Comprehensive ion-exchange and adsorption study of the distribution of exchanging inorganic cations over the interlayer gaps of vermiculite

The exchange of Co²⁺ ions on Na-vermiculite has been comprehensively studied by the ionexchange, adsorption, and X-ray diffraction methods. It has been shown that vermiculite is distinguished by high selectivity to Co²⁺ cations and Kielland dependence log $\tilde K_m (\theta )$ increasing with filling of ion-exchange sites with sorbed cations rather than a decreasing one that is observed for common systems. It has been established that the ion exchange is accompanied by segregation of Na+ and Co²⁺ cations in separate interlayer gaps of vermiculite with the final formation of a disordered layered “cake” composed of separate silicate layers and interlayer gaps enriched with Na⁺ and Co²⁺ ions.