Oil Droplet Diameter Research Articles

Nanohybrids from direct chemical self-assembly of poly(styrene-alt-maleic anhydride) as pH-responsive particulate emulsifiers.

The nanohybrid particulate emulsifiers based on poly(styrene-alt-maleic anhydride) (SMA) were facilely prepared via the direct chemical self-assembly triggered by the aminolysis of SMA with 3-aminopropyltriethoxysilane (APTES) and the in situ polycondensation of APTES under refluxing in acetone. Transmission electron microscopy and scanning electron microscopy confirmed the spherical-like morphology of the nanohybrids. Dynamic light scattering and electrophoresis revealed the structure transition of the nanohybrids in response to pH change. The emulsification study showed that the nanohybrids were effective particulate emulsifiers when homogenized with various oils including toluene, paraffin oil, silicone oil, isooctyl palmitate, dicaprylyl carbonate, and propylheptyl caprylate. The nanohybrid particulate emulsifiers exhibited pH-sensitivity, and the diameter of paraffin oil droplets remarkably increased with pH of the nanohybrid aqueous dispersion decrease. Also, the reduced dynamic interfacial tension predicted the thermodynamically unstable state of the emulsions prepared at high pH values. Most interesting, the paraffin oil-in-water high internal phase emulsions (HIPEs) with a high oil volume fraction of 83.3% were formed when the nanohybrids were heavily flocculated by adding HCl. The HIPEs were pH-responsive and capable of demulsification with the addition of an alkaline solution showing a potential application in the oil industry.

Gas–Liquid and Liquid–Liquid Mass Transfers in Simulated and Actual High Cell Density Fermentations

Mass transfer in microbial fermentation affects growth and product formation. Adequate mass transfer is particularly important in high cell density fermentation (HCDF). Gas–liquid and liquid–liquid mass transfers were investigated in high cell density aerobic fermentation of Candida rugosa with palm oil as a sole carbon and energy source. Established correlations were used to predict volumetric mass transfer of palm oil and oxygen in simulated and actual HCDFs, respectively. For liquid–liquid system, a good agreement was found between specific area a determined from oil droplet diameter measurement and theoretical consideration. Consequently, this allowed for reliable determination of kLa in this system. In gas–liquid mass transfer, somewhat larger range of variation was observed between kLa value obtained from theoretical determination and actual measurement. The differences highlighted an important gap in the understanding of complex gas–liquid dynamics of the highly useful HCDF system. The use of established correlations in actual HCDF highlighted both their utility and limitation.

Oil Produced Water treatment for oil removal by an integration of coalescer bed and microfiltration membrane processes

This article presents an experimental investigation of Oil Produced Water (OPW) treatment for oil removal by integration of two processes: coalescer bed and microfiltration membranes (MFs). The objective is to overcome operational problems and limitations that both the processes present when used separately.The coalescer bed was formed by cationic exchange resins, working in upflow condition. The MF unit used a polyetherimide hollow fiber submerged module with a permeation area of 0.5m2.The investigations were conducted by using synthetic OPW with oil concentrations of 200–400mgL−1 and oil droplet diameters from 3 to 8μm. In the coalescer bed the fluid velocity ranged from 4.4 to 17.4mh−1 and the bed height was 5cm. The water recovery rate in MF was kept in the range of 0.75–0.90 by using a transmembrane pressure varying from −12 to −30 kPa.The coalecer bed worked in steady state conditions, reaching an efficiency of 35–52%. The overall efficiency of the integrated process reached 93–100% and the oil contents ranged from 0.1 to 14.8mgL−1. These results indicate that the effluent in the integrated process has quality not only for injection, but also for reuse purposes.

A New Method for Determining the Emulsion Stability Index by Backscattering Light Detection

AbstractIn the present study, the Δbackscattering (ΔBS) method was developed as a simple and sensitive tool for determining the emulsion stability index (ESI) by backscattering light detection. The backscattering light detection method uses emulsion‐scanning technology to monitor physical behavior in an emulsion as a function of storage time. Emulsions were prepared by the homogenization (8,000 rpm for 2 min at 25C) of distilled water and perilla oil containing Tween 60, and the sample was quiescently incubated in a vial at 25C for 11 h. To confirm this new methodology, the sum of ΔBS at the clarified layer, obtained from the backscattering flux profiles over the storage period, was compared with the ESI determined by the volumetric method. Our backscattering light detection method was compared with the volumetric method based on the emulsifier content. The sum of ΔBS at the clarified layer decreased as the ESI decreased, with a correlation of 0.999, 0.993, 0.998 and 0.998 for emulsions stabilized with 200, 300, 400 and 500 μmol of emulsifier, respectively. Regardless of the emulsifier content in the emulsion, the R2 values for the fit curve, calculated by plotting the sum of ΔBS at the clarified layer against the ESI determined by the volumetric method, revealed strong linear relationship (R2 = 0.953). Our results suggest that the backscattering light detection method is a new tool for the quantitative determination of the ESI in an emulsion system.Practical ApplicationsThe acceptable way for the emulsion characterization is the determination of emulsion stability by measuring creaming rate and/or oil droplet diameter. Although the determination of oil droplet diameter provides the various information on the emulsion stability, it needs the expensive instruments based on dynamic light scattering or laser diffraction analysis. On the other hand, creaming is monitoring the change in the height of the boundary between the creamed and serum layers with naked eyes. In many cases, however, the condition of emulsions (such as their color, viscosity, and oil content, etc) prevents the clear reading of the boundary. The backscattering light detection described in this study could be a promising method which enables the accurate analysis of emulsion stability regardless of the limitations mentioned above.

Formulation and Evaluation of Avocado Oil Nanoemulsion Hydrogels Using Sucrose Ester Laureate

Nanoemulsion is a new class of emulsion with uniform and extremely small droplet sizes, typically in the range of 20-200 nm. Avocado oil was proven to be used as anti-aging and moisturizing agent. This study aimed to characterize nanoemulsion hydrogels prepared using avocado oil and sucrose ester laureate as surfactant. The nanoemulsion hydrogels were prepared by nanophase emulsification technique. These formulations were examined using zetasizer to determine the mean diameter of dispersed oil droplets, polydispersibility index (PDI) and zeta potential.The viscosity of the prepared nanoemulsion hydrogel was also studied. The results revealed that nanoemulsions prepared with 50% w/w oil, 30% w/w glycerol and 20% w/w surfactant showed droplets size below 200 nm with good polydispersibility index and zeta potential < -30 mV. The optimum formulation of nanoemulsion was prepared in the form of nanoemulsion hydrogel using carbopols 934 and 940. The results of the rheology for the nanoemulsion hydrogel showed that the storage modulus (G) which describes the elasticity of the component were greater than the loss modulus (G) values that reveals the viscosity of the component.

Dynamic processes of indigenous microorganisms from a low-temperature petroleum reservoir during nutrient stimulation

Compared to medium-high temperature petroleum reservoirs (30°C-73°C), little is known about microbial regulation by nutrients in low-temperature reservoirs. In this study, we report the performance (oil emulsification and biogas production) and community structure of indigenous microorganisms from a low-temperature (22.6°C) petroleum reservoir during nutrient stimulation. Culture-dependent approaches indicated that the number of hydrocarbon-oxidizing bacteria (HOB), nitrate-reducing bacteria (NRB) and methane-producing bacteria (MPB) increased by between 10- and 1000-fold, while sulfate-reducing bacteria (SRB) were observed at low levels during stimulation. Phylogenetic analysis of the 16S rRNA gene indicated that Pseudomonas, Ochrobactrum, Acinetobacter, Halomonas and Marinobacter, which have the capability to produce surfactants, were selectively enriched. Methanoculleus, Methanosaeta, Methanocorpusculum and Methanocalculus showed the largest increase in relative abundance among archaea. Micro-emulsion formed with an average oil droplet diameter of 14.3μm (ranging between 4.1μm and 84.2μm) during stimulation. Gas chromatographic analysis of gas production (186mL gas/200mL medium) showed the levels of CO2 and CH4 increased 8.97% and 6.21%, respectively. Similar to medium-high temperature reservoirs, HOB, NRB, SRB and MPB were ubiquitous in the low-temperature reservoir, and oil emulsification and gas production were the main phenomena observed during stimulation. Oil emulsification required a longer duration of time to occur in the low-temperature reservoir.

Biocompatible nanodispersions as delivery systems of food additives: A structural study

Nanodispersions based on food grade biocompatible materials were developed and structurally characterized to be used as carriers of bioactive compounds with specific nutritional value. The main idea was to formulate concentrated solutions of specific food components at the nanoscale to be consumed either on their own or as integrating parts of classic foods, upon aqueous dilution. For this purpose microemulsions consisting of (R)-(+)-limonene/ethanol/Tween 40/water/propylene glycol were formulated in the presence and in the absence of squalene, gallic acid and octyl gallate. The limits of the single-phase region as described by pseudo-ternary phase diagrams were related to the nature of the food additive. The more extended monophasic region was obtained when octyl gallate was added in the system. Interfacial properties of the microemulsions were studied by electron paramagnetic resonance (EPR) spectroscopy employing the nitroxide spin probe 5-doxylstearic acid (5-DSA). In general guest molecules decreased the flexibility of the surfactant monolayer as manifested from the calculation of rotational correlation time (τR) and order parameter S of 5-DSA. Particle size measurements were performed using dynamic light scattering (DLS) and oil droplet diameters in the range of 11.7 to 17.4nm were observed. The addition of squalene resulted in the formulation of larger oily droplets whereas octyl gallate formed smaller ones. Finally SAXS experiments provided qualitative information of o/w microemulsions showing squalene solubilization in the dispersed oily phase, octyl gallate localization on the membrane and gallic acid solubilization in the continuous aqueous phase.

Preparation of micro- and nano-emulsions of soybean oil and removal of sorbed phenanthrene from sandy soil

Soybean oil was used as a biodegradable extracting agent for the removal of sorbed phenanthrene (PHE) in sandy soil. In this study, several methods of forming emulsions using soybean oil and their extraction properties were investigated. The stable and homogeneous oil emulsions were formed more effectively by ultrasonication (U1) than by homogenization (H1). Moreover, homogenization before ultrasonication (HU1) established more stable emulsions than U1 alone. The mean diameter of oil droplets in U1 or HU1 was reduced to the nanometer range (approximately 70 nm) by U1 with 750W using a high-power sonic tip operated at 33% amplitude and 20 kHz frequency for 5 min. The extraction efficiency of sorbed PHE from soil by oil emulsions increased with decreasing size of droplets of oil emulsions; the maximum extraction of PHE was achieved with HU1. Thus, nano-emulsions of vegetable oil made by U1 could be an environmentally benign alternative for effectively washing soil.

The ultrasonic measurement of high water volume fraction in dispersed oil-in-water flows

The oil–water two-phase flow experiment was carried out in a vertical upward pipe to study the responses of the pulsed ultrasonic sensor and vertical multiple electrode array sensor. Based on the finite element calculation, it is found that the calculated ultrasonic levels are very sensitive to the concentration variations of dispersed oil phase, and the oil droplet diameter can affect the ultrasonic field. Moreover, the technique of symbolic dynamic filtering is used to analyze the ultrasonic fluctuating signals, and extract the anomaly flow measure from the signals of ultrasonic sensor. The results show that, the anomaly flow measure linearly increases when the oil volume fraction yo is lower than 0.35. However, for higher oil volume fraction (yo>0.35) the variation of flow measure presents an irregular distribution with the change of oil volume fraction. These interesting and significant findings suggest that the pulsed ultrasonic technique can potentially be a powerful tool for measuring the high water volume fraction of dispersed oil-in-water two-phase flows.

Microcapsule production employing chickpea or lentil protein isolates and maltodextrin: Physicochemical properties and oxidative protection of encapsulated flaxseed oil

Flaxseed oil was microencapsulated, employing a wall material matrix of either chickpea (CPI) or lentil protein isolate (LPI) and maltodextrin, followed by freeze-drying. Effects of oil concentration (5.3–21.0%), protein source (CPI vs. LPI) and maltodextrin type (DE 9 and 18) and concentration (25.0–40.7%), on both the physicochemical characteristics and microstructure of the microcapsules, were investigated. It was found that an increase in emulsion oil concentration resulted in a concomitant increase in oil droplet diameter and microcapsule surface oil content, and a decrease in oil encapsulation efficiency. Optimum flaxseed oil encapsulation efficiency (∼83.5%), minimum surface oil content (∼2.8%) and acceptable mean droplet diameter (3.0μm) were afforded with 35.5% maltodextrin-DE 9 and 10.5% oil. Microcapsules, formed by employing these experimental conditions, showed a protective effect against oxidation versus free oil over a storage period of 25d at room temperature.

Design of microstructure of zirconia foams from the emulsion template properties

In this work, we investigate the correlations between structural and rheological properties of emulsified aqueous sol and the porous microstructure of monolithic zirconia foams, manufactured by the integrative combination of the sol–gel and emulsification processes. Macroporous zirconia ceramics prepared using different amounts of decahydronaphthalene, as oil phase, are compared in terms of the emulsion microstructure and ceramic porosity. A combination of electrical conductivity, oil droplet diameter, and rheological measurements was used to highlight the key effect of the dynamic structural properties of the emulsion on the porosity of the ceramic zirconia foam. The minimization of drying shrinkage by appropriate sol–gel mineralization of the oil droplet wall enabled versatile and easy tuning of the ceramic foam microstructure, by fine adjustment of the emulsion characteristics. The foam with the highest porosity (90%) and the lowest bulk density (0.40 g cm−3) was prepared from emulsion with 80 wt% of decahydronaphthalene, which also showed a bicontinuous structure and elevated flow consistency.

Preparation of Microcapsules with Liquid Droplet Coalescence Method Followed by Phase Separation

Novel preparation method of microencapsules was developed on the basis of the liquid coalescence method followed by phase separation. Oil droplets of limonene dissolving expanded polystyrene as a shell material were forced to collide and coalesce with the Isopar oil droplets of core material in the continuous wates phase. When two kinds of oil droplets are collided and coalesced with each other, expanded polystyrene dissolved in the limonene oil may be phase-separated in the oil droplets newly formed to form the microcapsule shell, because the Isopar oil was a poor solvent for expanded polystyrene but a good solvent for the limonene oil. In the experiment, the diameter (or number) of limonene oil droplets dissolving expanded polystyrene was mainly changed, because the coalescence frequency between the droplets is strongly dependent on the number of droplets. Favorable core shell types of microcapsules with the shell thickness from 1.0 to 5.0 μm were able to be prepared under all the experimental conditions adopted here.

Cascade partial coalescence phenomena at electrolyte–oil interfaces and determination of bounds for the surface potential

Small oil droplets (diameter <500 μm) in slow, steady, buoyancy-driven rise through pure or salty water at neutral pH exhibit a cascade partial-coalescence phenomenon upon soft collision with quasi-planar aqueous electrolyte solution–oil interfaces. For droplets of pure toluene, n-heptane, and their mixtures (heptol), and for moderate-strength electrolytes, the cascade partial-coalescence process continues until a critical droplet size is reached. We infer that this outcome is due to the oil–water interface being electrically charged and use the last partial-coalescence event in the sequence to estimate lower- and upper-bounds for the absolute value of the electrical potential of the interface.

HYDROCYCLONE APPLICATIONS IN PRODUCED WATER: A STEADY-STATE NUMERICAL ANALYSIS

Hydrocyclones are devices used to treat produced water in the petroleum industry. These gadgets are employed especially at offshore fields, due to restrictions of charge and space. Several factors may affect the performance of the oil/water separation by hydrocyclones. Among these factors are the geometry and processing capacity of the hydrocyclones, oil droplet size, density difference between the phases, pressure drops, and temperature fluctuation. This paper aims to analyze the effects of inlet fluid mixture temperature and oil droplet size on hydrocyclone performance in separating dispersed heavy oil from continuous streams of water. The experiment used a commercial package, ANSYS CFX 11. Numerical results clearly indicate that superficial velocity and oil mass flow rate in the overflow have a positive relationship with oil droplet size and temperature. The pressure drop decreased from 155.857 to 141.966kPa and the separation efficiency changed from 58.97 to 60.11% when the inlet temperature increased from 20 to 100°C using a 40μm oil droplet diameter.

Stabilization of multilayered emulsions by sodium caseinate and κ-carrageenan

The influence of the κ-carrageenan concentration and pH on the properties of oil-in-water multilayered emulsions was studied. Multilayered emulsions were prepared by the mixture of a primary emulsion stabilized by 0.5% (w/v) sodium caseinate (Na-CN) with κ-carrageenan solutions with different concentrations (0.05–1% w/v). The emulsions were evaluated at pH 7 and 3.5. At pH 7, there was little adsorption of κ-carrageenan onto the droplet surface and a depletion flocculation was observed when the polysaccharide concentration exceeded 0.5% (w/v). At pH 3.5, a mixed κ-carrageenan–Na-CN second layer was formed around the protein-covered droplets and the emulsions showed bridging flocculation at lower polysaccharide concentrations (0.05–0.25% w/v). Stable emulsions could be formed with the highest κ-carrageenan concentration (1% w/v) at both pH values (7.0 and 3.5). Thus, stable emulsions were successfully produced using protein–polysaccharide interfacial complexes, and the oil droplet diameter, zeta potential and rheological properties of these emulsions were not affected by changes in the pH.

Enhancing saltiness in emulsion based foods

Abstract Background The concept of enhancing saltiness perception in emulsions and a liquid food formulated with the emulsions (ambient vegetable soup) through increasing salt concentration in the continuous phase while retaining the fat content of the (aqueous continuous) product was evaluated. This was accomplished by increasing the droplet phase volume using duplex emulsion technology. Viscosity and droplet size distribution was measured. Saltiness evaluation was based on simple paired comparison testing (2-Alternate Forced Choice tests, BS ISO 5495:2007). Results Single and duplex emulsions and emulsion-based products had comparable mean oil droplet diameters (25 to 30 μm); however, viscosity of the duplex emulsion systems was considerably higher. Sensory assessment of saltiness of emulsion pairs (2AFC) indicated duplex technology enhanced saltiness perception compared to a single emulsion product at the same salt content (6.3 g/100 g) in both simple emulsions and the formulated food product (P = 0.0596 and 0.0004 respectively) although assessors noted the increased viscosity of the duplex systems. The formulated food product also contained pea starch particles which may have aided product mixing with saliva and thus accelerated tastant transport to the taste buds. Lowering salt content in the duplex systems (to levels of aqueous phase salt concentration similar to the level in the single systems) resulted in duplex systems being perceived as less salty than the single system. It appears that the higher viscosity of the duplex systems could not be “overruled” by enhanced mixing through increased droplet phase volume at lowered salt content. Conclusions The results showed that salt reduction may be possible despite the added technology of duplex systems increasing the overall measured viscosity of the product. The changes in viscosity behavior impact mouthfeel, which may be exploitable in addition to the contribution towards salt reduction. With a view to applying this technology to real processed foods, it needs to be tested for the product in question but it should be considered as part of a salt reduction tool box.

Stabilization of acidic soy protein-based dispersions and emulsions by soy soluble polysaccharides

Soy soluble polysaccharides (SSPS) are shown to prevent destabilization of soy protein isolate (SPI) dispersions and SPI-based oil-in-water (O/W) emulsions under acidic conditions. Addition of SSPS above a critical concentration (0.25 wt%) increased the stability of 0.50 wt% SPI dispersions against aggregation and phase separation under conditions where SPI would normally precipitate (near its isoelectric point). Though SSPS neutralized SPI surface charge via electrostatic interaction, there was increased stability against aggregation due to steric repulsion. At acidic pH, addition of 1 wt% NaCl electrostatically screened protein–polysaccharide complexation which led to SPI precipitation and sedimentation. However, the order of salt addition had a significant impact on charge screening, with salt added before pH adjustment reducing SPI–SSPS complexation whereas it had less effect when added afterwards. Salt penetration efficacy diminished with decreasing pH. O/W emulsions (5 wt% oil) prepared with 0.50 wt% SPI destabilized at pH 4–5 due to protein aggregation, but addition of ≥0.25 wt% SSPS improved emulsion stability by inhibiting protein–protein interactions thus limiting increases in oil droplet diameter over time. Overall, both dispersion and emulsion stability greatly depended on pH, ionic strength and SSPS concentration. These results demonstrated that SSPS could effectively stabilize acidic SPI dispersions and that SPI–SSPS interactions may be used as a tool to improve the kinetic stability of SPI-based O/W emulsions.

PH-dependent characteristics of gel-like emulsion stabilized by threadfin bream sarcoplasmic proteins

Threadfin bream sarcoplasmic proteins (TBSP) were identified by 2-dimensional polyacrylamide gel electrophoresis and the major proteins were likely be pyruvate kinase, creatine kinase, aldolase, and carbonic anhydrase. Emulsifying and rheological properties of emulsion stabilized by TBSP at pH 3, 7.5, and 12 were investigated. Surface hydrophobicity of TBSP increased with pH. Emulsifying activity index was highest at pH 3 followed by pH 12 and pH 7.5. The mean droplet diameter (d3,2) was in the order of pH 7.5 > pH 3 > pH 12 at oil volume fraction ranging from 0.1 to 0.5. A decrease of oil volume fraction resulted in a reduction of oil droplet diameter. At oil volume fraction of 0.5, TBSP-stabilized emulsion at pH 7.5 and 12 exhibited gel-like characteristics, while liquid emulsion was observed at pH 3, based on visual observation and dynamic rheological analysis. Storage modulus (G′) values of emulsion at all studied pH values increased with temperature, implying the development of protein gel network upon heating. The gel-like emulsion at pH 12 absorbed more protein and water than at pH 7.5. Protein retention and water holding capacity of emulsion increased with oil volume fraction. Hydrophobic interactions between proteins and oil droplets were likely responsible for the development of a gel-like emulsion.

Structural Properties Induced by the Composition of Biocompatible Phospholipid-Based Microemulsion and Amphotericin B Association

Anionic microemulsions (MEs) containing soya phosphatidylcholine, Tween-20, sodium oleate as surfactant, and cholesterol as oil phase were investigated as drug carriers for amphotericin B. Depending on the composition of the microemulsion, various structures, which differently interact with amphotericin B, can be formed. The nanostructured systems were characterized by photon correlation spectroscopy, rheological behavior, and polarized light microscopy. The results reveal that the droplet diameters increased with amphotericin B incorporation for all ranges of surfactant and oil phase. For both amphotericin B-unloaded and amphotericin B-loaded microemulsions, the profile of the oil droplet diameter decreased with increasing the surfactant concentration, demonstrating the stabilizing effect of the surfactant. The increase in the oil phase proportions led to the growth of the droplet diameter, clearly demonstrating the limit of the surfactant organization in the oil-water interface. The amphotericim B incorporation into microemulsion increased with the fraction volume of the oil phase and the surfactant concentration reaching a plateau at high contents. This profile could be quantitatively analyzed by the framework of the pseudo-phase model that considers the amphotericim B distribution between the oil and the aqueous phases. The rheological analysis showed a pseudoplastic behavior with little thixotropic characteristic. Under polarized light, the system of interest showed a dark background characteristic of dispersed droplets. However, for both amphotericim B-loaded and amphotericim B unloaded microemulsions, the increase in the O/S ratio led to the formation of ordered structures with lamellar arrangements.

Nanoemulsion formulation of fisetin improves bioavailability and antitumour activity in mice

The natural flavonoid fisetin (3,3′,4′,7-tetrahydroxyflavone) has shown antitumour activity but its administration is complicated by its low water solubility. Our aim was to incorporate fisetin into a nanoemulsion to improve its pharmacokinetics and therapeutic efficacy. Solubility and emulsification tests allowed to develop an optimal nanoemulsion composed of Miglyol® 812N/Labrasol®/Tween® 80/Lipoid E80®/water (10%/10%/2.5%/1.2%/76.3%). The nanoemulsion had an oil droplet diameter of 153±2nm, a negative zeta potential (−28.4±0.6mV) and a polydispersity index of 0.129. The nanoemulsion was stable at 4°C for 30 days, but phase separation occurred at 20°C. Pharmacokinetic studies in mice revealed that the fisetin nanoemulsion injected intravenously (13mg/kg) showed no significant difference in systemic exposure compared to free fisetin. However, when the fisetin nanoemulsion was administered intraperitoneally, a 24-fold increase in fisetin relative bioavailability was noted, compared to free fisetin. Additionally, the antitumour activity of the fisetin nanoemulsion in Lewis lung carcinoma bearing mice occurred at lower doses (36.6mg/kg) compared to free fisetin (223mg/kg). In conclusion, we have developed a stable nanoemulsion of fisetin and have shown that it could improve its relative bioavailability and antitumour activity.