Natural solar photolysis of total organic chlorine, bromine and iodine in water

• Published in: Water research (Oxford) Vol. 92; pp. 69 - 77
• Main Authors: Abusallout, Ibrahim, Hua, Guanghui
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2016
• Subjects: Benzopyrans - chemistry; Bromine; Bromine - radiation effects; Chlorine; Chlorine - radiation effects; Degradation; Disinfection byproducts; Drinking water; Halogenation - radiation effects; Hydrogen-Ion Concentration; Iodine; Iodine - radiation effects; Irradiation; Kinetics; Molecular Weight; Nitrates - analysis; Photolysis; Photolysis - radiation effects; Rivers - chemistry; Solar photolysis; Sulfites - analysis; Sunlight; Total organic bromine; Total organic chlorine; Total organic iodine; Water - chemistry; Water Quality; Total organic chlorine; Total organic iodine; Solar photolysis; Disinfection byproducts; Total organic bromine
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2016.01.047

Municipal wastewater has been increasingly used to augment drinking water supplies due to the growing water scarcity. Wastewater-derived disinfection byproducts (DBPs) may negatively affect the aquatic ecosystems and human health of downstream communities during water reuse. The objective of this research was to determine the degradation kinetics of total organic chlorine (TOCl), bromine (TOBr) and iodine (TOI) in water by natural sunlight irradiation. Outdoor solar photolysis experiments were performed to investigate photolytic degradation of the total organic halogen (TOX) formed by fulvic acid and real water and wastewater samples. The results showed that TOX degradation by sunlight irradiation followed the first-order kinetics with half-lives in the range of 2.6–10.7 h for different TOX compounds produced by fulvic acid. The TOX degradation rates were generally in the order of TOI > TOBr ≅ TOCl(NH2Cl) > TOCl(Cl2). High molecular weight TOX was more susceptible to solar photolysis than corresponding low molecular weight halogenated compounds. The nitrate and sulfite induced indirect TOX photolysis rates were less than 50% of the direct photolysis rates under the conditions of this study. Fulvic acid and turbidity in water reduced TOX photodegradation. These results contribute to a better understanding of the fate of chlorinated, brominated and iodinated DBPs in surface waters. [Display omitted] •TOX degradation kinetics by natural sunlight irradiation was evaluated.•Solar photolysis rates followed the order of TOI > TOBr ≅ TOCl(NH2Cl) > TOCl(Cl2).•High molecular weight TOX degraded faster than low molecular weight TOX.•The nitrate and sulfite indirect TOX photolysis rates were less than the direct photolysis rates.•Fulvic acid and turbidity in water reduced TOX photodegradation.