Alkaline Activation of Bentonite

The results of alkaline activation of natural bentonite from the Logonsky deposit using a 2 wt.% sodium carbonate solution with variation of treatment temperature and duration are presented. The effect of activation conditions on the cation exchange capacity, as well as on the technological properties of the material (moisture content, plasticity number, and pH of a 5 wt.% suspension), was evaluated. It is shown that increasing the temperature to 60 °C leads to an increase in cation exchange capacity, reaching a maximum at a treatment time of 3–5 h, which is associated with intensification of Ca²⁺/Na⁺ exchange in the interlayer positions of montmorillonite. A further increase in temperature to 70–80 °C is accompanied by a decrease in cation exchange capacity, probably due to partial structural changes and a reduction in the fraction of active exchange sites. An optimal activation regime providing high cation exchange capacity while maintaining satisfactory technological properties of the material was established.