Separation of Biphenyl Nitrile Compounds by Microemulsion Electrokinetic Chromatography with Mixed Surfactants

A mixture of nine biphenyl nitrile compounds with high hydrophobicity and similar structures was successfully separated by microemulsion electrokinetic chromatography (MEEKC) within 30 min. The buffer system contained 100 mmol/L sodium dodecyl sulfate (SDS), 80 mmol/L sodium cholate (SC), 0.81% heptane, 7.5% n-butanol, 10% acetonitrile and 10 mmol/L borate. The addition of SC, organic modifiers, sample preparation and temperature all showed remarkable effect on the separation. Meanwhile, the MEEKC method was briefly compared with micellar electrokinetic chromatography (MEKC) method.

Formation and Characteristics of Middle-phase Microemulsions——Effect of Synergism of Surfactants, Alcohol and Oil

Microemulsions can be divided into simple-phase microemulsions and multi-phasemicroemulsions. The former is a system with only an independent phase while the lat-ter corresponds to a multi-phase system comprising the microemulsions and another(oil or water) or two (oil and water) phases. When the microemulsions are in the mid-

Interaction of nonionic surfactant AEO_9 with ionic surfactants

The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, A EO9 α =0.5. The surface properties of the surfactants, critical micelle concentration (CMC), effectiveness of surface tension reduction (γCMC), maximum surface excess concentration (Γmax) and minimum area per molecule at the air/solution interface (Amin) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were determined. Mixtures of both AEO9/SDS and AEO9/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness.

Synthesis of nanoiron by microemulsion with Span/Tween as mixed surfactants for reduction of nitrate in water

Denitrification of nitrate in groundwater using iron nanoparticles has received increasing interest in recent years.In order to fabricate iron nanoparticles with homoge-neously spherical shape and narrow size distribution,a simple and“green”method was developed to synthesize iron nano-particles.The conventional microemulsion methods were modified by applying Span 80 and Tween 60 as mixed sur-factants.The maximum content of water in the Water-in-oil(W/O)microemulsion and its appropriate forming conditions were found,and then the microemulsion system consisting of saturated Fe^(2+)solution was used to synthesizeα-Fe ultrafine particles by redox reaction.The nanoparticles were characterized by using powder X-ray diffraction(XRD)and transmission electron microscopy(TEM).The results show that the average diameter of the particle is about 80-90 nm.The chemical activity of the obtained iron nanoparticles was studied by the denitrification experiment of nitrate.The results show that under the experimental conditions,iron removed most of the 80 mg/L nitrate within 30 min.The mass balance of nitrate reduction with nanoscale Fe indicates that endproducts are mainly ammonia.Two possible reaction pathways for nitrate reduction by nanoscale iron particles have been proposed in this work.

Surfactant-free oil/water and bicontinuous microemulsion composed of benzene,ethanol and water

Generally,a microemulsion consists of oil,water,surfactant and sometimes cosurfactant.Herein,we report a novel suffactant-free microemulsion（denoted as SFME） composed of benzene,water and ethanol without the amphiphilic molecular structure of traditional surfactant.The phase behavior of the ternary system was investigated,finding that there were a single-phase region and a two-phase region in ternary phase diagram.The electrical conductivity measurement was employed to investigate the microregion of the single-phase region,and a bicontinuous microregion and a benzene-in-water（O/W） microemulsion microregion were identified,which was confirmed by freeze-fracture transmission electron microscopy（FF-TEM） observations.The sizes of the microemulsion droplets are in the range of 20-50 nm.

Poly(ethylene oxide) Solubilization in Reverse Microemulsion:Conductivity and UV-Vis Spectra Studies

The effect of poly (ethylene oxide) (PEO) on the w/o microemulsion is studied. The addition of PEO induces a decrease of attractive interaction between droplets in reverse microemulsion. Due to the absence of interaction between cationic surfactant and neutral polymer, the polymer molecules are forced into the interior of water core, avoiding the interfacial region.

Study on the Phase Behavior of Supercritical CO2/Dynol-604/Water System and Solubilization of Methyl Orange in the Microemulsions

It was found that Dynol-604, a non-fluorous and no silicon-containing nonionic surfactant, was soluble in supercritical (SC) CO2. The phase behavior of SC CO2/Dynol-604/water system was studied. The results showed that one-phase water-in-CO2 microemulsions could be formed. The solubilization of methyl orange in the microemulsions proved further the existence of water domain in the microemulsions.

Molecular dynamics simulation study onπ-πstacking of Gemini surfactants in oil/water systems

Whereas theπ-πstacking interactions at oil/water interfaces can affect interfacial structures hence the interfacial properties,the underlying microscopic mechanism remains largely unknown.We reported an all-atom molecular dynamics(MD)simulation study to demonstrate how the Gemini surfactants with pyrenyl groups affect the interracial properties,structural conformations,and the motion of molecules in the water/n-octane/surfactant ternary systems.It is found that the pyrenyl groups tend to be vertical to the interface owing to theπ-πstacking interaction.Besides,a synergistic effect between theπ-πinteraction and steric hindrance is found,which jointly affects the coalescence of liquid droplets.Therefore,the existence of aromatic groups and a moderate number of surfactants helps to form microemulsion.This work provides a molecular understanding of Gemini surfactants with aromatic groups in microemulsion preparation and applications.

Preparation of BaMgAl_(10)O_(17):Eu^(2+) and Its Phase Behavior in Microemulsion System

BaMgAl10O17 ： Eu^2＋ （BAM） was prepared in the microemulsion system and its phase behavior was studied. There exists a small region in the reverse microemulsion system where the dispersed particles are of spherical form. In this way, BAM blue phosphor with good dispersion can be synthesized. The microemulsion phase diagrams of the pseudo-ternary system （Triton X-100/cosuffactant-oil-BAM brine） were first established intuitively by the dilution method. The microstructure of microemulsions was determined through eyeballing, conductance technique, and polar optical microscopy. Its phase behavior is affected by various factors, such as temperature （room temperature, 30, 40 ℃）, oil, surfactants, and cosurfactants in microemulsions. According to the phase diagrams, the microemulsion system of Triton X-100/1-hexanol-hexane-BAM brine was chosen to prepare the precursor. The BAM phosphor can be obtained via sintering the precursor at a comparatively low temperature. The phosphors were characterized by XRD and vacuum ultraviolet （VUV） spectra.

CALORIMETRIC STUDIES ON THE STRUCTURE OF MICROEMULSION WITH NONIONIC SURFACTANT

Enthalpic studies on the state of water in hex-adecane/hexanol/ AEO8/water system have been conducted. The results show that water exists in three states such as bound water,trap water and free water. The enthalpic effect of condition that water to oil ratio is in the abnormal rheology region, the negative thixotropy of the system is directly proportional to the enthalpy.

Surface Properties and Etherification in Microemulsion Systems of Novel Bronsted Acid Surfactants

Novel Bronsted acid-surfactants with different alkyl chains were synthesized via a two-step process, and their surface properties were studied. The critical micelle concentration（cmc）, surface tension at the cmc（γcmc）, and ability of these compounds to lower the surface tension by 0.02 N/re（C20 and pC20） were investigated at 25 and 40 ℃. The molecular architecture of the compounds strongly influenced these physicochemical parameters. The ability of these compounds to lower surface tension was found to be good. Etherification in microemulsions formed by these surfactants as well as dodecylbenzenesulfonic acid（DBSA） was performed; surfactants 3a and 3b were found to be much more efficient than dodecylbanzenesulfonic acid（DBSA）.

Cationic Microemulsion Polymerization of Alkyl Acrylates

Here we present the polymerization of n-butyl acrylate (BA), ethyl acrylate (EA) and methyl acrylate (MA) in tri-component microemulsions, using a cationic surfactant such as dodecyl trimetyl ammonium bromide in water, as a function of temperature, initiator type and, monomer and initiator concentration. The final latexes are transparent and blue color, with particle size ranging between 20 and 60 nm determined by quasielastic light scattering (QLD) and SEC molar masses of the order of 106 g/mol. Reaction times are short and reaction rates are high with final conversions between 70 and 98% depending on the monomer and the reaction conditions.

微乳液的制备及煤泥浮选应用研究

采取Schulman法制备煤油微乳液,从不同表面活性剂、亲水亲油平衡值(HLB值)、助表面活性剂中筛选最佳组分以确定煤油微乳液的体系组成。利用煤油/Tween 80-Span 80/正丁醇/水微乳液作为浮选捕收剂,对陕西南梁煤矿煤泥进行了系列浮选实验对比研究,结果表明,Span 80-Tween 80为复合乳化剂,正丁醇为助乳化剂,油水比为4∶1,HLB为9时,所制备的微乳液性能最稳定;制备微乳液为油包水型(W/O),整体粒径大小分布在10~100 nm,并且低含量状态下可以降低水的表面张力,从而实现良好的浮选效果。与煤油相比,在精煤灰分基本保持不变的情况下,精煤产率提高至65.12%,可燃体回收率达到94.78%,浮选完善指标达到72.45%,为选煤厂提高精煤产率,降低药剂消耗提供了思路。

食品中自微乳体系的组成、制备及促进生物活性物质生物利用的研究进展

随着人们健康膳食意识的增强,开发食品功能作用引起了人们的广泛关注。自微乳体系是一种由油相、表面活性剂、助表面活性剂和生物活性物质以一定比例混合后形成的无水预浓缩体系。通过自微乳体系荷载食品生物活性物质可改善其生物利用度,并充分发挥其生理及药理活性。本文系统综述了自微乳的基本性质、组分及制备方法,整理了近年来自微乳体系在食品领域促进生物活性物质生物利用的应用实例,为自微乳体系在食品领域的推广应用提供了参考。

以Cu(Ac)_(2)-Zn(Ac)_(2)溶液为水相的W/O微液滴尺度的有效调控

微乳液常被用来制备纳米材料,而对微液滴尺寸的有效调控对于纳米材料制备至关重要。本文研究了在Triton X-100微乳液体系中,以Cu(Ac)_(2)-Zn(Ac)_(2)电解质水溶液为水相时,微液滴尺度的变化情况。实验结果表明:在4~12nm的范围内,可以通过改变微乳液中水含量和电解质溶液种类来调节液滴的大小。在一定范围内,无论是水体系还是电解质溶液体系中,微液滴的平均粒径都随着水含量的增加而增大。电解质溶液中金属离子与水分子之间的作用力不同,导致微液滴的粒径分布呈现出不同的变化。需要注意的是,电解质的加入对于微乳液的外观和稳定性没有影响。在以链状烷烃作为油相形成的Cu(Ac)_(2)-Zn(Ac)_(2)电解质微乳液体系中,微液滴的粒径分布更加均匀。最后,本文采用所述的微乳液方法成功制备了CuO-ZnO纳米颗粒。本研究结果对于实现微乳液液滴尺度的可控调节和纳米材料的制备具有重要意义。

Ag/ZIF-8复合材料的制备及其光降解性能

在无表面活性剂微乳液中制备了ZIF-8材料,并采用光致还原法将纳米Ag负载于ZIF-8表面,制备了负载量不同的系列Ag/ZIF-8复合材料。XRD、SEM、XPS、UV-DRS以及光电性能测试表明Ag成功负载到ZIF-8中,且光电性能大幅度提高。对比考察了ZIF-8和Ag/ZIF-8对有机染料的光降解效率,提出了光催化机理。由于Ag纳米粒子和ZIF-8的协同效应,其所形成的异质结构Ag/ZIF-8表现出了优异的光催化活性。

无表面活性剂微乳液体系双甲基增强硅气凝胶的制备与性能研究

硅气凝胶是由SiO_(2)粒子相互聚合组成的一种新型多孔功能材料,以水/乙醇/正己烷无表面活性剂微乳液体系为溶剂,采用酸碱两步溶胶-凝胶法在无需溶剂替换和表面改性的前提下制备无表面活性剂微乳液体系双甲基增强硅气凝胶。采用SEM、FT-IR、BET和接触角等手段对所得样品进行表征,确定增强相二甲基二乙氧基硅烷的最适添加量。结果表明:当二甲基二乙氧基硅烷添加量为0.08 mol时,无表面活性剂微乳液体系双甲基增强硅气凝胶的密度为0.157 g/cm^(3),孔隙率为93%,BJH平均孔径3.92 nm,疏水角为152.5°。

微乳液皮革脱脂剂的制备及性能研究

研究了微乳液主表面活性剂种类及配比、助表面活性剂种类、主表面活性剂与助表面活性剂比值及主表面活性剂与D-柠檬烯的比值对伪三相图面积的影响,通过盐度扫描优化了水相中NaCl的用量,获得了微乳液最优制备工艺;通过动态光散射、电导率等对微乳液结构性能进行了表征。结果表明:当脂肪醇聚氧乙烯醚、十二烷基硫酸钠、异构醇醚为主表面活性剂且三者质量比为1∶1∶1,正丁醇为助表面活性剂,主表面活性剂与助表面活性剂的比值为2∶1,主表面活性剂与D-柠檬烯的质量比为2∶1,NaCl用量为4.8%水溶液为水相时,得到的双连续微乳液微乳区面积最大;微乳液的粒径为51.8 nm,多分散指数为0.274,具有较小的粒径及较好的分散性,表面张力为27.3 mN/m,界面张力为0.09 mN/m,乳化、润湿和稳定性能优异;微乳液皮革脱脂剂对多脂绵羊酸皮的脱脂率高于市售皮革脱脂剂。

磷脂基微乳液的制备及其负载白藜芦醇的性能研究

以2∶1的比例,将大豆磷脂和烷基糖苷羟丙基磺酸钠复配作为乳化剂制备O/W微乳液。通过拟三元相图法确定了最优配方:助表面活性剂为1,2-己二醇,油相为己二酸二丁酯,复配表面活性剂与助表面活性剂的质量比Km为1∶2,己二酸二丁酯在体系中的质量分数为8.00%,水添加量为60.00%,水中无机盐的浓度为0.1 mol/L。透射式电子显微镜显示该微乳液为球形,油滴均匀分布,粒径为15~25 nm。该体系对于白藜芦醇的最大负载量为(11.55±0.14)mg/mL,显示出良好的增溶效果。在1.00%白藜芦醇负载量下,微乳液展示出良好的稳定化效果,50℃保存28 d后的保留率为77.13%±0.51%,比未包裹的提升19.21%;在365 nm的紫外光照下保存32 h后的保留率为57.21%±0.32%,比未包裹的提升20.72%。白藜芦醇在该体系中24 h的经皮渗透量可达(461.12±35.01)μg/Cm^(2),对难溶性的多酚类化合物有着良好的促渗效果。

烷基二磺酸盐/氧化胺复配体系协同增强泡沫性能

为强化高温高盐油藏条件下表面活性剂的泡沫性能,将十二烷基二苯醚二磺酸钠(DDBS)和椰油酰胺丙基氧化胺(CAO)进行复配制备了二元表面活性剂体系,选择最佳n(DDBS)∶n(CAO)=6∶4的二元表面活性剂体系制备了泡沫封窜剂(SHY-1)。采用罗氏泡沫仪、表面张力仪对二元表面活性剂体系的临界胶束浓度(CMC)、该浓度时的表面张力(γCMC)和泡沫性能进行了测试。采用高温高压泡沫装置、自动岩心驱油装置对SHY-1的性能进行了评价。结果表明,二元表面活性剂体系在界面吸附单层和胶束中的相互作用参数在–3~–7之间,呈中等强度的协同作用;与单一DDBS和CAO相比,二元表面活性剂体系的CMC分别降低了87%和64%,表面张力分别降低了12%和15%,饱和吸附量增加136%和57%。SHY-1耐盐范围宽,在矿化度≤158308 mg/L、Ca^(2+)或Mg^(2+)质量浓度≤10000 mg/L时均具有良好的泡沫性能。在105℃、15 MPa条件下,质量浓度为2500 mg/L SHY-1在多孔介质中原位产生泡沫的表观黏度达到了180 mPa·s。