Nitrite-Induced Activation of Iodate into Molecular Iodine in Frozen Solution.

Author(s) Kim, K.; Ju, J.; Kim, B.; Chung, H.Young; Vetráková, L.'ubica; Heger, D.; Saiz-Lopez, A.; Choi, W.; Kim, J.
Journal Environ Sci Technol
Date Published 2019 Apr 09
Abstract

A new mechanism for the abiotic production of molecular iodine (I) from iodate (IO), which is the most abundant iodine species, in dark conditions was identified and investigated. The production of I in aqueous solution containing IO and nitrite (NO) at 25 °C was negligible. However, the redox chemical reaction between IO and NO rapidly proceeded in frozen solution at -20 °C, which resulted in the production of I, I, and NO. The rapid redox chemical reaction between IO and NO in frozen solution is ascribed to the accumulation of IO, NO, and protons in the liquid regions between ice crystals during freezing (freeze concentration effect). This freeze concentration effect was verified by confocal Raman microscopy for the solute concentration and UV-visible absorption spectroscopy with cresol red (acid-base indicator) for the proton concentration. The freezing-induced production of I in the presence of IO and NO was observed under various conditions, which suggests this abiotic process for I production is not restricted to a specific region and occurs in many cold regions. NO-induced activation of IO to I in frozen solution may help explain why the measured values of iodine are larger than the modeled values in some polar areas.

DOI 10.1021/acs.est.8b06638
ISSN 1520-5851
Citation Kim K, Ju J, Kim B, Chung HY, Vetráková L', Heger D, et al. Nitrite-Induced Activation of Iodate into Molecular Iodine in Frozen Solution. Environ Sci Technol. 2019.

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