Emulsion Viscosity Research Articles

CO2-switchable emulsion with controllable stability and viscosity based on chitosans and cetyltrimethylammonium bromide

Emulsions have extensive applications in food, cosmetics, and agriculture, while the requirements for emulsions differ in various fields. It is a challenge for one emulsion to satisfy multiple requirements in different applications. Herein, CO2-switchable emulsions with controllable stability and viscosity were prepared by a mixture of chitosans (CS) and CTAB. After adding low concentrations of CTAB (e.g. 0.5 mM), the viscous Pickering emulsions stabilized by CS alone were converted into moderate-viscous Pickering emulsions due to the competition adsorption between CS aggregates and CTAB at the oil-water interface. The transformation of emulsion types (such as Pickering and conventional emulsions) and the emulsion's stability and viscosity were controlled by CO2/N2 trigger. Furthermore, at high CTAB concentrations (≥ 0.8 mM), a novel long-term stable conventional emulsion was obtained after the CS aggregates at the oil-water interface were entirely replaced by CTAB. Compared with other stimuli, CO2 is recognized as a green trigger that doesn't cause contaminations in the system, which has potential applications in organic synthesis and polymerization. Our strategy provides a simple and effective method to smartly control the properties of the emulsions (such as the emulsion type, stability, and viscosity), obtaining an intelligent emulsion to meet different requirements in many applications.

Study of the liquid resistance effect of water-in-oil emulsions in porous media

During heavy oil recovery in the Bohai Oilfield, substantial emulsification of oil and water occurred, primarily forming water-in-oil (W/O) emulsions. This phenomenon could alter fluid dynamics within the subsurface porous media, potentially impacting well production performance. To elucidate the properties of water-in-oil emulsions and their associated liquid resistance effects, this study conducted a series of rheological tests, microscopic examinations, and injection experiments. The results show that the droplet size and distribution of water-in-oil emulsions were primarily influenced by shear rate and water content, which in turn modified emulsion viscosity. The stability of water-in-oil emulsions was reduced when they flowed through porous media. The increase in emulsion viscosity and the liquid resistance effect collectively enhanced the seepage resistance of water-in-oil emulsions flowing through porous media. Notably, when the emulsion droplet size exceeded the pore throat size, over 90% of the total seepage resistance was attributable to the liquid resistance effect. Conversely, when the majority of the emulsion droplets were smaller than the pore throat, the viscosity accounted for more than 60% of the seepage resistance. Water-in-oil emulsions flowed through cores with permeabilities ranging from 50 to 100 mD, exhibiting threshold pressure gradients between 35 and 43 MPa/m. At a core permeability of 300 mD, the threshold pressure gradient was significantly reduced to 1 MPa/m. The presence of a water-in-oil emulsion in the reservoir could result in a production pressure differential falling below the threshold pressure, thereby reducing reservoir productivity.

Adjuvant use for the management of pesticide drift, leaching and runoff.

Adjuvants are included in many pesticide spray mixtures to enhance the performance of the applied chemical. Many adjuvants which modify the emulsion or extensional viscosity of the tank-mixture have been found to offer benefits in drift management, primarily by eliminating or reducing the 'Fine' droplets included in the spray with diameters <100-200 μm that can move off-target in unfavorable conditions during ground, airblast and aerial pesticide applications. Among wind tunnel and field studies conducted around the world, there is consensus that while some adjuvants are effective for drift management, the performance varies on a case-by-case basis, requiring verification for each adjuvant which could be achieved through a programme such as certification based on showing a reduction in Fine droplets and/or a reduction in airborne drift. These can be measured in wind tunnel studies according to international standards. This article provides a review of the current science in this subject area, from the approaches to data collection to a review of existing data and regulatory application for encouraging and rewarding the use of appropriate adjuvants that have been demonstrated to reduce airborne spray drift potential and therefore the size of no-spray buffer zones appropriate to protect nontarget sensitive areas from drift exposure. Some adjuvants can offer the same reduction in drift as offered by hooded sprayer retrofits. A drift reduction programme based on adjuvant use could include testing candidate adjuvants for their effect on droplet size and reduction in Fine droplets when sprayed through reference nozzles and compared against sprays without the adjuvant. Testing could also be based alternatively on measurements of drift potential on collectors such as monofilament line in wind tunnel or field studies. Once shown to be effective in reducing 'Fines' or spray drift, adjuvants could be certified and then referenced on pesticide labels and/or regulatory or best management practice schemes to encourage their use and offer reductions in use restrictions or no-spray buffer zone sizes based on drift management. Studies have shown that some adjuvants can reduce pesticide leaching into soils and contamination of groundwater, as well as runoff of active ingredients from plants into the environment. Performance depends on the adjuvant type, the pesticide with which it is used, the soil or plant type, the timing and mass of water input from rainfall and climatic factors. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Fabrication and Characterization of Chitosan and Gelatin-Based Antimicrobial Films Incorporated with Different Essential Oils.

This study was performed to check the effect of different essential oils on chitosan and gelatin-based antimicrobial films. Films prepared from biopolymers contain better mechanical strength but lack in moisture barrier properties. In order to increase the moisture barrier properties of chitosan and gelatin-based films in the current research work, different essential oils, i.e., thyme, cinnamon, basil, ginger, and cumin, at varying concentrations (1.0, 1.5, and 2.0%) were incorporated. Moreover, the concentrations of glycerol (plasticizer) and emulsifier (Tween 20) were kept constant to maintain homogeneity in the research. Antimicrobial films composed of gelatin and chitosan infused with essential oils were evaluated for their physicochemical (emulsion stability, particle size, and viscosity), FT-IR, microstructural (scanning electron microscopy), moisture barrier (water vapor permeability), and antimicrobial properties (E. coli, Salmonella, and S. aureus). Study outcomes elucidated significant variations (p < 0.05) as the concentration of essential oil was increased in the film solutions. An increased concentration of essential oil (2.0%) significantly enhanced the moisture barrier properties (1.12 ± 0.03 g.mm/kPa.h.m2). Nevertheless, the tensile strength decreased (38.60 ± 1.4 to 31.50 ± 1.5 MPa) from 1 to 2%. The increase in essential oil concentration in the emulsion-based films also influenced their physicochemical characteristics, such as droplet size, viscosity, and emulsion stability. At lower concentrations (1.0%), films exhibited a uniform microstructure but lacked moisture barrier properties. Antimicrobial properties against E. coli, Salmonella, and S. aureus showed an increased inhibition effect as the concentration of essential oil was increased. Of the essential oil-based films, ginger- and basil-based films showed greater inhibition effects as compared to the other essential oils. Overall, antimicrobial films containing a 1.5% concentration of ginger and basil oil showed better results as compared to the other treatments for mechanical, moisture barrier, and antimicrobial properties, while films with a 2.0% oil concentration showed better antimicrobial and moisture barrier properties but lacked in mechanical properties. Essential oil-based antimicrobial films have prospective applications in foods, specifically in fresh and processed food items such as seafood, meat, chicken, and sausages.

Soy proteins with various surface properties prepared by limited enzymatic hydrolysis and their potential on emulsion thickening and controlling lipolysis

In recent years, proteins with designed surface properties as interfacial stabilizers to obtain functional emulsions with controlled lipolysis has received increasing attention. In this work, four types of soy proteins (I, II, III, IV) with different surface properties were obtained by controlled enzymatic hydrolysis (Neutrase). Protein particle size, morphology, surface hydrophobicity and interfacial wettability were analyzed along with changes in subunits composition and secondary structure, aiming to establish a certain relationship between protein surface properties and its capacity in modulating emulsion properties. Specifically, Type I (α’, α, β, A and B subunits) as protein nanoparticles showed high surface hydrophobicity (+84%) and could form a thick interface to delay lipolysis (k1-24.0%, k-24.2%) through Pickering effect. Type II (α, β, A and B subunits) as protein aggregates in larger size showed high surface hydrophobicity (+45%) and roughness, which could enhance viscosity (equivalent to that of φ0.3–0.4 oil fraction) and delay lipolysis (k1-24.0%) by bridge flocculation. Further hydrolysis caused partial precipitation (originated from β and B subunits) and the soluble portion (Type III and IV) with decreased surface hydrophobicity and increased structural flexibility showed poor emulsification capacity and formed weak interface. It can be concluded that regulating subunit composition by enzymatic hydrolysis is an effective way to obtain proteins with multi-surface properties, which plays a vital role in modulating emulsion viscosity and lipolysis behavior. Results from the present study could provide a new strategy for the design of low-calorie emulsions for weight management.

Physicochemical properties, photostability, and digestive characteristics of natural emulsion system fabricated by recombinant rice bran oil bodies for lutein ester delivery

Rice bran oil bodies (RBOBs), as natural oil-in-water emulsions, can be used as a good carrier for delivering hydrophobic functional ingredients. In this work, the lutein ester-loaded rice bran oil body (LRBOB) emulsions were successfully prepared by restructuring the RBOBs natural structure through heat treatment and high-pressure homogenization. The physicochemical properties, photostability, and in vitro digestion of LRBOB emulsions with different oil body concentrations were investigated. The LRBOB emulsion with 50% RBOBs had maximum lutein ester encapsulation efficiency (94%) with larger mean particle size (566.44 ± 18.05 nm) and zeta potential (−43.87 ± 0.8 mV), exhibiting good physical stability and an amorphous structure of lutein ester. Meanwhile, the emulsion droplets formed a network structure through mutual adsorption, as observed by CLSM. Moreover, the apparent viscosity of LRBOB emulsion was increased with the increase of RBOBs concentration, showing a shear thinning behavior. Within the linear viscoelastic range, the emulsions mainly displayed elastic rheological characteristics. Furthermore, the photooxidation studies showed that the LRBOB emulsion retained a maximum of 37% lutein ester after 96 h of UV irradiation, and the half-life was extended to 58.89 h. Meanwhile, a higher amount of RBOBs effectively reduced lipid and protein oxidation and minimized color difference, indicating that RBOBs could effectively improve the stability of lutein ester. Based on the results of in vitro simulated digestion, LRBOB emulsion showed higher free fatty acid release (32%) and lutein ester bioaccessibility (40.17%) in the adult model, but is not recommended for infant diets. This work will provide a new delivery vehicle for the utilization of raw lutein materials, expanding the potential applications of natural plant oil bodies.

Fabrication and characterization of oxidized starch-xanthan gum composite nanoparticles with efficient emulsifying properties

This study involved the preparation of nanoparticles by combining oxidized starch (OS) with xanthan gum (XG), and emulsions were prepared from this nanoparticle. The physical and chemical characteristics, as well as the emulsification properties of oxidized starch-xanthan gum composite nanoparticles (OGNP), were analyzed. The findings revealed that the OGNP retained spherical shape after the addition of XG, although their diameter increased from approximately 50–150 to 200–400 nm. Zeta potential decreased with XG content. Moreover, emulsions prepared from OGNP exhibited outstanding thermal stability, also showing enhanced storage stability. In addition, emulsions had different rheological properties at different pH values. The apparent viscosity and shear stress of emulsions under alkaline conditions were lower than that of neutral conditions. NaCl increased the apparent viscosity of OGNP-stabilized emulsions while reducing their thermal stability. The nanoparticles prepared in this study have efficient emulsification properties and can extend the application of OS.

Tilapia head gelatins to stabilize fish oil emulsions and the effect of extraction methods

The preparation and use of gelatins from fish by-products have attracted much attention in the field of food science. Herein, four types of tilapia head gelatins were extracted and characterized: hot water-pretreated gelatin (HWG), acetic acid-pretreated gelatin (AAG), sodium hydroxide-pretreated gelatin (SHG), and pepsin enzyme-pretreated gelatin (PEG). The gel strength values followed the order: PEG (74 ± 1 Bloom) > AAG (66 ± 1) > HWG (59 ± 1) > SHG (34 ± 1). The foaming properties, fish oil emulsion viscosity, emulsion activity, and emulsion stabilization ability followed this order: PEG > HWG ≥ AAG > SHG. The effect mechanisms of extraction methods and gelatin concentrations on the emulsion stability involved the interfacial tension, emulsion viscosity, and fat-binding capacity. This work provided important knowledge for analyzing the relations between the structure and function of gelatin. It also provided a high-value application method of fish wastes.

Multiscale approach to the characterization of the interfacial properties of micellar casein and whey protein blends and their effects on recombined dairy creams

In this study, whipped cream with blends of micellar casein (MCN) and whey protein (WPI) in different ratios were prepared to investigate the role of protein interfacial behavior in determining foam properties at multiple scales, using theoretical modeling, and microscopic and macroscopic analysis. Fluid force microscopy has been used for the first time as a more realistic and direct means of analyzing interfaces properties in multiphase systems. The adsorption kinetics showed that the interfacial permeability constant of WPI (4.24 × 10-4 s−1) was significantly higher than that of the MCN (2.97 × 10-4 s−1), and the WPI interfacial layer had a higher modulus of elasticity (71.38 mN/m) than that of the MCN (47.89 mN/m). This model was validated via the mechanical analysis of the fat globules in real emulsions. The WPI-stabilized fat globule was found to have a higher Young's modulus (219.67 Pa), which contributes to the integrity of its fat globule morphology. As the ratio of MCN was increased in the sample, however, both the interfacial modulus and Young's modulus decreased. Moreover, the rate of partial coalescence was found to increase, a phenomenon that decreased the stability of the emulsion and increased the rate of aeration. The mechanical analysis also revealed a higher level of adhesion between MCN-stabilized fat globule (25.16 nN), which increased fat globule aggregation and emulsion viscosity, while improving thixotropic recovery. The synergistic effect of the blended MCN and WPI provided the highest overrun, at 194.53 %. These studies elucidate the role of the interfacial behavior of proteins in determining the quality of whipped cream and provide ideas for the application of proteins in multiphase systems.

Wpływ temperatury złożowej i elementów składowych na parametry reologiczne emulsji wodno-ropnych

This article investigates the correlation between freezing temperature, viscosity, and oil deposit levels in samples from the Muradkhanli and Surakhany fields, as well as in model oils created under laboratory conditions, both in commodity and emulsion forms. The focus is on the influence of asphaltene-resin-paraffin compounds, the primary components of these samples. Laboratory experiments were conducted at temperatures of 10°C, 20°C, 40°C, and 60°C, utilizing crude oil samples with dilution levels ranging from 5% to 40% for emulsified oil. Freezing temperatures and viscosity values were determined using established standard methods, while the amount of paraffin deposits was assessed through the "Cold finger test" method. Analysis of numerous experiments revealed that freezing temperature, viscosity of water-oil emulsions, and paraffin deposit levels formed on cold surfaces primarily hinge on the temperature of emulsion formation and the water content percentage. It was also observed that water content affects the rheological properties of emulsions formed at 10°C and 20°C, while freezing temperature undergoes minimal changes. An increase in water content leads to heightened viscosity. However, in water-oil emulsions formed at 40°C and 60°C, rheological parameters exhibit different trends. Emulsions formed at 40°C demonstrate maximum freezing temperatures, accompanied by increased asphaltene-resin-paraffin deposits and viscosity across the temperature spectrum. Conversely, water-oil emulsions formed at 60°C exhibit minimal freezing temperatures, deposit content, and viscosity values. Thus, the analysis of water-oil emulsion group composition indicates that these emulsions are mainly stabilized and rendered stable by the presence of asphaltene-resin components.

Emulsifying and interfacial properties of glutenin processed by pH-shifting treatment

Modifying and improving protein functionality is crucial for expanding the application of proteins in the food industry. The aim of this study was to investigate the effect of pH-shift treatments on the emulsifying and interfacial properties of glutenin (Glu). Glu was exposed to acidic (pH 1–3) and basic (pH 10–13) pH values for 4 h and subsequently neutralized for refolding. The pH-shifting treatments significantly improved Glu surface wettability with three-phase contact angle from 66.21 ± 2.31° to 91.4 ± 0.88°. The alkali shift treatment resulted in samples with larger Kdiff values. The treated samples also showed amplitude and frequency dependence in their E, Ev, and Ed values, with higher E and Ed values indicating an elastic membrane at the interface. Emulsions prepared from Glu treated with alkali shift treatment exhibited smaller particle size, larger ζ-potential, and more stable storage properties. The rheological results indicated higher viscosity, thixotropy and creep of emulsions prepared from alkali shift treated Glu. In conclusion, treatment of Glu with alkali shift resulted in significant improvements in emulsifying and interfacial properties, suggesting that Glu may be a more promising ingredient for use in food.

Impact mechanism of active nanofluid on oil–water two-phase seepage during and after fracturing fluid invasion in tight oil reservoirs

Due to damage caused by fracturing fluid invasion, tight oil reservoirs exhibit slow post-hydraulic fracturing production recovery and low productivity. This study investigates the impact of a nanoclay-based active agent system on oil–water two-phase flow during and after fracturing fluid invasion, emphasizing its potential for enhancing recovery in tight oil reservoirs. Laboratory experiments using crude oil and natural core samples analyze the mechanism of how nanofluids affect oil–water distribution and flow characteristics during fracturing fluid invasion and oil recovery stages. Results show that nanofluids rapidly disrupt the emulsified state of “water-in-oil” emulsions, reducing emulsion viscosity by 84.19% and oil–water interfacial tension by two orders of magnitude, facilitating oil droplet dispersion and deformation and altering the wettability of oil-wet rock surfaces to aid crude oil detachment. Nanofluids increase the accessible volume of the water phase in pores and throats, enlarging flow paths for fracturing fluid flowback and oil recovery. The oil recovery process post-fracturing fluid invasion is delineated into three stages: substantial fracturing fluid flowback in the first stage, with nanofluids reducing the fluid return rate by 11.08% upon crude oil breakthrough; emulsion droplets occupying pores and throats in the second stage, with nanofluids reducing additional resistance during emulsion flow; and continuous oil production in the third stage, with nanofluids consistently and stably altering rock surface wettability to reduce invaded rock matrix resistance to oil flow. The findings of this study hold potential value in mitigating damage from fracturing fluid invasion in tight oil reservoirs.

Influence of Varying Oil-Water Contents on the Formation of Crude Oil Emulsion and Its Demulsification by a Lab-Grown Nonionic Demulsifier.

This study describes how varying oil/water contents affect emulsion formation and the impact they have on emulsion droplet size, viscosity, and interfacial behavior. Crude oil (continuous phase) volume fractions of 40, 50, 60, and 70 vol % were probed in the various W/O emulsions formed. Experimental results from optical morphology revealed the emulsion droplets kept reducing as the crude oil fraction kept increasing, while the droplets were nearly unnoticeable in the emulsions derived from 60 and 70% crude oil. The viscosity-shear rate of emulsions produced from 40, 50, and 60 vol % crude oil exhibited a non-Newtonian behavior owing to the substantial volume of water content in their emulsions, whereas the viscosity-shear rate of the emulsion with 70 vol % crude oil exhibited a Newtonian behavior similar to the pure crude oil, suggesting a thorough blending of oil-water at this crude oil fraction. Besides, the viscosity-temperature measurements revealed that the viscosity of these emulsions diminished as the temperature increased and the viscosity reduction became more noticeable in an emulsion comprising 70 vol % crude oil. In the interfacial assessment, the increased crude oil content in the produced emulsion led to a sharp reduction in the interfacial tension (IFT). The IFT values after 500 s contacts between the emulsion and water (surrounding phase) were 11.86, 10.02, 8.08, and 6.99 mN/m for 40, 50, 60, and 70 vol % crude oil, respectively. Demulsification experiments showed that water removal becomes more challenging with a large volume of crude oil and a small water content. Demulsification performances of the lab-grown nonionic demulsifier (NID) after 10 h of demulsification activity at room temperature (25 °C) were 98, 90, 17.5, and 10% for the emulsions formed from 40, 50, 60, and 70 vol % crude oil, respectively, indicating that the demulsification degree decreases with an increasing crude oil content. Viscosity-time determination was applied to affirm the activity of NID on the emulsion formulated with a 50% crude oil fraction. The injection of NID in this emulsion triggered a sharp viscosity reduction, indicating the adsorption of NID at the oil-water interface and disruption of emulsifiers, enabling emulsion stability.

Concentrated O/W Emulsion Stability of Non-Ionic Chitosan Oligomer Surfactants Modified by Epoxidized Fatty Chains at pH7: Influence of Emulsification Conditions

In this study, chitosan-based surfactants were synthesized by epoxy–amine chemistry to stabilize concentrated O/W emulsions at pH7. Chitosan was first depolymerized by nitrous deamination to obtain chitooligosaccharides (COS) with degrees of polymerization of 10 (DP10) and 20 (DP20). Then, three different epoxidized fatty chains, i.e., octyl/decyl glycidyl ether (C9), hexadecyl glycidyl ether (C16) and epoxidized cardanol (card), were grafted onto the amine groups of chitosan to form six amphiphilic structures. NMR measurements revealed grafting efficiencies ranging from 1 to 30% while HLB values ranged from 13 to 20. The relationships between these surfactant structures and their adsorption properties were investigated by tensiometric measurements, highlighting the need for a short hydrophilic moiety and high grafting efficiency to obtain the best adsorption. Subsequently, concentrated O/W emulsions (66% of oil) at pH7 were produced using COS-based surfactants and the impact of stirring time and speed during the emulsification process was described through rheological, droplet size and microscopy measurements. Finally, emulsions were stored over 2 months in order to study the destabilization phenomenon into the mixture, i.e., coalescence and creaming, by using laser granulometry and Turbiscan. Results demonstrated that stability could be enhanced by increasing emulsion viscosity, reducing droplet size or optimizing the adsorption layer at the O/W interfaces.

Design of Janus Nanoparticles for Mobility Control in Heterogeneous Reservoirs.

Unfavorable mobility ratios in heterogeneous reservoirs have resulted in progressively poor waterflood sweep efficiency and diminishing production. In order to address this issue, our study has developed amphiphilic-structured nanoparticles aimed at enhancing the microscopic displacement capability and oil displacement efficiency. First, the transport process of Janus nanoparticles in porous media was investigated. During the water flooding, Janus nanoparticle injection, and subsequent water flooding stages, the injection pressure increased in a "stepped" pattern, reaching 0.023, 0.029, and 0.038 MPa, respectively. Second, emulsification effects and emulsion viscosity experiments demonstrated that the amphiphilic structure improved the interaction at the oil-water interface, reducing the seepage resistance of the oil phase through emulsification. In porous media, Janus nanoparticles transported with water exhibit 'self-seeking oil' behavior and interact with the oil phase, reducing the viscosity of the oil phase from 19 to 5 mPa·s at 80 °C. Finally, the core model displacement experiment verified the characteristics of Janus nanoparticles in improving the oil-water mobility ratio. Compared with the water flooding stage, the recovery percent increased by 20.8%, of which 13.7% was attributed to the subsequent water flooding stage. Utilizing the asymmetry of the Janus particle structure can provide an effective path to enhanced oil recovery in inhomogeneous reservoirs.

Unraveling the emulsifying activity of bio-based ionic liquids in the formation and stabilization of oil-in-water emulsions

Bio-based ionic liquids (ILs), especially those derived from fatty acids (FAs) have been considered promising compounds for the agri-food and bioproduct industries, due to their sustainable appeal, possibly low or non-toxic effect and the nutritional value of FAs. However, studies have been mainly focused on the use of ILs as greener solvents. This work investigated the application of ILs derived from FAs and diethanolamine as emulsifiers to form and stabilize oil-in-water emulsions using ultraturrax (PM) and high-pressure homogenization (H). The influence of the IL type obtained from different FAs (stearic or oleic acids), and vegetable oil type (sunflower or olive oil) and concentration (30:70 or 70:30, oil:water phase ratio) on the formation and stabilization of emulsions was evaluated. This study was focused on the zeta potential of IL aqueous solutions in different pH conditions, interfacial tension between vegetable oils and IL aqueous solutions at different concentrations, kinetic stability, droplet size and size distribution, optical microscopy, viscosity profile and rheological behavior of the emulsions. ILs presented highly negative ZP charge (−12.97–−74.81), high emulsifying ability at low concentrations (1 %) and led to emulsions with high kinetic stability (>30 days). The electrostatic stabilization mechanism may predominate over the steric in IL-based emulsions. The stabilization of emulsions with ILs was associated to lower oil droplet size (D3,2 = 0.60–4.09 µm, D4,3 = 0.95–9.91 μm) and emulsion viscosity (4.8 mPa·s-1.13 Pa·s), which were related to the IL molecular structure, oil type and concentration, and process. Emulsions prepared with stearic-based IL and sunflower oil by PM+H presented higher kinetic stability. The proposed ILs are presented as highly effective emulsifiers with potential application in the agri-food, pharmaceutical and cosmetic industries.

Modelling W/O/W double emulsions preparation in static mixers: Accounting for the shear-thinning behaviour of the dispersed phase

The dispersion of a shear-thinning non-Newtonian fluid using in-line mixers to prepare double emulsions is investigated experimentally and numerically in this study. A two-step method is adopted for the preparation of double emulsions, comprising in a first step the preparation of a reverse water-in-oil (W/O) emulsion using a high-shear rotor-stator device. This inner emulsion is dispersed in a second step into an outer aqueous phase by continuous parallel pumping of both phases through a set of static mixers. The second preparation step is modelled using a population balance equation (PBE) accounting for droplet breakage inside the mixers. Since the inner emulsion behaves as a shear-thinning fluid, the breakage efficiency depends on the local shear rate. Using classical turbulent breakage kernels is therefore inappropriate, hence there is a need for a kernel accounting for the shear-thinning character of the dispersed phase. To tackle this issue, single-phase CFD simulations of the fluid flow through the mixers are carried out showing a high shear rate magnitude near the walls of the pipe and the mixer crossbars. To avoid CFD-PBE direct coupling, the probability density function (PDF) of the shear rate is extracted from the CFD simulations. This PDF is then used to develop a volume-averaged PBE, where a classical Ostwald-de Waele model is employed to relate the apparent viscosity of the inner emulsion to the shear rate. Different experimental parameters influencing the quality of the dispersion are investigated, including the fraction of the inner emulsion phase, the oil viscosity and the inner and outer aqueous phase viscosities. In the different cases, the model captures the transient evolution of the droplet size distribution of the W/O/W double emulsions at the outlet of the mixers while the computational time remains very low.

Rheological and microstructural characterization of lotus seed milks and their glucono-δ-lactone induced acid-set milk gels: 2. effect of oil addition

In a recent paper (Li, Li, Zhao, Cui, & Hemar, 2023) we showed that it was possible to manufacture lotus seed milks (LSM) and to use Glucono-δ-lactone (GDL) to prepare LSM acid-gels. LSM milks are known to have a very low lipid content, thus here the effect of soya oil addition is investigated in order to understand how LSM fortification with oil can affect its viscosity, and the mechanical and structural properties of the acid LSM gels. The oil was homogenized under conditions which resulted in oil droplets sizes in the range 0.1–0.4 μm. Heating the emulsions (80 °C, 30 min) resulted in a slight increase in particle size due to coalescence. The viscosity of emulsions was quasi-Newtonian and increased markedly with the increase in oil concentration. This was explained partly by the adsorption of the LSM aggregates at the interface of oil droplets, which increases considerably the effective volume fraction of the oil droplets. LSM emulsions when acidified by GDL formed colloidal gels with oil droplets embedded in the protein network, where the syneresis decreased with oil concentration, suggesting that the oil droplets should be considered as active fillers. The gel strength increased linearly with the oil concentration, but with a higher rate for the unheated emulsions than the heated ones. This is due to the decrease in the oil droplets number because of coalescence. This study demonstrates that homogenization of oil into LSM offers a route to manipulate the physico-chemical properties of the LSM emulsions and their acid gels.

A Feasibility Study on Enhanced Oil Recovery of Modified Janus Nano Calcium Carbonate-Assisted Alkyl Polyglycoside to Form Nanofluids in Emulsification Flooding.

Emulsification flooding can effectively enhance crude oil recovery to solve the problem of petroleum shortage. In this work, a modified Janus Nano Calcium carbonate (JNC-12) with a particle size of 30-150 nm was synthesized, and an in situ emulsification nanofluid (ISEN) was prepared with JNC-12 and alkyl polyglycoside (APG). Scanning electron microscope (SEM) showed that the dispersion of JNC-12 in air or APG solution was better than Nano Calcium carbonate (Nano CaCO3). The emulsification properties, interfacial tension, and expansion modulus of ISEN were studied, and the result showed that with the increase in salinity, the emulsification rate decreased, the water yield rate increased, the interfacial tension first decreased and then increased, and the expansion modulus first increased and then decreased. With the increase in temperature, the emulsification rate, emulsion viscosity, and interfacial tension decreased. With the increased oil-water volume, the water yield rate and the emulsion viscosity increased. With increase in the concentration of JNC-12, the water yield rate, the emulsion viscosity, and the interfacial tension decreased but the expansion modulus increased. The emulsion generated by emulsifying ISEN with crude oil was an O/W emulsion, the crude oil viscosity was 4-10 times that of emulsion, and the average particle size of emulsion was 1.107 μm. The addition of ISEN caused the decrease in interfacial tension of oil-water to 0.01-0.1 mN/m. The wettability alteration experiment found that ISEN could change the lipophilic rock to hydrophilic rock. Finally, the core displacement experiments showed that compared with the first water flooding, the oil recovery of the second water flooding after ISEN flooding enhanced by 17.6%. This research has important guiding significance for in situ emulsified nanofluid flooding to enhance oil recovery.

Plant-Based Oil-in-Water Food Emulsions: Exploring the Influence of Different Formulations on Their Physicochemical Properties.

The global focus on incorporating natural ingredients into the diet for health improvement encompasses ω-3 polyunsaturated fatty acids (PUFAs) derived from plant sources, such as flaxseed oil. ω-3 PUFAs are susceptible to oxidation, but oil-in-water (O/W) emulsions can serve to protect PUFAs from this phenomenon. This study aimed to create O/W emulsions using flaxseed oil and either soy lecithin or Quillaja saponins, thickened with modified starch, while assessing their physical properties (oil droplet size, ζ-potential, and rheology) and physical stability. Emulsions with different oil concentrations (25% and 30% w/w) and oil-to-surfactant ratio (5:1 and 10:1) were fabricated using high-pressure homogenization (800 bar, five cycles). Moreover, emulsions were thickened with modified starch and their rheological properties were measured. The physical stability of all emulsions was assessed over a 7-day storage period using the TSI (Turbiscan Stability Index). Saponin-stabilized emulsions exhibited smaller droplet diameters (0.11-0.19 µm) compared to lecithin (0.40-1.30 µm), and an increase in surfactant concentration led to a reduction in droplet diameter. Both surfactants generated droplets with a high negative charge (-63 to -72 mV), but lecithin-stabilized emulsions showed greater negative charge, resulting in more intense electrostatic repulsion. Saponin-stabilized emulsions showed higher apparent viscosity (3.9-11.6 mPa·s) when compared to lecithin-stabilized ones (1.19-4.36 mPa·s). The addition of starch significantly increased the apparent viscosity of saponin-stabilized emulsions, rising from 11.6 mPa s to 2117 mPa s. Emulsions stabilized by saponin exhibited higher stability than those stabilized by lecithin. This study confirms that plant-based ingredients, particularly saponins and lecithin, effectively produce stable O/W emulsions with flaxseed oil, offering opportunities for creating natural ingredient-based food emulsions.