Synthesis and performance of a series of dual hydroxyl sulfobetaine surfactants

Five kinds of dual hydroxyl sulfobetaines with different carbon atom numbers in hydrophobic chain were synthesized by using linear saturated alcohol, epichlorohydrin and dimethylamine, and then their structures were characterized by FTIR and H-1 NMR. The stability of all synthesized betaine surfactants in hard water was at level 4, which indicated they had high tolerance on hard water. Their CMC and.cmc were lower than the conventional cationic surfactant dodecyltrimethylammonium bromide and anionic surfactant sodium dodecyl, so they had more excellent surface activities. With the chain length increasing from C-8 to C-14, the surface activities, emulsifying properties and foaming properties of these betaine surfactants improved because surfactant molecules tightly arranged in the oil-water interface, but there was abnormal phenomenon of surface activity and foam property from C-14 to C-16 due to overlong hydrophobic chain. According to the results of the experiment, C14SB was the most practical in the five kinds of surfactants, which was potential candidate to enhance oil recovery in oil field. The performances of C14SB were as follows: CMC = 2.2. 10(-4) mol/L, gamma(cmc) = 30.9 mN/m and the time of bleeding 10 mL water t = 375 s at 2 g/L the optimum emulsification concentration.