Water and Carbon Dioxide Capillary Bridges in Nanoscale Slit Pores : Effects of Temperature, Pressure, and Salt Concentration on the Water Contact Angle
We perform molecular dynamics (MD) simulations of a nanoscale water capillary bridge (WCB) surrounded by carbon dioxide over a wide range of temperatures and pressures (T = 280-400 K and carbon dioxide pressures PCO2 ≈ 0-80 MPa). The water-carbon dioxide system is confined by two parallel silica-bas...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1985. - 40(2024), 35 vom: 03. Sept., Seite 18439-18450 |
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| Weitere Verfasser: | , , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2024
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article |
| Zusammenfassung: | We perform molecular dynamics (MD) simulations of a nanoscale water capillary bridge (WCB) surrounded by carbon dioxide over a wide range of temperatures and pressures (T = 280-400 K and carbon dioxide pressures PCO2 ≈ 0-80 MPa). The water-carbon dioxide system is confined by two parallel silica-based surfaces (hydroxylated β-cristobalite) separated by h = 5 nm. The aim of this work is to study the WCB contact angle (θc) as a function of T and PCO2. Our simulations indicate that θc varies weakly with temperature and pressure: Δθc ≈ 10-20° for PCO2 increasing from ≈0 to 80 MPa (T = 320 K); Δθc ≈ -10° for T increasing from 320 to 360 K (with a fixed amount of carbon dioxide). Interestingly, at all conditions studied, a thin film of water (1-2 water layers-thick) forms under the carbon dioxide volume. Our MD simulations suggest that this is due to the enhanced ability of water, relative to carbon dioxide, to form hydrogen-bonds with the walls. We also study the effects of adding salt (NaCl) to the WCB and corresponding θc. It is found that at the salt concentrations studied (mole fractions xNa = xCl = 3.50, 9.81%), the NaCl forms a large crystallite within the WCB with the ions avoiding the water-carbon dioxide interface and the walls surface. This results in θc being insensitive to the presence of NaCl |
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| Beschreibung: | Date Revised 07.09.2024 published: Print-Electronic Citation Status PubMed-not-MEDLINE |
| ISSN: | 1520-5827 |
| DOI: | 10.1021/acs.langmuir.4c01185 |