Gas and liquid interaction in hydrophobic nano-environment (GLIHNE) is ubiquitous in many natural and energy-related technologies, such as water and gas transportation in biological cells, shale gas exploitation, water management in proton exchange membrane fuel cells, and geological carbon dioxide sequestration. With the confinement effect of HNE, the gas-liquid interaction (GLI) is distinct from that in the bulk phase. However, both gas and liquid motions are difficult to be measured at the nanoscale, which has posed the primary challenge in revealing the GLIHNE experimentally. In this dissertation, a liquid nanofoam (LN) system has been used as a platform to experimentally investigate the GLIHNE. The LN system composes of a hydrophobic nanoporous media with a non-wetting liquid phase. Due to the hydrophobic surface of the nanopores, liquid molecules cannot enter the nanopores spontaneously. With the aid of external pressure, the liquid molecules can infiltrate into the nanopores by overcoming the surface energy barrier. The GLI only has a secondary effect on the liquid infiltration behavior of the LN system. When the applied external pressure is removed, the spontaneous liquid outflow behavior of the infiltrated liquid molecules has been observed. The spontaneous liquid outflow is dominantly affected by the GLIHNE. More importantly, the nanoscale liquid outflow has been successfully quantified by the LN system performance at the macroscale. This dissertation presents the first systematic study on GLIHNE by illustrating the effects of nanopore size, ions, gas amount, and holding conditions. First of all, it is known that the nanopore size can influence both SLI and GLI in HNE. However, the nanoporous material has a pore size distribution. By developing a consecutive-step compression mode, the pore size distribution has been subdivided into several narrow segments. It has been proven that the nanopore size is negatively correlated with the degree of liquid outflow and GLI is enhanced in smaller nanopores. Secondly, to better understand the GLIHNE, it is necessary to decouple GLI from SLI in the HNE. To this end, a set of LN systems have been specifically designed to have the same liquid infiltration behavior, i.e. the same SLI in the HNE. While the unloading process of these LN systems, the degree of liquid outflow varies, which is dominated by the ion effect on the GLIHNE. Results show that both cations and anions have a more profound effect on gas solubility in nano-confined liquid than that in the bulk liquid phase due to the gas oversolubility effect. In addition, the effect of anions is more pronounced than cations on GLIHNE, which breaks down the conventional theory in the bulk phase. Thirdly, a different amount of additional gas phase has been introduced into one particular LN system consisting of the same liquid-solid composition. A remarkable difference in the degree of liquid outflow has been observed, indicating the GLIHNE is highly sensitive to the amount of gas phase. As the gas amount increases, the degree of liquid outflow from hydrophobic nanochannels is considerably promoted. This is due to the bulk liquid being saturated by the additional gas and the earlier termination of the gas outflow process from the HNE. Lastly, the gas diffusion in the liquid phase confined in HNE has been studied by holding an LN system at different pressure levels for various time durations. It has been demonstrated that the gas diffusion progress exhibits an exponentially decaying rate. In addition, distinct from the bulk case, pressure poses a pronounced effect on the GLIHNE.
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