Phase structure and aqueous stability of TRPO waste incorporation into Gd2Zr2O7 pyrochlore

The present work explores the potential of Gd2Zr2O7 pyrochlore based materials for incorporation of trialkyl phosphine oxides (TRPO) waste which is a mixture of multi-nuclides with multi-valence. A series of (Gd,A)2(Zr,B)2O7 ceramics were synthesized to investigate the influence of multi-nuclides incorporation on phase structure and aqueous stability of Gd2Zr2O7. XRD and BSE results show that all the ceramics exhibit a single pyrochlore structure. Raman spectroscopy reveals that the degree of structural order for (Gd,A)2(Zr,B)2O7 solid solutions increases with enhanced TRPO waste content. In addition, aqueous stability testing was carried out using the MCC-1 static leach test method. The results demonstrate that the normalized release rates of the elements in TRPO waste are kept in a low value below 10−4 g m−2 d−1. La shows the highest normalized release rate of all the involved elements, while Zr exhibits the best chemical stability.