Studying the characteristics of iodine sorption in synthetized ion-exchangers

Iodine is an essential micronutrient for humans and animals due to its important role as a component of thyroid hormones. Kazakhstan is a country, most regions of which suffer from a natural deficiency of iodine. At the same time, the country has a rich resource base for obtaining iodine and its compounds. These are formation waters of oil fields under development containing 0.001–0.005% iodine. To extract iodine from natural oil-field brines, we have proposed ion-exchange materials obtained from the waste of the oil refining industry. The article presents the results of studying the characteristics of iodine sorption in the synthesized ion exchangers. The synthesis of ion exchangers was carried out by polycondensation of dihydric phenols (1,3 dioxybenzene, 1,2 dioxybenzene, 1,4 dioxybenzene), hexamethylenediamine, and formaldehyde. The following sorption characteristics of iodine by the synthesized ion exchangers were studied: the influence of the pH of a solution on iodine sorption; kinetic curves of iodine sorption; iodine sorption isotherms; mechanism of iodine sorption. It has been established that the sorption of iodine on the synthesized samples is essentially independent of the pH of a medium, and the degree of its extraction in the entire area under study is 94–100%. Studies have been carried out on the dependence of the degree of extraction and the logarithm of the iodine distribution coefficient on the duration of the process. The sorption capacity of the synthesized ion exchangers with respect to iodine was estimated depending on the structure of the ion exchanger and sorption conditions. It has been established that sorbents based on 1,4 dioxybenzene, which are distinguished by high kinetic abilities and static exchange capacity (SEC = 2283.88 mg/g), are most preferable for iodine extraction. The mechanism of sorption of iodine by synthesized ion exchangers has been determined.