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Effect of Ultrasonication on Stability of Oil in Water Emulsions.


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Effect of ultrasonic waves on stability of oil in water system of light liquid paraffin oil (HLB = 12) as internal phase and tween20 (HLB = 16.7), span20 (HLB = 8.6) as emulsifying agents was studied. A comparison was made to determine the stability of emulsions prepared by mechanical agitation method and ultrasonication technique. Droplet size measurement method was used to determine the stability of emulsions. Physico-chemical parameters like concentration of emulsifying agent, volume fraction of dispersed phase, viscosity of continuous phase by adding glycerin to water were compared apart from the effect of emulsification time on stability of emulsions prepared with mechanical stirring and ultrasound. Ocular micrometer was used to determine the droplet size of the dispersed phase. Emulsions prepared by ultrasonic technique were found to be more stable for longer duration of time when compared to emulsions prepared by mechanical agitation which can be attributed to the small droplet size which is thermodynamically stabilized. Ultrasonic technique gave more stable emulsions than with mechanical agitation method. Emulsification time, volume fraction of dispersed phase, viscosity of continuous phase and concentration of emulsifying agents played a major role in the stability of emulsions.
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International Journal of Drug Delivery 3 (2011) 133-142
Research Article
Effect of Ultrasonication on Stability of Oil in Water Emulsions
Kiran A. Ramisetty1 and R. Shyamsunder1*
*Corresponding author:
R. Shyamsunder
1University College of
Technology, Dept of
Pharmaceuticals and Fine
Osmania University,
Hyderabad, India.
Effect of ultrasonic waves on stability of oil in water system of light
liquid paraffin oil (HLB = 12) as internal phase and tween20 (HLB =
16.7), span20 (HLB = 8.6) as emulsifying agents was studied. A
comparison was made to determine the stability of emulsions
prepared by mechanical agitation method and ultrasonication
technique. Droplet size measurement method was used to determine
the stability of emulsions. Physico-chemical parameters like
concentration of emulsifying agent, volume fraction of dispersed
phase, viscosity of continuous phase by adding glycerin to water
were compared apart from the effect of emulsification time on
stability of emulsions prepared with mechanical stirring and
ultrasound. Ocular micrometer was used to determine the droplet
size of the dispersed phase.
Emulsions prepared by ultrasonic technique were found to be more
stable for longer duration of time when compared to emulsions
prepared by mechanical agitation which can be attributed to the
small droplet size which is thermodynamically stabilized.
Ultrasonic technique gave more stable emulsions than with
mechanical agitation method. Emulsification time, volume fraction
of dispersed phase, viscosity of continuous phase and concentration
of emulsifying agents played a major role in the stability of
Keywords: Liquid paraffin, Tween 20, Span 20, emulsification,
ultrasound technique, volume fraction of dispersed phase..
In an emulsion system, the finely divided droplets
are referred to as the dispersed phase,
discontinuous or internal phase; the liquid
surrounding the droplets is called the non-
dispersed phase, continuous phase or external
phase. The addition of a third component acting
at the interface to retard phase separation is called
emulsifier or emulsifying agent.
Since emulsions, in most instances, are two-phase
systems, it is customary to define the type of
emulsion by considering whether the oil is in the
internal or external phase. If the oil is in the
internal phase, the emulsion type will be an oil-
in-water, o/w; or, conversely, if the water is in the
internal phase, water-in-oil, w/o; type is achieved.
Secondary emulsion (multiple-emulsion): it
contains two internal phase, for instance, o/w/o or
w/o/w. It can be used to delay release or to
increase the stability of the active compounds.
ISSN: 0975-0215
doi:10.5138/ ijdd.2010.0975.0215.03063
©, All rights reserved.
Ramisetty et al. International Journal of Drug Delivery 3 (2011) 133-142
The first objective to be attained in emulsification
is to reduce the internal phase (oil or water) into
small globules [3-6]. This can be accomplished
only if an external source of energy in the form of
work is supplied. The energy may be in the form
of human or mechanical work. Theoretically, it is
possible to calculate the energy required to
produce a quantity of an emulsion having a
definite particle size by the use of the equation
Where W is the free surface energy in ergs is, is
the surface tension in dynes/cm, and , the
surface area in cm2. The work necessary to
produce an emulsion of a specific volume and
particle size may be reduced if the internal
tension ( ) is lowered [8-9]. This may be
accomplished by the addition of an emulsifying
agent having surface-active properties. The
selection of an emulsifying agent, which lowers
the interfacial tension considerably, will be an
important factor to consider when emulsification
is desired [10-12]. However, it is not necessarily
true that those agents who are not markedly
reducing the interfacial tension are poor
emulsifying agents [13].
Surface orientation
At the interface of oil and water, the molecule
must posses a polar group and a nonpolar group,
both of about equal magnitude. In this particular
case, the molecule would orient itself in such a
way that the polar group (hydrophilic head) will
face the water, while the nonpolar group
(hydrophilic tail) faces the oil [14-19]. Consider
now the case of a molecule having a very large
polar group in comparison to the non-polar
group. This type of molecule will be more soluble
in the water and, thus, will move away from the
oil and enter the main portion of the water. The
molecule with a large nonpolar group will
migrate into the main portion of the oil phase
Experience has shown that emulsifying agent
having a greater degree of hydrophilic property
than hydrophobic will usually produce an oil in
water emulsion, while a more hydrophilic
surface-active agent will usually give water in oil
emulsion [20-23]. Bancroft noted this tendency a
number of years ago and concluded that the phase
in which the emulsifying agent was more soluble
would be the continuous or the external phase
Materials and methods
Light liquid paraffin oil (Sd Fine-chem. ltd),
Tween 20 (polyoxyethylene sorbitan mono
oleate), Span 20 (Sorbitan monooleate), Glycerin,
distilled water, ocular microscope with stage
Preparation of Emulsions
By mechanical agitation method
An emulsion of 60ml was prepared by taking,
20% of light liquid paraffin oil and span20 in a
beaker and tween20 was added to 77% of
distilled water in another beaker as tween20 is
miscible in water and span20 is oil miscible
followed by pouring dispersed phase to
Ramisetty et al. International Journal of Drug Delivery 3 (2011) 133-142
continuous phase. Here percentage of
emulsifying agent was kept to 3%. This
composite solution was then subjected to
mechanical agitation by placing the agitator at the
middle of interface between the dispersed phase
and continuous phase, at 1000 RPM. Proper
mixing of the phases gives the good emulsion
which is white in color.
By Ultrasonication method
Emulsion with above concentrations was
prepared by applying the ultrasound using
sonicator with adjustable height hadle with
operating frequency of 20 KHz at 3mm of depth
from the surface of the emulsion solution. Time
of insonation is variable, which was measured by
using stopwatch. Temperature of the sample was
measured with thermometer, as time of
insonation increases the temperature of the
emulsion will increases. Emulsion prepared from
ultrasonicator is milky white in colour.
Evaluation of emulsions
In this experiment, a study was made to compare
the stability of emulsion prepared by two
different methods i.e. mechanical stirring and
ultrasonic horn tip method by examining the
following physicochemical parameters affecting
the emulsion stability.
1. Effect of stirring time and irradiation
2. Effect of volume fraction emulsifying
3. Effect of volume fraction of oil phase or
dispersed phase.
4. Effect of viscosity of continuous phase.
Effect of stirring time and irradiation time
Effect of time was studied on emulsions stability
at fixed amount of emulsifying agent and fixed
volume fraction of dispersed phase. Here 20% of
dispersed phase volume and 3% of the
emulsifying agent is used in total amount of 60ml
oil. Volume fraction of dispersed phase φ = 0.2
and Volume of the dispersed phase is 12ml. Total
amount emulsifying agent used is 3% means
1.8ml. in this volume fraction tween20 is 42%
means 0.756ml and volume fraction span20 is
58% means 1.048ml. And continuous phase
volume is 46.2ml.
Eight samples were taken and subjected to
mechanical stirring at 1000rpm by varying the
time from 1, 2, 3, 4, 5, 6, 7 and 8minutes.
Similarly another eight samples of same
compositional biphasic mixture were subjected to
ultrasoincation by ultrasound horn tip, at 20 KHz
frequency with increasing the time of insonation
in the range of 1, 2, 3, 4, 5, 6, 7 and 8 minutes.
Immediately after completion of emulsification
1ml of emulsion sample was taken and diluted
with 10ml of water in a test tube and was
observed under microscopic stage micrometer to
observe the number of droplets in the
microscopic premises. By counting this number
of droplets the average droplet size was measured
by sauter diameter.
32 = Σ ni di3/ Σ ni di2
Effect of volume fraction of emulsifying agent
Effect of volume fraction of the emulsifying
agent was studied by keeping the time of
emulsification (5min) and volume of the
dispersed phase (φ = 0.2) as constant. The
volume fraction of the emulsifying agent was
varied from 3% to 15% and were subjected to
emulsification by mechanical and ultrasonic
method. Finally the droplet size of the emulsion
was measured by stage micrometer as mentioned
Effect of volume fraction of oil phase or
dispersed phase:
In this experiment emulsification time (5minutes)
and volume fraction of emulsifying agent (9%)
were kept constant with varying concentrations
volume fraction of dispersed phase. In order to
prevent the phase inversion, the total percentage
of oil was not exceeded more than 40%. The
prepared emulsions were subjected to
emulsification by mechanical and ultrasonic
method. Finally the droplet size of the emulsion
Ramisetty et al. International Journal of Drug Delivery 3 (2011) 133-142
was measured by stage micrometer as mentioned
Effect of continuous phase viscosity
Viscosity of the solution was measured by using
broke field viscometer. From the experiments
considering the emulsification time, amount of
emulsifying agent and volume fraction of the
dispersed phase were kept constant, now by
adding the glycerin to the water increased the
viscosity of the continuous phase. In this process
the volume fractional volume of emulsifying
agent was 0.9 means 5.4ml, volume fraction of
the dispersed phase is φ = 0.2 means 12ml, time
of emulsification was 5minutes. To the remaining
amount of 42.6ml of water, glycerin was added in
the volume fraction 0.5, 1.0, 1.5 and 2.0 volume
continuous phase. After the emulsions were
prepared by mechanical agitation and ultrasonic
method, the viscosity of the prepared emulsions
was determined by viscometer followed by
droplet size measurement using stage micrometer
method as discussed earlier.
From the above experiments, a graph was plotted
taking volume % of droplets and droplet size in
microns with time of mechanical agitation or time
of sonication applied to the sample.
Results and discussion
Effect of stirring time and irradiation time
By comparing the above figures (1 and 2)
obtained for droplet size distribution of the
droplets of emulsions, prepared from mechanical
stirring, and ultrasonic irradiation, it can be
observed that, as the emulsification time is
increased the droplets distribution curve become
narrow in shape, which indicates that number of
droplets in uniform size in this narrow range are
more and hence the stability of emulsion will be
more. At minimum time of stirring or irradiation
the droplet size distribution curve, become wider
in range indicating droplets in this region are less
in number, with wide spread of non uniform
particles size distribution. As the time of
emulsification was increased from 1min to 8min
droplet distribution is in narrow range, increasing
the stability of emulsions. As the time of
sonication was increased temperature of the
emulsion was found to increase which can be
attributed to physical effect of ultrasonic
Ramisetty et al. International Journal of Drug Delivery 3 (2011) 133-142
Figure 1: Volume of drop size distribution with emulsification time by mechanical stirring at constant emulsifying agent (3%)
and volume fraction (φ = 0.2) of the oil.
Figure 2: Volume of drop size distribution with emulsification time by ultrasonic irradiation at constant emulsifying agent (3%)
and volume fraction (φ = 0.2) of the oil.
With an increase in the temperature, the
interfacial tension as well as the viscosity is
expected to decrease considerably. The decrease
in the interfacial tension is observed to set in the
interfacial instability, which increases the number
of dispersed phase droplets. With an increase in
temperature, the number of nuclei giving rise to
cavitation may increase due to an increase in the
vapour pressure of the cavitation medium. With
an increase in the cavitational events and
intensity, the breakage of large droplets to form
small droplets is observed to be increasing. When
the power is kept constant at 30 W, the droplets
formed are initially small. They show a slight
increase in size at a time of 1 min and then go on
reducing if irradiated further until 8 min.
Effect of volume fraction of emulsifying agent
The surfactant plays a critical role in both droplet
break-up and coalescence. The surfactant aids
droplet break-up by lowering the interfacial
tension, which reduces the resistance to droplet
deformation. The most important role of the
surfactant is to prevent the immediate re-
coalescence of newly formed droplets by rapid
adsorption to, and stabilization of, the newly
formed interface.
Invariably the requirements of both droplet
break-up and coalescence dictate that small
molecule surfactants are the most suited to the
formation of nano-emulsions because of their
greater ability to rapidly adsorb to interface and
their much lower dynamic interfacial tensions. As
observed from the Figures (3 and 4), with the
increase in the surfactant concentration from 3%
to 9%, the particle size of the droplets was found
to decrease up to 15% giving narrow particle size
distribution. As the emulsifying agent amount
increases it surrounds the oil droplets uniformly
decreasing the interfacial tension between the oil
droplets. With the increase in the emulsifying
Ramisetty et al. International Journal of Drug Delivery 3 (2011) 133-142
agent concentration resulted in the formation of
more stable emulsions with ultrasonicator than in
the mechanical stirring.
Figure 3: Effect of emulsifying agent on droplet size distribution of emulsions prepared from mechanical stirring.
Ramisetty et al. International Journal of Drug Delivery 3 (2011) 133-142
Figure 4: Effect of emulsifying agent on droplet size distribution of emulsions prepared from ultrasonication
Effect of volume fraction of oil phase or
dispersed phase:
From Figures (5 and 6) it can be observed that
with the increase in the volume fraction of the
dispersed phase the droplet size of the oil phase
was found to increase in both mechanical
agitation and ultrasonication method. The droplet
size of the oil phase in mechanical agitation
varied from 13.9 to 25.1µm while in
ultrasonication method it varied in the range of
1.29 to 4.21 µm. As the volume fraction of
dispersed phase increases viscosity of dispersed
phase increases then it is hard to break the oil
droplets, and it is observed that droplet size is
decrease in ultrasound than in the mechanical
stirring because it requires more power to break
the oil droplets and penetrate the droplets into the
continuous phase. Mechanical stirring could not
give required energy to break oil droplets. Using
ultrasonic irradiation fragmentation of the
droplets becomes more. However, at the starting
of insonation it is hard to form a cavity bubble.
This cavity bubble increases rapidly and collapse
then the rupturing of the oil droplets becomes
more. As the dispersed phase concentration
increases, it requires more time to rupture the
droplets. So size of the droplets increases by
further addition of oil content. From the graphs, it
can be observed that as the dispersed phase
fraction increases droplet size distribution
becomes wider with increase in mean number of
droplets having non-uniform size. As the non
uniformity of the droplets becomes more the
stability of emulsion was found to decrease.
Emulsions prepared from ultrasound were found
to have narrow range of particles in the low
fraction of dispersed phase. However, it becomes
wider as the dispersion phase content increases.
Ramisetty et al. International Journal of Drug Delivery 3 (2011) 133-142
Figure 5: Droplet size distribution of the oil particles with varying concentrations of dispersed phase at constant emulsification
time of 5minutes and emulsifying agent 9% in Mechanical agitation.
Ramisetty et al. International Journal of Drug Delivery 3 (2011) 133-142
Figure 6: Droplet size distribution of the oil particles with varying concentrations of dispersed phase at constant emulsification
time of 5minutes and emulsifying agent 9% in Ultrasonication
Effect of continuous phase viscosity
Here glycerin is act as secondary stabilizing
agent, which was added to increases the viscosity
of continuous phase thus reducing the mobility of
droplets in order to prevent them from
coalescing. As viscosity of the continuous phase
increased stability of emulsion was found to
increase which can be attributed to the continuous
medium surrounding the droplets and it resist the
coalescence of the droplets mean while there was
increase in droplet size (Figure 7). Agglomeration
of the droplets was found to decrease, but with
the increase in the continuous phase viscosity it
require more time of insonation or stirring to
incorporate the oil phase into continuous phase.
Droplet size also more as continuous phase
viscosity increases.
Figure 7; Droplet size of the oil with varying viscosity of continuous phase in mechanical agitation and ultrasonication
With our simple, three-component, model
system, comparison of two types of
emulsification processes was made, first one
using mechanical agitation method and the
second one involving power ultrasound at low
frequency (20 kHz), affords several interesting
results in favor of the ultrasound technique.
Smaller average drop sizes d32 (down to
1.125µm) can be obtained with ultrasound. Time
of emulsification plays a major role in decreasing
the droplet size of the emulsions. Ultrasound
technique gives more stable emulsions than the
mechanical stirring technique. Emulsifying agent
resist the coalescence of droplets to agglomerate
and brought the stable emulsions in both the
mechanisms but in the ultrasound it effects more
on stability as increased in volume fraction.
Droplet size distribution of low content
emulsifying agent emulsions is wider in range
than with that are having more content of
emulsifying agent. There is an increment in
droplet size has been observed with increment in
dispersed phase volume fraction but it was less in
ultrasound technique when compared with
mechanical stirring. Here droplet size increases as
the viscosity of continuous phase increases but
the stability increases with time of storage. An
extension of this work would require the study on
ultrasonic parameters like irradiation power
irradiation frequency.
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... US homogenization of low-fat mayonnaise at 20 kHz and 750 W significantly changed its microstructure and increased its stability. The effect of US treatment has been widely studied in previous studies, and it has been found that it increases emulsion stability (Li, Xiang, Wang, & Gong, 2019;Ramisetty & Shyamsunder, 2011). In case of over processing, it is detrimental to the stability of mayonnaise (Kaltsa, Gatsi, Yanniotis, & Mandala, 2014;Sui et al., 2017). ...
The present research explored the potential of probe ultrasoun d homogenizer and hydrocolloids in formulating and stabilizing ma mayonnaise. The effect of ultrasonic (US) treatment (1 2 min at 20 %, 30 %, 40 % amplitude) and stabilizers xanthan gum (XG; 0.5% w/w), guar gum (GG; 0.5% w/w), and XG/GG (1:1) on emulsion storage stability (ESS), ph ysicoch em ical and rheological properties of mayonnaise were stud ied. Rheological data comprising of shear rate () and shear stress () was analysed through four different rhe-ological models (Herschel-Bulkley, Casson, Power Law, and Carreau-Yasuda models), and their fitness was evaluated. The samples exhibited non-Newtonian, pseudoplastic be haviour with flow be haviour index (n) < 1 and consistenc y index (K) 43 .58-72 .38 Pa s n. The apparent viscosity me asured at a shear rate of 0-20 /sec, was decreased steeply, by the application of 40 % am plitude, most prominent in GG samples (1 00 7 Pa s to 60 8 Pa s) wh ile compared with XG (1 62 5 Pa s to 13 04 Pa s). The increase in US am plitude caused a linear increase in the refractive index (ranging from 1.36 81 to 1.37 91) and decreased pH (rang-ing from 3.68 6 to 3.52 3). A significant redu ction in wh iteness (L* value) from 78 .300 to 73 .860 was noted for XG/GG (1 :1) samples. The ESS decreased with an increase in US am plitude, and 40 % US am plitude-modu lated GG sample had the least ESS (9 0.14 %) am ong all treated and control samples. However, treated samples had higher ESS than the ma rket sample (8 6.50 %) .
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... Two conventional methods for energy input in emulsion preparation are mechanical agitation and ultrasonification. While both ways can be used successfully in emulsion preparation, it has been observed that ultrasonification reduces droplet size and increasing size uniformity of the dispersed phase better than that of mechanical agitation (Ramisetty and Shyamsunder, 2011). ...
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The production of wastewater during hydrocarbon recovery is an unresolvable factor of the oil and gas industry. Oil wells in the US produce on average, nearly 10 barrels of water for every 1 barrel of oil. Most of the produced water is reinjected back into the formation. However, recent studies may have linked increases in localized seismic activity to corresponding rises in wastewater well injection. Consequently, environmental discharge or reuse regulations are becoming more rigorous for produced water. Produced wastewater often originates from areas where water repurposing is an attractive option due to limited water resources in the area. Current water treatment solutions have not been universally successful as practical solutions due to high treatment material costs, long treatments cycles, and the production of additional environmental waste. Therefore, the need for a cost-effective, environmentally safe, and low waste producing water treatment method may change the outcome of millions of barrels of unusable water produced each year. This study explores the recent advancements in nanotechnology to treat oil field wastewaters and demonstrates a newly discovered material’s ability to reduce residual oil concentrations below discharge limits. Iron oxides are commonly found in the environment and display a unique characteristic of superparamagnetism that is desirable for produced water treatment. The inherent magnetism of these particles allows them to be physically manipulated by a magnetic field and can be used to separate trapped oil from oil-in-water emulsions. The principal objective of this study is to examine the abilities of magnetite (Fe2O4) and maghemite (γ-Fe2O3) nanoparticles to reduce residual oil concentrations in produced water samples containing both dispersed and dissolved oil. Amine-coated magnetite xv nanoparticles have shown oil removal capabilities in previous studies. The nanoparticles for this study were sourced from a local laboratory and also purchased commercially for comparison. The characteristics of the nanoparticles were measured and analyzed for comparative analysis and particles selection to optimize the water treatment process. Iron oxide nanoparticles used in water treatment tests relied on carefully designed oil removal experiments, emulsion production, and nanoparticle recovery and recyclability tests. The oil removal tests were conducted with prepared oil-water emulsions at known concentrations and with locally sourced produced water samples. The oil removal tests include the combination of an oil-water emulsion and dispersed nanoparticles in varying concentrations. After mixing the solution, the cloudy oil-water emulsions were made clear almost immediately when an external magnet was applied, indicating good oil-nanoparticle adherence. Oil concentration measurements via non-dispersive infrared spectroscopy confirmed the removal of oil as seen visually in the tests. Initial emulsion oil concentrations were reduced after nanoparticle treatment from 1,000 ppm to less than 10 ppm (>99% oil removal efficiencies). The oil removed from the O/W emulsions was then separated from the nanoparticles to be reused in additional treatment cycles. Maghemite maintained >98% oil removal efficiencies for up to at least ten cycles. These test results confirm iron oxide nanoparticles as a viable treatment solution for produced waters and most importantly, provide an environmentally safe method for removing oil contaminants from oilfield waters without the production of additional waste.
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The efficient use of supplied energy is the basis of the discrete-impulse energy supply (DIES) concept. In order to explore the possibility of using DIES to intensify the hydromechanical processes, the emulsification of milk fat (homogenization of milk, preparation of spreads) and, in particular, the processing of cream cheese masses, were studied. Whole non-homogenized milk, fat emulsions, and cream cheese mass were the object of investigation. To evaluate the efficiency of milk homogenization, the homogenization coefficient change was studied, which was determined by using the centrifugation method, as it is the most affordable and accurate one. To provide the proper dispersion of the milk emulsion, six treatment cycles must be carried out under the developed cavitation mode in a static-type apparatus, here resulting in a light grain-like consistency, and exhibiting the smell of pasteurized milk. The emulsions were evaluated according to the degree of destabilization, resistance and dispersion of the fat phase. On the basis of the obtained data with respect to the regularities of fat dispersion forming in the rotor-type apparatus, the proper parameters required to obtain technologically stable fat emulsion spreads, possessing a dispersion and stability similar to those of plain milk creams, were determined. It was determined that under the DIES, an active dynamic effect on the milk globules takes place. The rheological characteristics of cheese masses were evaluated on the basis of the effective change in viscosity. The effect of the mechanical treatment on the structure of the cheese masses was determined.
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Ultrasonic treatment is a promising crude oil preparation method implemented using emitters of ultrasonic vibrations in the 1–100 kHz frequency range. The optimum conditions of applicability of this method and the impact parameters are determined and ultrasonic oil treatment technology is investigated for different volume water contents of the emulsion. It is shown that under the impact of acoustic vibrations the disperse phase droplets coalesce and the demulsification process occurs more actively than in traditional thermochemical dewatering process. The conditions of applicability of the method is analyzed and the technological advantage of breaking stable water-oil emulsions for field oil preparation in the Perm Krai (Perm Region) is assessed. Based on the experimental data, relationships describing the nature of the effect of ultrasonic impact parameters on stable water-oil emulsions breaking at different water contents and under phase inversion conditions are investigated.
Two miniaturized sample preparation techniques, ultrasound-assisted emulsification microextraction (USAEME) and micro-solid-phase extraction (μ-SPE) have been integrated for the pre-concentration of four polar chlorophenoxy acid (CPA) herbicides from environmental aqueous samples. An metal-organic framework, MIL-101(Cr), characterized by its high porosity and large surface area, was explored as a sorbent. Despite the simplicity and convenience of μ-SPE, its use can potentially be limited by a long equilibration time, especially when applied to polar analytes. However, as demonstrated in this work, this drawback can be overcome by employing 1-octanol as a medium during the USAEME step to concentrate, and transport the polar herbicides through the polypropylene membrane of the μ-SPE device, onto the MIL-101(Cr). After μ-SPE, the herbicides were desorbed using 125 μL of organic solvent, and analyzed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Under the most favorable conditions, wide calibration ranges with good linearity (r² ≥ 0.995) are attained for all the herbicides. The limits of detection of the method range between 7.20 and 58.1 ng L⁻¹ while the limits of quantification (LOQs) range between 24.0 and 194 ng L⁻¹. The LOQs determined are lower than the guidelines set by the World Health Organization for the respective herbicides. USAEME-μ-SPE-UHPLC-MS/MS also shows good repeatability, with relative standard deviations ≤15.2%. Enrichment factors are between 21 and 70. The method was applied to the analysis of tap and reservoir waters, in which satisfactory relative recoveries ranging between 64.4% and 106% were obtained. The MIL-101(Cr) exhibited superior extraction capability in comparison to activated carbon and multi-walled carbon nanotubes.
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Understanding the complexity of fragmentation processes is essential for regulating intercellular communication in mechanistic biology and developing bottom-up approaches in a large range of multiphase flow processes. In this context, self-fragmentation proceeds without any external mechanical energy input allowing one to create efficiently micro- and nanodroplets. Here we examine self-fragmentation in emulsion nanodroplets stabilized by solid particles with different surface features. Mesoscopic modelling and accelerated dynamics simulations allow us to overcome the limitations of atomistic simulations and offer detailed insight into the interplay between the evolution of the droplet shape and the particle finite-size effects at the interface. We show that finite-size nanoparticles play an active role in the necking breakup, behaving like nano-scale razors, and affect strongly the thermodynamic properties of the system. The role played by the particles during self-fragmentation might be of relevance to multifunctional biomaterial design and tuning of signaling pathways in mechanistic biology.
Nanoemulsion synthesis has proven to be an effective way for transportation of immobile, insoluble bioactive compounds. Citronella Oil (lemongrass oil), a natural plant extract, can be used as a mosquito repellent and has less harmful effects compared to its available market counterpart DEET (N, N-Diethyl-meta-toluamide). Nanoemulsion of citronella oil in water was prepared using cavitation-assisted techniques while investigating the effect of system parameters like HLB (Hydrophilic Lipophilic Balance), surfactant concentration, input energy density and mode of power input on emulsion quality. The present work also examines the effect of emulsification on release rate to understand the relationship between droplet size and the release rate. Minimum droplet size (60 nm) of the emulsion was obtained at HLB of 14, S/O S/O = Surfactant to oil weight ratio (g/g).¹ ratio of 1.0, ultrasound amplitude of 50% and irradiation time of 5 min. This study revealed that hydrodynamic cavitation-assisted emulsification is more energy efficient compared to ultrasonic emulsification. It was also found that the release rate of nanoemulsion enhanced as the droplet size of emulsion reduced.
OBJECTIVE: Learning about the progress of the nanoemulsion drug carrier in the application of the insoluble medicament. METHODS: According to the recent literature and our groups work in this area, the nanoemulsion in improving the bioavailability of poorly soluble drugs has been discussed in many aspects, including its formulation mechanism, preparation methods, Pharmacokinetic, pharmacodynamics and modern application of the traditional Chinese medicine preparation in the recent research. RESULTS: Nanoemulsion carrier insoluble drugs could significantly improve oral absorption rate and bioavailability, enhance targeting effect and reduce the drugs toxicity. CONCLUSION: The select of the optimal scale of production based on the medicinal properties process allowed the nanoemulsion insoluble drugs to achieve a good therapeutic effect after oral administration.
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Oil-in-water emulsions are an important vehicles for the delivery of hydrophobic bioactive compounds into a range of food products. The preparation of very fine emulsions is of increasing interest to the beverage industry, as novel ingredients can be added with negligible impact to solution clarity. In the present study, both a batch and focused flow-through ultrasonic cell were utilized for emulsification with ultrasonic power generation at 20–24 kHz. Emulsions with a mean droplet size as low as 135 ± 5 nm were achieved using a mixture of flaxseed oil and water in the presence of Tween 40 surfactant. Results are comparable to those for emulsions prepared with a microfluidizer operated at 100 MPa. The key to efficient ultrasonic emulsification is to determine an optimum ultrasonic energy intensity input for these systems, as excess energy input may lead to an increase in droplet size.Industrial relevanceThe preparation of oil-in-water emulsions is a common feature of food processing operations. The use of ultrasound for this purpose can be competitive or even superior in terms of droplet size and energy efficiency when compared to classical rotor­stator dispersion. It may also be more practicable with respect to production cost, equipment contamination and aseptic processing than a microfluidisation approach. The present paper shows that ultrasound can be effective in producing nanoemulsions for use in a range of food ingredients.
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The efficient production of nanoemulsions, with oil droplet sizes of less than 100nm would facilitate the inclusion of oil soluble bio-active agents into a range of water based foods. Small droplet sizes lead to transparent emulsions so that product appearance is not altered by the addition of an oil phase. In this paper, we demonstrate that it is possible to create remarkably small transparent O/W nanoemulsions with average diameters as low as 40nm from sunflower oil. This is achieved using ultrasound or high shear homogenization and a surfactant/co-surfactant/oil system that is well optimised. The minimum droplet size of 40nm, was only obtained when both droplet deformability (surfactant design) and the applied shear (equipment geometry) were optimal. The time required to achieve the minimum droplet size was also clearly affected by the equipment configuration. Results at atmospheric pressure fitted an expected exponential relationship with the total energy density. However, we found that this relationship changes when an overpressure of up to 400kPa is applied to the sonication vessel, leading to more efficient emulsion production. Oil stability is unaffected by the sonication process.
This paper presents basic research results for production of W/O, O/W and W/O/W cosmetic emulsions under ultrasonic irradiation. A technology for the continuous and batch treatment of fluid mixtures with ultrasound was characterized using cosmetic emulsions as model systems. If cavitation is the dominant mechanism of droplet disruption, these results have to be taken into account for an optimal design of the emulsification apparatus geometry. The theoretical model supports experimental work. The experimental findings prove that final drop size essentially depends on specific power density. Drop size decreases with increasing residence time in the ultrasonic field until a system specific, minimum drop size is obtained. Ultrasonic irradiation leads to turbulent flow conditions on a macroscopic and a microscopic scale. The model based on the theory of turbulent drop bread-up predicts drop size and can be used to design equipment for ultrasonic emulsification. Emulsion used were stabilized using a combination of hydrophilic and hydrophobic surfactants. The ratio of this surfactants is important in achieving stable cosmetic emulsions. It was shown that emulsifier concentration plays great role in controlling the emulsification processes as well as the structured features of the droplets. The rheological behavior and morphological evolution during the ultrasonic emulsification were characterized systematically. The rheological properties were used to asses emulsion stability.
Cavitational reactors are a novel and promising form of multiphase reactors, based on the principle of release of large magnitude of energy due to the violent collapse of the cavities. An overview of this novel technology, in the specific area of process intensification of chemical processing applications, in terms of the basic mechanism and different areas of application has been presented initially. Recommendations for optimum operating parameters based on the theoretical analysis of cavitation phenomena as well as comparison with experimentally observed trends reported in the literature have been presented. A design of a pilot scale sonochemical reactor has been presented, which forms the basis for development of industrial scale reactors. Some experimental case studies using industrially important reactions have been presented, highlighting the degree of intensification achieved as compared to the conventional approaches. Guidelines for required further work for ensuring successful application of cavitational reactors at industrial scale operation have been presented. Overall it appears that considerable economic savings is possible by means of harnessing the spectacular effects of cavitation in chemical processing applications.
The influence of temperature on the ultrasonic properties of oil-in-water emulsions was investigated. The ultrasonic velocity and attenuation coefficient of a series of corn oil-in-water emulsions with different disperse phase volume fractions (φ=0 to 0.5) and mean droplet radii (r=0.1 to 0.5 μm) were measured as a function of temperature (5 to 50°C). These measurements were in reasonable agreement with predictions made using ultrasonic scattering theory. The ultrasonic velocity of the emulsions was particularly sensitive to their composition, temperature and droplet size. Around 15°C, the ultrasonic velocity was fairly insensitive to oil concentration. Below this temperature, it increased with oil concentration, whilst above this temperature it decreased. The ultrasonic velocity increased with droplet size. The attenuation coefficient of the emulsions was much more sensitive to composition and droplet size, rather than temperature. It increased with oil concentration and decreased with temperature. The implications of these results for the use of ultrasound for determining the size distribution and concentration of droplets in emulsions are investigated.
The ultrasonic irradiation for crude oil pretreatment to enhance desalting process was investigated. The intensity and irradiation time of ultrasound were studied. The settling time and the temperature of treatment for crude oil were also studied. Micrographs in this paper showed that the sizes of water drops were enlarged by more than 30% after the proper ultrasonic irradiation. The crude oil was pretreated for 5 min at 80 °C in the standing-wave field with frequency of 10 kHz and with ultrasonic intensity of 0.38 W cm−2. After the pretreatment, the dewatering rate and desalting rate were up to 92.6% and 87.9%, respectively in 90 min of settling time. The resulting final salt content of 3.85 mg L−1 is acceptable for refinery.
Emulsification processes are determined both by droplet disruption and droplet re-coalescence. This paper explains the fundamentals of droplet disruption in laminar and turbulent flow. Emulsification results from different continuous emulsification machines are compared with respect to the energy density (specific volumetric energy input) achieved. This is the first time that such a comparison has been made for both droplet disruption itself and droplet disruption superimposed by re-coalescence.
The effect of processing conditions (Ultra Turrax (UT) and valve homogeniser (VH)) and protein concentration (0.37–2.93% w/w) on stability of 50% o/w emulsions prepared with commercial WPC were investigated by optical and rheological methods. The UT emulsions were slightly or not flocculated and presented Newtonian behaviour. The D43 constantly decreased with increasing protein concentration, the UT emulsions becoming more stable to the creaming process. The VH emulsions presented flocculation and an appreciably smaller particle size, which also decreased with WPC until reaching stability. These emulsions were Newtonian at the lowest concentration but presented shear thinning and hysteresis at the other concentrations. The low-shear viscosity increased with WPC, which suggested that the extent of flocculation was protein concentration dependent. The VH emulsions showed more stability to the creaming process and presented a delay phase which, surprisingly, increased with protein concentration. These results could be explained by a structure formation through a flocculation mechanism, as a consequence of a depletion mechanism and bridging flocculation.