Rapid transformation from Cs-geopolymers to Cs-defined ceramics by microwave sintering

Cs-defined ceramics are considered to be ideal solidification forms for 137Cs with high solubility, high volatility, and high mobility in Cs-containing nuclear wastes. In this study, a process consisting of low-temperature solidification and subsequent rapid microwave sintering was proposed to treat the simulated nuclide 137Cs. Cs-geopolymer (CsGP) precursors were first prepared to form solidified forms containing simulated 137Cs under ambient conditions. Afterwards, a rapid transformation from CsGP to Cs-defined ceramics was realized by microwave sintering below 1100 °C for 30 min, which could effectively avoid the Cs volatility while Cs entered into Cs-defined ceramic lattices under conventionally long-term and high-temperature sintering. As-prepared Cs-defined ceramics exhibited superior chemical durability, and the normalized Cs+ leaching rate was as low as 3.06 × 10−4 g/(m2.d).