Effect of number of oxypropylene on dynamic interfacial tensions of extended surfactants

Effect of the numbers of oxypropylene on dynamic interfacial tensions (IFT) of five extended surfactants C12-14PmE2S (m = 0, 3, 5, 8 and 12) were investigated. The effects of electrolyte (NaCl and CaCl2) concentration, salinity, surfactant concentration were studied in detail. The IFTs between C12-14PmE2S aqueous solutions and n-decane obtained ultralow range at optimum NaCl concentration expect C12-14E2S. The optimum salinity (S*) decreased with increase of number of oxypropylene. Also, the IFTs of C12-14P8E2S and C12-14P12E2S approached or obtained ultralow IFT in a wide range of CaCl2 concentrations. The IFTs between C12-14P12E2S aqueous solution and n-decane decreased as salinity increased. With increasing surfactant concentration, the values of IFT decreased initially and then increased.