| Full text | |
| Author(s): |
Coelho, Felipe M.
;
Vinogradov, Jan
;
Derksen, Jos J.
;
Franco, Luis F. M.
Total Authors: 4
|
| Document type: | Journal article |
| Source: | Journal of Chemical Physics; v. 161, n. 4, p. 16-pg., 2024-07-28. |
| Abstract | |
Scaling ionic charges has become an alternative to polarizable force fields for representing indirect charge transfer effects in molecular simulations. In our work, we apply molecular dynamics simulations to investigate the properties of NaCl aqueous solutions in homogeneous and confined media. We compare classical integer- and scaled-charge force fields for the ions. In the bulk, we validate the force fields by computing equilibrium and transport properties and comparing them with experimental data. Integer-charge ions overestimate dielectric saturation and ionic association. Both force fields present an excess in ion-ion correlation, which leads to a deviation in the ionic conductivity at higher ionic strengths. Negatively charged quartz is used to simulate the confinement effect. Electrostatic interactions dominate counter-ion adsorption. Full-charge ions have stronger and more defined adsorption planes. We obtain the electroosmotic mobility of the solution by combining the shear plane location from non-equilibrium simulations with the ionic distribution from equilibrium simulations. From the Helmholtz-Smoluchowski equation, the zeta potential and the streaming potential coupling coefficient are computed. From an atomic-scale perspective, our molecular dynamics simulations corroborate the hypothesis of maximum packing of the Stern layer, which results in a stable and non-zero zeta potential at high salinity. The scaled-charge model representation of both properties is in excellent qualitative and quantitative agreement with experimental data. With our work, we demonstrate how useful and precise simple scaled-charge models for electrolytes can be to represent complex systems, such as the electrical double layer. (AU) | |
| FAPESP's process: | 20/13300-6 - Molecular dynamics simulations for studying equilibrium properties of confined mixtures |
| Grantee: | Felipe Mourão Coelho |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |
| FAPESP's process: | 21/13068-9 - Thermodiffusion of CO2 in water: the Impact of the geothermal gradient in the carbon sequestration within deep saline aquifers via molecular simulation |
| Grantee: | Felipe Mourão Coelho |
| Support Opportunities: | Scholarships abroad - Research Internship - Doctorate (Direct) |
| FAPESP's process: | 18/02713-8 - Molecular dynamics of confined fluids: equilibrium and transport properties |
| Grantee: | Luís Fernando Mercier Franco |
| Support Opportunities: | Research Grants - Young Investigators Grants |