Effect of CTAB Concentration on Foam Properties and Discussion Based on Liquid Content and Bubble Size in the Foam

Abstract

Surfactants known as frothers are widely used in froth flotation to produce small bubbles and stabilize the froth, meanwhile, froth stability plays an important role in determining the product grade and recovery achieved from a mineral flotation process, and therefore it is of great significance to study the effect of surfactant on foam properties. However, foam properties, especially foam stability concerning liquid content of foam and evolution of bubble size, in flotation has received little attention. In this study, we intensively investigated the foamability and foam stability of different concentration cetyltrimethylammonium bromide (CTAB) solutions. Experiments were carried out using a commercially available instrument, Foam Scan, which determined simultaneously the foaming time, foam volume, the liquid content of foam and bubble size distribution. Particularly, the evolution of bubble size can be allowed to determine at a regular time interval. The results showed that as an increase in CTAB concentration, the foamability continuously increased till reached a constant at a critical micelle concentration (CMC), however, the foam stability initially increased and then presented a little decrease when the tested concentrations were larger than its CMC. An argument based on foam drainage, bubble coalescence and coarsening processes is proposed to account for the effect of CTAB concentration foam properties.