Oil-water Interface Research Articles

Quality characteristics of peanut protein-based patties produced with pre-emulsified olive oil as a fat replacer: Influence of acylglycerol type

The emulsion (O/W) may be used as a fat replacer to develop healthier meat analogs. The purpose of this work was to evaluate the effects of oil incorporation methods (direct oil addition and emulsion addition) and oil types [triacylglycerol (TAG) and diacylglycerol (DAG)] on the quality characteristics of peanut protein-based patties crosslinked by transglutaminase (TGase). The patties formulated with emulsions showed larger texture parameters (springiness, cohesiveness and gumminess), lower cooking loss and higher acceptability compared with directly adding oil. The rheological results confirmed that the presence of emulsions strengthened the gel structure in patties, which allowed the patties containing emulsions to stabilize free water. Whereas, TAG-based emulsion was more effective than DAG-based emulsion in improving quality of products, possibly because the competitive adsorption at oil-water interface of DAG reduced the crosslinking between the interfacial protein and adjacent protein molecules. This study revealed the relationship between the acylglycerol type in emulsion and the patty quality, providing a reference for the development of plant-based patties.

In-situ grafting of dextran on oil body associated proteins at the oil–water interface through maillard glycosylation: Effect of dextran molecular weight

Oil bodies, which are lipid-storage organelles in plant seeds, are stabilized by monolayer of phospholipids and oil body associated proteins (OBAPs). OBAPs have unique interfacial characteristics but poor water-solubility because they contain long hydrophobic segments. In this paper, dextran with different molecular weights (5, 10, and 20 kDa) was grafted onto the C- and N-terminal ends of OBAPs through in situ Maillard reaction on the surface of oil bodies. Grafting of dextran increases the length of the hydrophilic region of OBAPs, which improves their solubility and function as interfacial stabilizers. Changes in chemical bonds after grafting were observed via confocal-Raman microscopy. After de-lipidization, the physicochemical properties of OBAPs–dextran conjugates were analyzed using solubility and infrared spectroscopy. The interfacial behavior was evaluated using critical micelle concentration and interfacial rheology. The results showed that grafting of dextran improved the solubility of the OBAPs by 20-fold. The contents of α-helix and β-sheet in the OBAPs–dextran conjugates decreased, when compared with OBAPs. The critical micelle concentration of OBAPs–dextran conjugates ranged from 1.20 to 4.92 μg/mL. Grafting of dextran, especially high molecular weight, improved the capacity of the OBAPs to increase the interfacial pressure. Our results provide an efficient and eco-friend method for modification of membrane proteins.

Analysis of Surfactant and Polymer Behavior on Water/Oil Systems as Additives in Enhanced Oil Recovery (EOR) Technology through Molecular Dynamics Simulation: A Preliminary Study

The decline in oil production has led to the development of the Enhanced Oil Recovery (EOR) technology to increase oil production. Chemical injection is one of the methods in EOR by injecting surfactants or polymers into reservoir wells. To understand the properties and dynamics of surfactants and polymers at the nanoscale, computational studies using molecular dynamics simulation were carried out. In this study, surfactant Sodium Dodecyl Benzene Sulfonate (SDBS) and polymers such as Polyacrylamide (PAM) were used to investigate their effect on the oil-water interface system at the atomic level. Molecular dynamics simulation was carried out using Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to calculate the diffusion coefficient and Interface Formation Energy (IFE) value for the addition of the surfactant and polymers. The simulation results show that the addition of the surfactant and polymers affects the water-oil interface system differently. The diffusion coefficient results indicates that there are strong interactions between SDBS and dodecane with D of 0.01358. While for PAM, the interactions with water are more significant with D of 0.059. The results of the IFE calculation value also show that the addition of SDBS and PAM makes the water-oil interface system more stable with the negative IFE value of -197.51 and -13.13 Kcal/mol respectively. The results of this study will be used as a reference and a basis for designing new surfactants or polymers that will led to more oil recovery.

An amphiphilic nano titanium dioxide based nanofluid: Preparation, dispersion, emulsion, interface properties, wettability and application in enhanced oil recovery

The emulsification flooding is an effective method for enhance oil recovery. In this work, an amphiphilic nano titanium dioxide (ANTD) was prepared by the chemical reaction of nano titanium dioxide (NTD) with the titanate coupling agent. The contact angle experiments shown that the contact angle of NTD changed from 11.6° to 110.6°after modification, which became more lipophilic. The dispersion testing shown that Span85 was the best dispersant for ANTD. The nanofluid was configured by using 0.05 g of ANTD and 100 ml of 0.05 % Span85, which was tested by the emulsification experiment, the interface tension experiment and the dilatation rheological experiment. The result shown that the nanofluid can be emulsified to form the W/O emulsion with the crude oil, the average emulsion particle size was 1.96 µm, and the nanofluid could reduce the oil-water interface tension and improve the strength of the interface film. The wettability alteration experiment shown that the nanofluid can change the core from oil-wet to water-wet. The flow displacement experiment demonstrated that the oil recovery rate increased by 26.4 % after the nanofluid flooding. Finally, the Nuclear Magnetic Resonance experiment shown that the nanofluid could reduce the oil-water mobility rate, and expand the swept volume, thus enhancing oil recovery.

Interfacial Rheological and Emulsion Properties of Self-Assembled Cyclodextrin-Oil Inclusion Complexes.

To investigate the effect of the molecular size of alkanes and the cavity size of cyclodextrins (CDs) on the formation of interfacial host-guest inclusion complexes, the interfacial tension (IFT) of CD (α-CD, β-CD, γ-CD) solutions against oils (hexadecane, dodecylbenzene) was determined by interfacial dilational rheology measurements. The results show that the "space compatibility" between CDs and oil molecules is crucial for the formation of interface host-guest inclusion complexes. Hexadecane with a smaller molecular size can form host-guest inclusion complexes with small cavities of α-CD and β-CD, dodecylbenzene with a larger molecular size can form interfacial aggregates with the medium-sized cavity of β-CD easily, and the polycyclic aromatic hydrocarbon molecules in kerosene can form inclusion complexes with the large cavity of γ-CD. The formation of interfacial inclusion complexes leads to lower IFT values, higher interfacial dilational modulus, nonlinear IFT responses to the interface area oscillating, and skin-like films at the oil-water interface. What's more, the phase behavior of Pickering emulsions formed by CDs with different oils is explored, and the phenomena in alkane-CD emulsions are in line with the results in dilatation rheology. The interfacial active host-guest structure in the kerosene-γ-CD system improves the stability of the Pickering emulsion, which results in smaller emulsion droplets. This unique space compatibility characteristic is of great significance for the application of CDs in selective host-guest recognition, sensors, enhanced oil recovery, food industries, and local drug delivery.

Robust SiO2/polymer hybrid microcapsule synthesized via emulsion photo-polymerization and its application in self-lubricating coatings

In this work, a novel kind of SiO2/polymer hybrid microcapsule encapsulating lubricant oil was prepared via a facile one-pot emulsion photo-polymerization method. In our strategy, an emulsion with the oil phase composed of SiO2 particles, photo-curable prepolymer, dichloromethane, photo-initiator and lubricant oil was firstly prepared. In the process of solvent evaporation, phase separation occurred between the photo-curable prepolymer and lubricant oil, and SiO2 particles migrated to the oil-water interface. After UV irradiation, the photo-curable prepolymer was photo-polymerized to form microcapsule shell, and SiO2/polymer hybrid microcapsule was yielded. The whole process could be finished within several minutes at room temperature, which was energy-saving and time-saving. The surface morphology of the microcapsule and the element distribution on the surface of the shell were investigated by SEM and EDS. The solvent resistance and mechanical property of hybrid microcapsules were tested. The morphology, the solvent resistance and the mechanical properties of SiO2/polymer hybrid microcapsule was controlled by adjusting the amount of SiO2 particles added in the oil phase. It was found that the introduction of SiO2 in the microcapsule shell could significantly improve the solvent resistance and mechanical properties of microcapsule. The synthesized hybrid microcapsule was embedded into epoxy resin for fabricating self-lubricating coatings. The friction and wear test results showed that the tribological property of the epoxy resin coating was significantly improved with the incorporation of the microcapsule. When the content of SiO2/polymer microcapsules was 10 wt%, the friction coefficient of the composite coating was 0.062, almost one-tenth of that of the pure epoxy coating (0.53).

Micro-scale simulation of adsorption-diffusion behaviors of nanoparticles onto mobile oil/water interface

A novel, hybrid pore-scale simulation method using Lattice-Boltzmann (LB) coupled with Langevin-Dynamics (LD) is proposed to investigate the physics of nanoparticles onto oil/water interface. Based on the LB method, the high-resolution characterization of oil-water interface is established. Then, in a fashion of discrete LB forcing source distribution, the LD method is introduced to characterize the effects of Brownian motion, thermal fluctuation-dissipation, multi-body hydrodynamics, and particle-particle interactions. By the means of the new LB-LD coupling model, the adsorption and diffusion characterization of nanoparticles onto oil/water interface are investigated. Moreover, by introducing the interference coefficient and non-equilibrium time, a modified Langmuir adsorption equation is first established by more accurately quantifying the adsorption characterization of nanoparticles and the consequent impacts onto the oil/water interfacial force (IFT), which cannot be accurately described by the classical Langmuir model. For the example of SiO2 nanoparticles adsorption, it is observed that small-size nanofluids with high concentration could accelerate the adsorption of nanoparticles. In addition, both the lateral and longitudinal diffusion coefficients of nanoparticles in the water phase and onto interface are obtained, and of which the underlying mechanisms are explained by introducing residual oil. The proposed simulation method provides valuable insights into how nanoparticles adsorb and diffuse onto oil/water interface and how oil/water IFT can be reduced.

Preparations, application of polysaccharide-protein nanoparticles and their assembly at the oil-water interface.

With the development of nanotechnology, nanoparticles have played an important role in pharmaceuticals, foods and materials, in particular, protein/polysaccharide based composite nanoparticles have received attention from researchers for safety and green production. This paper summarized in detail the preparation methods, applications of protein/polysaccharide nanoparticles (PPNPs) in recent years, especially the mechanism of stabilizing the oil-water interface. Currently, the polysaccharides applied are more traditional, such as chitosan, pectin and carboxymethyl cellulose, so there is still a lot of room for the development of raw materials that can be used to prepare PPNPs. Based on this, we also proposed three promising polysaccharides: seaweed polysaccharide, lycium barbarum polysaccharide and lactobacillus exopolysaccharides, describing their characteristics as well as their application prospects, this article can serve as a reference for interested researchers.

The emulsions stabilized by Dodecylbenzenesulfonic acid/asphaltene/hydrolyzed polyacrylamide: Emulsion morphology, stability, and rheology

Aqueous mixtures of dodecylbenzene sulfonic acid (DBSA) and hydrolyzed polyacrylamide (HPAM) are commonly used to enhance oilfield recovery. These two components coupled with asphaltenes (ASP) in crude oil, play a key role in stabilizing the emulsions produced during oil recovery. In this study, the stability of emulsions made with ASP, DBSA, and HPAM as emulsifiers was examined. We discovered that the three ingredients were synergistically adsorbed at the oil–water interface with a synergistic index of 1.075 for interfacial tension (IFT). HPAM enhanced the viscosity and increased the anion content of the dispersed system in the emulsion. DBSA acted as the main anionic surfactant, benefiting to form and stabilize the emulsion droplets. ASP was adsorbed at the oil–water interface to form a rigid interfacial film. When the three ingredients co-existed, they formed a complex adsorption unit with synergistic adsorption, in which DBSA dominated. As the concentration of the three ingredients increased, the emulsion stability showed a trend of enhancing first and then decreasing. This study is dedicated to providing a theoretical basis for the elucidation of the stability of the oil–water system in oil sludge containing polymers.

The quality of whipped cream: Effect of polyglycerol ester on the crystallization of fat blend and the properties of interface

This study investigated the effect of polyglycerol ester (PGE) on the crystallization of fat blend and the properties of interface, as well as their influence on the quality of whipped cream. PGE, as a nucleation inducer, facilitated the nucleation of fat blend, thereby forming small and uniform crystals. When PGE concentration was lower than 0.10 wt%, PGE coexisted with sodium caseinate (SC) at oil-water interface, decreasing the interfacial tension as well as increasing the interfacial elasticity modulus (E′) and the interfacial protein concentration (ζ), therefore improving the stability of emulsions. Moreover, PGE could increase the extent of partial coalescence and the ζ in whipped creams, leading to the formation of firmly foam structures, which in turn increased the firmness and decreased the serum loss. When PGE concentration was higher than 0.10 wt%, PGE displaced SC, decreasing the E′ and the ζ, thereby some large and irregular fat globules were observed in emulsions which caused the instability of emulsions. Besides, low degree of partial coalescence and ζ resulted in the formation of loose and fragile foam structures, thereby decreasing the firmness and increasing the serum loss of whipped creams. Overall, this study could provide theoretical guidance on how to accurately control and modify the quality of whipped creams.

A low-energy emulsification platform based on a Diet Coke–Mentos reaction-derived bubbly flow for formulating various emulsions as drug carriers

The formulation of a drug using high-energy emulsification commonly causes drug deterioration. Exploiting the well-known Diet Coke–Mentos reaction (DCMR), a U-shaped tube reactor that can generate an eruption of bubbly flow that can serve as a low-energy emulsification platform, is proposed. The liquid in the U-tube reactor is a supersaturated solution of aqueous CO2, which mimics Diet Coke. When glass beads with rough surfaces, mimicking Mentos, are dropped into the carbonated water, an eruptive bubbly flow is spontaneously created, mediating effective emulsification at a compound water–oil interface. Experimental results demonstrate that DCMR-mediated bubbly flow may provide a versatile platform for the production of “oil-in-water” or “water-in-oil” droplets and Pickering emulsion composite particles as drug carriers. The DCMR-derived bubbly flow is generated without significant temperature elevation, so the activity of the drug to be emulsified is unaffected. In vivo results reveal the feasibility of using this low-energy emulsification platform to formulate an emulsion system that contains catalase, a temperature-sensitive oxidoreductase, to mitigate an experimentally formed paw inflammation in mice. The as-proposed emulsification platform is attractive for formulating numerous drug delivery systems on a small-scale in a customized manner to meet the needs of each individual for personalized medicine.

Surfactant-influenced oil–water slip and flow in nanochannels studied by molecular dynamics and theoretical modeling

This work uses molecular dynamics (MD) methods to investigate oil–water two-phase flow in hydrophilic nanochannels with surfactants adsorbed at the oil–water interface. We reveal two new discontinuous effects of nanoscale fluid flow: (i) the velocity distribution in the water layer is not a univariate function of the pressure gradient, and (ii) the apparent viscosity in the oil–water interface region is a function of surfactant concentration and pressure gradient. Based on the MD results, a layered theoretical model describing the discontinuous effects at the nanoscale is developed. The theoretical model provides quantitative two-dimensional functions for oil–water interface slip and fluid mass flux with pressure gradient and surfactant concentration. Surfactants significantly inhibit oil–water slip and reduce fluid mass flux. This study thus provides important insights into the theoretical and numerical models for shale or tight oil production predictions.

Numerical investigation on the interaction of an oscillating bubble with the interface of a non-Newtonian fluid

The dynamics of an oscillating bubble near a liquid–liquid interface is a complex multiphase flow problem due to the highly nonlinear interaction, such as interface fragmentation and bubble tearing. When one of the liquid mediums is non-Newtonian, its constitution would significantly influence both the bubble motion and the interface evolution. In this study, a numerical model is established based on the Eulerian finite element method with the non-Newtonian fluid described by the Herschel–Bulkley model. The numerical model is validated by comparing with experimental results for a non-spherical pulsating bubble at a water–oil interface and the analytical solution for the laminar flow of non-Newtonian fluids in a circular tube. According to the simulation and analysis with different case parameters, our findings suggest that the non-Newtonian fluid forms a crater when squeezed by the bubble, and the downward jet can penetrate the bubble and further deepen the crater. As the distance parameter increases, the crater gradually disappears or even bulges. Furthermore, the yield shear stress can give non-Newtonian fluid plastic properties similar to a solid, effectively reducing the bubble's pulsation and jet load. Additionally, the flow behavior index n comes from the power-law model for non-Newtonian fluids and significantly impacts the jet's impact process. When n≤1, the crater is likelier to become funnel-shaped, whereas when n > 1, it is likelier to become bullet-head-shaped. In addition to enhancing the bubble's nonsphericity, the reduction in Reynolds number also weakens the crimp deformation of the interface. When the distance parameter is zero, the larger the buoyancy parameter and the less deformable the non-Newtonian fluid, the easier the bubble to split by the annular jet.

Preparation and Catalytic Properties of Lipase Immobilized on Epoxy‐functionalized Starch Nanoparticles

AbstractAs a natural macromolecular material, starch is an ideal carrier for enzyme immobilization because of its widely available source, easy regeneration and excellent biodegradability. However, the natural starch cannot be directly used for immobilization due to the large particle size and excessive hydrophilicity. In this paper, the epoxy groups were grafted onto esterified starch by bifunctional reagents. The grafting efficiency of epoxy groups was increased by starvation drop addition. The changes of contact angle and particle size are conducive to the adsorption of immobilized enzyme at the water oil interface in the subsequent enzyme catalytic reaction, hence improve of the lipase activity. The maximum amount of lipase mobilized on such modified starch was ∼143.7 mg/g, which was near 40 mg/g higher than that of those from direct crosslinking. The immobilized enzymes showed excellent resistance to organic solvents and good reusability. Immobilization of lipases on epoxy‐functionalized starch nanoparticles can potentially improves the possibility of enzymes industrial application.

Experimental and molecular dynamics studies of physicochemical properties of highly thickening and active nanofluids based on acrylamide modified silica

Binary compound flooding is an important technology that continuously promotes stable oil reservoir production. By comparing with traditional binary compound flooding, the binary system with nanoparticles has higher application value in enhanced oil recovery (EOR). In this work, we prepared a flexible polymeric brushes hybrid nano-silica star-like hydrophobically associative polyacrylamide (SHPAM). Subsequently, a surfactant named alkyl alcohol polyoxyethylene ether sulfonate (CEOS) was selected to study physicochemical properties of nanofluids through a combination of experiments and simulations. The results indicated that the prepared nanofluids had good dispersion stability in strong brine. When the concentration of monomer SHPAM reached 2000 mg/l, its thickening performance was the best. Significantly, even if the concentration of SHPAM was reduced (750 mg/l), the thickening performance of nanofluids (107.2 mPa s) was better than that of monomer SHPAM. Interestingly, the nanofluids ensured the same degree of reduction in interfacial tension as the alone CEOS (the order of 10−2 mN/m). The molecular simulation showed that the nanofluids could stably adsorb on the oil–water interface and form a layer of interfacial film to increase the viscosity and reduce the interfacial tension. The prepared nanofluids could significantly change the wettability of the core and improve producing degree in the pore throat above 1.0–10 μm about 40%. We envisage that this nanofluidic material can apply in EOR with high efficiency and low cost.

Mechanistic study of the effect of hydrocarbon unsaturation on the distribution state of water molecules at the oil-water interface by oblique incident reflectance difference technique

Mechanistic study of the effect of hydrocarbon unsaturation on the distribution state of water molecules at the oil-water interface by oblique incident reflectance difference technique

Interfacial effects of gallate alkyl esters on physical and oxidative stability of high fat fish oil-in-water emulsions stabilized with sodium caseinate and OSA-modified starch.

Effects of sodium caseinate (SC) and its combination with OSA-modified starch (SC-OS; 1:1) alone and with n-alkyl gallates (C0-C18) on the physical and oxidative stability of high-fat fish oil-in-water emulsion were evaluated. SC emulsion contained the smallest droplets and highest viscosity due to the fast adsorption at droplet surfaces. Both emulsions had non-Newtonian and shear-thinning behavior. A lower accumulation of lipid hydroperoxides and volatile compounds was found in SC emulsion due to its better Fe2+ chelating activity. The incorporated short-chain gallates (G1>G0∼G3) in SC emulsion had a strong synergistic effect against lipid oxidation compared to that of SC-OS emulsion. The better antioxidant efficiency of G1 can be related to its higher partition at the oil-water interface, while G0 and G3 had a higher partition into the aqueous phase. In contrast, G8, G12, and G16 added emulsions indicated higher lipid oxidation due to their internalization inside the oil droplets.

Synthesis of Highly Efficient CsPbBr3@Pb-MOF Photocatalyst at the Water-Oil Interface by Ultrasonication

In recent years, all inorganic perovskites have proven to be excellent photocatalytic materials. However, its poor stability and severe recombination of photogenerated electrons and holes have hindered its wide application. Herein, we employed a convenient and rapid one-pot sonochemical method to incorporate CsPbBr3 into Pb-MOF, aiming to enhance the stability and efficiency of photogenerated electron transfer. The CsPbBr3@Pb-MOF shows good photocatalytic efficiency, and 70% tetracycline hydrochloride (TCH) water solution is decomposed at 60 min visible light (λ>420 nm) irradiation. Meanwhile, CsPbBr3@Pb-MOF exhibits excellent photocatalytic stability.

Colloidal cesium lead bromide-based anisotropic nanorods for improving outcoupling in perovskite light-emitting diodes

ABSTRACT Photon extraction is one of the major issues limiting outcoupling efficiency in perovskite light-emitting diodes (PeLEDs). Light outcoupling in PeLEDs is typically limited by the disparity in refractive indices among the consisting layers and the difficulty of producing directed emitters in the emitting layers. Here, anisotropic nanorod-based perovskite with colloidal cesium lead bromide was introduced to address the issue via the oil–water interface chemical stripping transition method. It was confirmed that the horizontal transition dipole moments of 73% and refractive index value of 1.86 of the ANRs-based perovskites enhance outcoupling efficiency in PeLEDs. Finally, we achieved green-emitting ANR-PeLEDs with a current efficiency of 45.9 cd/A, power efficiency of 40.0 lm/W, and external quantum efficiency of 18.4% (turn-on voltage 3.3 V), with Commission Internationale de l'Eclairage (CIE) coordinates of (0.073, 0.71). These findings suggest further research into the anisotropic 1D shape of perovskite, which could improve the optoelectrical performance of PeLEDs.

Design of Proanthocyanidins and TiO2 Nanoparticles-Based Novel Emulsions as a Platform for UV Protection.

A white oil-in-water novel emulsion stabilized by TiO2 nanoparticles with UVB shielding properties and proanthocyanidins with antioxidant activity was prepared, where the proanthocyanidins aggregated at the oil-water interface to reduce interfacial tension while TiO2 nanoparticles were dispersed in the continuous water phase to hinder droplet coalescence. It was found that the average oil droplet size was less than 10 μm and decreased with the increase of proanthocyanidins concentration, but the increase of the content of TiO2 nanoparticles had little effect on it. The combination of TiO2 nanoparticles and proanthocyanidins was versatile for oil phases with different polarities, and the resulting emulsion exhibited high stability in the face of centrifugation, heating and prolonging storage time. After encapsulating the UVA filter avobenzone in white oil, the emulsion was endowed with the ability to resist UVB and UVA. Further, the emulsion showed great free radical scavenging ability for superoxide anion radical (⋅O2 - ), hydroxyl radical (⋅OH) with the clearance rate of over 70 %, indicating the good antioxidant activity. The ingenious combination of UVB, UVA filter and antioxidant with emulsion as carrier provides a new idea for the preparation of full-band sunscreen emulsion.