Development of Geopolymeric Kaolinite/Clinoptilolite Matrices for Radioactive Waste Disposal

Geopolymer matrices based on alkali-activated natural aluminosilicates—kaolinite and clinoptilolite—are obtained. Their potential application for the immobilization of radionuclides is studied using Cs+ as an example. The optimal kaolinite/clinoptilolite ratios are determined, enabling the production of matrices with compressive strengths of up to 40 MPa and an immobilized cesium content of up to 1.5 wt % (as Cs2O). The leaching rate of Cs+ from the geopolymer matrix is estimated in aqueous and alkaline environments. It is shown that geopolymer matrices are promising materials for the disposal of radioactive waste.