Oxidation of iodide and hypoiodous acid by non-chlorinated water treatment oxidants and formation of iodinated organic compounds: A review

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 386; p. 123822
• Main Authors: Li, Juan, Jiang, Jin, Pang, Su–Yan, Cao, Ying, Zhou, Yang, Guan, Chaoting
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.04.2020
• Subjects: Ferrate; Hypoiodous acid (HOI); Iodide (I−); Iodinated organic compounds (I-OCs); Manganese oxidants; Peroxide-based oxidation processes; Hypoiodous acid (HOI); Ferrate; Iodinated organic compounds (I-OCs); Iodide (I−); Peroxide-based oxidation processes; Manganese oxidants
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2019.123822

[Display omitted] •Oxidation kinetics and mechanisms of I− and HOI by non-chlorinated oxidants are summarized.•HOI half-life increases in the order of O3 < Fe(VI) < PMS < HOCl < Mn(VII) < NH2Cl at neutral pH.•HOI shows considerable reactivity towards phenolic and carbonyl compounds.•I-THMs, IAAs, I-AcAms, and iodinated aromatics are formed in non-chlorinated oxidation processes.•Future challenges relating to I-OCs during water treatment are discussed. Iodinated organic compounds (I-OCs) have raised significant public concerns due to their high toxicity. Iodide (I−) as an inorganic source of I-OCs is ubiquitously present in raw waters. I− can be easily oxidized by water treatment oxidants/disinfectants generating reactive iodine species such as hypoiodous acid (HOI), which can further react with organic compounds generating I-OCs. The oxidation of I−/HOI by chlorinated oxidants/disinfectants (e.g., chlorine (HOCl) and monochloramine (NH2Cl)) as well as formation of I-OCs during these processes has been extensively studied and well reviewed. Hence, the present work focuses on the latest findings on the transformation of I−/HOI as well as formation of I-OCs during non-chlorinated oxidation processes including permanganate, manganese dioxide, ferrate, and peroxide-based oxidation processes. First, oxidation kinetics of I−/HOI by these non-chlorinated oxidation processes and the mechanisms involved were summarized. Reactivity and pathways of HOI reaction with different targets (i.e., phenolic compounds, carbonyl compounds, and natural organic matters (NOM)) were then discussed. Further, formation of I-OCs (e.g., iodoform, iodoacetic acid, iodoacetamides, and iodinated aromatics) during these non-chlorinated oxidation processes was elucidated. Finally, the challenges and new perspectives in this field were discussed.