Sofronov D. Regularity of dehydration of the lithium, sodium and cesium iodides in vacuum

Object of the investigation: lithium (LiI·3H2O, LiI·H2O, LiI), sodium (NaI·2H2O, NaI) and cesium (CsI) iodides.Aim of the investigation: determination of an influence of decomposition condition of the crystalline hydrates on formation of oxygen containing impuritiesMethods of investigation and instruments: baric method, mass-spectroscopy, infrared spectroscopy, Fisher method.Theoretical results and novelty. For the first time systematic investigation of the lithium, sodium, cesium iodides dehydration in vacuum has been performed. The processes of oxidation and carbonization of the crystalline hydrates of lithium and sodium iodides have been studied in the temperature range 20-150oC in vacuum. It was shown that reason of water elimination at heating of sodium and cesium iodides in the temperature range 150-450oC is connected with impurities of hydroxides decomposition. The hydroxides were formed by the iodides hydrolysis. Interaction between the lithium iodide crystal hydrate and oxygen was observed tolead to lithium peroxide. The crystalline hydrates of lithium and sodium iodides were shown to posses high reactivity with respect to oxygen containing components of air (СО2, О2) in comparison with waterless compounds.Practical results and novelty. The methods of the lithium, sodium, cesium iodides dehydration that provides preparation of the salts with low content of oxygen containing impurities has been developed. The method of NaI·2H2O dehydration in microwave field allowing to increase dehydration rate in 5-6 times has been proposed. The sodium iodide purification method from product of pyrolysis by means of oxidation by dry air at 400-450oC has been proposed. Field of application: inorganic chemistry