Solvent extraction separation of thorium(IV) from nitric acid with Cyanex 272

Thorium (IV) has been quantitatively extracted from 1x10-3 M nitric acid with 1x10-3 M Cyanex 272 in xylene. It has been stripped from the organic phase with 4 M hydrochloric acid and determined spectrophotometrically as its complex with Arsenazo(III) at 655 nm. The method developed has been applied for the separation of thorium(IV) from chromium(Vi), vanadium(V), hafnium(IV), zirconium(IV), titanium(IV), iron(III), cobalt(II), calcium(II) and some rare earth elements. The applicability of the method has been checked for separation of thorium(IV) from associated elements in the synthetic mixtures and monazite sand. The method is simple, rapid and selective for thorium(IV) with a relative standard deviation of 0.27%. (author)