Perlova N. Sorption of Uranium(VI) compounds from aqueous solutions by synthetic ion exchangers

Zirconium-silica inorganic sorbents, organic-inorganic sorbents based on cation exchanger Dowex HCR-S modified by zirconium hydrophosphate, and organic ion exchangers FIBAN were used. Expediency and high efficiency of U(VI) removal from dilute aqueous solutions by studied synthetic ion exchangers were scientifically grounded and experimentally proved on the basis of established colloid-chemical regularities of sorption. Studied materials in comparison with the known sorbents, have higher sorption capacity, and using of offered materials makes it possible to decrease their consumption, to shorten the time of sorption, to reuse regenerated ion exchangers. The methods such as sorption-desorption of nitrogen, standard contact poremetry, spectroscopy (roentgenofluorescent, NMR 31Р, IR), microscopy (optical, TEM), microelectrophoresis were used for study of the sorbents colloid-chemical properties (specific surface, pores diameter, particles size and isoelectric point), its composition and morphology. The relationship between efficiency of U(VI) sorption and listed factors has been established. The sorption rational conditions (sorbent dosage, solution pH, sorption time, temperature) were determined. Under these conditions the remaining concentration of U(VI) didn't exceed the MPC. The sorption kinetics and isotherms were analyzed with the help of modern colloid-chemical models. The kinetic and thermodynamic parameters of sorption were calculated. Conditions for the regeneration of sorbents were established. The U(VI) sorption mechanism was proposed. Studied sorbents can be used for complex purification model solutions from U(VI) and other ions, in particular, Fe(III), under rational conditions of sorption. The methods of U(VI) removal from carbonate, nitrate and chloride solutions in wide range of U(VI) initial concentrations (5-100 mg dm-3) with possibility of sorbents regeneration and receiving of concentrated U(VI) containing solutions were proposed.