Structure and Leaching Resistance of Ba(NO3)2-Pretreated High-Level Liquid Glass Waste Form.

In order to increase solubility of sulfur in borosilicate glass, SO₄^2- ions in simulated high-level liquid waste (HLLW) with relatively high content of sulfur and sodium were pretreated by adding Ba(NO₃)₂ solution, and then borosilicate glass waste form was prepared by melt-quenching method. The effects of pretreated HLLW on the structure and leaching resistance were mainly investigated. The results show that the waste loading can be increased to 23% (mass fraction) without phase separation after the Ba(NO₃)₂ pretreatment. The normalized elemental mass loss of Na, B and Si of the HLLW-loaded samples are one order of magnitude lower than that of the pure borosilicate glass. Furthermore, the leaching resistance of the glass waste form has no significant change with increasing HLLW content. ¹¹B and ²⁹Si MAS NMR analyses indicate that part of BO₃ transforms into BO₄ structural units and a polymerization of the glass network occurs after HLLW addition. [ABSTRACT FROM AUTHOR]