Kinetics and mechanism of the leaching of sodium from A-terskite and its influence on ion-exchange properties

摘要

NMR (23)Na spectroscopy, conductometry, calorimetry, and EDs electron microprobe are used to study the ion mobility, the kinetics of the leaching of sodium and the influence of the leaching on the ion-exchange properties of A-terskite (H (x) Na(4 - x) ZrSi(6)O(15)(OH)(2) center dot H(2)O), a natural microporous material with a high selectivity with respect to Cs(+). The leaching of Na(+) ions by water is preceded by their transition into a mobile state in the zeolite channels of the sorbent. Over the temperature range of 20 to 90A degrees C, the kinetics of leaching at the initial stage is limited by diffusion in the liquid phase, becoming of dispersion character at late stages. The activity of A-terskite in the process of ion exchange with Cs(+) increases with the degree of leaching.