Properties of Binary Surfactant Mixtures of Anionic Gemini Surfactant and Amphoteric Surfactant

The surface tension of the mixed system of linear alkylated diphenylmethane sulfonate and amphoteric surfactant didodecylmethylcarboxyl betaine along with their different combinations has been investigated in 0.1 M salt solutions at 313 K. The surface chemical parameters of the mixture were also calculated. The results show that the critical micelle concentration (CMC) and gamma(CMC) of the mixture are always lower than those of the individual surfactants, which indicates synergistic effects between the surfactant molecules. The interfacial tension of the Chinese Shengli crude oil and the connate water can be reduced to 5 x 10(-3) mN . m(-1) at 70 degrees C with the mixture of alkylated diphenylmethane sulfonate and didodecylmethylcarboxyl betaine.