Nonpolar Oil Research Articles

Tribological properties and lubrication mechanism of manganese phosphate trihydrate as lubricant additives

A deeper insight into two interacting frictional surfaces in nanosized spaces, especially the molecular groups at interfaces is considered to be important to friction reduction. In this paper, we report Mn3(PO4)2·3 H2O (MnP) nanosheets with loosely packed structure and high porosity as oil-base additives that can achieve good dispersion in oil because of their adsorption with strong capillary effect. Lubrication with MnP additives for titanium alloy, the average friction coefficient (COF) and wear rate (WR) can be reduced by 66.81 % and 98.78 %, respectively. It was confirmed that the extraordinary friction-reducing property was due to the solid-liquid interface with Coulomb repulsion between polar groups on MnP nanosheet and non-polar oil molecules, which resulted in a slip surface with low viscous shear force. The shear force of this solid-liquid interface was correlated with the different oxygen contents and the viscosity of lubricating oil, which showed different intermolecular forces. Additionally, any connectivity between this solid-liquid interface would increase the adhesion, for example, hydrogen bondings and dispersant. Our results establish a lubrication interface with Coulomb repulsion that can improve the tribological behavior of lubricating oil.

Effect of oil carboxylate hydrophobicity on calcite wettability and its reversal by cationic surfactants: An experimental and molecular dynamics simulation investigation

The oil-wet state of carbonate reservoirs presents a serious challenge for oil recovery. While cationic surfactants are able to reverse the wettability, their efficiency depends on the oil composition, particularly on the carboxylates as the main surface-active compounds. In this study, calcite surface was aged by two distinct carboxylates: a shorter, less hydrophobic octanoate and a more hydrophobic stearate. The surface wettability and its reversal by a quaternary ammonium cationic surfactant were studied both experimentally by contact angle measurements and Scanning Electron Microscopy (SEM) imaging, and by molecular dynamics (MD) simulations. Both simulations and experiments show that aging with the more hydrophobic stearates yields more strongly oil-wet surfaces, whose wettability is more difficult to reverse by the cationic surfactant, than aging with octanoates. While the surfactant ultimately reverses the wettability in both cases, significantly higher surfactant concentration is required for the stearate-aged calcite. The difference in the wettability can be rationalized by the greater hydrophobicity of the stearate, which strengthens both the surface adsorption and attraction of the non-polar oil phase.

Electrochemistry in bicontinuous microemulsions derived from two immiscible electrolyte solutions for a membrane-free redox flow battery

HypothesesBicontinuous microemulsions (BMEs) have attracted attention as unique heterogeneous mixture for electrochemistry. An interface between two immiscible electrolyte solutions (ITIES) is an electrochemical system that straddles the interface between a saline and an organic solvent with a lipophilic electrolyte. Although most BMEs have been reported with nonpolar oils, such as toluene and fatty acids, it should be possible to construct a sponge-like three-dimensionally expanded ITIES comprising a BME phase. ExperimentsDichloromethane (DCM)–water microemulsions stabilized by a surfactant were investigated in terms of the concentrations of co-surfactants and hydrophilic/lipophilic salts. A Winsor III microemulsion three-layer system, consisting of an upper saline phase, a middle BME phase, and a lower DCM phase, was prepared, and electrochemistry was conducted in each phase. FindingsWe found the conditions for ITIES-BME phases. Regardless of where the three electrodes were placed in the macroscopically heterogeneous three-layer system, electrochemistry was possible, as in a homogeneous electrolyte solution. This indicates that the anodic and cathodic reactions can be divided into two immiscible solution phases. A redox flow battery comprising a three-layer system with a BME as the middle phase was demonstrated, paving the way for applications such as electrolysis synthesis and secondary batteries.

Effects of Polarity of Polymers on Conformation and Lubricating Film Formation of Adsorbed Films

The conformations and lubricating film formation ability of adsorbed films on metal surfaces formed by poly(alkyl methacrylate) (PAMA) homopolymers with different polarities from nonpolar lubricant oil were investigated. It was found that as the polarity of the polymers became higher, the chains in the adsorbed films adsorbed more loosely to the surfaces (i.e., they formed more loops and tails). The loosely adsorbed chains temporarily trapped free polymer chains flowing into the gap between sliding surfaces, resulting in a much thicker lubricating film. Thus, the sliding surfaces were better protected from wear caused by direct contact. On the other hand, flattened chains occupying in the adsorbed film formed by low polarity-polymers could not trap free polymer chains, resulting in a thinner lubricating film.

Nitrogen-Doped Carbon Dot as a Lubricant Additive in Polar and Non-polar Oils for Superior Tribological Properties via Condensation Reaction.

Nitrogen-doped lubricating additives have been proved to be an effective strategy to improve the tribological properties of lubricating oil. However, the traditional preparation methods of nitrogen-doped lubricating additives have the defects including harsh preparation conditions and a time-consuming preparation process. Herein, we report a preparation method of nitrogen-doped carbon dot (NCD) lubricating additives in a short time by one-step aldehyde condensation reaction at room temperature. The small size effect and nitrogen-containing functional groups of NCD lubricating additives provide favorable conditions for their dispersion and low friction in base oil. The tribological properties of NCD lubricating additives in sunflower oil (SFO) and PAO10 were systematically evaluated. The results show that NCD lubricating additives could reduce the average friction coefficient of SFO from 0.15 to 0.06 and PAO10 oil from 0.12 to 0.06, and the wear width is also decreased by 50-60%. In particular, the friction curve is very stable, and the friction coefficient was maintained at about 0.06 even under the working time of 5 h. By analyzing the morphology and chemical properties of the worn surface, the lubrication effect of NCDs is attributed to its small size effect and adsorption, which was easy to enter the friction gap to fill and repair. Furthermore, the doping of nitrogen induces the occurrence of friction chemical reactions, forming a friction film of nitrides and metal oxides at the friction interface, which effectively reduces the friction and wear of the surface. These findings provide a possibility for the convenient and effective preparation of NCD lubricating additives.

Potential larvicidal bioefficacy of copper sulfide-based hybrid nanoemulsions of eucalyptus oil against Aedes aegypti (Linnaeus).

Nanotechnology, an emerging field, has acquired considerable attention for the control of vectors. The present study aimed to synthesize, characterize copper sulfide- and eucalyptus oil-based hybrid nanoemulsions and investigate their larvicidal potential against Aedes aegypti by studying larvicidal bioassay, morphological aberrations, histopathological alterations, biochemical analysis and evaluation of risk assessment in non-target organisms. Hybrid nanoemulsions were prepared by mixing aqueous copper sulfide nanoparticles (CuSNPs) with non-polar eucalyptus oil in five ratios (1:1, 1:2, 1:3, 1:4 and 1:5) by sonication, screened and characterized using Transmission electron microscopy (TEM). Larvicidal activity was recorded and toxicity values were calculated by log-probit method. Morphological, histological and biochemical changes were examined in Aedes aegypti larvae after treatment. Nanohybrids were also tested under simulated conditions and against non-target organism. The nanohybrid ratio of 1:5 was found to be stable after thermodynamic stability tests. TEM studies revealed average size of 90±7.90 nm with globular shape. LC50 and LC90 toxicity values of prepared CuSNPs were calculated out to be 5.00 and 5.81ppm after 24 hours treatment. Effective concentration of prepared nanohybrid (6.5ppm) tested under simulated conditions showed maximum larvicidal mortality after 48 hours of exposure. No toxicity towards the Mesocyclops spp. was observed after treatment of these nanohybrids even up to 21 days. Copper sulfide based hybrid nanoemulsions were found to show efficient larvicidal property which can be used for the formulation of ecofriendly bio-larvicide against Aedes aegypti.

Macroscale superlubricity by a sacrificial carbon nanotube coating

Superlubricity, i.e., coefficient of friction (COF) below 0.01, was earlier limited to microscale in controlled environments in the earlier literature and more recently realized for macroscale sliding of ceramic or carbon surfaces lubricated by water or other polar fluids. However, there is lack of report of superlubricity for the most common bearing system, i.e., steel-steel contact in non-polar oil lubrication. Here we present ultra-low COF of 0.001–0.007 by using a sacrificial coating composed of vertically-aligned carbon nanotubes (CNTs) for macroscale steel-steel sliding under minimum quantity lubrication (MQL) of a polyalphaolefin (PAO) oil in the ambient environment. Raman spectroscopy and electron microscopy analyses detected graphene-containing tribofilms on both the steel surfaces, which was produced by the fractured CNT flakes and metallic wear debris during running-in. The in situ formed graphene-graphene contact interface presumably possesses a low shear resistance leading to superlubricity. The presence of oil, despite as little as one droplet, has proven to be crucial. Such a superlubricity performance has shown good sustainability in extended testing of more than 500,000 cycles and strong ability of accommodating changes in sliding conditions. Results here demonstrate feasibility with fundamental insights for achieving ambient environment macroscale superlubricity.

Synergistic Lubrication for Textured Surfaces Using Polar and Nonpolar Lubricants

Abstract The synergistic effect of surface texturing and lubricants with various viscosity and polarity properties is an attractive and unexplored topic. In this study, surface texturing characterized by circular dimples has been manufactured on steel surfaces in advance, which can improve the lubrication of frictional units compared with the bare disc under different lubricants. Then, three lubricants, low-viscosity and nonpolar white oil, high viscosity and nonpolar silicone oil, and highly viscous and polar castor oil, were used to evaluate the interaction between surface texture and the lubricating oil. The contact angles of each lubricant on the textured and bare surface were measured to investigate the lubricant intermolecular force and wettability. The oil film thickness simulation and tribological experiments were conducted. The tribological results indicate that lubricants with varied characteristics work differently due to their different properties on textured surfaces. Castor oil exhibits the best tribological properties of the three oils used to supply the textured surfaces, which may attribute to its ability to generate strong boundary adsorption films as well as a thickened interfacial layer, and it could reduce the intensity of asperity interaction.

Enzymatic demulsification of long-chain alkanoylcholine-based oil-in-water emulsions and microemulsions

Long-chain alkanoylcholines (LCAC) are potential candidates to limit viruses’ transmission and suitable substrates of butyrylcholinesterase (BChE) to be hydrolyzed. Thus, BChE-catalyzed LCAC hydrolysis is expected to be a safer and greener demulsification strategy in demulsifying LCAC-based emulsions and/or microemulsions. Myristoylcholine bromide (MCB)-based oil-in-water (O/W) emulsions with different oils, from hydrocarbon nonpolar oil (octane and D80) to ester-containing polar oil (jojoba oil and edible oil) as well as the complex oily mixture (crude oil), were constructed. MCB-based microemulsions were constructed by pseudo-ternary phase diagram method. The BChE-catalyzed hydrolysis of MCB was monitored by using of two-phase titration. MCB-based O/W type emulsions and microemulsion can be actively demulsified by using of BChE under mild conditions of pH = 7.4 and 37 °C. No lethal adverse effect of the oil type on the BChE-catalyzed hydrolysis of MCB was observed in demulsifying emulsions. BChE can be reused and presented an excellent reusability over five times of recycling, clarifying a promising prospect of this enzymatic demulsification strategy in the treatment of LCAC-emulsified wastewater.

Linear alkyl-benzenesulfonate-based protic ionic liquids: Physicochemical properties and tribological performance as lubricant additives to a non-polar base oil

• Two new families of protic ionic liquids were synthesized, characterized, and studied as additives to a non-polar oil. • The presence of any protic ionic liquid in the non-polar oil reduced friction and wear of steel disk. • The improved lubrication performance is attributed to an oxygen-rich tribolayer on steel surfaces. Advanced additives are crucial to improve the tribological performance of the base lubricants. A series of protic ionic liquids (PILs) derived from linear alkyl-benzenesulfonic acids with different alkyl chain length, and alkanol amines with different basicity were easily synthesized in the laboratory. The molecular structures of the PILs were established through proton magnetic resonance and Fourier transform infrared spectroscopy. Their thermal behavior was evaluated by differential scanning calorimetry and thermogravimetric analysis. The sliding wear and frictional performance of the PILs used as additives to mineral oil were studied by using a reciprocating ball-on-flat tribometer in a steel-steel contact. The solubility and stability of the PILs were also examined and related to their frictional behaviors. The worn steel surfaces were characterized by a non-contact profilometer, scanning electron microscope, energy-dispersive X-ray spectroscope and Raman microscope. The results showed that all PILs improved the lubricity of mineral oil with the concentration of only 1 wt%. The friction-reducing and anti-wear capacities of these PILs as additives were analyzed and discussed from their structures (different cations associated with anion moieties in different alkyl chain length) and the formed tribo-films.

Solvation CoMFA-QSTR and CoMSIA-QSTR Models for Predicting the Antiwear Properties of Lubricant Additives

Abstract The relationship between the molecular structures of lubricant additives and their antiwear properties was assessed using 36 nitrogen-containing heterocyclic organic compounds to generate quantitative structure tribo-ability relationship (QSTR) models. In the modeling process, the molecular structure of the base oil was employed as the solvation factor, employing n-octadecane as a substitute for the liquid paraffin used to generate the original experimental data. Comparative molecular field analysis (CoMFA)-QSTR and comparative molecular similarity indices analysis (CoMSIA)-QSTR models incorporating solvation by n-octadecane were established and compared with QSTR models that did not involve solvation. The solvation CoMFA-QSTR and CoMSIA-QSTR models exhibited excellent fitting abilities and were highly robust when predicting lubricant performance. These models were superior to nonsolvation models in this regard. These models also generated useful information regarding potential changes to molecular structure to improve antiwear properties. Electrostatic fields were found to be very important factors in antiwear models. Because the original experiments used a nonpolar base oil, the solvation factor had no obvious effect on the antiwear characteristics of the polar additives and so the predictive abilities of the solvation and nonsolvation models were similar.

Impact of salinity on fluid/fluid and rock/fluid interactions in enhanced oil recovery by hybrid low salinity water and surfactant flooding from fractured porous media

Wettability alteration of the porous medium from oil-wet (OW) to neutral-wet or even water-wet (WW) is proposed as one of the main mechanisms behind the enhanced oil recovery (EOR) by the Low Salinity Water Flooding (LSWF). However, our recent studies for a specific crude-oil/brine/rock of the oil reservoir in the Middle East, shows that LSW (diluted sea water) is not that much effective, neither to change the wettability of the surface nor to significantly increase the oil recovery factor. This obstacle becomes more challenging when we deal with fractured formations, where the imbibition of injected fluid from fracture into matrix and its propagation within the matrix, is the main macroscopic mechanism of the EOR. Chemical EOR, in which the chemical additive is added to the injecting brine, is one of the hybrid techniques which can boost oil recovery in such cases. In this study, CTAB as a cationic surfactant was added to brine solutions with different ionic strengths (i.e., sea water (SW), 10 times diluted sea water (10dSW) and 2 times concentrated sea water (2cSW)). Contact angle, zeta potential of both fluid/fluid and fluid/rock surfaces, and IFT tests were conducted to shed insight on interactions in crude oil/brine and rock/brine interfaces and the role of ionic strength. Finally, dynamic micromodel tests were performed in oil-wet fractured porous media to observe the impact of the added surfactant along with different ionic strength on displacement mechanisms and oil recovery.Experimental results show that neither electrical double layer expansion nor multiple ion exchange mechanisms cannot justify the observed detachment of oil droplets from the oil-wet substrates in the presence of the CTAB. Surfactant are absorbed on the oil/brine interface by the embedment of their hydrophobic tails in oil. Both surfactant molecules and the non-polar oil components (that are attracted to hydrophobic tail of surfactant molecules), are attracted to the solution via the hydrophilic parts of the surfactants. The effectiveness of this mechanism is dependent on both the concentration of the surfactant and concentration of the ions in brine.In the case that the aforementioned mechanism is adequately dominant and effective, the small droplets of oil will be detached from continuous oil bulk, resulting in oil to be broken to smaller droplets which enhances the detachment of the oil bulk from oil-wet substrates. This fluid/fluid interaction mechanism also promotes the imbibition of the aqueous phase into the matrix and also its propagation within the matrix.

Maximum Incorporation of Soft Microgel at Interfaces of Water in Oil Emulsion Droplets Stabilized by Solid Silica Spheres.

The incorporation of soft hydrophilic particles at the interface of water in non-polar oil emulsion droplets is crucial for several applications. However, the stabilization of water in non-polar oil emulsions with hydrophilic soft material alone is, besides certain exceptions, not possible. In our previous works, we showed that stabilizing the emulsions with well-characterized spherical hydrophobic silica nanospheres (SNs) and soft equally charged microgel particles (MGs) is a robust strategy to stabilize w/o emulsions while still incorporating a large amount of MGs at the interface. In the present study, we address the question of what the maximum amount of MGs at the interface in these kinds of emulsion droplets can be. By using well-characterized mono-disperse SNs, we are able to calculate the fraction of interface covered by the SNs and complementary that of the present MG. We found that it is not possible to decrease the SN coverage below 56% irrespective of MG softness and SN size. The findings elucidate new perspectives to the broader topic of soft/solid stabilized emulsions.

Interfacial Adhesion between Fatty Acid Collectors and Hydrophilic Surfaces: Implications for Low-Rank Coal Flotation.

Fatty acids, which are enriched in vegetable oil, have attracted much attention in low-rank coal flotation because of their unique chemical structure. In this study, density functional theory calculations, molecular dynamics simulations, and atomic force microscopy were employed to investigate the adsorption structure and forces between collectors and hydrophilic surfaces. The results show that fatty acids can be easily adsorbed onto surfaces through hydrogen bonds, and can cover the oxygen sites. The existence of hydration film on hydrophilic surfaces prevented nonpolar molecules from being able to adsorb, while polar fatty acids could adsorb and expel water molecules. The adhesion force between the RCOOH-terminated probe and the surface appeared in the retraction process, which differed significantly from that of the RCH3-terminated probe, indicating that polar fatty acids are more suitable as flotation collectors for low-rank coal than nonpolar hydrocarbon oil. The simulation and AFM test revealed the mechanisms of polar fatty acids, and can provide guidance for low-rank coal flotation applications.

Characteristic Forced and Spontaneous Imbibition Behavior in Strongly Water-Wet Sandstones Based on Experiments and Simulation

Forced and spontaneous imbibition of water is performed to displace oil from strongly water-wet Gray Berea (~130 mD) and Bentheimer (~1900 mD) sandstone core plugs. Two nonpolar oils (n-heptane and Marcol-82) were used as a non-wetting phase, with viscosities between 0.4 and 32 cP and brine (1 M NaCl) for the wetting phase with viscosity 1.1 cP. Recovery was measured for both imbibition modes, and pressure drop was measured during forced imbibition. Five forced imbibition tests were performed using low or high injection rates, using low or high oil viscosity. Seventeen spontaneous imbibition experiments were performed at four different oil viscosities. By varying the oil viscosity, the injection rate and imbibition modes, capillary and advective forces were allowed to dominate, giving trends that could be captured with modeling. Full numerical simulations matched the experimental observations consistently. The findings of this study provide better understanding of pressure and recovery behavior in strongly water-wet systems. A strong positive capillary pressure and a favorable mobility ratio resulting from low water relative permeability were main features explaining the observations. Complete oil recovery was achieved at water breakthrough during forced imbibition for low and high oil viscosity and the recovery curves were identical when plotted against the injected volume. Analytical solutions for forced imbibition indicate that the pressure drop changes linearly with time when capillary pressure is negligible. Positive capillary forces assist water imbibition, reducing the pressure drop needed to inject water, but yielding a jump in pressure drop when the front reaches the outlet. At a high injection rate, capillary forces are repressed and the linear trend between the end points was clearer than at a low rate for the experimental data. Increasing the oil viscosity by a factor of 80 only increased the spontaneous imbibition time scale by five, consistent with low water mobility constraining the imbibition rate. The time scale was predicted to be more sensitive to changes in water viscosity. At a higher oil-to-water mobility ratio, a higher part of the total recovery follows the square root of time. Our findings indicate that piston-like displacement of oil by water is a reasonable approximation for forced and spontaneous imbibition, unless the oil has a much higher viscosity than the water.

The superior lubricating performance and unique mechanism of oil-soluble protic ionic liquids with short alkyl chains

HypothesisIonic liquids (ILs), as lubricant additives, can greatly improve the lubricating behavior of the frictional interfaces. However, it is urgent to explore ILs with good oil solubility in nonpolar oils, and it is necessary to further study and verify the lubrication mechanism of ILs from the perspective of alkyl chain length. ExperimentsFive protic ILs (PILs) with varying alkyl chain lengths were synthesized by proton transfer method. As additives in PAO oil, their tribological properties were investigated on SRV-V tester. Through molecular dynamics simulation, the adsorption behavior of PILs at the frictional interface was illustrated. FindingsThe tribological properties of base oil could be significantly improved by adding PIL additives, but interestingly, PILs with short-chain anions showed better lubricating performance, which contradicted most of the early findings. Further analyses revealed that PILs achieved effective lubrication by the tribochemical interaction between anions and frictional interface, and the formation of cationic protective layer. However, PILs with shorter-chain anions form a denser protective layer that can better support the interfacial anions to participate in tribochemical reactions and thus abnormally exhibit superior lubricating performance than those with longer-chain anions.

Development of Antimicrobial Edible Film Enriched with Double Emulsion of Cinnamon (Cinnamomum burmannii) Essential Oil

The edible film can be used as a carrier of bioactive compounds that contributed to the shelf life or nutritional benefit of food products; however, the addition of bioactive compounds relied greatly on the compatibility of the bioactive compound toward the edible film matrix. Most of the bioactive compounds are nonpolar which incompatible with the polar nature of the edible film. In this research, the nonpolar essential oil of cinnamon, a potent antimicrobial agent, was made into a double emulsion. The double emulsions were made through a two steps emulsification stages, with CaCl2 as the inner water phase and guar gum as the outer water phase. The physicochemical characteristics (stability, viscosity, and droplet size) and the antimicrobial activity of the double emulsion were observed. The double emulsion showed stability up to 7 days of storage at room temperature with high antimicrobial activity; MBC values of 0.86, 1.37, 0.31, and 0.51 mg/mL against E. coli , S. aureus , R. stolonifera , and A. niger , respectively. Different concentrations (5%,10%,15%) of both emulsions were added into edible film suspension. The formation of double emulsion showed a promising result as a means to incorporate nonpolar compounds into basic edible film formulation to increase its functional properties while retaining their physicochemical characteristic. All formulations showed good edible film characteristics, with edible film with 8% essential oil showing a high inhibition zone (15.81 dan 6.92 mm) toward E. Coli and R. stolonifer , 0.0052 mm thickness, the tensile strength of 6.32 MPa, 13% elongation and WVTR of 1.06 g/cm 2 .h.

Interaction between hydrocarbon oil and hydrophilic mineral surfaces: A chemical force microscopy and molecular dynamics simulation study

Hydrocarbon oil collectors are typically used in the mineral flotation process to increase the hydrophobicity of the mineral surface. However, the mechanism of action of hydrocarbon oil on hydrophilic mineral surfaces remains unclear. This study innovatively applied chemical force microscopy (CFM) and molecular dynamics (MD) simulations to study the interactions between hydrocarbon oil and hydrophilic mineral surfaces. The CFM results showed that the interactions between RCH3, ROH, RCOOH, and RNH4+ and the hydrophilic mineral surface are always repulsive, and can be well described by Derjaguin–Landau–Verwey–Overbeek theory, which considers both van der Waals and electrostatic forces. The type of functional group significantly influenced the adhesion force between the hydrocarbon oil collector and hydrophilic mineral surface, and the adhesion forces followed the order RNH4+ > ROH > RCOOH > RCH3, indicating that polar hydrocarbon oil molecules adhered strongly to the hydrophilic mineral surface, whereas nonpolar hydrocarbon oil molecules did not adhere to this surface. MD simulation results showed that polar micro-oil droplets easily spread on the hydrophilic surface, while nonpolar micro-oil droplets were difficult to spread. Hydrophilic mineral surfaces preferentially attract water molecules and repel hydrophobic hydrocarbon oils, which reduces the adsorption energy of nonpolar hydrocarbon oils. Polar hydrocarbon oil is an effective collector for increasing the surface hydrophobicity of hydrophilic minerals. The combination of MD and CFM illustrated the mechanism of action of hydrocarbon oil collector molecules, which provides a theoretical reference for mineral flotation separation.

Inverse ISAsomes in Bio-Compatible Oils-Exploring Formulations in Squalane, Triolein and Olive Oil.

In contrast to their more common counterparts in aqueous solutions, inverse ISAsomes (internally self-assembled somes/particles) are formulated as kinetically stabilised dispersions of hydrophilic, lyotropic liquid-crystalline (LC) phases in non-polar oils. This contribution reports on their formation in bio-compatible oils. We found that it is possible to create inverse hexosomes, inverse micellar cubosomes (Fd3m) and an inverse emulsified microemulsion (EME) in excess squalane with a polyethylene glycol alkyl ether as the primary surfactant forming the LC phase and to stabilise them with hydrophobised silica nanoparticles. Furthermore, an emulsified -phase and inverse hexosomes were formed in excess triolein with the triblock-copolymer Pluronic® P94 as the primary surfactant. Stabilisation was achieved with a molecular stabiliser of type polyethylene glycol (PEG)-dipolyhydroxystearate. For the inverse hexosomes in triolein, the possibility of a formulation without any additional stabiliser was explored. It was found that a sufficiently strong stabilisation effect was created by the primary surfactant alone. Finally, triolein was replaced with olive oil which also led to the successful formation of inverse hexosomes. As far as we know, there exists no previous contribution about inverse ISAsomes in complex oils such as triolein or plant oils, and the existence of stabiliser-free (i.e., self-stabilising) inverse hexosomes has also not been reported until now.

Synergetic adsorption of dodecane and dodecylamine on oxidized coal: Insights from molecular dynamics simulation

In order to explore the synergetic adsorption mechanism of nonpolar hydrocarbon oil and cationic amine on OC (oxidized coal) surface, the MD (Molecular Dynamics) simulations were used to simulate the wettability of OC surface and the dynamic characteristics of DDC (Dodecane)/DDA (dodecylamine) adsorption on OC/water interface under different complex conditions. Water molecules in a nano water droplet have strong hydrogen bond adsorption with the OC surface, which is easy to be wetting and spread along the surface to occur strong hydration of OC surface. DDC can adsorb on OC surface well, while DDA cations can not. When DDC and DDA are co-adsorbed on OC surface, can have a synergistic adsorption effect. The synergistic adsorption mechanism is mainly that, after DDC adsorbed on OC surface, its carbon chain will adsorb partial DDA cations through dispersion interaction, thus promoting the effective adsorption of DDA cations on OC surface. Synergistic adsorption of DDC and DDA can not only improve the surface hydrophobicity of OC, but also reduce the surface negative electricity through the adsorption of DDA cations, to achieve the effect of effectively promoting the agglomeration of particles, which is very beneficial to the efficient separation and settlement of oxidized coal.