Nonpolar Oil Research Articles

Turning Low-Cost Filter Papers to Highly Efficient Membranes for Oil/Water Separation by Atomic-Layer-Deposition-Enabled Hydrophobization

It remains a great challenge for the simple and affordable production of membranes for oil/water separation. We prepare low-cost but highly efficient paper-based membranes for oil/water separation through hydrophobic modification to filter papers. The simple modification contains only two steps: a thin layer of aluminum oxide is first coated on the surface of the filter paper by atomic layer deposition, and silane molecules are subsequently coupled on the precoated aluminum oxide layer via their reaction with hydroxyl groups on the surface. Both the alumina layer and the silanization layer are very thin with a total thickness less than 10 nm. The modified filter paper is endowed with strong hydrophobicity and oleophilicity, therefore exhibits strongly retarded permeation to water and enhanced permeation to nonpolar oils. The modified filter paper is demonstrated to show excellent separation efficiencies greater than 90% in the separation of various types of oils and organic solvents from their mixtures wi...

Anisotropic mobility of particles near the interface of two immiscible liquids

Three-dimensional mobility of colloidal particles in the close vicinity of a liquid-liquid interface is experimentally quantified and compared with established theories. Evanescent wave-based particle tracking velocimetry is used to measure the Brownian motion of fluorescent spheres near an interface between water and non-polar oil. The experimental results confirm that the mobility of particles suspended in the less viscous liquid is anisotropically suppressed. The measured hindered mobility are in agreement with theoretical models.

Controlling the surface charge of water droplets in non-polar oils

We show that the surface charge and, hence, the electrophoretic mobility of water droplets dispersed in non-polar oils can be adjusted in magnitude and sign through the addition of ionic surfactants. The positive, native charge of water-in-oil droplets is reduced by increasing the concentration of the anionic surfactant SDS in the water. At high enough SDS concentration, the droplet charge becomes negative. This mechanism works with, both, silicone as well as paraffin oils and is limited by the critical micelle concentration of SDS in water, at which the interface is saturated by the surfactant. Direct, physical contact-charging of water droplets at biased electrodes, however, overrides any charge due to chemical species at the water–oil interface and confers an overall charge of the same sign as the electrode potential to the droplets. The possibility to easily adjust the droplet charge by chemical as well as physical means permits flexible electrophoretic manipulation in microfluidic devices.

Synthesis and interfacial properties of ethoxylated cationic surfactants derived from n-dodecyl glycidyl ether

In this study, cationic surfactants were synthesized to improve solubility in water by adding ethylene oxide as a hydrophilic group to the intermediates of di-hydroxyl cationic surfactant molecules. The structure of resulting product was elucidated by 1H NMR, FT-IR and HR/MS. The CMCs of BA-2-MA and BA-5-MA surfactants were found to be 9.01×10−4 and 4.92×10−3mol/L respectively and the surface tensions at their CMC conditions were 28.64 and 32.22mN/m respectively. The interfacial tensions measured between 1wt% surfactant solution and n-decane were found to be in the same order of magnitude as those exhibited between micellar solutions and nonpolar oils.

Durable superoleophobic fabric surfaces with counterintuitive superwettability for polar solvents

SignificanceSmart superoleophobic (SOP) cotton fabric surfaces are created only through a controlled fluorosilanization treatment, exhibiting the first‐ever extreme wetting behaviors displaying ultrarepellency to nonpolar oils and counterintuitive superwettability for all polar solvents. The smart durable SOP surfaces, demonstrated chemically, thermally, and mechanically, render great potential practical and industrial applications in robust oil shielding, effective antifouling, highly energy efficient self‐cleaning, and solely gravity‐driven oil–water separations. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2752–2756, 2014

HYDROPHOBIC AGGLOMERATION OF MINERAL FINES IN AQUEOUS SUSPENSIONS AND ITS APPLICATION IN FLOTATION: A REVIEW

Hydrophobic agglomeration is originated from the hydrophobic attraction between particles, which is essentially different from electrolyte coagulation and polymer flocculation. It is applied to mineral processing in floc-flotation process to improve the recovery of mineral fines. In this paper, the applications of this phenomenon in mineral fines were summarized, including the origin of hydrophobic agglomeration, the main factors affect hydrophobic agglomeration (particle hydrophobicity, shear rate and duration, nonpolar oil and tank geometry), as well as hydrophobic agglomeration based separation processes (carrier flotation and floc-flotation).

Stabilization of thin liquid films by repulsive van der Waals force.

Using high-speed video recording of bubble rise experiments, we study the stability of thin liquid films trapped between a rising bubble and a surfactant-free liquid-liquid meniscus interface. Using different combinations of nonpolar oils and water that are all immiscible, we investigate the extent to which film stability can be predicted by attractive and repulsive van der Waals (vdW) interactions that are indicated by the relative magnitude of the refractive indices of the liquid combinations, for example, water (refractive index, n = 1.33), perfluorohexane (n = 1.23), and tetradecane (n = 1.43). We show that, when the film-forming phase was oil (perfluorohexane or tetradecane), the stability of the film could always be predicted from the sign of the vdW interaction, with a repulsive vdW force resulting in a stable film and an attractive vdW force resulting in film rupture. However, if aqueous electrolyte is the film-forming bulk phase between the rising air bubble and the upper oil phase, the film always ruptured, even when a repulsive vdW interaction was predicted. We interpret these results as supporting the hypothesis that a short-ranged hydrophobic attraction determines the stability of the thin water film formed between an air phase and a nonpolar oil phase.

Fluorescence Behavior of Single Guest Molecules in Nonpolar Oil Droplets Covered with Stabilizing Surfactants

By using confocal and wide-field microscopic techniques we have investigated fluorescence behaviors of a single perylenediimide derivative, N,N′-dipropyl-1,6,7,12-tetrakis(4-tert-butylphenoxy)-3,4,9,10-perylenetetracarboxydiimide (BP-PDI), in ca. 200–300 nm sized droplets of n-octane covered with surfactant molecules. The guest dye did not show distinguishable blinking in the droplets prepared with a nonionic surfactant, Triton X-100, while frequent blinking was observed in the droplets with a cationic surfactant, trimethylstearylammonium chloride (STAC). The survival time of the guest dye before the permanent photodegradation was much longer in the droplets with Triton X-100 than those with STAC. On the basis of the analysis with a model assuming the transition from the S1 state to the dark state (DS) and the permanent photodegradation during the dark state, it was deduced that the probability of the transition from the S1 state to the DS in the droplet with STAC, 7.2 × 10–6, was significantly larger than that with Triton X-100, 1.1 × 10–6. On the other hand, the probability of the photodegradation during the dark state was comparable between these two systems. These results indicate that the probability of transition from the S1 state to the DS essentially dominates the survival time of the guest dyes. Fluorescence polarization measurements also revealed that guest dyes frequently stay in the vicinity of polar interface in the droplets prepared with STAC.

Investigation of molecular partitioning between non polar oil droplets and aqueous solution using double potential step chronoamperometry

Double potential step chronoamperometry (DPSC) is demonstrated as a technique for investigating partitioning between a solute in aqueous solution and non-polar oil droplet(s) immobilised at an electrode. Here a species in aqueous solution which does not partition into the oil phase is converted at the electrode surface into another species which either does not or does partition into the oil drop. The first case is investigated experimentally by considering generation of the ionic redox species, FcTMA(2+) from FcTMA(+), while the second case is exemplified by studies of Br2 generation from Br(-). The case of molecular partitioning at the three phase interface has received little attention hitherto. To maintain oil droplet stability a boron-doped diamond electrode is employed functionalised with Pt nanoparticles to impart electrocatalytic activity on the electrode towards Br2 production. An arrangement is utilised where the droplet(s) sit(s) on (but does not cover) the electrode surface. We show both experimentally and through finite element simulation how the charge-time profile for the generation and collection of electroactive species can be used to obtain information on the extent of partitioning and how this is affected by factors such as the number and size of droplets. Finally, we highlight the suitability of this approach for investigating reactions which take place within the droplet.

The wetting of steel, DLC coatings, ceramics and polymers with oils and water: The importance and correlations of surface energy, surface tension, contact angle and spreading

The importance of wetting is becoming increasingly obvious and its control is inevitable in many engineering applications, including tribology and interface nanotechnology. However, the relations between the key parameters affecting surface–liquid wetting behaviour under realistic conditions are not very well understood, especially for typical engineering materials and lubricants (oils), often leading to exceptions and contradictions, which impede their use in engineering models and theories, and so the possible optimisation of the interfaces of engineering systems. In this paper we present the correlations between the contact angle, the spreading, the surface tension and the surface energy of fourteen frequently used engineering materials belonging to four different classes of materials (steel, DLC coatings, ceramics, and polymers) wetted with four different liquids: three oils (a non-polar synthetic oil of two different viscosities and a polar natural-based oil) and water. The results represent systematically and consistently obtained data about the wetting-relevant parameters of the selected materials and lubricants and numerous correlations between them. However, the most striking result suggests that the spreading parameter correlates very linearly with the surface energy for all the materials and liquids studied, in both the adhesion-wetting and spreading-wetting regimes. The experimentally determined spreading vs. surface energy correlation functions that appear generally valid for a broad range of properties of the materials and oils can thus be applied as an engineering tool to tailor and design the required/desired wetting performance and nature of the solid–liquid interfaces. The spreading parameter SP – in contrast to the contact angle – was found to be a reliable and relevant parameter for describing the wetting of oils with selected engineering materials.

Lubrication Mechanism of Phosphonium Phosphate Ionic Liquid Additive in Alkylborane–Imidazole Complexes

The assessment of ionic liquids (ILs) as lubricants in several tribological systems has shown their ability to provide remarkable reduced friction and protection against wear, whether they are used as additives or in the neat form. However, their corrosion and limited solubility in non-polar hydrocarbon oils represent the bottleneck-limiting factors for the use of ILs as lubricants. Therefore, in order to tackle these problems, mixtures of alkylborane–imidazole complexes with one halogen-free IL as additive were used in this study. The knowledge of the additive–surface interactions and hence the understanding of tribological properties are an important issue for lubricant formulations and were also investigated in this work. Thus, combination effects between two ionic liquid additives, a halogenated and a halogen-free one, were evaluated by a ball-on-disc-type tribometer under boundary lubrication conditions. Effective friction reduction and anti-wear properties have been demonstrated in tribological investigations when adding between 0.7 and 3.4 wt% of the halogen-free IL into base fluid composed of alkylborane–imidazole complexes. X-ray photoelectron spectroscopy analyses of the steel specimens were conducted to study the correlation between tribological properties and chemical surface composition of the boundary films formed on the rubbing surface. This work suggests potential applications for using halogen-free ILs as additives for synthetic ionic liquid lubricants.

Ionic Liquids as Antiwear Additives in Base Oils: Influence of Structure on Miscibility and Antiwear Performance for Steel on Aluminum

The use of ionic liquids as additives to base oil for the lubrication of steel on aluminum was investigated. The miscibility and wear performance of various phosphonium, imidazolium, and pyrrolidinium ionic liquids in a range of polar and nonpolar base oils was determined. The structure and ion pairing of the ionic liquids was found to be important in determining their miscibility in the base oils. In wear tests, some of the miscible base oil/IL blends reduced the aluminum wear depth when compared to that found with the base oil alone. The nonpolar base oil/IL blends were able to withstand higher wear-test loads than the polar base oil/IL blends. At 10 N, as little as 0.01 mol/kg of IL, or 0.7-0.9 wt %, in the nonpolar base oils was enough to drastically reduce the wear depth on the aluminum. XPS analysis of the wear surfaces suggested that the adsorbing of the IL to the surface, where it can form low-shear layers and also react to form tribofilms, is important in reducing friction and wear. The largest reductions in wear at the highest load tested were found for a mineral oil/P6,6,6,14 (i)(C8)2PO2 blend.

Damages on the lubricated surfaces in bearings under the influence of weak electrical currents

A special bearing tester was constructed to investigate the damage behavior on the lubricated surfaces in bearings with the passage of weak electrical currents as low as ∼1 mA. The results showed that when polar glycerine was used as the lubricant, many narrow and deep pits formed on the lubricated surfaces. In contrast, when the experimental conditions under the lubrication of the nonpolar paraffin oil were close to those under the lubrication of polar glycerine oil, damages on the lubricated surfaces were unobvious. Emergence of microbubbles in polar lubricants with the passage of electrical currents was proposed to be responsible for the observed damages on the lubricated surfaces.

Charge of water droplets in non-polar oils

Recent advances in droplet manipulation methods by electric fields and signals require a deeper understanding of water droplet charge. In this paper, we have investigated the electrophoretic motion of individual water microdroplets injected into non-polar silicone and paraffin oil by video optical microscopy on an individual droplet basis to determine droplet charge. It was found that the initial surface charge density of surfactant free droplets directly after injection from a micropipette is positive and of the order of 10−6 C/m2, regardless of pH and ion concentration in the range from pH 4 to pH 10 and from 0.01 mmol/l to 1.5 mol/l, respectively. The experimental results together with molecular dynamics simulations show that the nature and polarity of the charge can be explained by anisotropic orientation of water molecules at the interface rather than selective adsorption of ions. Furthermore, we showed that slip at the liquid-liquid boundary must be taken into account when interpreting electrophoretic measurements of droplets.

Study on Drainage Oil to Prepare Collectors of Coal Flotation

At present, kerosene is one of the most widely used non-polar hydrocarbon oil collector agent in coal flotation in China, kerosene is difficult to dissolve in water, with good collector, but the dosage is comparatively large in the actual production.The drainage oil is from the dining recycled goods and the waste of animal flesh, can be used for preparation of fatty acid collector, which not only to reduce environmental pollution,but also to reduce the risk of food safety. At the same time, if drainage oil can replace the kerosene in coal collection, it will improve the coal preparation plant efficiency and solve the problem of shortage of national resources. In this study, we use Huangling coal as raw material for flotation experiment, use kerosene, diesel, drainage oil and emulsified drainage oil as collectors. Adding different collectors in the same flotation conditions to research the yield of clean coal, the clean coal ash and the yield of tailings by changing the dosage of collectors. The results show when adding to OP emulsifier and the proportion of water and oil is 6:4, flotation effects is the best, the yield of clean coal is 88.67%, the ash of clean coal is from 9.16% down to 8.63%, the yield of tailings is 11.32% .

Characterization of Optical Properties in Water-in-Oil Emulsion

There have been few studies on the factors that determine the overall appearance of emulsions. Optical properties are quite important in determining the perceived quality of emulsion-based products. The overall appearance of an emulsion is determined by the way that it interacts with electromagnetic radiation in the visible region of the spectrum, for example, reflection, transmission, adsorption, and scattering. These interactions are principally determined by the characteristics of emulsion droplets (size, concentration, and refractive index). The present study aims at characterizing the optical properties and rheological behaviors of water-in-oil emulsions, especially macroemulsions. There is a decrease in the absorbance spectra as increasing glycerin ratio in aqueous phase because the difference of refractive index between oil phase and aqueous phase decreased, which improved the transparency of water-in-oil emulsion. The absorbance of linear and branched surfactant emulsions were smaller than that of alkyl modified branched surfactant emulsion. Moreover the transparency of emulsions prepared with linear and branched surfactants was much clearer than that of alkyl modified branched surfactant emulsion. The absorbance spectra also showed that low polar oil attributed to the more transparent emulsion, compared with high polar or nonpolar oil. However, these kinds of oils were not helpful to prepare transparent emulsion because the appearance of these emulsions was translucent or opaque, even if polyols in aqueous phase was 30 wt%.

A Study on the Stability of Emulsion by Polyglycerol Ester

Experiments of emulsion particles state of using polyglycerol ester emulsifier and the stability in accordance with the change of time were conducted using several oil. Experimental results confirmed that there is little difference in the stability and particle size depending on the type of oil. Most stable oil with polyglycerol ester is polar oil of silicon series and fatty acid ester oil, hydrocarbon oil of the nonpolar oil (Mineral oil, squalane, polydecene) was the most unstable state. And vegetable oils showed the stable form of particles with polyglycerol ester emulsifier.

A Review of Ionic Liquid Lubricants

Due to ever increasing demands on lubricants, such as increased service intervals, reduced volumes and reduced emissions, there is a need to develop new lubricants and improved wear additives. Ionic liquids (ILs) are room temperature molten salts that have recently been shown to offer many advantages in this area. The application of ILs as lubricants in a diverse range of systems has found that these materials can show remarkable protection against wear and significantly reduce friction in the neat state. Recently, some researchers have shown that a small family of ILs can also be incorporated into non-polar base oils, replacing traditional anti-wear additives, with excellent performance of the neat IL being maintained. ILs consist of large asymmetrical ions that may readily adsorb onto a metal surface and produce a thin, protective film under boundary lubrication conditions. Under extreme pressure conditions, certain IL compounds can also react to form a protective tribofilm, in particular when fluorine, phosphorus or boron atoms are present in the constituent ions.

Polyurethane-based nanoparticles as stabilizers for oil-in-water or water-in-oil Pickering emulsions

Well-defined polyurethane (PU)-based grafted copolymers with poly(2-(dimethylamino)ethyl methacrylate) (PDEM) side chains were prepared by a combination of radical polymerization and condensation reaction. They can self-assemble in water to form nanoparticles with PU as the core and hydrophilic PDEM chains as the shell. Tuning the pH value of the solutions allowed these nanoparticles to stabilize either oil-in-water (O/W) or water-in-oil (W/O) Pickering emulsions. Stable O/W emulsions were obtained with PU-based nanoparticles in the pH 3–5 or pH 11–12 range due to their better affinity to the aqueous phase. In contrast, changing the pH value to the range of 8–9 significantly changed the stabilizing behavior of the nanoparticles, leading to the formation of stable W/O emulsions. Additionally, the effect of oil polarity on the emulsification behavior of the PU-based nanoparticles was investigated. For highly non-polar oil like n-hexane, only O/W emulsions were generated and the resulting emulsions showed no response to pH change.

보조계면활성제가 노닐페놀 에톡실레이트 계면활성제, 탄화수소 오일, 물로 이루어진 삼성분계의 상평형 및 동적거동에 미치는 영향

본 연구에서는 보조계면활성제 첨가가 nonylphenol ethoxylate (NP) 계면활성제, 물, 탄화수소 오일의 3성분으로 이루어진 시스템의 평형 및 동적 거동에 미치는 영향을 살펴보았다. 실험에서 사용한 펜탄올, 옥탄올, 데칸올 등의 보조계면활성제는 모두 소수성 첨가제로 작용하였으며, 소수성 증가 효과는 알코올의 사슬 길이 증가 및 첨가량 증가에 따라 증가하였다. 계면활성제 시스템이 친수적인 조건에서는 비극성 오일의 종류에 상관없이 시간에 따라 오일의 크기가 감소하였으며, 마이셀 용액에 의한 탄화수소 오일의 가용화는 diffusion-controlled 메커니즘이 아닌, interface-controlled 메커니즘을 따름을 확인할 수 있었다. 반면에 소수성 조건에서는 과포화로 인하여 일어나는 자발적 유화 현상과 물과 계면활성제의 오일상으로의 확산으로 인한 오일의 크기 증가가 관찰되었다. 비극성 탄화수소 오일과 계면활성제 수용액 사이의 시간에 따른 계면장력 측정 결과는 동적 거동 실험결과와 일치하는 경향을 나타내었다. 한편 middle-phase 마이크로에멀젼을 포함한 3상이 형성되는 조건에서는 매우 낮은 계면장력으로 인하여 오일이 수용액 상에 빠른 속도로 가용화되었고 작은 방울 형태로 유화되었다. In this study, the effects of cosurfactant on phase equilibrium and dynamic behavior were studied in systems containing nonylphenol ethoxylate (NP) surfactant solutions and nonpolar hydrocarbon oils. All the cosurfactants used during this study such as n-pentanol, n-octanol and n-decanol acted as a hydrophobic additive and the hydrophobic effect was found to increase with both increases in chain length and amount of addition of a cosurfactant. Dynamic behavior studies under hydrophilic conditions showed that the solubilization of hydrocarbon oil by NP micellar solution is controlled by an interface-controlled mechanism rather than a diffusion-controlled mechanism. Both spontaneous emulsification of water into oil phase and expansion of oil drop were observed under lipophilic conditions because of diffusion of surfactant and water into oil phase. Under conditions of a three phase region including a middle-phase microemulsion, both rapid solubilization and emulsification of oil into aqueous solutions were found mainly due to the existence of ultralow interfacial tension.