Formation of Haloacetonitriles, Haloacetamides, and Nitrogenous Heterocyclic Byproducts by Chloramination of Phenolic Compounds

Abstract

18The potential formation of nitrogenous disinfection by-products (N-DBPs) was investigated from the 19 chloramination of nitrogenous and non-nitrogenous aromatic compounds. All molecules led to the 20 formation of known N-DBPs (e.g., dichloroacetonitrile, dichloroacetamide) with various production 21 yields. Resorcinol, a major precursor of chloroform, also formed di-/tri-chloroacetonitrile, di-/tri-22 chloroacetamide, and haloacetic acids, indicating that it is a precursor of both N-DBPs and 23carbonaceous DBPs (C-DBPs) upon chloramination. More detailed experiments were conducted on 24 resorcinol to understand N-DBPs formation mechanisms and to identify reaction intermediates. Based 25 on the accurate mass from high resolution Quadrupole Time-of-Flight GC-MS (GC-QTOF) and 26 fragmentation patterns from electronic impact and positive chemical ionization modes, several 27 products were tentatively identified as nitrogenous heterocyclic compounds (e.g., 3-chloro-5-hydroxy-28 1H-pyrrole-2-one with dichloromethyl group, 3-chloro-2,5-pyrroledione). These products were 29 structurally similar to the heterocyclic compounds formed during chlorination, such as the highly 30 mutagenic MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) or halogenated pyrroles. To 31 our knowledge, this is the first time that the formation of halogenated nitrogenous heterocyclic 32 compounds is reported from chloramination process. The formation of these nitrogenous by-products 33 during chloramination might be of concern considering their potential toxicity. 34 ABSTRACT ART35 36 37 INTRODUCTION 38

The formation of disinfection by-products from the chlorination and chloramination of amides

“…Interestingly, the aromatic nature of hydroxybenzamide did not favour HAcAm formation as much as expected during both chlorination and chloramination. Literature suggests that a ring-cleavage reaction is triggered when the aromatic ring is activated by the hydroxyl group, encouraging chlorine electrophilic substitution (Chu et al, 2010b;Hureiki et al, 1994;Nihemaiti et al, 2016). However, either chloramine cannot trigger the rapid opening of the benzene ring (Chu et al, 2009) or the HAcAms previously formed at lowercontact times, regardless of their amount, were prone to hydrolyse at a faster rate.…”

“…However, recently Huang et al (2012) found that DCAcAm can be generated independently from DCAN during both chlorination and chloramination. That study suggested the need for investigating alternative pathways and potential nitrogenous and non-nitrogenous N-DBP precursors in drinking water during the application of chlor(am)ine (Chu et al, 2010a(Chu et al, , 2010bKimura et al, 2013;Le Roux et al, 2016;Nihemaiti et al, 2016). Interestingly, the DCAcAm yields reported from model precursor studies, that include amino acids, are significantly lower than those of DCAN (Chu et al, 2010b), whereas in studies that include real water matrices the levels of the two N-DBP groups are similar (mean: 1.4 µg/L and 1 µg/L, respectively) (Krasner et al, 2006).…”

“…The highest formation potential for DCAcAm has been linked to natural waters with significant hydrophilic acid fractions in the organic matter (Chu et al, 2010a), especially those characterised by protein-like structures. Several researchers have investigated the potential of these nitrogen-rich species, often associated with wastewater-impacted or algal-rich water matrices, such as amino acids (both aliphatic and aromatic), proteins, pyrroles, pyrimidines, lignin phenols to act as N-DBPs precursors by chlorinating and chloraminating model precursor compounds (Bond et al, 2014;Chu et al, 2010a;Chuang et al, 2015;Le Roux et al, 2016;Nihemaiti et al, 2016). Bond et al (2014), assessed the effect of both chlorination and chloramination of seven model amine compounds at three pH values (6, 7 and 8), and quantified the concentrations of DCAN, TCAN, chloroform and TCNM.…”

pH-Dependent Degradation of Diclofenac by a Tunnel-Structured Manganese Oxide

“…In past decades, Mn-oxides have been used to remove antibacterials and compounds with phenolic and fluoroquinolonic moieties [20,21], triazine, aromatic N-oxides [22], tetracyclines [23], and estrogenic compounds such as the synthetic hormone 17R-ethinylestradiol [24,25] and as an alternative treatment for wastewater or groundwater containing DIC because Mn-oxides are cheap and operated-friendly [26,27]. These compounds may be endocrine disruptors (EDS) and precursors of harmful disinfection byproducts such as haloacetonitriles, haloacetamides, and nitrogenous heterocyclic [28].…”

Temperature dependence of hydroxyl radical reactions with chloramine species in aqueous solution

“…However, the simultaneous presence of chloramines and chlorine reacting with DOM can increase overall DBP production (Wang et al, 2016), and the reaction of monochloramine with DOM and other trace chemical contaminants can produce N -nitrosodimethylamine and other species such as aromatic halogenated DBPs (Pan and Zhang, 2013; Hua et al, 2015; LeRoux et al, 2016; Pan et al, 2016; LeRoux et al, 2017; Jiang et al, 2017; Tian et al, 2017) that can be more toxic than trihalomethanes and haloacetic acids, but are currently not as widely regulated (Krasner et al, 2013; Pan et al, 2013; Gong et al, 2016; Guo et al, 2016; Nihemaiti et al, 2016; Zeng et al, 2016; Spahr et al, 2017). The specific timing of chloramination in the water treatment train is thus very important; chloramines need to be generated at specific times that allows for maximum microbial inhibition while minimizing harmful DBP formation (Carlson and Hardy, 1998; Hua and Reckhow, 2007; Wang et al, 2016).…”