I. V. Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials, Kola Scientific Centre, Russian Academy of Sciences

V. I. Ivanenko, Senior Researcher, e-mail: Ivanenko@chemy.kolasc.net.ru
R. I. Korneykov, Junior Researcher
E. P. Lokshin, Head of Laboratory

Sorption methods can be advantageously applied to extracting microquantities of toxic metal cations from complex in chemical composition liquid process wastes of nuclear power plants (¹³⁴Cs, ¹³⁷Cs, ⁹⁰Sr, ⁶⁰Со) and non-ferrous metallurgy wastes (Co, Ni, Cu). Standing out among inorganic sorbents are titanium (IV) hydrophosphates. Their functional properties depend on composition and yield to improvement. To improve sorption purification of liquid wastes from toxic metals, there were examined the dependence of ion-exchange properties of titanophosphate sorbents on the degree of hydration and modification by transition metal cations differing in electronegativity from titanium (IV). In this work, we have investigated the relationships between the static exchange capacity, specific surface cation exchange constant and the sorbent composition when sorbing the metals cations. It has been shown that the highly hydrated sorbent samples can achieve a static exchange capacity, which is close to theoretical and equals the HPO₄-group content in the sorbent. The effect of the sorbed metal cation nature on the value of static exchange capacity and the constant of heterogeneous displacement of protons for metal cations was studied. Compared to oxohydroxophosphate titanium sorbents, the modified ones have greater exchange constant values and stability to acid solutions, preserve a high value of static exchange capacitance at a smaller specific content of coordination water in sorbent. The modified sorbents can be effectively used for purification of liquid radioactive wastes from radionuclides ^134,137Cs, ⁹⁰Sr, ⁶⁰Со with high contents of non-radioactive element salts, and also for extraction of non-ferrous metal cations from industrial effluents, which must be followed by desorbing and concentrating under a simultaneous sorbent regeneration for further utilization.

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