Interaction between traces of yttrium and iron(III) in aqueous solutions—I: The state of yttrium in the solution

Abstract

The state of trace concentrations of yttrium (using 88Y) in aqueous solutions and its interaction with ∼ 3·10 −7M and 3·10 −5M iron was investigated by the methods of dialysis, centrifugation and electromigration. It is concluded that trace yttrium (< 10 −9 M) exists in solutions of pH lower than 3·5 as simple Y 3+ ion, while at higher pH values pseudocolloids are formed. These colloids are positively charged at pH < 6 and their formation is mostly due to cation exchange of yttrium ions on the surface of fortuitous colloidal impurities. In the pH region 6–10 coprecipitation with ferric hydroxide proceeds, whereas at pH > 10 both this coprecipitation and adsorption of yttrium on to foreign colloidal impurities may take place. The resulting colloids are negatively charged. In the solutions having a concentration of 2·10 −6M Y and ∼ 3·10 −7M Fe yttrium cations prevail up to pH ∼ 7 and colloidal yttrium hydroxide is formed above pH 8. Some information on the charge on this hydroxide and that of 3·10 −5M iron(III) hydroxide has also been obtained.