A novel gas inducing rotor-stator impeller for gas-liquid foam generation

Abstract

A novel gas inducing rotor-stator impeller was used to produce foam from viscous non-Newtonian shear thinning liquid and non-ionic surfactant Tween 80. Foam produced under various experimental conditions, was characterised based on the bubble size and foam half-life. Higher impeller speed and solution viscosity, resulted in smaller size bubbles and more stable foam. Higher gas hold-up is associated with reduction in bubble size and, longer mixing times resulted in increase in bubble size because of coalescence. Empirical models were developed to predict the foam bubble size and its half-life and a good correlation between the measured data and the predicted data was obtained (R2 > 0.94). Foam bubble size was found to be a function of Reynolds number, mixing time number and Froude number. Foam half-life was found to be dependent on the same dimensionless number along with the Weber number. It is shown that, gas inducing impeller, can produce foam with similar properties at ambient conditions and with better process control, compared to foam produced by conventional agitation-based devices.