Effect of treatment temperature on the immobilization of Cs and Sr to HZr2(PO4)3 using an autoclave

Abstract The proton-type crystalline zirconium phosphate, HZr 2 (PO 4 ) 3 , was used to immobilize Cs + or Sr 2+ by mixing HZr 2 (PO 4 ) 3 and an aqueous solution of CsNO 3 or Sr(NO 3 ) 2 in an autoclave at 160–400 °C. The Cs or Sr immobilized HZr 2 (PO 4 ) 3 was further kept in the open air at 300–700 °C. The effect of treatment temperature on the immobilized amount of Cs or Sr in HZr 2 (PO 4 ) 3 and the leaching rate of Cs or Sr from its immobilized HZr 2 (PO 4 ) 3 was discussed from the standpoint of crystalline structure. The immobilization and the stabilization of Cs or Sr in HZr 2 (PO 4 ) 3 produced in an autoclave at 250 °C were better achieved by additional thermal treatment in the open air at 700 °C.