Ion specific effects in foam films

• Ion specific effects are observed in foam films
• The affinity of larger ions to the film surface is stronger than for small ions due to hydrophobic solvation at the interface.
• The choice of ions has a strong effect on surface potential, thickness and stability of foam films
• Anion effects occur even at slightly negatively pre—charged foam film surfaces.
• The air/water interface is negatively charged

Ion specific effects are pronounced at surfaces. Therefore foams and foam films are suitable objects to study ion specific effects. The relative amount of adsorbed ions is ususally indirectly determined by disjoining pressure isotherms. The determined potential of the film surfaces is discussed in context with the surface charge of the neat air/water interface.

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