Immobilization of alkali, alkaline-earth and rare-earth elements by crystalline zirconium phosphate HZr2(PO4)3

Abstract

The immobilization of alkali metal elements (MI = Li, Na, K, Rb, Cs), alkaline-earth metal elements (MII = Mg, Ca, Sr, Ba) and rare-earth metal elements (MIII = La, Nd, Sm, Gd, Dy, Ho, Er, Yb) in crystalline zirconium phosphate HZr2(PO4)3 was performed by mixing each of the nitrate salts [MINO3, MII(NO3)2 and MIII(NO 3)3] with the HZr2(PO4)3 powders followed by a thermal treatment at 700°C for 5 h. The leaching test of these immobilized products, MIZr2(PO4) 3, MIIZr4(PO4)6 and MIIIZr6(PO4)9, were carried out at 160°C for 24 h in 1 mol·dm-3-HCl using an autoclave. The leaching rate of MI, MII and MIII showed a tendency to decrease with an increase in the ionic radius of MI, MII and MIII, respectively, regardless of the valence of the immobilized metal elements. © 2012 The Ceramic Society of Japan. All rights reserved.