【作者】 刘苗； 王策； 周贺； 张磊； 张路； 赵濉；

【Author】 Miao Liu;Ce Wang;He Zhou;Lei Zhang;Lu Zhang;Sui Zhao;Technical Institute of Physics and Chemistry,Chinese Academy of Sciences;University of Chinese Academy of Sciences;

【机构】 中国科学院理化技术研究所； 中国科学院大学；

【摘要】 研究了含油酸的正癸烷与含碱的不同表面活性剂溶液之间的界面张力(IFT)。结果表明,随着碱浓度的增大,SDBS和TX-100的IFT都增大,CTAB的IFT先增大后降低。无碱的表面活性剂溶液与含油酸的正癸烷模拟油接触后,具有界面活性的表面活性剂和油酸分子都会向界面扩散,油酸与表面活性剂分子在界面上混合吸附。而油酸带有少量的电荷(分子模拟的带电量是-0.104),与CTAB(带电量+0.874)混合吸附减弱CTAB之间的静电斥力,从而在界面紧密排布;与TX-100混合吸附无静电作用;与SDBS(带电量-1.032)由于有较强静电排斥作用在界面排布疏松,故三者在无碱条件下的IFT顺序是CTAB<TX-100<SDBS。含碱的体系中有油酸钠(带电量-0.874)生成,油酸钠与SDBS和TX-100都是混合吸附,与SDBS有静电排斥使得界面层疏松,IFT升高,在TX-100中自身的静电排斥使得IFT升高。含少量碱的CTAB中,油酸钠容易扩散到水相,IFT升高;含碱较多时,油酸钠与CTAB在界面形成"离子对",IFT值在1mN/m数量级。更多还原

【Abstract】 The interfacial tensions(IFT) of oleic acid model oil against surfactant solutions containing alkali have been measured by spinning drop method.With the increase of alkali concentration,the IFTs of SDBS and TX-100 increase,while the IFTs of CTAB increase firstly and then decrease.The surfactant and oleic acid molecules will diffuse to interface and form mixed adsorption films.The mixed adsorption of oleic acid molecules(with little charge of-0.104) with CTAB(+0.874) weakens the electrostatic repulsion effect between CTAB,which makes CTAB pack closely at interface.There is no electrostatic effect between TX-100 and oleic acid.On the other hand,oleic acid has a strong electrostatic repulsion with SDBS(-1.032),which makes the interfacial layer loosely.Consequently,the IFT values of three surfactants without alkali obey the order of CTAB < TX-100< SDBS.For surfactant solutions containing alkali,sodium oleate(-0.874) will be produced and mixed adsorbs with SDBS and TX-100.The sodium oleate has a electrostatic repulsion effect with SDBS,which results in the increase of IFT.In TX-100 system,the produced sodium oleate partitions into the aqueous and makes IFT increase.For CTAB aqueous containing little alkali,sodium oleate easily diffused to bulk phase,therefore IFT increases.With the increase of alkali concentration in CTAB aqueous,sodium oleate forms "ion pairs" with CTAB,IFT value is at the around of1 mN/m.更多还原