The effect of residual water content on preferential adsorption in carbon dioxide – methane – illite clay minerals: A molecular simulation study

A combination of Monte Carlo and molecular dynamics simulations was carried out to estimate mixed CO2/CH4 adsorption isotherms on illite surfaces in the presence of water. Three bulk phase mixture compositions are explored to study the effect of concentrations on competitive sorption in illite bearing two positions for the isomorphic substitutions. The computed isotherms are compared with those predicted for dry systems to deduce the effect of water on CO2 and CH4 interactions with the clay surfaces. The hydration of the counter-balancing ions in pore space is studied to evaluate sorption-desorption processes at the basal clay surfaces. Sensitivity parameters reflecting preferential CO2/CH4 sorption, density profiles, and surface occupancy times are reported and analyzed.