Alkaline earth ion exchange study of pure silica LTA zeolites using periodic first-principles calculations. (17th October 2019)

• Record Type: Journal Article
• Authors: Kocevski, Vancho; Hu, Shenyang Y.; Besmann, Theodore M.
• Is Part Of: New journal of chemistry. Volume 43:Number 43(2019)
• Page Start: 16835
• Page End: 16840
• Publication Date: 2019-10-17
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c9nj04091a
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : The Linde Type A (LTA) zeolite capability to exchange alkaline earth ions is analyzed using DFT calculations, considering the systems to be in water and vacuum, investigating the LTA's potential as a material for radioactive decontamination processes. Abstract : Experiments show that zeolites, such as Linde Type A (LTA), are promising materials for radioactive decontamination processes. In this work, the thermodynamic properties associated with alkaline earth ion (Ca 2+, Sr 2+ and Ba 2+ ) exchange in pure silica LTA was studied using periodic first-principles calculations. The adsorption energies of alkaline earth ions compared with that of Na + were investigated. The driving forces for alkaline earth exchange and related isotherms were calculated, and analyzed as a function of the electron chemical potential. The results demonstrate that Na + in a pure silica LTA can completely be removed by Ba 2+ and almost completely be removed by Sr 2+ from a stream, but cannot be effectively exchanged by Ca 2+ . We also showed that electron-donating dopants should suppress Sr 2+ and Ba 2+ ion exchange, and that there is a substantial preference for incorporating Ba 2+ over Sr 2+ . Lastly, the substantial difference between the adsorption energies of the ions in an assumed vacuum and those computed in water suggests that a solvation model is needed for accurate representation of ion adsorption in an LTA zeolite.