膜乳化和微流控法制备单分散W／O乳液的研究

以油相为连续相、水相为分散相,分别采用SPG膜乳化法和微流控技术制备出了单分散W／O乳液。对两种制备单分散乳液的方法进行了系统比较。结果表明,微流控技术不仅更易操作,而且制备出的W／O乳液单分散性更好。     

制备单分散含单体O/W乳液的SPG膜乳化过程

采用Shirasu多孔玻璃（SPG）膜乳化法制备了单分散含对苯二甲酰氯（TDC）单体的O/W乳液,系统地研究了SPG膜乳化过程的影响因素.实验结果表明,采用SPG膜乳化法制备单分散O/W乳液时,选择阴离子表面活性剂比考虑亲水亲油平衡（HLB）匹配更重要;增大分散相或连续相的黏度,能够改善乳液的单分散性和稳定性;随着单体浓度增加,乳液的单分散性变差,液滴的平均粒径逐渐变小.当SPG膜孔径大于1.0 μm左右时,可得到单分散的含TDC单体乳液;而当孔径小于1.0 μm左右时,水分子更容易扩散并溶解到油水界面甚至油相内部与TDC生成对苯二甲酸（TPA）,TPA积累到一定程度在油水界面上析出将膜孔堵塞,从而无法制得单分散乳液.随着乳化时间增长,乳液的平均直径逐渐变小、单分散性逐渐变差.     

单分散油包水乳液制备的研究进展

单分散油包水(W/O)乳液在食品、化妆品、药剂以及高分子微球微囊合成等方面具有广泛的应用。该文综述了近年来单分散W/O乳液的主要制备方法及其基本原理,此外还简要介绍了其在单分散温敏性微球微囊和可生物降解微球微囊合成方面的应用,以期为单分散W/O乳液的制备提供参考。     

二次膜射流乳化法制备单分散乳状液研究

为解决传统膜乳化法制备单分散O/W型乳状液中存在的粒径和通量的矛盾,介绍了采用二级陶瓷膜乳化在射流条件下制备单分散O/W乳状液的方法。2套一体式陶瓷膜乳化装置被串联使用,一级膜乳化采用孔径为0.16μm的ZrO2陶瓷膜,二级膜乳化采用孔径为1.5μm的-αA l2O3陶瓷膜。以甲苯/水体系为研究对象,阴离子表面活性剂(SDS)和非离子表面活性剂(乳化剂OP)分别被用作乳化剂。2种情况下均可获得单分散的乳液,能耗分别是1.53×105J/m3和1.21×105J/m3。因此,该方法可在较低的能耗下制备单分散乳液。     

陶瓷膜乳化法制备O/W乳状液

膜乳化法是获得高质量单分散稳定乳状液的一种简单有效方法,以氧化铝陶瓷微滤膜为乳化媒介,大豆油为分散相,含有乳化剂的去离子水为连续相,直接制备O/W乳液.比较了膜乳化法与机械搅拌法的乳化效果;考察了乳化剂浓度、膜两侧压差和磁力搅拌转速对乳化效果的影响.结果表明:乳化剂浓度2%、膜面压差0.12MPa、搅拌转速450r/min为最佳乳化条件.     

微流控法以单乳为模板制备单分散中空微囊的研究

单分散中空微囊在化工、医药、生物技术等领域有着广阔的应用前景。本文采用微流控技术制备了含甲基丙烯酸β羟乙酯和甲基丙烯酸甲酯两种单体的单分散水包油（O／W）乳液,并以此为模板,在致孔剂的作用下,光引发聚合成功制备了单分散聚甲基丙烯酸β羟乙酯-甲基丙烯酸甲酯的中空微囊。用光学显微镜和扫描电子显微镜对微囊进行系统的表征,结果表明,微囊的粒径在40μm左右,尺寸分布较窄,具有良好的单分散性,微囊外表面光滑,内表面粗糙,囊壁较薄,为中空结构。本研究中提出的方法为单分散中空微囊的制备提供了一条新的途径。     

二次膜射流乳化法制备单分散乳液模板的研究

乳液模板法是一种制备高度有序多孔材料的重要方法,而膜乳化法则是一种新型的通过膜结构制备乳液的方法。文中提出了一种采用二次膜射流乳化制备单分散乳液模板的方法,平均孔径为0.16μm和1.5μm的陶瓷膜分别被作为两次乳化的乳化介质。采用异辛烷/甲酰胺体系为研究对象,嵌段高分子聚(乙二醇)聚(丙二醇)聚(乙二醇)作为乳化剂。实验表明一级膜乳化过程的通量为75.4 L/(m2.h),二级膜乳化过程的通量可达到169.9 L/(m2.h)。所得单分散乳液模板的平均粒径为1.8μm,且在10 h内能保持较好的稳定性。     

膜乳化法制备单分散聚苯乙烯多孔微球

为了解决用传统方法制备微球粒径不均的缺点，实验使用自制的膜乳化装置，通过膜乳化法制备粒径在12～20μm、单分散系数小于20％的聚苯乙烯多孔微球．使用扫描电镜考察多孔微球的表面形貌及孔径．结果表明：膜孔径是影响微球粒径的决定性因素；适当的膜乳化压力、乳化剂和分散剂浓度是生产粒径均一微球的重要条件；在致孔剂DBP质量分数为20％时，微球的平均孔径为0．12μm．     

膜乳化法原理及其制备单分散高分子微球的进展

介绍了膜乳化法的原理及其影响因素,由膜乳化法制备的单分散高分子微球具备粒径均一、分布可控等特点;综述了由膜乳化法制备的单分散高分子微球在化妆品、生物医药、化工等相关领域的应用研究进展.     

一体化陶瓷外膜乳化装置制备O/W型乳状液

引　言膜乳化技术是将分散相以很小的压力压过膜孔 ,在膜表面形成微小的液滴 ,并通过剪切力的作用使小液滴从膜表面脱落而进入连续相的新型乳化技术 .该方法具有低能耗、低剪切力、需要表面活性剂较少、生成的乳液颗粒均匀等特性[1,2 ] ,所用的膜主要有微孔玻璃膜[3] 和陶瓷膜两种[4 ] .微孔玻璃膜的孔径分布较窄 ,通常在小于平均孔径±15 %的范围内变化 ,因此制备出的乳状液粒径分布较窄 ,但对称膜固有的高阻力导致膜的通量较小(通常在 2～ 4 0L·m- 2 ·h- 1) ,制约了其在工业领域的应用 .而陶瓷膜由于具有较高的通量被较多地用于工业化…     

Fibrous ceramic membrane constructed by mullite whiskers for the treatment of oil-in-water emulsions

Ceramic membranes with high porosity and excellent separation efficiency are necessary for the efficient treatment of large-scale wastewaters. However, the conventional ceramic membranes are usually prepared by particles-packing, which inhibits the advances of separation efficiency because of the low porosity and connectivity. Here, a fibrous ceramic membrane with mullite whiskers-interlocked structure was prepared by gas-solid reaction. The effects of aluminum fluoride (AlF₃) on the formation and growth of mullite whiskers, and then the permeability and selectivity of the ceramic membranes were investigated. With the increase of AlF₃ contents, the mullite phase evolved from needle-like, rod-like to flake-like structure, thus the catalyst accelerated the growth of mullite whiskers in the diameter direction. For the ceramic membrane sintered at 1400°C, the porosity increased from 58% to 76% while the average pore sizes increased from 0.65 to 3.93 μm because of the whisker-constructed structures. For the ceramic membrane sintered at 1450°C, the emulsion flux increased stably from 295 L/(m²·h) to 992 L/(m²·h) with the increase of trans-membrane pressure, and the oil rejection exceeded 98%. Thus, this study provides a feasible strategy for the preparation of ceramic membranes with high porosity and excellent separation performances.     

Preparation of water-in-oil and ethanol-in-oil emulsions by membrane emulsification

In this work, water-in-oil emulsions (W/O) and ethanol-in-oil emulsions (E/O) emulsions were prepared successfully by membrane emulsification. The emulsifiers selected were PGPR and MO-750 for the W/O and E/O emulsions, respectively. For W/O emulsions prepared with an oil pre-filled membrane, the dispersed flux was lower and the droplet size sharper than that obtained with a water pre-filled membrane. On the contrary, for E/O emulsions prepared with the membrane pre-filled with oil, the dispersed phase (ethanol) rapidly pushed out the oil from the membrane pores. Therefore, the pre-treatment of the membrane had almost no effect on the dispersed phase flux and on the droplet size. The droplet size distribution of the E/O emulsion was close to that obtained with a classical homogenizer. The dispersed phase fluxes were high and no fouling was observed for our experimental conditions (1.6 l emulsion, 10 wt% ethanol). These results confirm that membrane emulsification could be an interesting alternative for the preparation of E/O emulsions for the purpose of biodiesel fuels, considering the scale-up ability of membranes and their potentiality for industrial processes.     

Novel extensional device to efficiently form fine oil-in-water food emulsions

Two immiscible liquids are commonly mixed by mechanically dispersing one into the other to form emulsions. Surfactants or emulsifiers confer stability. Mechanical mixing, in practice, is an energy-intensive shear flow that is ineffective when the ratio of the dispersed-phase viscosity to the continuous-phase viscosity exceeds about four. Extensional flows are not subject to this viscosity ratio limit. This superiority of extensional flow was exploited to fabricate a novel, continuous-flow, cone-shaped device with an extensional strain of eight to make fine soybean oil-in-water emulsions. A spherical insert having a wall clearance of 25 μm was an effective design factor. Starting with ‘coarse’ 50 wt.% oil emulsions, two stretching episodes were needed for size reduction. The temperature rise was negligible, and the results were independent of the emulsifier type employed. Increasing flow rate and stretching episodes, reducing wall clearance, enhancing emulsifier concentration, and multiple passes through the device gave progressively smaller drops; the volume-averaged diameter became less than 2 μm, and the number-averaged diameter reached 0.5 μm, narrowing the size distribution. The emulsions that formed had a high viscosity and were stable. The performance of a scaled-up device was compared with other mixers. At equivalent energy density and 50 wt.% oil, drop sizes were similar for a valve homogenizer but larger for a rotor-stator mixer. At 80 wt.% oil, the rotor stator-mixer again required more energy for the same drop size, but emulsions prepared with the valve homogenizer broke. The findings of this study can help to design industrial-scale energy-efficient extensional-flow dominant devices for the formation of food emulsions.     

陶瓷微滤膜制乳技术研究

选择水-煤油体系(体积比为水：煤油：10：1)，分别用机械搅拌法和陶瓷微滤膜制备乳液．研究了乳化剂及增稠剂阿拉伯树胶的浓度对乳液稳定性的影响。实验结果表明：对于水一煤油体系，选择质量分数为0．8％的Tween80为乳化剂，加入质量分数为1％的阿拉伯树胶为增稠剂，用0.1μm陶瓷微滤膜为分散介质可以制备粒径分布均匀的乳化液体系，且膜两侧压差及连续相流速对乳液稳定性的影响不大。     

基于膜射流乳化技术的TiO2大孔陶瓷制备方法研究

A novel method to prepare macroporous TiO2 ceramic, based on membrane emulsification was reported.To solve the paradox between the instability of nonaqueous emulsion and long emulsification time required by themembrane emulsification, a two-stage ceramic membrane jet-flow emulsification .was. proposed. Discussion wasconducted on the evolution of droplet size with time, which followed the Ostwalcl npemng theory. And a monodispersed nonaqueous emulsion with an average droplet size of 1.6μm could beprepared. Using the emulsion, as atemplate, TiO2 ceramics with an average pore size ot 1.1 μm were obtaineed. Tne material could be prospectivelyused for preparation of catalysts, adsorbents, and membranes.     

Preparation of micron-scale monodisperse oil-in-water microspheres by microchannel emulsification

Micron-scale monodisperse oil-in-water (O/W) micropheres (MS) were prepared using a novel microchannel (MC) emulsification technique. The characteristics of the MS preparation and the O/W-MS prepared were studied. Soybean oil and medium-chain triacyglycerol (MCT) were used as the disprrsed phase, and physiological saline was used as the continuous phase. Silicon MC with 1 to 3μm-equivalent channel diameters were employed. A novel MC module was devised to easily recover the O/W-MS prepared. The effects of the channel shape on the behavior of MS formation, on the MS size, and on the distribution were investigated. An MC with a terrace at the MC outlet stably yielded micron-scale monodisperse O/W-MS; the MS had diameters of about 5 μm, and their coefficients of variation were below 9%. Monodisperse food-grade O/W-MS with diameters of about 4 μm could be obtained by using polyglycerol fatty acid ester as the surfactant. The size and size distribution of the recovered O/W-MS remained almost constant over 60 d, demonstrating their long-term stability.     

Argan oil-in-water emulsions: Preparation and stabilization

We prepared stable oil-in-water emulsions of argan oil with two different types of mixtures of nonionic emulsifiers. Three different types of oil (Israeli argan oil, Moroccan argan oil, and soybean oil) were emulsified with mixtures of Span 80 and Tween 80. The optimum HLB value for argon oil was 11.0 (±1.0). The argan oil-in-water emulsions were stable for more than 5 mon at 25°C. Synergistic effects were found in enhancing stability of emulsions prepared with sucrose monostearate. The origin of the oil and the internal content of natural emulsifiers, such as monoglycerides and phospholipids, have a profound influence on its interfacial properties and on the stability of the argan oil-in-water emulsions.