十六烷基三甲基溴化铵-珍珠粉相互作用及其稳定乳液的双重相转变

系统研究了阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）对生物质颗粒珍珠粉制备Pickering乳液的类型、微观结构的影响，同时解析了CTAB/珍珠粉稳定乳液从O/W型到W/O型再到O/W型的双重相转变现象。通过分散性观察、Zeta电位的测定、三相接触角和珍珠粉的荧光标记等手段深入剖析了CTAB与珍珠粉颗粒之间的相互影响。结果表明，在未添加CTAB和CTAB浓度较低时（0.01 mmol/L）时，珍珠粉能单独形成O/W型的Pickering乳液，乳化粒子为非球形且有一定聚结。当CTAB的浓度增加到0.05和0.20 mmol/L时，CTAB在珍珠粉表面吸附增强了颗粒的疏水性，润湿性的变化导致乳液类型从O/W型转变到W/O型，此时乳液的微观结构为球形，且尺寸分布较窄。随着CTAB浓度的进一步增加到0.90 mmol/L,CTAB在油水界面上取代吸附的珍珠粉颗粒，荧光显微镜观察验证了此时形成的O/W型乳液是由过量的CTAB来稳定。即通过简单地增加阳离子表面活性剂CTAB的浓度，就能实现乳液从O/W型到W/O型，再到O/W型的双重相转变。     

从HLB转相温度(PIT)到液晶(LC)

乳剂有水包油型的和油包水型的,在大多数情况下分别标示为O/W型和W/O型,在O/W型申分散着油粒子,在W/O型中分散着水粒子。形成粒子的相叫做内相或分散相,粒子分相的相叫做外相或连续相。表面活性剂中亲油基和亲水基分别朝向油相一侧和水相一侧,吸附在粒子表面。当然,一部分是溶解在两相中的。乳剂是呈O/W型还是W/O型,是受所用表面活性剂的HLB、温度、内相比、添加顺序等因素影响着。当所用的表面活性剂的HLB值低时形成W/O型,当HLB值高时形成O/W型。这一点可用班克洛夫特(Bancroft)规则加以解释,这一规则所阐明的是较多溶解表面活性     

利用稳定性分析仪研究化学破乳过程

利用Turbiscan LabExpert稳定性分析仪研究了化学破乳过程,揭示了破乳过程中模型乳状液体系的絮集、聚并、沉淀、上浮、分相等现象,并定量分析了上述现象发生的速率以及分散相液滴的粒径变化等。结果表明:W/O型模型乳状液的中部发生的是水滴的絮集和聚并,而O/W型模型乳状液的中部保持稳定。W/O型模型乳状液顶部和O/W型模型乳状液底部分别发生的是油相的上浮和水相的下沉,其它部分相对稳定。随着破乳的进行,W/O型模型乳状液中部的内部水滴平均粒径从29.07μm(0h)逐渐增大到73.17μm(1.8h),而O/W型模型乳状液中部的内部油滴平均粒径从12.95μm(0h)逐渐增大到14.03μm(1.6h)。     

反相乳化井降粘体系研究

稠油热采中出现W/O型稠油,使得稠油的粘度增大,开采变得更加困难,利用化学剂来改变乳状液的类型,使W/O的稠油转变为O/W的乳状液,是降低稠油粘度的重要方法,通过降粘剂在稠油中的分散、乳化等作用,与稠油发生乳化,将W/O型乳状液转变为O/W型乳状液,达到乳化反转降粘的目的,可增加原油的流动性,延长蒸汽吞吐周期,提高稠油井产量。     

三元复合驱中原油乳化作用研究

通过乳状液稳定实验考察了大庆油田碱-表面活性剂-聚合物三元复合驱过程乳状液的形成机理、乳状液类型及稳定性。结果表明,大庆原油与碱反应1d时,测得其浓相体积分数为25%,所形成的乳状液为O/W型乳状液,而随着原油与碱作用时间的增加,其浓相体积分数达到40%以上,形成W/O型乳状液,且乳状液稳定性随作用时间增加而增强。大庆原油与水溶性表面活性剂ORS-41溶液作用时,所形成的乳状液为O/W型,且乳状液的稳定性与原油和ORS-41作用时间的长短关系较小。原油与NaOH和ORS-41混合溶液作用时,形成上层为W/O型乳状液,下层为O/W型乳状液的混合体系。     

有机概念图在日用化学工业中的应用 第三讲 乳液的制备

乳液是油和水两种互不相溶的物质在乳化剂(以下简称SAA)存在下乳化了的溶液。乳化是一种液体分散在另一种液体中的过程。乳化广泛应用于各个行业。根据SAA的性质和数量可以将油和水乳化成油包水型(LZ简称B型,即W/O 型)和水包油型(以下下简称A型,即O/W型)的乳液,而这些乳液在条件变化时会发生转向(W/O、O/W),因此,在各种条件下长期保持乳液的稳定是不     

水包油型纳米乳的影响因素及稳定性研究

以硬脂酸甘油酯为主要表面活性剂,采用高压均质、超声波等高能乳化法制备水包油型(O/W)纳米乳,研究了油脂、醇类、金属离子、增稠剂及制备方法对O/W型纳米乳粒径大小的影响。结果表明,油脂类中肉豆蔻酸异丙酯和霍霍巴油对O/W型纳米乳粒径为500～520 nm;醇类中甘油对乳液粒径的降低能力最强,为360 nm;盐类中,适合浓度的条件下随着盐类价态的增加,乳液粒径从400 nm降低至340 nm;增稠剂中,随着增稠剂量的增加,乳液粒径增加,从280 nm增加至310 nm。探究出高能乳化制备O/W型纳米乳的关键指标及O/W型纳米乳的不稳定性机制符合奥斯特瓦尔德熟化。     

水包油型纳米乳的影响因素及稳定性研究

以硬脂酸甘油酯为主要表面活性剂,采用高压均质、超声波等高能乳化法制备水包油型(O/W)纳米乳,研究了油脂、醇类、金属离子、增稠剂及制备方法对O/W型纳米乳粒径大小的影响。结果表明,油脂类中肉豆蔻酸异丙酯和霍霍巴油对O/W型纳米乳粒径为500～520 nm;醇类中甘油对乳液粒径的降低能力最强,为360 nm;盐类中,适合浓度的条件下随着盐类价态的增加,乳液粒径从400 nm降低至340 nm;增稠剂中,随着增稠剂量的增加,乳液粒径增加,从280 nm增加至310 nm。探究出高能乳化制备O/W型纳米乳的关键指标及O/W型纳米乳的不稳定性机制符合奥斯特瓦尔德熟化。     

W/O型乳状液蜡沉积研究与发展

系统阐述了国内外W/O型乳状液蜡沉积研究进展,并着重分析了乳状液蜡沉积影响因素、蜡沉积机理、乳状液蜡沉积实验装置及油水两相蜡沉积动力学模型的建立。目前,W/O型乳状液的蜡沉积研究还有很多关键问题尚未解决,如蜡沉积层的形成过程、蜡晶颗粒的沉积概率及剪切剥离机理等。对W/O型乳状液蜡沉积机理和规律进行深入研究,需要以W/O型乳状液的微观机理研究为基础,重点探索分散体系下分散相液滴对胶凝过程、蜡分子扩散路径、界面吸附及老化等的影响,解决制约W/O型乳状液蜡沉积机理研究和预测模型准确性等关键问题;目前,W/O型乳状液蜡沉积测试手段较单相原油研究还比较单一,将核磁共振(NMR)、X射线衍射(XRD)及光谱测试等先进手段用于乳状液中蜡沉积的研究将成为未来发展方向之一。     

超声波对稠油乳化的影响

超声波会使稠油的组分发生变化,对稠油有一定的降粘作用。超声波作用高含水W/O乳状液在没有乳化剂存在的条件下,能够形成O/W乳状液,这种方式形成的乳状液与加乳化剂转相形成的O/W乳状液相比,稳定性比较差,液滴粒径分布范围变宽,但主要分布范围变窄,液滴分散情况较好。流变性虽然遵循幂律流体规律,非牛顿性有所减弱。从微观观察来分析,在本实验研究范围内,经超声波处理后的高含水W/O乳状液形成的O/W乳状液并非严格意义上的乳状液。     

Stability of vitamin A in oil-in-water-in-oil-type multiple emulsions

The stabilityof vitamin A was studied in thee different emulsions: oil-in-water (O/W), water-in-oil (W/O), and oil-in-water-in-oil (O/W/O). The stability of retinol (vitamin A alcohol) in the O/W/O emulsion was the highest among the thee types of emulsions; remaining percentages at 50°C after 4 wk in the O/W/O, W/O, and O/W emulsions were 56.9, 45.7, and 32.3, respectively. With increasing peroxide value of O/W and W/O emulsifiers, the remaining percentage of vitamin A palmitate and retinol in the emulsions decreased significantly, indicating that peroxides in the formulae accelerate the decomposition of vitamin A. Organophilic clay mineral (an oil gelling agent and a W/O emulsifier) also affected the stability of retinol; synthesized saponite was better than naturally occurring bentonite for retinol stability. The stability of retinol in the O/W/O emulsion increased with increasing inner oil phase ratio (φ_i), whereas in O/W it was unaffected by φ_i. Encapsulation percent of retinol in the O/W/O emulsion, the ratio of retinol in the inner oil phase to the total amount in the emulsion, increased with increasing φ_i. The remaining percent of retinol in the O/W/O emulsion was in excellent agreement with encapsulation percent, suggesting that retinol in the inner oil phase is more stable than that in the outer oil phase. Addition of antioxidants (tert-butylhydroxytoluene, sodium ascorbate, and EDTA) to the O/W/O emulsion improved the stability of retinol up to 77.1% at 50°C after 4 wk. We conclude that the O/W/O emulsion is a useful formula to stabilize vitamin A.     

Evaluation of an oleic acid water-in-oil-in-water-type multiple emulsion as potential drug carriervia the enteral route

A water-in-oil-in-water (W/O/W) emulsion composed of oleic acid was used as a carrier of carboxyfluorescein (CF)via the enteral route, as a model for future drug transport. The absorption of CF in the small intestine of rats given the emulsion (W/O/W group) was compared with the absorption in a group administered CF alone (CF group), and a surface-active agent in CF solution (MM group). Higher amounts of CF were absorbed in the W/O/W and MM groups than in the CF group. At 120 min, the amount of CF remaining in the intestinal tract was smaller in the MM group than in the W/O/W group. In the early period, CF excretion into bile was higher in the MM group than in the W/O/W group was higher than in the MM group (non-specific). The blood CF level was significantly higher at 240 and 360 min in the W/O/W group than in the other two groups. The highest concentration in lymph was found in the W/O/W group. The W/O/W emulsion was considered superior to the micelles because it maintained a higher blood level of CF over long periods and transferred it to the lymph. This suggests that the W/O/W emulsion is applicable as a drug carriervia the enteral route.     

The pharmacokinetics of water-in-oil-in-water-type multiple emulsion of a new tacrolimus formulation

We developed a water-in-oil-in-water (W/O/W)-type multiple emulsion of a new tacrolimus formulation. A potential approach to avoid the complications of systemic immunosuppression and simultaneously enhance immunosuppressive efficacy is to deliver immunosuppressive agents locally to the site of the target organs. The W/O/W emulsion is dispersed oil drops containing smaller water droplets that allow the delivery of drugs preferentially to the reticuloendothelial system (RES). Since the liver and the spleen are primary components of the RES, and the brain and the kidney have a poor RES, we hypothesized that a W/O/W emulsion of tacrolimus would prossess the pharmacokinetic benefits of local immunosuppression. We evaluated this hypothesis in a rat model. The tacrolimus levels of whole blood, the liver, spleen, brain, and kidney in rats given intravenous emulsions of tacrolimus (W/O/W group) were compared with a group administered tacrolimus alone (T group). There were no significant differences between the pharmacokinetic parameters of W/O/W group and T group based on whole blood data. However, the W/O/W group had significantly decreased tacrolimus levels in the brain and kidney, and significantly increased levels in the liver and spleen compared with the T group. These data suggest that the W/O/W emulsion is applicable as an intravenous drug carrier for local immunosuppression.     

The fuel properties of three-phase emulsions as an alternative fuel for diesel engines

Diesel engines are employed as the major propulsion power for in-land and marine transportation vehicles primarily because of their rigid structure, low breakdown rate, high thermal efficiency and high fuel economy. It is expected that diesel engines will be widely used in the foreseeable future. However, the pollutants emitted from diesel engines (in particular nitrogen oxides and particulate matter) are detrimental to the health of living beings and ecological environment have been recognized as the major air pollution source in metropolitan areas and have thus attracted much research interest. Although diesel oil emulsion has been considered as a possible approach to reduce diesel engine pollutants, previous relevant applications were restricted to two-phase emulsions. Three-phase emulsions such as oil-in-water-in-oil briefly denoted as O/W/O emulsions and water-in-oil-in-water, denoted as W/O/W, have not been used as an alternative fuel for any combustion equipment. Studies on the properties of three-phase emulsion as fuel have not been found in the literatures. The emulsification properties of an O/W/O three-phase diesel fuel emulsion were investigated in this experimental study. The results show that the mean drop size of the O/W/O emulsion was reduced significantly with increasing homogenizing machine revolution speed. An increase in inner phase proportion of the O/W/O emulsion resulted in increasing the emulsion viscosity. The viscosity of O/W/O emulsion is greater than that for water-in-oil (denoted briefly as W/O emulsion) for the same water content. More stable emulsion turbidity appeared for three-phase O/W/O diesel emulsions added with emulsifier with HLB values ranging from 6 to 8. In addition, three-phase O/W/O emulsions with greater water content will form a larger number of liquid droplets, leading to a faster formation rate and greater emulsion turbidity at the beginning but a faster descending rate of emulsion turbidity afterwards. The potential for using O/W/O emulsions as an alternative fuel for diesel engines was also evaluated.     

A novel method for preparing oil-in-water-in-oil type multiple emulsions using organophilic montmorillonite clay mineral

A stable formula using oil-in-water-in-oil (O/W/O) type multiple emulsions was investigated. The components consisted of hydrophilic nonionic surfactant (HCO-60), organophilic montmorillonite, and lipophilic nonionic surfactant (DIS-14). O/W/O emulsions were prepared by a double-step procedure in which an O/W emulsion was prepared in the first step, and then the O/W emulsion was “re-emulsified” in an oil phase with organophilic montmorillonite. The diameter of the innermost oil droplets decreased with increasing HCO-60 content (0.1–3%), while the viscosity showed a maximum at 1% of HCO-60, indicating that the yiel of re-emulsification is highest at this condition. Viscosity of the O/W/O emulsion increased with increasing organophilic montmorillonite and DIS-14. According to the results of a phase ratio study, viscosity and stability of the O/W/O emulsion decreased at high weight fraction of inner oil phase (0.4–0.5), indicating that the excess amount of inner oil phase is absorbed by the outer oil phase. These results revealed that the weight fraction of inner oil phase should be kept below 0.3 for a stable O/W/O emulsion. A similar study on the weight fraction of O/W phase [фO/W)/O] suggested that the O/W/O emulsion is stable at ϕ(O/W)/O=0.65–0.70.     

Development of method for estimating drop diameter in the manufacturing process of functional O/W microcapsules

A new method for preparing functional O/W microcapsules using a process involving O/W/O emulsion as particle formation was developed. Coenzyme Q10 (CoQ10) or reduced coenzyme Q10 (QH) was used as the core substance. QH oxidized fast when exposed to air. O/W microcapsules were manufactured by conventional liquid phase drying method (LPD). The purpose of this study is to develop a simple method of estimating drop diameter which is possible to evaluate immediately the mean drop diameter during the microencapsulation process without the usual photographic measurement. This developed estimation is possible to predict a Sauter mean diameter by measuring the amount of inner CoQ10 released from O/W emulsion droplet. The amount of inner oil phase released from O/W emulsion has correlation with increased total surface area of O/W emulsion droplet caused by breaking droplet. Released rate of CoQ10 from O/W emulsion droplet to outer continuous phase under different rotational speed and emulsion viscosity was measured with an absorption spectrometer. As a result of the changes of released inner CoQ10 amount, droplet breakage under low emulsion viscosity was promoted by agitation speed. It is concluded that droplet dispersion state during manufacturing of O/W microcapsules was evaluated well by applying the developed estimation method.     

Effects of NOx-inhibitor agent on fuel properties of three-phase biodiesel emulsions

Biodiesel is one of the more promising alternative clean fuels to fossil fuel, which can reduce the emissions of fossil fuel burning, and possibly resolve the energy crisis caused by the exhaustion of petroleum resources in the near future. The burning of biodiesel emits much less gaseous emissions and particulate matter primarily because of its dominant combustion efficiency. However, the high oxygen content in biodiesel not only promotes the burning process but also enhances NO_x formation when biodiesel is used as fuel. Biodiesel emulsion and the additive of NO_x-inhibitor agent are considered to reduce levels of NO_x emissions in this experimental study. The biodiesel was produced by transesterification reaction accompanied with peroxidation process. A three-phase biodiesel emulsion of oil-in water drops-in oil (O/W/O) and an O/W/O biodiesel emulsion containing aqueous ammonia were prepared afterwards. The effect of the existence of NO_x-inhibitor agent on the fuel properties and the emulsion characteristics of the O/W/O biodiesel emulsions were investigated. The experimental results show that the burning of the O/W/O biodiesel emulsion and the O/W/O biodiesel emulsion containing aqueous ammonia had larger fraction of fuel burnt and thus larger heat release than the neat biodiesel if water content is not considered for the calculation of heating value. The addition of aqueous ammonia within the dispersed phase of the O/W/O biodiesel emulsion appeared to deteriorate the emulsification characteristics. A smaller quantity of emulsion and greater kinematic viscosity were formed while a larger carbon residue and actual reaction-heat release also appeared for this O/W/O biodiesel emulsion. Aqueous ammonia in the O/W/O biodiesel emulsion produces a higher pH value as well. In addition, the number as well as the volumetric fraction of the dispersed water droplets is reduced for the O/W/O biodiesel emulsion that contains aqueous ammonia.     

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。     

Effects of molecular weight distribution of nonionic surfactants on stability of O/W emulsions

From the relationship between the distribution width of oxyethylene (OE) or alkyl chains and O/W emulsions stability, it became evident that even with the same average OE or alkyl chain lengths, the phase-inversion temperature (PIT) and O/W emulsion stability depend on width. However, emulsification at the PIT invariably results in a very stable O/W emulsion. Emulsifiers with a large distribution width of OE or alkyl chains were also found to improve O/W emulsion stability.     

水/油/水双重乳液内、外水相间作用能分析

通过考察范德华力和静电作用力两个主要因素,建立了一个用以计算双重乳液内、外水相间相互作用能的数学模型.利用此模型,首先计算分析了无吸附层和存在单吸附层时相互作用能的变化趋势,并重点考察了存在两个不同吸附层时此相互作用能的变化.发现在一定的静电作用条件下,随着两个界面间的间距(D)不同,内外水相间的相互作用也有所不同:(1)当D较大时,如果油相的Hamaker常数(AM-M)介于内、外水相的Hamaker常数(AP-P和AC-C)之间,则内外水相间的相互作用始终为微弱的排斥力;否则为微弱的吸引力.(2)当D很小时,如果AM-M介于内、外两个吸附层的Hamaker常数(AA1-A1和AA2-A2)之间,则内外水相间的相互作用表现为较强的排斥力,有利于系统的稳定;否则为吸引力,不利于系统的稳定.