Bubble formation in water with addition of a hydrophobic solute

Ryuichi Okamoto, Akira Onuki

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Abstract: We show that phase separation can occur in a one-component liquid outside its coexistence curve (CX) with addition of a small amount of a solute. The solute concentration at the transition decreases with increasing the difference of the solvation chemical potential between liquid and gas. As a typical bubble-forming solute, we consider O2 in ambient liquid water, which exhibits mild hydrophobicity and its critical temperature is lower than that of water. Such a solute can be expelled from the liquid to form gaseous domains while the surrounding liquid pressure is higher than the saturated vapor pressure pcx. This solute-induced bubble formation is a first-order transition in bulk and on a partially dried wall, while a gas film grows continuously on a completely dried wall. We set up a bubble free energy ΔG for bulk and surface bubbles with a small volume fraction ϕ. It becomes a function of the bubble radius R under the Laplace pressure balance. Then, for sufficiently large solute densities above a threshold, ΔG exhibits a local maximum at a critical radius and a minimum at an equilibrium radius. We also examine solute-induced nucleation taking place outside CX, where bubbles larger than the critical radius grow until attainment of equilibrium. Graphical abstract: [Figure not available: see fulltext.]

Original languageEnglish
Article number72
Pages (from-to)1-12
Number of pages12
JournalEuropean Physical Journal E
Issue number7
Publication statusPublished - Jul 1 2015
Externally publishedYes


  • Flowing Matter: Liquids and Complex Fluids

ASJC Scopus subject areas

  • Biotechnology
  • Biophysics
  • Chemistry(all)
  • Materials Science(all)
  • Surfaces and Interfaces


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