Watts, Heath D.;Kubicki, James D.;Kabengi, Nadine published 《Connecting Thermodynamics of Alkali Ion Exchange on the Quartz (101) Surface with Density Functional Theory Calculations》. The research results were published in《Journal of Physical Chemistry A》 in 2022.Application of 7791-11-9 The article conveys some information:
Periodic plane-wave d. functional theory (DFT) calculations were performed on the α-quartz (SiO2) (101) surface to model exchange of adsorbed Li+ and either Na+, K+, or Rb+ in inner- and outer-sphere adsorbed, and aqueous configurations, which are charge-balanced with 2 Cl–. SiO– or SiOH groups represented the adsorption surface sites. The SiO– models included 58 H2O and 2 H3O+ mols. to approx. an aqueous environment, whereas the SiOH models had 59 H2O and 1 H3O+ mols. The goal of this work is to calculate the heats of exchange for these alkali ions and to compare the results with those measured by flow microcalorimetry to ascertain the most probable mechanisms for these cations exchanging on the α-quartz (101) surface. Energy minimizations of each alkali ion adsorbed as outer-sphere complexes on SiOH surface sites, and as inner- and outer-sphere complexes on SiO– surface sites, were used to determine the energy of exchange (ΔEex) with Li+ for comparison with exptl. determined ΔHex values. Here, we present a novel method for calculating ΔEex using the difference in energies of geometry-optimized end member models. The aqueous and surface structures produced are similar to those observed exptl. Although the trend for the calculated ΔEex values is consistent with those from the heats of exchange measured exptl., the magnitude of our modeled ΔEex results is significantly larger than select exptl. data from the literature; we discuss the reasons for this discrepancy herein. The relative energy differences of the various configurations modeled have implications for the measurements of the surface charge via potentiometric titrations due to the more active role of alkali cations in quartz surface chem. that have been previously considered as inert background electrolytes. And Rubidiumchloride (cas: 7791-11-9) was used in the research process.
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Reference:
Chloride – Wikipedia,
Chlorides – an overview | ScienceDirect Topics