Coalescence of bubbles in liquid

Abstract

Abstract Coalescence of bubbles is important for the destabilisation of gas–liquid dispersions. The theories of coalescence used at present are reviewed. The film drainage theory and the stochastic theory of coalescence have been discussed with their merits and drawbacks. The influence of van der Waals, electrostatic double layer, steric and solvation forces on the coalescence process has been discussed. The importance of adsorption of surfactant molecules at the air/water interface in presence and in absence of salt on coalescence time has been explained. Difference between the experimental conditions under which the foam films collapse and the bubble coalescence experiments has been pointed out. Possible reasons behind the failure of the film drainage models in predicting the coalescence time have been explained. Some directions for future research have also been discussed.