Formation of Larger Molecular Weight Disinfection Byproducts from Acetaminophen in Chlorine Disinfection

Abstract

Acetaminophen is widely used to treat mild to moderate pain and to reduce fever. Under the worldwide COVID-19 pandemic, this over-the-counter pain reliever and fever reducer has been drastically consumed, which makes it even more abundant than ever in municipal wastewater and drinking water sources. Chlorine is the most widely used oxidant in drinking water disinfection, and chlorination generally causes the degradation of organic compounds, including acetaminophen. In this study, a new reaction pathway in the chlorination of acetaminophen, i.e., oxidative coupling reactions via acetaminophen radicals, was investigated both experimentally and computationally. Using an ultraperformance liquid chromatograph coupled to an electrospray ionization-triple quadrupole mass spectrometer, we detected over 20 polymeric products in chlorinated acetaminophen samples, some of which have structures similar to the legacy pollutants “polychlorinated biphenyls”. Both C–C and C–O bonding products were found, and the corresponding bonding processes and kinetics were revealed by quantum chemical calculations. Based on the product confirmation and intrinsic reaction coordinate computations, a pathway for the formation of the polymeric products in the chlorination of acetaminophen was proposed. This study suggests that chlorination may cause not only degradation but also upgradation of a phenolic compound or contaminant.

Stochastic Dynamic Mass Spectrometric Quantitative and Structural Analyses of Pharmaceutics and Biocides in Biota and Sewage Sludge

“…The presence of benzalkonium chloride disinfectants in the environment promotes the abundance and diversity of antibiotic resistance genes in sewage sludge microbiomes [ 10 ]. Antibiotics, as surfactants and environmental pollutants, represent a widespread concern and ecotoxicological risk [ 23 , 24 , 25 , 31 , 32 ].…”

“…There is an environmental effect of the pharmaceutics on physiological processes in wild animals. The same can be said for paracetamol (tylenol or acetaminophen), which is a commonly used anti-inflammatory, antipyretic, and analgesic medication [ 32 , 34 , 35 ]. It can be found in tap water from the pharmaceutical industry and in urban and hospital waste [ 36 ].…”

Contributions of Pharmaceuticals to DBP Formation and Developmental Toxicity in Chlorination of NOM-containing Source Water

“…In addition, the contributions of pharmaceuticals to the TOX formation were slightly higher in the bromide-free samples than those in the bromide-containing samples, probably because there is a higher propensity for electron transfer instead of electrophilic substitution in the reactions of HOBr with certain pharmaceuticals than with NOM. 55 Modeled Contributions of Pharmaceuticals and NOM to TOX Formation. The finalized kinetic model, which included reactions of chlorine with pharmaceuticals, NOM, halogenated intermediate DBPs and bromide, is summarized in Table 1.…”

“…54 Density functional theory (DFT) is one of the most popular computational methods for determining the electronic structure of a molecular system. 55,56 In developing the kinetic model in this study, DFT was applied to assist in investigating the reaction mechanism and estimating the reaction rate constants.…”

Probing into the mechanisms of disinfection by-product formation from natural organic matter and model compounds after UV/chlorine treatment

“…8,47 Similarly, Cl˙, ClO˙, and Cl 2 ˙− generated in the UV/chlorine process react with phenol to form phenoxy radicals, 9 an intermediate also leading to the formation of benzoquinones and polymers. 48,49 These products are not as reactive toward chlorine as phenol, 49 resulting in lower TCAA formation.…”