Original scientific paper

Precipitation and Hydrolysis of Uranium(VI) in Aqueous Solutions. II. Uranyl Nitrate - Sodium Carbonate - Alkaline Earth Chlorides

H. Furedi ; Department of Physical Chemistry, Institute »Ruder Boskovic« and Laboratory of Physical, Chemistry, Faculty of Science, Zagreb, Croatia, Yugoslavia
B. Težak ; Department of Physical Chemistry, Institute »Ruder Boskovic« and Laboratory of Physical, Chemistry, Faculty of Science, Zagreb, Croatia, Yugoslavia

Abstract

The precipitation systems: uranyl nitrate (2X IQ-3N) - sodium
carbonate - Me chlorides (Me = Ba, Sr, Ca, Mg) were
investigated and compared. The corresponding precipitation diagrams
were constructed by plotting the percentage of uranium
precipitated as a function of the concentrations of sodium carbonate
and alkaline earth chloride.
Solid phase formation starts in all systems at sodium carbonate
concentration of 1.6.X 10-aN and pH"' 5, when a critical concentration
of the particular alkaline earth chloride, necessary for
precipitation, is exceeded. A precipitation maximum with more
than 80% of uranium precipitated occurs at 3X 10-:w of sodium
carbonate and pH ,.., 6. At high concentrations of both sodium carbonate
and alkaline earth chloride uranium is coprecipitated with
the corresponding alkaline earth carbonate. The coprecipitation
regions are shifted to higher co·ncentrations of the precipitating
components in the normal order of alkaline earth ions. A region
with less than 15°/o of uranium precipitated separates the
regions of precipitation and coprecipitation of uranium in the
presence of strontium, calcium and magnesium chloride. With
barium chloride in solution, this minimum is replaced by a
»transitional« precipitation region with 55- 95% of uranium precipitated. When sodium carbonate is present in concentrations
higher than the concentr11tions of alkaline earth chloride soluble
complex, uranyl carbonates prevail in all systems.

Keywords

Hrčak ID:

208300

URI

https://hrcak.srce.hr/208300

Publication date:

30.12.1964.

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