Quantitative analysis of CO2 adsorption on kaolinite under different environmental factors based on high-pressure and supercritical tests

Kaolinite, a prevalent clay mineral, demonstrates potential for CO₂ capture and geological sequestration. This research analyzed how moisture levels and temperature influence CO₂ adsorption in kaolinite using high-pressure and supercritical adsorption experiments. Nitrogen adsorption tests examined pore structure variations in kaolinite before and after CO₂ adsorption across different environmental conditions. X-ray Diffraction, Scanning Electron Microscopy, and Energy Dispersive X-ray Spectroscopy characterized mineral composition and elemental distribution changes in raw kaolinite and CO₂-exposed samples under both dry and wet conditions. Findings indicate that higher moisture content reduces CO₂ adsorption capacity and modifies isosteric heat of adsorption in kaolinite. Elevated temperature and humidity also altered specific surface area, pore volume, and average pore size post-adsorption. Most significantly, this study identifies a critical moisture threshold (∼15 %) for pore stability and reveals the dual role of mineralogical changes in governing both structural integrity and long-term chemical trapping. These findings provide transformative insights for predicting and optimizing the security of geological CO₂ sequestration.