Effect of Curved Interface of Spray Aerosols on Liquid-vapor Phase Equilibrium of Multicomponent Hydrocarbon Mixtures

In the case of an oil spill, oil may be aerosolized together with sea spray by oceanic wave breaking and bubble bursting, resulting in ejecting droplets into the atmosphere in two forms of film and jet drops. Film drops are generally less than 1μm in radius and are more representative of the surface film composition. Therefore, the multicomponent hydrocarbon mixtures from the oil slick are likely present in the film drop aerosols that are in the order of nanometers in size. The curved surface of such nanoscale droplets provides a high liquid-vapor interface curvature for hydrocarbon liquid-vapor mixtures as they vaporize. In addition to pressure and temperature, the liquid-vapor interface curvature plays a key role in dictating the phase transition criteria. In bulk, the liquid-vapor interface is flat, so its effect is negligible. However, in the case of hydrocarbon mixture being present on the surface of a nano-aerosol, the phase behavior and phase composition of multicomponent hydrocarbon mixtures are altered, due to high liquid-vapor interface curvature and capillary effects being dominant. Here, we develop a flash calculation phase behavior model to quantify this effect depending on the aerosol size and hydrocarbon mixture composition. Our results show that the nanoscale radii of curvature of such small oily sea spray aerosols alters the phase behavior of multicomponent hydrocarbon mixtures, hosted on the surface of seawater aerosols, which ultimately governs the composition and properties of emitted hydrocarbons and their environmental and human health impacts.