PNNL

Abstract

Using first-principles calculations we studied the adsorption of alkali ions in the pure silica Linde Type A (LTA) zeolite. The probability of adsorbing the alkali ions from solution on the LTA, as well as the driving force for ion exchange between Na+ and other alkali ions at the different adsorption sites were analysed. From the calculated ion exchange isotherms we show that it is plausible to exchange Na+ with K+ and Rb+ in water, but that is not the case for systems in vacuum. We also demonstrate a solvation models should be used for accurate representation of ion exchange in an LTA, but one needs to be careful when introducing dispersion interactions.