capillarity-enhanced thin-film mineral coating in 3D-printed porous micromodel

In subsurface-related applications such as hydrocarbon recovery, carbon geo-sequestration and water filtration, 3D-printed porous media, usually polymer-based material, are quite different from natural rocks. It is highly desireable to functionalize 3D-printed models in mimicking the surface chemistry of natural rocks. Here, we propose a surface-coating approach by seeding calcite nanoparticles (CalNPs) followed by in-situ growth of calcite crystals along the inner surfaces of as-printed 3D micromodels. Notably, suface coating inside porous media is quite challangeing compared to the flat surfaces due to the capillary effect in the irregular pores/throats. To guarantee the coating uniformity, we tuned the properties of coating solutions for a lower surface tension, lower viscosity and higher volatility. In this way, we promote the formation of an ultra-thin liquid film in confined space of porous media. The stability of the coating layer, specifically the CalNPs, was also investigated using water-flush experiments. The capillary-rise enhanced nanoparticle stability is revealed from atomic force microscope (AFM) analysis. Through this work, we provide guidance on thin-film coating in porous media, where the effect of capillarity is a critical issue and requires careful attention.