ИСТИНА

Sorption and extraction processes are widely used in hydrometallurgy of rare and radioactive elements in the NFC. То combine the advantages of these processes obtained materials, the properties occupying an intermediate position between the sorbents and extractants [1-5]. Impregnates (SIR) and Levextrel-resins have properties that depend on both the type of extractant and the porous characteristics of the matrices. They differ in the method of preparation: into the impregnates the extractant is introduced Ьу impregnating the carrier, and into the Levextrel-resin - in the process of polymer matrix synthesis. Due to the lack of chemical bond between the extractant and the sorbent, extractant losses occur in contact with aqueous solutions, which deter1nine the economic feasibility of using materials of this type. Analysis of the literature data shows that extractant losses, which were evaluated under different, usually incomparaЫe conditions, are up to 5-20 % for 3-50 sorption cycles. The aim of this investigation is to identify the physicochemical laws of the transition of the extractant into the solution during the operation of impregnates and Levextrel-resin used for the recovery of rare and radioactive elements. It was found that the transition of the extractant into the solution from the Levextrel-resin contained org anophosphorus extractants occurs in accordance with its solubility in the aqueous phase. The obtained S-shaped isother·1ns leaching of the active phase of Levextrel-resin confirm that in the polymer matrix, the extractant is in the drip -liquid or dissolved state. It was found that the process of leaching the extractant from the Le vext rel -res in Ь)' aqueous solutions proceeds in the mixed diffusion region, and the contribution of intemal diffusion in reases ,,·ith increasing temperature. The activation energy of leaching has а negative value, which i deter111ined Ь)· the peculiarities of the structure of matrix. It was shown, that the presence of trace amounts о me 1- he aqueous solution and on the sorbent slightly affected Ьу the loss of the extractant.