Nanobubbles located at solid–liquid interfaces have become a topic of immense current interest due to new scientific phenomena and arising applications in many fields. These gaseous domains have heights up to tens of nanometers and, due to anomalously high contact angles (measured through the liquid phase), have widths up to tens of micrometers. These pancake shaped bubbles are surprisingly stable. We have investigated the thermodynamics of interfacial nanobubbles. By considering the free energy of diffusionally isolated nanobubbles we explore the conditions for interfacial nanobubble thermodynamic stability. Importantly in our analysis we include the role of dissolved gas in the liquid and partitioning of the gas between the liquid and the bubble. We use a free energy consistent with the Gibbsian composite system thermodynamics approach and chemical potentials for a weak solution of either carbon dioxide or nitrogen gas in water. For this thermodynamic stability analysis of interfacial nanobubbles we consider the anomalously high contact angle as a known input. One of the key findings of our work is that interfacial nanobubbles can be thermodynamically stable only in supersaturated solutions and only with an anomalously high contact angle. Following the stability analysis we discuss possible ways to understand the anomalously high contact angle.

Thermodynamics of nanobubbles at solid–liquid interfaces

256th National Meeting (2018)

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