Surface Condensation of CO₂ onto Kaolinite

Abstract

The fundamental adsorption of CO 2 onto poorly crystalline kaolinite (KGa-2) under conditions relevant to geologic sequestration has been investigated using a quartz crystal microbalance (QCM) and density functional theory (DFT) methods. The QCM data indicated linear adsorption of CO 2 (0−0.3 mmol of CO 2 /g of KGa-2) onto the kaolinite surface up through the gaseous state (0.186 g/cm 3 ). However, in the supercritical region, the extent of CO 2 adsorption increases dramatically, reaching a peak (0.9−1.2 mmol of CO 2 /g of KGa-2) near 0.40 g/cm 3 , before declining rapidly. DFT studies of interactions of CO 2 with kaolinite surface models confirm that surface adsorption is favored up to ∼0.34 g/cm 3 of CO 2 , showing distorted T-shaped CO 2 −CO 2 clustering, typical of supercritical CO 2 aggregation over the surface at higher densities. Beyond this point, the adsorption energy gain for any additional CO 2 becomes smaller than the CO 2 interaction energy (∼0.2 eV) in the supercritical medium, resulting in the desorption of CO 2 from the kaolinite surface.

Competitive sorption of CO2 and H2O in 2:1 layer phyllosilicates

“…Micro gravimetric measurements from the QCM followed a procedure recently described by Schaef et al, (2014). 7-30 µg of clay were deposited on the active area of one or both sides of the quartz crystal and dried at 50°C.…”

Effects of water and supercritical CO2 on the mechanical and elastic properties of Berea sandstone

“…Considering the mineralogy of the Berea samples and the results of the image analysis, it appears that kaolinite has been affected by the CO 2 . Indeed some recent experimental studies pointed out that CO 2 can be adsorbed onto kaolinite (Schaef et al, 2014) and that interactions between clay minerals and supercritical CO 2 can lead to detachment and partial removal of inter-granular clay from the rock matrix as a consequence of CO 2 diffusion within the clay layer structures and related changes in the interlayer electrical forces (Berrezueta et al, 2013). This, in turn is likely to affect the elastic properties of the rock due to the fact that kaolinite removal in particular microstructural locations may lower the overall stiffness of the rock.…”

Mineralization of Carbon Dioxide: A Literature Review

“…Yet, the maximum CO 2 sorption capacity of kaolinite and of certain shales tended to decrease with decreasing moisture content [59]. Additionally, CO 2 adsorption onto kaolinite surface initially increases with increasing CO 2 density, reaching a peak near 0.4 g cm -3 , before declining rapidly due to competition between the surface kinetics and energetics of the CO 2 -mineral surface and CO 2 -CO 2 interactions; DFT (density functional theory) studies confirmed that CO 2 adsorption at kaolinite surface is favored over CO 2 clustering up to the density of 0.34 g cm -3 [60]. For black shales, Nuttall et al [61] found a positive correlation between CO 2 sorption capacity and organic carbon content, whereas no correlation with the clay mineral content was observed.…”