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1.
During extraction of crude oil, water is generally present in the oil. This water‐in‐oil (w/o) mixture undergoes turbulent flow that promotes sheer forces, resulting in the appearance of emulsions. These emulsions can be highly stable due to the presence of compounds with polar characteristics such as asphaltenes, which act as natural emulsifiers and form resistant films at the oil–water interface. Nonionic surfactants based on polyoxides are widely used to prevent the formation or to break down w/o emulsions. To shed more light on the destabilization mechanism of w/o emulsions promoted by these surfactants, in this study the techniques of tensiometry and Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR‐ATR) were applied to study the interface formed by poly(ethylene oxide)‐poly(propylene oxide) (PEO‐PPO) block copolymers and asphaltenic petroleum fractions. Initially, the critical micelle concentration of the copolymers in aqueous solution was determined. The results agreed with those found by tensiometry. The bottle test was used to evaluate the break‐down of the w/o emulsions in the presence of the PEO‐PPO block copolymers, and the results presented good agreement with those obtained by tensiometry and FTIR‐ATR. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

2.
Oil in water (o/w) nanoemulsions were synthesized in order to be evaluated as an alternative to petroleum emulsions destabilization processes and inhibition of foam formed in the crude oil. The nanoemulsions were prepared by the high energy method through High Pressure Homogenizer (HPH), utilizing poly(propylene glycol) (PPG) and xylene solvent as oil phase and different polarity polyether silicone surfactants samples. These nanoemulsions were evaluated in respect to their efficiency in the petroleum demulsification process. The results of these tests showed that nanoemulsions performance on the destabilization of petroleum emulsions is influenced by the utilized surfactant's polarity. The nanoemulsions and pure samples of PPG and xylene solvent were evaluated concerning capacity of formed foam inhibition in petroleum (antifoam test), and the results showed no significant influence of samples on foam stability. Petroleum/saline water added interfacial tension measurements, added or not the nanoemulsions were executed and showed that the additives adsorption in the interface is related to the surfactant's polarity and nanoemulsion drop size. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40889.  相似文献   

3.
The critical electric field (cef) technique has been utilized to measure the stabilities of a variety of water‐in‐model oil and petroleum emulsions. The cef method allows for a fast, reproducible, and quantitative gauge of emulsion stability. Here, we have used cef to measure the stability of water‐in‐heptane‐toluene‐asphaltene emulsions and confirmed the importance of solvation of asphaltenes and the state of asphaltene aggregation to emulsion stability. Emulsion stability increased with the concentration of soluble asphaltenes near the point of precipitation. Droplet sizes were measured with optical microscopy in order to calculate interfacial areas and film thicknesses. It was found that film thickness increased with asphaltene concentration up to the solubility limit, above which increased concentration had little effect, and cef increased with interfacial film thickness up to a monolayer coverage of asphaltene aggregates, above which film thickness had a much smaller effect. These findings were applied to a cef investigation of water‐in‐ppetroleum emulsions to develop correlations of the stability of water‐in‐ccrude oil emulsions. A strong correlation (coefficient = 0.95) was found for cef with the product of asphaltene concentration and the difference in hydrogen to carbon atomic ratios of the asphaltenes and petroleum solvent. The development of a kinetic model and its fit to experimental data revealed the effects of asphaltene chemistry, solvency, and resin concentration on the adsorption and consolidation of emulsion stabilizing interfacial films.  相似文献   

4.
Differing from conventional emulsions, water‐in‐oil (W/O) emulsions are produced with no additional surfactants in this study. The testing results show that both interfacial tension (IFT) and dilational modulus at all salinities and pH are much higher than those of normal emulsions. A high IFT is not good for making emulsions, but a higher dilational modulus will contribute to more stable emulsions. Emulsion stability declines slightly as salinity increases and the most unstable W/O emulsion appears at pH = 7. To deeply understand the effects of salinity and pH on emulsion stability, petroleum acid is extracted and characterized using Fourier transform ion cyclotron resonance mass spectrometry.  相似文献   

5.
The effects of diacylglycerols rich in medium‐ and long‐chain fatty acids (MLCD) on the crystallization of hydrogenated palm oil (HPO) and formation of 10% water‐in‐oil (W/O) emulsion are studied, and compared with the common surfactants monostearoylglycerol (MSG) and polyglycerol polyricinoleate (PGPR). Polarized light microscopy reveals that emulsions made with MLCD form crystals around dispersed water droplets and promotes HPO crystallization at the oil‐water interface. Similar behavior is also observed in MSG‐stabilized emulsions, but is absent from emulsions made with PGPR. The large deformation yield value of the test W/O emulsion is increased four‐fold versus those stabilized via PGPR due to interfacial crystallization of HPO. However, there are no large differences in droplet size, solid fat content (SFC), thermal behavior or polymorphism to account for these substantial changes, implying that the spatial distribution of the HPO crystals within the crystal network is the driving factor responsible for the observed textural differences. MLCD‐covered water droplets act as active fillers and interact with surrounding fat crystals to enhance the rigidity of emulsion. This study provides new insights regarding the use of MLCD in W/O emulsions as template for interfacial crystallization and the possibility of tailoring their large deformation behavior. Practical Applications: MLCD is applied in preparing W/O emulsion. It is found that MLCD forms unique interfacial Pickering crystals around water droplets, which promote the surface‐inactive HPO nucleation at the oil‐water interface. Thus MLCD‐covered water droplets act as active fillers and interact with surrounding fat crystals, which can greatly enhance the rigidity of emulsion. This observation would provide a theoretical reference and practical basis for the application of the MLCD with appreciable nutritional properties in lipid‐rich products such as whipped cream, shortenings margarine, butter and ice cream, so as to substitute hydrogenated oil. MLCD‐stabilized emulsions can also be explored for the development of novel confectionery products, lipsticks, or controlled release matrices.  相似文献   

6.
Palm-oil-in-water emulsions were prepared with mixtures of Tween 40 and Span 40 in various proportions. Stability and droplet-size distribution of the emulsions were monitored. Interfacial tensions of the palm oil/water interface were also determined in the presence of these emulsifier mixtures. Emulsifying efficiency of the emulsifier mixtures was assessed. No synergistic effect of Tween 40 (sorbitan monopalmitate with 18–22 moles of ethylene oxide) and Span 40 (sorbitan monopalmitate) was found on interfacial tension. Tween 40 alone (hydrophilic-lipophilic balance value 15.6) at 1.0% w/w gave palm oil emulsions that were stable for more than 30 d at 60°C. Emulsifier mixtures of Tween 40 and Span 40 with hydrophilic-lipophilic balance values in the range of 8.0–8.6 produced stable emulsions only at much higher emulsifier-mixture concentrations. The inherent nature of the oil and the accompanying natural surface-active materials present in the oil can influence the prevailing conditions at the oil/water interface and alter composition of the interfacial film and hence its stability.  相似文献   

7.
梁格  黄翔峰  刘婉琪  熊永娇  彭开铭 《化工进展》2022,41(12):6557-6572
超疏水三维多孔材料基于润湿性和毛细作用可有效吸附回收水中浮油,近年来在乳化液的油水分离中也得到应用。本文重点从超疏水三维多孔材料的设计制备、对乳化液的油水分离效果、油滴在材料中的分离机制3个方面展开分析与评价。文中指出:材料设计制备方面,以海绵为主的多孔材料主要通过修饰低表面能物质和构建粗糙结构获得超亲油疏水性,疏水改性后的材料具备较高的油吸附容量(31~131g/g)。乳化液油水分离评价方面,超疏水三维多孔材料处理的对象多为O/W模型乳化液,油浓度低、表面活性剂浓度低、液滴粒径为微米级,少见对实际乳化液的处理;应用方式包括基于吸附作用的浸泡处理和吸附协同拦截作用的过滤处理两类;分析发现影响油水分离效果的关键是材料的孔径、表面疏水性和带电性。作用机制方面,疏水多孔材料吸附乳化油的作用过程仍停留在理论推测层面,主要观点为材料通过笼状孔道结构和疏水表面高效捕集和吸附油滴,油滴聚并破乳形成油层而被分离。虽然超疏水三维多孔材料在乳化液油水分离应用研究中取得了一定进展,但仍需探究其对实际废乳化液的适用性,设计开发连续分离设备以实现工程应用;结合原位观测、数值模拟、力学解析等方法解析油滴在多孔材料中的迁移转化规律和关键环节,以揭示其作用机制。  相似文献   

8.
New quaternary ammonium salts are synthesized by octylamine, nonylamine, dodecylamine, and hexadecylamine reacting with propylene oxide at a mole ratio of 1:2, followed by reaction with 2‐chloroethanol. By tensiometric measurements of aqueous solutions, their surface activity has been determined. Using the results of these measurements and electroconductometric studies, important parameters such as critical micelle concentration (CMC), efficiency of surfactant adsorption, surface pressure at the CMC, changes of Gibbs free energies for micelle formation, and adsorption were estimated. By application of the Gibbs adsorption isotherm, indices such as maximum surface excess concentration and minimum surface area/molecule at the air–water interface were also calculated. Petroleum‐collecting properties of these surfactants were investigated. Among these quaternary ammonium surfactants, the surfactant based on dodecylamine, propylene oxide, and 2‐chloroethanol exhibits the highest petroleum‐collecting capacity.  相似文献   

9.
The influence of petroleum sulphonate (TRS) on interfacial properties and stability of the emulsions formed by formation water and asphaltene, resin and crude model oils from Gudong crude oil was investigated by measurement of interfacial shear viscosity, interfacial tension (IFT) and emulsion stability. With increasing petroleum sulphonate concentration, IFT between the formation water and the asphaltene, resin and crude model oils decreases significantly. The interfacial shear viscosity and emulsion stability of asphaltene and crude model oil system increase for the petroleum sulphonate concentration in the range 0.1% to 0.3%, and decrease slightly when the concentration of the surfactant is 0.5%. There exists a close correlation between the interfacial shear viscosity and the stability of the emulsions formed by asphaltene or crude model oils and petroleum sulphonate solution. The stability of the emulsions is determined by the strength of the interfacial film formed of petroleum sulphonate molecules and the natural interfacial active components in the asphaltene fraction and the crude oil. The asphaltene in the crude oil plays a major role in determining the interfacial properties and the stability of the emulsions.  相似文献   

10.
New experimental results are presented on the pipeline flow behavior of water‐in‐oil (W/O) emulsions with and without a polymeric additive in the aqueous phase. The emulsions were prepared from three different oils of different viscosities (2.5 mPa s for EDM‐244, 6 mPa s for EDM‐Monarch, and 5.4 mPa s for Shell Pella, at 25 °C). The W/O emulsions prepared from EDM‐244 and EDM‐Monarch oils (without any polymeric additive in the dispersed aqueous phase) exhibited drag reduction behavior in turbulent flow. The turbulent friction factor data of the emulsions fell well below the Blasius equation. The W/O emulsions prepared from EDM‐244 oil exhibited stronger drag reduction as compared with the EDM‐Monarch oil. The W/O emulsions prepared from Shell Pella oil exhibited negligible drag reduction in turbulent flow and their friction factor data followed the Blasius equation. The Shell Pella emulsions were more stable than the EDM‐244 and EDM‐Monarch emulsions. When left unstirred, the EDM‐244 and EDM‐Monarch emulsions quickly coalesced into separate oil and water phases whereas the Shell Pella emulsions took a significantly longer time to phase separate. The Shell Pella oil emulsions were also milkier than the EDM emulsions. The addition of a polymer to the dispersed aqueous phase of the W/O emulsions had a significant effect on the turbulent drag reduction behavior.  相似文献   

11.
张辛铖  何林  隋红  李鑫钢 《化工进展》2022,41(7):3534-3544
重质油包水(W/O)乳液普遍存在于石油开采与加工过程中,因其高黏度、高密度、强界面稳定特性,导致重质油包水乳液分离困难,生产成本增加。为了提高重质W/O乳液的分离效率,本文探究了温度与甲苯加入量对重质油黏度的影响规律。在此基础上,研究了上述降黏过程与脱水率之间的协同机制。采用自制的TJU-3破乳剂对重质W/O乳液进行破乳,通过调整破乳剂在乳液中的浓度和破乳温度得到了最佳工艺条件。利用分子模拟的方法构建了重质油平均分子模型并计算了SARA四组分在不同甲苯含量的重质油中的扩散系数,分析了甲苯添加量对重质油中SARA四组分相互作用的影响规律,研究了沥青质分子和TJU-3破乳剂分子在油水界面的运移过程。结果表明:重质油的黏度降低到1500mPa·s时,可实现在1h内完全破乳;黏度降低到50mPa·s时可实现在20min内完全破乳。当破乳剂在乳液中的浓度为400mg/L时,乳液的脱水率最高;破乳温度为60℃时,破乳速度最快。SARA四组分中胶质的扩散系数增大最显著,是重质油的黏度能被甲苯迅速降低的主要原因。TJU-3分子能够破坏沥青质界面膜,进而实现破乳。该协同机制和工艺条件可为石油工业中重质W/O乳液的低温快速破乳工艺提供参考。  相似文献   

12.
Glycerol monooleate (GMO)-stabilized liquid water-in-vegetable oil emulsions are difficult to stabilize due to the desorption of GMO from the water-vegetable oil interface toward the oil phase. This work improved the stability of GMO-stabilized liquid 20 wt% water-in-canola oil (W/CO) emulsion by modifying the dispersed aqueous phase composition with hydrogen bond-forming agents. As a control, 20 wt% water-in-mineral oil (W/MO) emulsion was also utilized. Different concentrations of hydrogen bond-forming agents (citric acid (CA), ascorbic acid (AA), low methoxyl pectin (LMP)) with and without salts (sodium chloride (S) or calcium chloride (Ca)) were added to the aqueous phase before emulsification, which enhanced emulsifier binding to the water–oil interface. W/CO emulsion without any aqueous phase additive destabilized instantly, whereas W/MO emulsion stayed stable during the week-long observation. The addition of hydrogen bond-forming agents and salts significantly improved emulsion stability. LMP, with many hydrogen bond-forming groups, was able to provide the highest emulsion stability after 7 days in both oils compared to AA, CA and their mixtures with S. Emulsions with both oils formed weak gels due to the formation of an extensive network of water droplet aggregates. Overall, the hydrogen bond-forming agents interacted with GMO at the interface, thereby favoring their presence at the water droplet surface and significantly improving the stability of liquid W/CO emulsions. The knowledge developed in this research can be useful in utilizing GMO to stabilize liquid water-in-oil emulsions without using any fat crystal network.  相似文献   

13.
Double emulsions are commonly stabilized by monomeric and/or polymeric emulsifiers. Pickering stabilization by solid particles such as colloidal microcrystalline cellulose has been mentioned only once as a possible technique to stabilize the external interface of the water-in-oil-in-water emulsion. No further work was carried out exploring this option. The present study shows that solid microcrystalline fat particles of α-form are capable of adsorbing at the water-oil interface and, together with other hydrophobic emulsifiers, can stabilize water-in-oil (W/O) emulsions. The crystals must be submicron in size in order to effectively adsorb and arrange at the interface. Large crystals do not fit and were found to flocculate as free crystals in the continuous oil phase. The α-form crystals can be obtained by flash-cooling saturated triglycerides in vegetable oils in the presence of emulsifiers, such as polyglycerol polyricinoleate (PGPR), that stabilize the dispersion and serve as α-tending crystal structure modifiers. It was assumed that PGPR also serves as a cross-linker or bridge between the crystalline fat particles and the water, and facilitates the anchoring of the fat particles in the oil phase in one direction while dangling itself in the water phase. The double emulsion droplets prepared with these W/O emulsions are relatively large in size (6–18 μm), but stable to coalescence. The marker (NaCl) does not seem to release with time, suggesting that the fat particles form microcapsules on the water interface, totally sealing the water from releasing its addenda. The systems seem to have a significant potential for food emulsions.  相似文献   

14.
Recent research has shown that the oxidative stability of oil‐in‐water emulsions is affected by the type of surfactant used as emulsifier. The aim of this study was to evaluate the effect of real food emulsifiers as well as metal chelation by EDTA and pH on the oxidative stability of a 10% n‐3‐enriched oil‐in‐water emulsion. The selected food emulsifiers were Tween 80, Citrem, sodium caseinate and lecithin. Lipid oxidation was evaluated by determination of peroxide values and secondary volatile oxidation products. Moreover, the zeta potential and the droplet sizes were determined. Tween resulted in the least oxidatively stable emulsions, followed by Citrem. When iron was present, caseinate‐stabilized emulsions oxidized slower than lecithin emulsions at pH 3, whereas the opposite was the case at pH 7. Oxidation generally progressed faster at pH 3 than at pH 7, irrespective of the addition of iron. EDTA generally reduced oxidation, as evaluated by volatiles formation in all emulsions, irrespective of pH and emulsifier type, except in the lecithin and caseinate emulsions where a pro‐oxidative effect was observed for some volatiles. The different effects of the emulsifier types could be related to their ability to chelate iron, scavenge free radicals, interfere with interactions between the lipid hydroperoxides and iron as well as to form a physical barrier around the oil droplets.  相似文献   

15.
Finely divided solids can stabilize emulsion droplets provided the solids are partially wetted by both the disperse liquid phase and the continuous liquid phase. The stabilisation of oil/water emulsions by finely divided solids in the presence of suitable organics has been related to the three phase (solid/oil/water) contact line. Schulman and Leja (1954a) and Taubman and Koretskii (1965) provide evidence that O/W emulsions are formed when the contact angle is less than 90° but inversion occurs to W/O emulsions when the contact angle exceeds 90°. We present a thermodynamic study of emulsion stabilization by finely divided solids, which is an extension of an earlier theory by Van der Minne (1928) who neglected interactions among the particles and droplets and also entropy effects due to Brownian motion. Only stable W/O emulsions are considered here. The starting point of the theory is an expression for the Helmholtz free energy associated with the oil/water interfaces stabilized by finely divided solids in the presence of surfactants. By minimising this free energy, it is shown that in a stable emulsion almost all the solid particles are adsorbed at the oil/water interface of the oil drops. This accounts for the experimental result that the average size of oil droplets decreases with increase in the concentration of solids. A particular example of emulsion stabilization by solids occurs in the hot water extraction process on the Athabasca oil sands. Both clay particles and anionic surfactants act as stabilizers of the bitumen droplets suspended in an aqueous alkaline environment.  相似文献   

16.
Upon adsorption at the oil/water interface, asphaltenes slowly form a glassy interphase. This robust, asphaltene-rich interphase is likely the reason for prolonged stability of crude oil/water emulsions and for the propensity of asphaltenic crude oils to alter the wettability of reservoirs. Here we adopt interfacial dilatation rheology using the oscillating pendant drop with axisymmetric drop shape analysis (ADSA) to investigate the relaxation mechanisms of asphaltenes adsorbed at the toluene/water interface. We compare classical viscoelastic models with the measured rheologic data and find that the frequency response of the dilatational moduli fits a combination of diffusion-exchange and surface-rearrangement mechanisms. The combined relaxation model is verified by solvent washing the asphaltenes from the interface and measuring the dilatational response of the resulting irreversibly adsorbed species. After washout, the oil-phase diffusion component of the frequency response disappears, and the relaxation time of the adsorbed film increases by an order of magnitude. Since the studied asphaltenes prove insoluble in the synthetic aqueous brine (pH?=?8.0), this result suggests that reversibly exchanging species in the oil phase weakens an interconnected asphaltene-gel/glass phase at the interface. Our experiments show, for the first time, that most of the surface-active asphaltenic molecules are irreversibly adsorbed from the oil phase.  相似文献   

17.
Dilational rheology method was used to study the interfacial rheology properties of Branch‐Preformed Particle Gel (PPG) and its interaction with Shengli crude oil fractions at the kerosene/water interface. The results showed that the interfacial dilational modulus increased monotonously with increasing PPG concentration, the high values of the modulus could be due to the formation of multilayer near the interface. Study on the interaction between PPG and crude oil components showed that different crude oil components have different interactions with PPG molecules at the oil/water interface. The acidic components can adsorb onto the interface and form mixed adsorption film by replacing the PPG molecules at the interface because of their smaller molecular size and stronger interfacial activity, which results in a dramatic reduction in dilational modulus, while asphaltenes have little effect on the dilational rheological behavior of PPG solution due to their lager molecular sizes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41337.  相似文献   

18.
Conventional emulsions are mostly stabilized by surfactants and for stabilization of oil-in-water emulsions the surfactants should be hydrophilic or with HLB numbers larger than seven. In this work, we report that edible oil-in-water emulsions can also be stabilized by surfactants with an HLB value close to seven. With edible sucrose ester C-1807 (HLB no. = 7) as emulsifier and three edible oils (canola oil, olive oil, soybean oil), edible oil-in-water emulsions can be stabilized by C-1807 at concentrations beyond its critical aggregation concentration (CAC). Although monomeric C-1807 behaves as an inferior emulsifier, they assemble to form multilamellar vesicles in water at concentrations higher than the CAC giving a viscoelastic/gel-like aqueous phase which is partly responsible for emulsion stabilization. Specifically, at 2 wt%, high internal phase emulsions (HIPEs) with ϕo = 0.75 can be obtained, which are stable against cooling–heating cycles between 5 and 30°C during storage. The vesicles disperse in the aqueous lamellae surrounding the oil droplets, which together with the viscoelastic/gel-like continuous phase prevents them from flocculation and coalescence.  相似文献   

19.
与传统表面活性剂稳定的乳液相比,固体纳米颗粒稳定的Pickering乳液具有较强的界面稳定性、多功能性、低毒性等优势,在生物医药领域具有较大的应用潜力。而相较于尺寸较大的微米级Pickering乳液,亚微米Pickering乳液具有更大的比表面积、更有效的递送效率,有望进一步拓展Pickering乳液在生物医药领域的应用。但由于Pickering乳液的制备影响因素众多,且相互制约,刚性的固体颗粒难以在较小的有限油水界面排布,增加了亚微米Pickering乳液的制备难度。本工作以制备稳定的亚微米Pickering乳液为研究目标,采用具有良好生物相容性的天然多糖–纤维素纳米晶(CNCs)为颗粒乳化剂,角鲨烯作为油相,考察了颗粒浓度、油水比例、水相成分、超声时间及频率对Pickering乳液粒径分布及稳定性的影响,最终得到了具有良好的储存稳定性和抗离心稳定性的粒径为638.7?8.40 nm的亚微米Pickering乳液(CNCs-PE)。通过激光共聚焦显微镜证实了CNCs吸附在油水界面,形成了Pickering乳液结构。利用CCK-8法评价了CNCs和CNCs-PE的细胞毒性,结果表明,两者都具有良好的细胞安全性。此外,将其用于吸附模型抗原OVA,吸附率达到约80%,且肌肉注射部位的切片结果也表明其注射安全性良好。此结果为亚微米Pickering乳液进一步研究提供了参考,并有望拓展CNCs稳定的亚微米Pickering乳液在生物医药领域的应用。  相似文献   

20.
A large number of processes are used to treat the oily water (oil emulsions in water) produced in the petroleum industry. The treatment strategy depends not only on the strictness of the environmental requirements in the jurisdiction where the water is discharged, but also on the relative treatment cost. The present study reports tests to assess the effectiveness of removing oil from oily water by adsorption in polymer nanocomposites. These composites were prepared from ionenes (cationic polyelectrolytes) and sodium bentonite or organophilic bentonite. They were characterized by infrared spectrometry, thermogravimetry, X‐ray fluorescence, and X‐ray diffraction. The oil‐removal effectiveness was evaluated by mixing nanocomposites and oily water in a shaker bath (batch test). In the tests conducted only with treated sodium bentonite and organophilic bentonite, the oil removal was ~ 70%, whereas the use of polymer nanocomposites raised the adsorption of oil to ~ 90%. These values depended on the mass of material, concentration of oil in the contaminated water, and the contact time. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

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