels of prominent airborne disinfection by-products at four indoor swimming pools
Published in Journal of Occupational and Environmental Hygiene, 2022
Elham Ahmadpour, Stephan Halle, Isabelle Valois, Patrick Eddy Ryan, Sami Haddad, Manuel Rodriguez, Badr El Aroussi, Sabrina Simard, Ianis Delpla, François Proulx, Robert Tardif, Maximilien Debia
To inactivate microbial pathogens and prevent waterborne diseases, swimming pool water undergoes disinfection. Among the major classes of disinfectants (chlorine-based, bromine-based, ozone, UV, and emerging disinfectants), chlorine is the most commonly used (Teo et al. 2015). However, regardless of which of these compounds are used, disinfection by-products (DBPs) will inevitably be formed. This is due to the unintended reactions between the disinfectant ions (chloride/bromide/iodide) and the corresponding constituents of natural organic matter (NOM). The types of NOM commonly found in pools include perspiration and urine, skin particles, hair, mucus, and personal care products (Hsu et al. 2009). Which of the numerous disinfection by-products are produced depends on the different disinfectants and variations in NOM concentration (Richardson et al. 2010). DBPs are classified into three major groups: (1) trihalomethanes (THMs), which include trichloromethane (TCM), dichlorobromomethane (DCBM), bromodichloromethane (BDCM), and bromoform (TBM); (2) halo acetic acids (HAAs) which include monochloroacetic acid (MCA), monoaromatic acid (MBA), dichloroacetic acid (DCA), dichloroacetic acid (DCA), bromo chloroacetic acid (BCA), and dibromo acetic acid (DBA); and (3) chloramines (CAMs), which include monochloramine (MCAM), dichloramine (DCAM), and trichloramine (TCA) (Tardif et al. 2015). While species from all three classes of DBPs could be present in the water, THMs and CAMs can transfer more easily from the water to the air surrounding swimming pools, mostly because of the high vapor pressure associated with these substances. In chlorinated swimming pools, TCM and TCA are the main species of concern from the THM and CAM groups, respectively (Tardif et al. 2016; Manasfi et al. 2017; Nitter and Svendsen 2019a; Felgueiras et al. 2020). Consequently, monitoring TCA and TCM levels has been the subject of several investigations (Villanueva et al. 2015; Manasfi et al. 2017).