Synchronous Moderate Oxidation and Adsorption on the Surface of γ-MnO 2 for Efficient Iodide Removal from Water

作者：Nan Wang, Gong Zhang, Ruoxi Xiong, Ruiping Liu, Huijuan Liu, Jiuhui Qu · 发表于：Environmental Science & Technology · 年份：2022 · DOI：10.1021/acs.est.2c01682 · 被引用次数：42 · 研究领域：Radioactive element chemistry and processing、Covalent Organic Framework Applications、Analytical chemistry methods development

Long-term exposure to excessive iodine via drinking water presents health risks. Moderate oxidation of iodide (I – ) to iodine (I 2 ) has a better iodine removal effect than excessive oxidation to iodate (IO 3 – ). This study combines computational and experimental methods to construct a heterogeneous interface with synchronous I – moderate oxidation and I 2 adsorption to increase the total iodine removal. Compared to other forms of crystal manganese dioxide (MnO 2 ), theoretical calculations predict that MnO 2 with a γ-crystal structure has the lowest adsorption energy, that is, −1.20 eV, and a slight overlap between the conduction and valence bands, which favors electron transfer between I – and Mn(IV) and I 2 adsorption. Thus, γ-type MnO 2 was designed by adjusting the precursor Mn sources and hydrothermal reaction conditions. The liquid chromatography–inductively coupled plasma–mass spectrometry and high-performance liquid chromatography confirmed that the total iodine concentration in water decreased from 173.7 to 36.3 μg/L after 2 h, with 200 mg/L γ-MnO 2 dosage lower than the national standard of 0.1 mg/L. A minute proportion of I – in water was converted to IO 3 – (approximately 1.1 μg/L). The current I – adsorbent performed better than previously reported ones. During iodine removal, most of the I – migrated from water to the surface of γ-MnO 2, and the ratio of I – to I 2 was determined to be 1:0.6 by X-ray photoelectron spectroscopy. This study evaluates iodine spe...