Preconcentration and separation for determination of Th in Monazite with chelating filter paper

A chelating filter paper "Expapier F-2", 2-hydroxy-propyliminodiacetic acid loaded on cellulose fiber, is described for simple preconcentration and separation of trace amounts of Th(IV) from rare earth ions(III). By a filtration procedure, Th (IV), Zr (IV), Fe (III), Sc(III), Y(III), and rare earth ions(III) were quantitatively retained on the Expapier F-2 from acetate buffer solutions (0.03 mol dm-3 CH3COONa) at pH 45. The quantitative retention pH of various metal ions were as follow; Th(IV) : 2.04.5, Ce(IV) : 4.76.0, Zr(IV) : 0.52.5, Sc(III) : 3.04.0, Y(III) : 3.05.2, Al(III) : > 5.0, Fe(III) : 1.72.0, rare earth metal ions(III) : 2.06.0. The complexing capacity of Expapier F-2 for these metal ions was (6.35±0.25)×10-2 meq g-1 at optimal pH. Metal ions retained on the Expapier F-2 were successively eluted with eluting solution (A) and (B). Rare earth metal ions(III), Sc(III), Y(III), Fe(III), Al(III) and other divalent ions were completely eluted with 20 cm3 of 0.03 mol dm-3 sodium acetate-hydrochloric acid solution {(A) : pH1.5} at a flow rate of 5 cm3 min-1. Th(IV) remained on the Expapier F-2 was completely eluted with 20 cm3 of 2 mol dm-3 hydrochloric acid(B); the amount was determined by fluorometry with flavonol reagent, ICP-AES method and/or XRF method. The present method is useful for rapid preconcentration and simple separation of Th in rare earth oxide from monazite mineral.