Radiochemical investigation of coprecipitation of microquantities of some hydrolyzable elements with hydroxides and oxides of metals

Coprecipitation of various amounts of Cr(3) (from 1 mcg to 3.26 mca) with Sn(4), Fe(3), Th, Be, Cd and Mg hydroxides is studied as a function of pH. It is shown that the basic-acidic interaction between micro- and macrocomponents depends on the difference in their acidic properties. The main coprecipitating compound of Cr(3) is a neutral hydroxocomplex Cr(OH)3. At pH when such complex does not exist the coprecipitation of Cr(3) appears to occur due to the interaction with the collector, provided the solution contains no positively charged hydroxocomplexes of the macrocomponent. This interaction is promoted by hydrolysis of Cr(3). In particular, at pH--1.5-3.0 even macroamounts of Cr(3) are capable of partial coprecipitation with Sn(4) hydroxide. It is suggested that hydrolysis of Cr(3) is enhanced by more acidic elements such as Sn(4) and Fe(3), and weakened by less acidic elements such as beryllium