Diffusivity of CO in HO: A Review of Experimental Studies and Molecular Simulations in the Bulk and in Confinement.

An in-depth review of the available experimental and molecular simulation studies of CO diffusion in HO, which is a central property in important industrial and environmental processes, such as carbon capture and storage, enhanced oil recovery, and in the food industry is presented. The cases of both bulk and confined systems are covered. The experimental and molecular simulation data gathered are analyzed, and simple and computationally efficient correlations are devised. These correlations are applicable to conditions from 273 K and 0.1 MPa up to 473 K and 45 MPa. The available experimental data for diffusion coefficients of CO in brines are also collected, and their dependency on temperature, pressure, and salinity is examined in detail. Other engineering models and correlations reported in literature are also presented. The review of the simulation studies focuses on the force field combinations, the data for diffusivities at low and high pressures, finite-size effects, and the correlations developed based on the Molecular Dynamics data. Regarding the confined systems, we review the main methods to measure and compute the diffusivity of confined CO and discuss the main natural and artificial confining media (i.e., smectites, calcites, silica, MOFs, and carbon materials). Detailed discussion is provided regarding the driving force for diffusion of CO and HO under confinement, and on the role of effects such as HO adsorption on hydrophilic confining media on the diffusivity of CO. Finally, an outlook of future research paths for advancing the field of CO diffusivity in HO at the bulk phase and in confinement is laid out.