Nanoconfined competitive adsorption and wettability transition.

Area of Science:

• Surface Science
• Physical Chemistry
• Geological Sciences

Background:

• Adsorption-driven wettability transitions are key to fluid-solid interfaces.
• Competitive adsorption in multi-species systems complicates interfacial energy and fluid behavior.
• Understanding these dynamics is vital for natural and industrial processes.

Purpose of the Study:

• To investigate CO2-n-decane competitive adsorption dynamics using molecular simulations and atomic force microscopy.
• To model wettability transitions in geological surface science.
• To quantify critical thresholds for adhesion forces driving wettability changes.

Main Methods:

• Molecular simulations were employed to study adsorption dynamics.
• Atomic force microscopy provided experimental validation.
• A 3D surface model (FadTP) was constructed to quantify adhesion forces and critical thresholds.

Main Results:

• CO2 displaces n-decane at 323.15 K and pressures above 1 MPa, preferentially adsorbing at the three-phase contact line.
• A stable CO2 adsorption layer forms at the solid-liquid interface, reaching 1.14 nm at 5 MPa, then thinning due to miscibility.
• A wettability transition line was defined in T-P space: TP=1.00-1.62×10^7·P+1.71·P^2.

Conclusions:

• Competitive adsorption significantly influences wettability transitions.
• CO2-induced wettability changes enhance efficiency and security in geological CO2 activities.
• Findings advance understanding and application in earth, environmental, industrial, and carbon neutrality efforts.