Understanding smectite to illite transformation at elevated (>100 °C) temperature: Effects of liquid/solid ratio, interlayer cation, solution chemistry and reaction time

Bentonite (mainly smectite) has been proposed as a buffer material in a nuclear waste repository, due to its low permeability, high swelling capability, and high ion exchange capacity. To evaluate the isolation performance of the material, it is important to understand a possible hydrothermal alteration of smectite to illite. We investigated the hydrothermal alteration of smectite under various physical and chemical conditions to identify key controlling factors of the process. The experiments were performed on