evaluating the effect of impurities on the diffusion coefficient of co2 by molecular dynamics simulation: application to co2 sequestration process

At the time, the increase in greenhouse gases is one of the most important environmental problems. geological co2 storage is considered as one of the feasible solutions. a high portion of co2 capture and storage (ccs) costs are devoted to capturing, purification, and transportation. the injection of co2 with impurities can reduce these costs and help the development of co2 sequestration projects. the diffusion coefficient is an important parameter in co2 storage in saline aquifers. in the previous studies, the diffusion coefficient of co2 in impure cases assumed to be unchanged. in this study, we considered two of the most important contaminants, n2 and so2, in two levels and computed the fick diffusion matrix by using molecular dynamics (md) simulation. outcomes of this study indicate the intense effect of impurities on the diffusion coefficient and show the reduction of the co2 main diffusion coefficient in all cases. this decrease can be in a range of 8-42% for co2-so2-water system and 7-46% for co2-n2-water system. these changes in the diffusion matrix can alter further steps of co2 sequestration such as the behavior of dissolution flux, the onset of convection, the motion of convective fingers, and their patterns. these results confirm the necessity to consider the effect of diffusion coefficient alteration in the co2 storage process.