Role of Salts in Performance of Foam Stabilized with Sodium Dodecyl Sulfate

Abstract Surface activity, foaming ability, and foam stability of SDS and salts mixtures are experimentally studied. It is shown that adding KCl or CaCl2 can increase the surface activity but decrease the foaming ability of SDS solution. The capacity to stabilize SDS foam decreases as KCl＞CaCl2＞NaCl. The SDS foam ageing is delayed due to the crystals blocked in the plateau borders and adsorbed on the surface of bubble films. When the SDS concentration is too high, the foam stability rises only if there are enough crystals in the plateau borders. The influence of crystal structure on foam stability has been investigated by using FESEM. The KDS crystals with lower random close-packing density stabilize SDS foam more efficiently than Ca(DS)2 crystals with higher random close-packing density. The understanding of this study is of great importance for the application of SDS foams in fire extinguishing and upstream petroleum industry.