Abstract
Despite the broad range of interest and applications, controls on the electric surface charge and the zeta potential of silica in contact with aqueous solutions saturated with dissolved CO2 at conditions relevant to natural systems, remains unreported. There have been no published zeta potential measurements conducted in such systems at equilibrium, hence the effect of composition, pH, temperature and pressure remains unknown.
We describe a novel methodology developed for the streaming potential measurements under these conditions, and report zeta potential values for the first time obtained with Fontainebleau sandstone core sample saturated with carbonated NaCl, Na2SO4, CaCl2 and MgCl2 solutions under equilibrium conditions at pressures up to 10 MPa and temperatures up to 40°C.
The results demonstrate that pH of solutions is the only control on the zeta potential, while temperature, CO2 pressure and salt type affect pH values. We report three empirical relationships that describe the pH dependence of the zeta potential for: i) dead (partial CO2 pressure of 10-3.44 atm) NaCl/Na2SO4, ii) dead CaCl2/MgCl2 solutions, and iii) for all live (fully saturated with dissolved CO2) solutions. The proposed new relationships provide essential insights into interfacial electrochemical properties of silica-water systems at conditions relevant to CO2 geological storage.
We describe a novel methodology developed for the streaming potential measurements under these conditions, and report zeta potential values for the first time obtained with Fontainebleau sandstone core sample saturated with carbonated NaCl, Na2SO4, CaCl2 and MgCl2 solutions under equilibrium conditions at pressures up to 10 MPa and temperatures up to 40°C.
The results demonstrate that pH of solutions is the only control on the zeta potential, while temperature, CO2 pressure and salt type affect pH values. We report three empirical relationships that describe the pH dependence of the zeta potential for: i) dead (partial CO2 pressure of 10-3.44 atm) NaCl/Na2SO4, ii) dead CaCl2/MgCl2 solutions, and iii) for all live (fully saturated with dissolved CO2) solutions. The proposed new relationships provide essential insights into interfacial electrochemical properties of silica-water systems at conditions relevant to CO2 geological storage.
Original language | English |
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Article number | 1226-1238 |
Number of pages | 13 |
Journal | Journal of Colloid and Interface Science |
Volume | 607 |
Issue number | Part 2 |
Early online date | 17 Sept 2021 |
DOIs | |
Publication status | Published - 28 Feb 2022 |
Bibliographical note
AcknowledgementsMiftah Hidayat was supported by the Aberdeen-Curtin PhD studentship. David Vega-Maza is funded by the Spanish Ministry of Science, Innovation and Universities (“Beatriz Galindo Senior” fellowship BEAGAL18/00259). The authors would also like to thank the Edith Cowan University for funding the design, manufacturing and testing of the experimental setup through RG14747 research grant awarded to the University of Aberdeen.
Keywords
- Zeta potential
- Sandstone
- Elevated temperature
- High pressure
- Supercritical CO2 conditions
- Carbonated aqueous solution
- Streaming potential method