Clathrate Adhesion Induced by Quasi-Liquid Layer.

Area of Science:

• Materials Science
• Physical Chemistry
• Energy Engineering

Background:

• Clathrate adhesion to surfaces is a long-standing challenge in the energy industry, contributing to pipeline blockages.
• Understanding the fundamental forces governing clathrate adhesion is crucial for developing mitigation strategies.

Purpose of the Study:

• To investigate the physical origin of adhesive forces between clathrates and solid surfaces.
• To elucidate the role of the quasi-liquid layer (QLL) on clathrate surfaces in adhesion.
• To explore methods for reducing clathrate adhesion.

Main Methods:

• Measurement of the adhesive force between tetrahydrofuran clathrate and a solid sphere.
• Characterization of the quasi-liquid layer (QLL) on the clathrate surface.
• Systematic variation of sphere surface roughness and hydrophobicity.

Main Results:

• A strong adhesive force was detected, originating from a capillary bridge formed by a nanometer-thick QLL.
• The nanoscale curvature of the capillary bridge resulted in significant negative Laplace pressure and capillary attraction.
• Adhesion decreased substantially with increased sphere roughness and hydrophobicity, indicating the effectiveness of surface modification.

Conclusions:

• The quasi-liquid layer (QLL) on clathrate surfaces is the primary source of strong adhesive forces via nanoscale capillary bridges.
• The dynamic expansion of the capillary bridge explains time-dependent increases in measured forces.
• Surface engineering, specifically increasing roughness and hydrophobicity, offers a viable strategy to mitigate clathrate adhesion in industrial applications.