In situ characterization of heterogeneous surface wetting in porous materials

• Published in: Advances in colloid and interface science Vol. 326; p. 103122
• Main Authors: Wang, Ying Da, Kearney, Luke M., Blunt, Martin J., Sun, Chenhao, Tang, Kunning, Mostaghimi, Peyman, Armstrong, Ryan T.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2024
• Subjects: Contact angle; In situ wettability; Multiphase flow; Porous media; Topology; Porous media; Contact angle; Topology; Multiphase flow; In situ wettability
• ISSN: 0001-8686; 1873-3727
• DOI: 10.1016/j.cis.2024.103122

The performance of nano- and micro-porous materials in capturing and releasing fluids, such as during CO2 geo-storage and water/gas removal in fuel cells and electrolyzers, is determined by their wettability in contact with the solid. However, accurately characterizing wettability is challenging due to spatial variations in dynamic forces, chemical heterogeneity, and surface roughness. In situ measurements can potentially measure wettability locally as a contact angle - the angle a denser phase (e.g water) contacts solid in the presence of a second phase (e.g. hydrogen, air, CO2) - but suffer from difficulties in accurately capturing curvatures, contact areas, and contact loops of multiphase fluids. We introduce a novel extended topological method for in situ contact angle measurement and provide a comparative review of current geometric and topological methods, assessing their accuracy on ideal surfaces, porous rocks containing CO2, and water in gas diffusion layers. The new method demonstrates higher accuracy and reliability of in situ measurements for uniformly wetting systems compared to previous topological approaches, while geometric measurements perform best for mixed-wetting domains. This study further provides a comprehensive open-source platform for in situ characterization of wettability in porous materials with implications for gas geo-storage, fuel cells and electrolyzers, filtration, and catalysis. [Display omitted] •A review of topological and geometrical in situ methods of wettability measurements on porous materials.•A novel Extended Topological Method is introduced and comparatively reviewed and benchmarked on mixed wetting porous media.•A detailed and simplified implementation and analysis of the ill-posed meshing stage alongside geometric methods of measurement.•Topological and geometric methods are similar on uniformly wet systems while geometric methods excel in mixed wet domains.•Open-sourced, enabling scientific community to expand in situ wettability characterization beyond its geoscience origins.