CO2 Adsorption Isotherm on Modified Calcite,Quartz, and Kaolinite Surfaces: Surface Energy Analysis

Interaction of CO₂ with mineral surfaces is of increasing importance to the activities related to CO₂ sequestration and enhanced oil recovery. Adsorption/interaction of CO₂ with mineral powder surfaces is addressed using microcalorimetric method coupled with gas chromatograph as a detector. Calcite powder surface is modified with stearic acid (SA) and asphaltene, while the silicate mineral powder surfaces (quartz and kaolinite) are modified with N,N-dimethyldodecylamine (NN-DMDA) and asphaltene. Unmodified calcite in presence of humidity has shown to have the highest capacity for CO₂ adsorption among the tested minerals, where a reaction may occur at the calcite surface. The adsorption capacity of calcite is reduced upon modification with SA and asphaltene. Similar observation is also shown with the modified silicate minerals with asphaltene. In contrast, for the modified silicate with NN-DMDA, the adsorption capacity of CO₂ increased, which may be explained by the interaction of CO₂ with the amine group of NN-DMDA.