A theoretical model for the synthesis of nanosized sorbents in porous media of ion-exchange xerogels has been developed, which takes into account the occurrence of one or more parallel reactions of insoluble substances formation. The model describes the diffusive transfer of inter-active substances in the porous medium of xerogel and the formation of insoluble substances both in the pores of the xerogel and on the outer surface of the porous matrix. Model calculations of barium sulfate formation in the pores of amorphous porous barium silicate have been carried out. The conditions of the process of insoluble barium sulfate formation in porous xerogel medium have been determined. The results of calculations agree well with estimates made on the basis of equilibrium thermodynamics data.
By the example of sorption-reagent materials (SRM) based on inorganic hydroxides the factors influencing the efficiency of the strontium sorption process are considered. It is shown that formation of a poorly soluble sediment in the porous system of the sorbent matrix is possible either in the form of microcrystals in the pore volume or in the form of thin X-ray amorphous layers on the pore surface, which in turn affects the selectivity of strontium extraction. The peculiarities of strontium sorption dynamics by SRM are considered. Mathematical model of strontium sorption dynamics in sorption-reagent systems is presented which allows not only to predict sorption behavior of material, form content of all system components at any moment of time and at any point of a column, but also to explain distinctive features of the process.
