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 C 12-14 P m E 2 S (m = 0, 3, 5, 8 and 12) were investigated. The effects of electrolyte (NaCl and CaCl 2 ) concentration, salinity, surfactant concentration were studied in detail. The IFTs between C 12-14 P m E 2 S aqueous solutions and n-decane obtained ultralow range at optimum NaCl concentration expect C 12-14 E 2 S. The optimum salinity (S * ) decreased with increase of number of oxypropylene. Also, the IFTs of C 12-14 P 8 E 2 S and C 12-14 P 12 E 2 S approached or obtained ultralow IFT in a wide range of CaCl 2 concentrations. The IFTs between C 12-14 P 12 E 2 S aqueous solution and n-decane decreased as salinity increased. With increasing surfactant concentration, the values of IFT decreased initially and then increased.