Why Is It Much Easier To Nucleate Gas Bubbles than Theory Predicts?

Abstract

Bubble nucleation from supersaturated gas solutions generally takes place at much lower supersaturations than are expected from the theory. Furthermore, the same theory predicts that the threshold concentration of gas needed to cause nucleation should be essentially independent of the gas species used, a finding contradicted by experiment. There are two general explanations: first, that the theory is wrong, or second, that there is a previously unidentified factor which is influencing the results of the experiments. Given the success of the fundamental theory in other areas, the second explanation is preferred. The previously unrecognized factor is identified here as being the surface activity of the gases which form the bubbles.

Imaging air volume fraction in sea ice using non-destructive X-ray tomography

“…The range of total gas content values for our samples was 1.6 to 6.5 mL L −1 , which is in the lower end of ranges reported by Matsuo and Miyake (1966), Tison et al (2002) and Crabeck et al (2014b). Zhou et al (2013) suggested that gas transport through sea ice occurs via processes diverging from those controlling the transport of salt.…”

“…Where the brine volume exceeds the permeability threshold for columnar ice of 5 % V b (Golden et al, 1998(Golden et al, , 2007, the ice layer is referred to as permeable. curs when SAT f > 1, so these subsaturated layers should be bubble-free, though bubble nucleation from saturated gas solutions has been observed at much lower saturations than theoretically expected (Lubetkin, 2003). On 14 January, 75 % of the bubbles observed were located in subsaturated permeable bottom layer of columnar sea ice.…”

“…Theoretically, nucleation occurs when the sum of the partial pressures of dissolved gases is higher than the local hydrostatic pressure. We therefore compared (i) the gas concentrations profile measured in bulk ice; C bulk ice to (ii) the theoretical inventory predicted by the solubility in brine at atmospheric saturation; C Saturation (i.e., the maximum concentration of O 2 , N 2 and Ar in the dissolved phase when the brine is not supersaturated; Carte, 1961;Lubetkin, 2003;Zhou et al, 2013). C Saturation is obtained by calculating the temperature and salinity-dependent solubility of O 2 , N 2 and Ar in the brine (Garcia and Gordon, 1992;Hamme and Emerson, 2004) and multiplying it by the relative brine volume (i.e., the brine volume fraction (V b ), see below) and expressed in mL L −1 of bulk ice.…”

Hydrophobically-associating cationic polymers as micro-bubble surface modifiers in dissolved air flotation for cyanobacteria cell separation

“…The association of polymers containing a large number of hydrophobic pendant groups, for example polymer HC10-h, may further strengthen polymer adhesion to bubbles. The grouping of the hydrophobic regions can also facilitate bubble nucleation via catalytic effects offered by the hydrophobic zones (Lubetkin, 2003), leading to bubbles formed with polymers in situ. When bubbles are formed in the presence of the polymer, little to no diffusion is required to associate a polymer to its surface.…”

Growing bubbles and freezing drops: depletion effects and tip singularities

“…Lubetkin [62] presented a list that illustrates the variety of arguments that have been put forward to explain the discrepancies between nucleation theory and experiments. The supersaturation ratio in the Champagne example is low compared to the theoretical predictions of ζ > 1000 in order for homogeneous nucleation to occur at room temperature [63].…”