Dispersion Forces Stabilize Ice Coatings at Certain Gas Hydrate Interfaces That Prevent Water Wetting

Abstract

Gas hydrates formed in oceans and permafrost occur in vast quantities on Earth representing both a massive potential fuel source and a large threat in climate forecasts. They have been predicted to be important on other bodies in our solar systems such as Enceladus, a moon of Saturn. CO 2 -hydrates likely drive the massive gas-rich water plumes seen and sampled by the spacecraft Cassini, and the source of these hydrates is thought to be due to buoyant gas hydrate particles. Dispersion forces cause gas hydrates to be coated in a 3-4 nm thick film of ice, or to contact water directly, depending on which gas they contain. These films are shown to significantly alter the properties of the gas hydrate clusters, for example, whether they float or sink. It is also expected to influence gas hydrate growth and gas leakage.

The Effect of Dissolved Gases on the Short-Range Attractive Force between Hydrophobic Surfaces in the Absence of Nanobubble Bridging

“…These results agree with the hypothesis that the dissolved gas content, affected by the salt concentration, is a crucial factor for controlling the attractive force between the hydrophobic surfaces, in the absence of nanobubble bridging capillary force. They are also supported by the recent literature which has pointed to the critical role of dissolved gases in aqueous thin films affecting dispersion forces in a wide range of important phenomena [39][40] .…”

Premelting of ice adsorbed on a rock surface

“…[1] As noted the theory presented in our work enables studies in multilayered systems where more than one film thickness can be varied. However, it should be stressed that very small changes in dielectric functions for water or ice (originating for instance from impurities, [4,26] presence of salt ions, [4,16,5] or from modelling based on a different set of optical data [99]) could influence the results, such as where premelting and ice formation near interfaces will occur. This sensitivity comes from the closeness of dielectric functions for ice and water as was pointed out many years ago by Elbaum and Schick.…”

“…[21,22,23,24,25] Along these lines, Casimir (Lifshitz) forces have further been proposed to be able to cause ice formation on some gas hydrate surfaces in water. [26] Such ice films, if present, could induce a size-dependent buoyancy for CO 2 gas hydrate clusters, for instance, in the underlying oceans on the moons Enceladus and Europa, potentially influencing any harboured life. [26] However, the problem of ice premelting and particularly the characterisation of a reliable equilibrium film thickness has remained a controversial topic for many years.…”

“…[26] Such ice films, if present, could induce a size-dependent buoyancy for CO 2 gas hydrate clusters, for instance, in the underlying oceans on the moons Enceladus and Europa, potentially influencing any harboured life. [26] However, the problem of ice premelting and particularly the characterisation of a reliable equilibrium film thickness has remained a controversial topic for many years. [2,21,22,27,7] Experimental results referring to the thickness of the equilibrium premelting layer at the ice-vapour interface performed since the 1980's differed by orders of magnitude.…”

Nontrivial retardation effects in dispersion forces: From anomalous distance dependence to novel traps

“…Thus, to introduce a scalable parameter for tuning the trap, we consider in our final example a two-component fluid surrounding the particle. For the dielectric functions of mixtures between fluid 1 (ε 1 ) in fluid 2 (ε 2 ) we use a Lorentz-Lorenz model [19,39,40], where we introduce the volume fraction p of fluid 1 in fluid 2. We chose the liquids bromobenzene and methanol in front of a polystyrene surface [17] as the dielectric function of the latter lies between both fluids.…”