Separation and Determination of Small Amounts of Rare Earths in Uranium

Abstract

A spectrophotometric method for the determination of total rare earths in the range 100 to 200 gamma is preseated. The chromophoric agent is 2-(1,8- dihydroxy3,6-disulfo-2-naphthylazo)-benzenearsonic acid (arsenazo). The absorbance is measured at 570 m mu and pH 7.0. The main objective of this investigation was to develop a method of determining rare earths in the presence of large amounts of uranium and small amounts of iron. As both metals interfere in the proposed spectrophotometric method for rare earths, an ion exchange method of separation is presented which is based on the absorption of uranium(VI) sulfate and iron(III) thiocyanate on a quaternary ammonium anion exchange resin. (auth)