功能化磁性纳米粒子在乳状液制备及破乳中的应用及作用机制

功能化磁性纳米粒子因其独特的理化性质,在乳状液制备与破乳领域的应用受到广泛关注。本文归纳了功能化磁性纳米粒子的制备方法、合成结构与特征性质,阐述了其在乳状液制备及破乳中的应用过程,重点分析了磁性纳米粒子在溶液中良好分散、稳定吸附于油水界面排布为膜结构的作用行为,尤其是磁性纳米粒子的磁响应特征对乳状液中界面性质、液滴形貌及运动状态的影响,并进一步总结出其表面性质及作用行为对稳定乳状液或使乳状液破乳的规律。针对磁性纳米粒子对乳状液稳定性影响规律的探究可为其在应用领域提供理论支持。最后本文就功能化磁性纳米粒子研究中亟待解决的新问题作出展望。     

高效原油破乳剂GE-189的制备与应用研究

以分子量大、活泼氢多、具有分支结构的瓜胶作起始剂，与环氧乙烷、环氧丙烷加成，首次合成出具有分支结构的瓜胶类原油破乳剂GE－189，并把这种破乳剂及其与常规破乳剂F3111的复配体系应用于不同油田原油乳状液的室内破乳脱水试验。结果表明，破乳剂复配体系在脱水速率、脱水效果等方面均优于各现场剂，把这种破乳剂与生物表面活性剂复配，于巴西海上油田原油乳状液的破乳脱水，能够显著提高原油乳状液的破乳脱水速率和脱水体积，两者之间表现出明显的协同作用。     

微波辐射破乳研究进展

综述了微波辐射破乳的有关研究进展。微波辐射是一种有效的破乳手段，与重力沉降、化学、加热等破乳方法相比，能显著地加速稠油体系，含天然表面活性物质、无机盐、固体粒子、三元复合驱剂等乳状液的破乳，提高破乳效果，并且能够提高破乳脱出水的透光率。无机盐与微波辐射两种破乳方式存在加和作用，在极少量的NaCl，MgCl2，caCl2，KCl存在时，用微波辐射120～150s，破乳率可达100％。微波辐射破乳作为一种很有吸引力的破乳方法已在实验室和油田现场取得成功。     

原油乳状液稳定性和破乳研究进展

本文从控制乳状液稳定性的一些因素－界面膜、界面张力、双电层、空间位阻、固体粒子、液晶、油相溶解度、连续相粘度等方面综述了有关乳状液稳定性的一些研究进展。对国内外有关原油乳状液的破乳研究也做了综述。同时，介绍了应用于乳状液稳定性研究的新的实验技术和仪器。     

优秀原油破乳剂所具备的性能初探

原油破乳剂是国内外油田矿场所必需的化学药剂,可在针对性的破乳剂性能选择上一直缺乏系统的理论支持。由于原油组成的复杂性,加上影响形成乳化原油的因素众多,给原油破乳剂的研究工作带来许多困难。本文从原油乳状液的形成机理入手,分析了乳状液的稳定性原因、破乳机理、破乳剂分子结构性能、物化性能与破乳效果,提出了优秀的原油破乳剂所应具备的性能。     

乳状液的形成、类型及破坏——以生物柴油制备过程中的水洗实验为例

碱催化法制备生物柴油过程中水洗时形成了大量的乳状液,如何快速、高效地破乳成为水洗过程的难点,通过实验对加热、高速离心分离、加入盐酸溶液、加入饱和食盐水溶液等方法的破乳效果进行了评价。因此以生物柴油制备时的水洗过程为例让学生完成"乳状液的形成、类型及破坏"实验课,不仅使学生掌握了乳状液的形成原因及类型,破乳方法及相应机理,巩固了课本知识,而且生物柴油引起了学生的极大兴趣,有利于提高学生的积极性和课程教学效果。     

脂肪醇对环氧乙烷环氧丙烷嵌段共聚物破乳效果的影响 Ⅱ.O/W型乳状液的破坏

环氧乙烷(EO)环氧丙烷(PO)的共聚物有较好的破乳效果,是目前较理想的破乳剂,已在油田得到应用。这类表面活性剂的特点是只要适当调节EO和PO的比例,就既可用作W/O型乳状液的破乳剂,也可用作O/W型乳状液的破乳剂,但关于后者的研究很少。前已报导加入脂肪醇可显著提高这类表面活性剂对W/O型乳状液的破乳效果。本文继续研究脂肪醇对这类表面活性剂破坏O/W型乳状液的影响。     

Span80-TBP-NaOH体系破乳方法及膜内反应研究

采用Span80-TBP-NaOH体系乳状液膜法提取红土矿浸出液中的镍,对提取分离后的乳液进行破乳实验,经过加热-离心联合破乳法,破乳率可达90%.通过比较提取镍前后,乳液的红外光谱图,证明了膜内反应的发生;通过比较原始油相和破乳后油相的红外光谱图,证明了破乳后油相的重复利用性.     

支状嵌段聚醚的界面聚集行为及对原油乳状液的破乳作用

合成了三种不同聚氧丙烯/聚氧乙烯(PPO/PEO)比例的含苯环支状嵌段聚醚, 通过界面张力、界面流变、表面压以及对原油乳状液的破乳脱水效果的测定, 考察了其界面聚集行为和破乳作用对PEO含量和分子量的依赖性, 并且对比研究了三种支状聚醚分子交联前后的破乳性能. 结果表明, PEO含量高且分子量大者,其单分子界面占据面积大, 在油/水界面达到吸附平衡的时间短, 其油/水界面扩张模量及扩张弹性均高于PEO含量较少者. 但是对原油乳状液的破乳脱水效果则是PEO含量居中的聚醚最好. 温度影响和交联与否的研究表明, 交联并不能提高分子量较大的聚醚对原油乳状液的破乳效果, 温度对聚醚分子交联前后的破乳效果有不同的影响规律. 本研究可为原油集输过程中化学品的选择与应用提供一定的依据.     

无机盐对支状嵌段聚醚破乳作用的影响

通过阴离子聚合反应合成了一种七支状聚氧丙烯/聚氧乙烯(PPO/PEO)三嵌段聚醚;考察了不同无机盐存在时对原油乳状液的破乳效果的影响;通过界面张力、浊点和界面膨胀流变性的测定探讨了其界面聚集行为和破乳作用对无机盐的依赖性.结果表明,盐溶型无机离子存在时,能提高聚醚的破乳效果,而盐析型无机离子存在时,不利于聚醚的破乳作用;温度升高破乳速度加快,但45℃时脱出的水质最清.     

Universality of an estimate of the minimum size of an equilibrium phase

The universality of an estimate of the minimum size of small particles with equilibrium phase properties is discussed. Liquid drops in the vapor phase and liquid in porous solids are considered. It is found that the sizes of thermodynamically-stable liquid drops and pore sizes are similar when there is stratifying of a fluid on two phases. It is suggested that the minimum sizes of particles with equilibrium phase properties are the same for magnetic materials as well. Examples of experimental data favoring this suggestion are shown.     

Encapsulated ionic liquids (ENILs): from continuous to discrete liquid phase

Encapsulated ionic liquid (ENIL) material was developed, consisting of ionic liquid (IL) introduced into carbon submicrocapsules. ENILs contain >85% w/w of IL but discretized in submicroscopic encapsulated drops, drastically increasing the surface contact area with respect to the neat fluid. ENIL materials were here tested for gas separation processes, obtaining a drastic increase in mass transfer rate.     

Cocrystal Formation through Mechanochemistry: from Neat and Liquid‐Assisted Grinding to Polymer‐Assisted Grinding

Mechanochemistry is an effective method for the preparation of multicomponent crystal systems. In the present work, we propose an alternative to the established liquid‐assisted grinding (LAG) approach. Polymer‐assisted grinding (POLAG) is demonstrated to provide a new class of catalysts for improving reaction rate and increasing product diversity during mechanochemical cocrystallization reactions. We demonstrate that POLAG provides advantages comparable to the conventional liquid‐assisted process, whilst eliminating the risk of unwanted solvate formation as well as enabling control of resulting particle size. It represents a new approach for the development of functional materials through mechanochemistry, and possibly opens new routes toward the understanding of the mechanisms and pathways of mechanochemical cocrystal formation.     

Thickness, stability and contact angle of liquid films on and inside nanofibres, nanotubes and nanochannels

While the stability of liquid films on substrates is a classical topic of colloidal science, the availability of nanostructured materials, such as nanotubes, nanofibres and nanochannels, has raised the question of how the stability of liquid films and their wetting behaviour is affected by nanoscale confinement. This paper will present the conditions for the stability of liquid films on and inside cylindrical solid substrates with nanometre scale characteristic dimensions. It is shown that the stability is determined by an effective disjoining/conjoining pressure isotherm which differs from the corresponding disjoining/conjoining pressure isotherm of flat liquid films on flat solid substrates. From the former, the equilibrium contact angles of drops on an outer or inner surface of a cylindrical capillary have been calculated as a function of surface curvature, showing that the expressions for equilibrium contact angles vary for different geometries, in view of the difference in thickness of the film of uniform thickness with which the bulk liquid (drops or menisci) is at equilibrium. These calculations have been extended to the case of glass nanocapillaries and carbon nanotubes, finding good agreement with experimental results in the literature.     

新型碱性离子液体催化剂高效催化合成吡喃酮[2,3-d]嘧啶酮和[2,3-d]嘧啶衍生物

制备了碱性离子液体1,1'-(丁烷-1,4-二基)双(1,4-二氮杂二环[2.2.2]辛烷-1-ium)羟化物,并采用红外光谱、1H核磁共振谱和pH值分析对其进行了表征.然后将它用于室温研磨条件下高效催化合成吡喃酮[2,3-d]嘧啶酮和[2,3-d]嘧啶.该法步骤简单,反应时间短,产物收率高,无需柱色谱分离,原料易得,且可回收利用.     

Solubilization of thermotropic liquid crystal compounds in aqueous surfactant solutions

We study the micellar solubilization of three thermotropic liquid crystal compounds by immersing single drops in aqueous solutions of the ionic surfactant tetradecyltrimethylammonium bromide. For both nematic and isotropic drops, we observe a linear decrease of the drop size with time as well as convective flows and self-propelled motions. The solubilization is accompanied by the appearance of small aqueous droplets within the nematic or isotropic drop. At low temperatures, nematic drops expell small nematic droplets into the aqueous environment. Smectic drops show the spontaneous formation of filament-like structures which resemble the myelin figures observed in lyotropic lamellar systems. In all cases, the liquid crystal drops become completely solubilized, provided the weight fraction of the liquid crystal in the system is not larger than a few percent. The solubilization of the liquid crystal drops is compared with earlier studies of the solubilization of alkanes in ionic surfactant solutions.     

On the derivation of Young's equation for sessile drops: nonequilibrium effects due to evaporation

Sessile liquid drops have a higher vapor pressure than planar liquid surfaces, as quantified by Kelvin's equation. In classical derivations of Young's equation, this fact is often not taken into account. For an open system, a sessile liquid drop is never in thermodynamic equilibrium and will eventually evaporate. Practically, for macroscopic drops the time of evaporation is so long that nonequilibrium effects are negligible. For microscopic drops evaporation cannot be neglected. When a liquid is confined to a closed system, real equilibrium can be established. Experiments on the evaporation of water drops confirm the calculations.     

Mechanochemical electrophilic fluorination of liquid beta-ketoesters

An improved substrate scope for the mechanochemical electrophilic fluorination of dicarbonyls is reported. The applicable substrates have now been broadened to include liquid β-ketoesters. Key to this capability is the inclusion of a grinding auxiliary (NaCl) to improve mass transfer and prevent pasting or gumming of the reaction mixture. Notably, the use of a small amount of acetonitrile is critical to increasing the rate of reaction, ensuring complete consumption of starting materials during the short reaction times as well as improving the selectivity for the monofluorinated product in the mill.     

Airborne chemistry: acoustic levitation in chemical analysis

This review with 60 references describes a unique path to miniaturisation, that is, the use of acoustic levitation in analytical and bioanalytical chemistry applications. Levitation of small volumes of sample by means of a levitation technique can be used as a way to avoid solid walls around the sample, thus circumventing the main problem of miniaturisation, the unfavourable surface-to-volume ratio. Different techniques for sample levitation have been developed and improved. Of the levitation techniques described, acoustic or ultrasonic levitation fulfils all requirements for analytical chemistry applications. This technique has previously been used to study properties of molten materials and the equilibrium shape and stability of liquid drops. Temperature and mass transfer in levitated drops have also been described, as have crystallisation and microgravity applications.The airborne analytical system described here is equipped with different and exchangeable remote detection systems. The levitated drops are normally in the 100 nL–2 L volume range and additions to the levitated drop can be made in the pL-volume range.The use of levitated drops in analytical and bioanalytical chemistry offers several benefits. Several remote detection systems are compatible with acoustic levitation, including fluorescence imaging detection, right angle light scattering, Raman spectroscopy, and X-ray diffraction. Applications include liquid/liquid extractions, solvent exchange, analyte enrichment, single-cell analysis, cell–cell communication studies, precipitation screening of proteins to establish nucleation conditions, and crystallisation of proteins and pharmaceuticals.     

Intrusion pressure to initiate flow through pores between spheres

In this work, clusters of three or four spheres were used to examine intrusion pressure. Polytetrafluoroethylene (PTFE) or polyamide 66 (PA66) spheres were arranged horizontally to create a single pore. Liquid drops of water or ethylene glycol were gently introduced from above. If the spheres were too large, drops flowed through as soon as they were deposited. If the spheres were too small, liquid was suspended in the neck of the pore and could not pass through; drops became unstable and fell to one side. Alternatively, if spheres of a certain size were chosen, then capillary forces initially prevented drops of lesser stature from breaking though. However, as these drops grew taller, they eventually reached a height where the gravitational force exceeded the capillary force and the liquid flowed through the pore. A simple model for intrusion pressure was derived. Estimates from the model agreed well with experimentally measured values.