(119x) Wettability Induced Preferential Bubble Nucleation of a Gas from a Multi-Gas Dissolved Liquid System

This research aims at verifying wettability induced preferential pressure-driven bubble nucleation of a gas from a multi-gas dissolved liquid present in a hydrophobic glass vial. The hydrophobic glass surfaces were prepared using (heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane (HT). The average air-water contact angle and the average roughness of the surfaces were found to be 114.6°±0.75° and 2.4-7.4 nm, respectively. Degassed DI water in the glass vial in a pressure cell was saturated with a known composition of carbon dioxide and methane gas mixture at 6000 mbar for 24 hours. The saturation time was estimated using one-dimensional bounded diffusion equation to ensure ≥ 99.99% saturated liquid. To initiate the pressure-driven bubble nucleation process, a 500 mbar step-down pressure was applied to the pressure cell at every 15^th minute until the bubble nucleation was observed. Methane and carbon dioxide compositions (vol.%) were measured using a micro gas chromatography (micro GC). A digital microscope was used to observe the bubble nucleation process. All the experiments were performed at room temperature (~22 °C).

The average onset bubble nucleation pressure was 4800±274 mbar. The average feed gas concentrations during saturation were 84.44±0.14% methane and 15.44±0.2% carbon dioxide. The corresponding average gas concentrations at onset pressure for bubble nucleation was found to be 85.24±0.48% and 13.12±0.52%, respectively. The increase in the methane gas concentration may be due to the preferential liberation of methane during the bubble nucleation process.