Some Properties of Iron(III) Selenite and Its Applications for the Determination of Thorium

Abstract

A new inorganic ion exchanger, iron(III) selenite has been synthesized having an Fe:Se ratio of 2:3 and cation exchange capacity of 0.40 meq g−1. It is fairly stable in water and dilute solutions of acids, bases, and salts. Ion distribution studies on twenty one metal ions have been done in water. Iron(III) selenite granules in H+-form have also been used as indicators in the determination of thorium in presence of some rare earth cations using hexacyanoferrate(II) as titrant. On the basis of chemical analysis, pH titrations, thermal and infrared analyses the following scheme for the decomposition of iron(III) selenite has been proposed: 2Fe2O3·3H2SeO3·2H2O\overset140°C→2Fe2O3·3H2SeO3\overset500°C→2Fe2O3.