Performance of geopolymers for direct immobilization of solvent extraction liquids: Metakaolin/LIX-84 formulations

Direct immobilization of organic wastes, such as solvent extraction liquids, is an imperative demand in the nuclear sector. This demand has been met in the present study through the development of typical metakaolin-based geopolymeric formulations containing 8% LIX-84 (8LIXGP45) which were pre-saturated with Cu2+. They were completely homogeneous at very young ages and had 28-day compressive strength values of twice the waste acceptance criteria. Effect of 0.1 M of nitric, hydrochloric or sulfuric acids on the leaching of Cu2+ were studied in comparison to de-mineralized water. All formulations performed well where most of Cu2+ was not easily removed and the wash-offs were the controlling leaching mechanisms. Characterization of 8LIXGP45 formulations, at the end of the leaching tests, assessed that the Cu2+-saturated LIX-84 did not moved out of the matrices, even under sever acidic attacks. This was obvious via the presence of copper in the elemental analyses which was associated by cuprite and chloromenite minerals in phase analyses. Fourier transform infrared spectra proofed the presence of all bonding vibrations of LIX-84 along with the geopolymeric ones. These were also noticed in the scanning electron micrographs. Hereby it is recommended to apply metakaolin-based geopolymers to directly immobilize this kind of organic wastes.