双尾硫酸盐表面活性剂的溶液性质

Solution Properties of Double-Tail Sulfate Surfactants

测试了3种双尾硫酸盐表面活性剂2-丁基辛基硫酸钠（GC12S）、2-己基癸基硫酸钠（GC16S）和2-辛基十二烷基硫酸钠（GC20S）的表面张力，评价了表面活性剂溶液与烷烃间的界面性质。实验结果表明，GC42S，GC16S，GC20S形成临界胶团的浓度分别为9．70，0．80，0．04mmol／L，临界胶团浓度（cmc）时的表面张力为28．50，27．56，24．91mN／m，比相应碳数的直链表面活性剂低得多；增加双尾硫酸盐表面活性剂的碳链长度，表面活性剂的溶解性降低，cmc降低。GC12 S的cmc比同碳数的直链十二烷基硫酸钠高，但界面张力低得多。双尾硫酸盐表面活性剂溶液与癸烷的界面张力达到最低界面张力的浓度随碳数的增加而降低，界面张力最低的是GC16S，其次是GC20S。加入NaCl后，短碳链的GC12S不能与烷烃产生超低界面张力，而长碳链的GC16S和GC20S溶液在NaCl质量分数分别为2．00％～3．00％和0．03％～0．10％时可与癸烷、十二烷、十四烷产生超低界面张力，达到1013mN／m数量级。

Properties of three double - tail sulfates as surfactants were studied, namely sodium 2 - butyl - 1 - octyl sulfate （ GC 12S ）, sodium 2 - hexyl - 1 - decyl sulfate （GCI6S） and sodium 2 - octyl - 1 - docecyl sulfate （ GC20 S ）. The surface properties, critical micelle concentration （ cmc ）, surface tension at cmc（γcmc ） and solution interfacial tensions （IPT） with 6 alkanes （hexane, octane, decane, dodecane, tetradecane and hexadecane） at different NaC1 concentrations were determined. γcmc of three sulfates are 28.50,27.56 and 24.91 mN/m, respectively, lower than those of single tail sulfates with same carbon number. The cmc of double - tail surfactants decrease with increase of carbon number of surfactants. The cmc of GC12S with branched chain is much higher than that of sodium dodecylsulfate with linear chain, but IPT with decane is much lower. The concentrations of double - tail surfactants at lowest IFT with decane decrease with increase of carbon number of surfactants. IFrs of GC16 S and GC20S solutions with decane, dodecane and tetradecane approach super low values down to the magnitude of 10 -3 raN/m, when corresponding NaCl mass fraction are 2.00% - 3.00% and 0.03% - 0.10%.