Study of CO₂-hydrate formation in contact with bulk nanobubbles: An investigation from experiment and...

Nanobubbles (NBs) have been extensively investigated as a sustainable promoter for gas hydrate nucleation, which also contribute to the hydrate memory effect. However, less attention afforded to their effects on the hydrate-growth process, thus lacking a complete perspective of the overall effects from NBs on hydrate formation. We hypothesize that their effect on CO₂ hydrate growth may vary depending on the properties of NBs.

This study investigates CO₂-hydrate nucleation and growth with a dual methodology. Laboratory experiments were conducted using bulk NBs generated either from CO₂ hydrate dissociation or electric-field-based electrostriction in virgin water. Simultaneously, molecular dynamics simulations examined hydrate growth in contact with a single NB containing CO₂ molecules.

Experimental results indicate that NBs promote hydrate nucleation, with finer ones from electric fields leading to a slight promotion at the onset of hydrate growth, followed by inhibition. MD simulations reveal that while NBs can serve as a gas source for growth, denser NBs hinder the process due to stronger gas-water interactions and CO₂ clustering. These results suggest that optimizing NB size and concentration is critical for maximizing gas-hydrate formation efficiency in industrial applications such as gas storage and carbon capture.