Adsorption and immobilization of actinides using novel SiO2–ZrO2-calcium alginate aerogels from high level liquid waste

The novel SiO 2 –ZrO 2 -calcium alginate aerogels were prepared by Sol–Gel process with phase separation method for investigating the adsorption and immobilization performance of the plutonium and minor actinides from high-level liquid waste (HLLW). The materials contained porous network structure with high surface area (233.44–481.08 m 2 /g) and pore volume (0.50–1.26 m 3 /g). The aerogels were superior adsorbents for the removal of plutonium and minor actinides, the maximum adsorption capacity and adsorption rate (35 °C, 75 rpm) reached 231.5 mg/g and 99.2%. For all the waste forms, SiO 2 , ZrO 2 and Ca 2 SiO 4 phases were simultaneously observed in the matrix. Moreover, Ce entered into Ca sites of Ca 2 SiO 4 and Zr sites of ZrO 2 . The substitution of Ca and Zr by Ce in the Ca 2 SiO 4 and ZrO 2 implies a promising disposal measure of actinides.