Emulsification by ultrasound: drop size distribution and stability (original) (raw)
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Ultrasound Emulsification—An Overview
Journal of Dispersion Science and Technology, 2002
Fundamentals and applications of ultrasound emulsification are reviewed. The importance of cavitation is stressed, as also is power input to the multiphase fluid. The influence ofsurf actants, polym eric stabilizers, temperature, pressure, and ultrasonic parameters such as frequency, residence time, acoustic intensity, and energy density are described. The effects ofother physicochemical parameters such as emulsifier concentration, disperse phase volume F action, and viscosity are discussed. Applications to both water-in-oil and oil-in-water emulsions are discussed.
Ultrasonics Sonochemistry, 2008
Ultrasonic emulsification of oil and water was carried out and the effect of irradiation time, irradiation power and physicochemical properties of oil on the dispersed phase volume and dispersed phase droplet size has been studied. The increase in the irradiation time increases the dispersed phase volume while decreases the dispersed phase droplets size. With an increase in the ultrasonic irradiation power, there is an increase in the fraction of volume of the dispersed phase while the droplet size of the dispersed phase decreases. The fractional volume of the dispersed phase increases for the case of groundnut oil-water system while it is low for paraffin (heavy) oil-water system. The droplet size of soyabean oil dispersed in water is found to be small while that of paraffin (heavy) oil is found to be large. These variations could be explained on the basis of varying physicochemical properties of the system, i.e., viscosity of oil and the interfacial tension. During the ultrasonic emulsification, coalescence phenomenon which is only marginal, has been observed, which can be attributed to the collision of small droplets when the droplet concentration increases beyond a certain number and the acoustic streaming strength increases.
Effect of Ultrasonication on Stability of Oil in Water Emulsions
International Journal of Drug Delivery, 2011
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.
Ultrasonics Sonochemistry, 2014
Emulsifier free emulsion was developed with a new patented technique for food and cosmetic applications. This emulsification process dispersed oil droplets in water without any emulsifier. Emulsions were prepared with different vegetable oil ratios 5%, 10% and 15% (v/v) using high frequency ultrasounds generated by piezoelectric ceramic transducer vibrating at 1.7 MHz. The emulsion was prepared with various emulsification times between 0 and 10 h. Oil droplets size was measured by laser granulometry. The pH variation was monitored; electrophoretic mobility and conductivity variation were measured using Zêtasizer equipment during emulsification process. The results revealed that oil droplets average size decreased significantly (p < 0.05) during the first 6 h of emulsification process and that from 160 to 1 lm for emulsions with 5%, 10% and from 400 to 29 lm for emulsion with 15% of initial oil ratio.
Minimising oil droplet size using ultrasonic emulsification
Ultrasonics Sonochemistry, 2009
The efficient production of nanoemulsions, with oil droplet sizes of less than 100 nm would facilitate the inclusion of oil soluble bioactive 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 40 nm from sunflower oil. This is achieved using ultrasound or high shear homogenization and a surfactant/co-surfactant/oil system that is well optimized. The minimum droplet size of 40 nm, 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 400 kPa is applied to the sonication vessel, leading to more efficient emulsion production. Oil stability is unaffected by the sonication process.
Journal of Petroleum & Environmental Biotechnology, 2017
An emulsion is the mixture of two immiscible fluids, where one fluid appears as droplets within another. In the oil and gas industry, produced crude oil generally comes with an appreciable amount of water within it in an emulsified form. Before produced crude oil can be prepared for purchase, the water associated with it must be removed. A process known as demulsification is required in order to separate an emulsion into its two phases. In the industry, a number of demulsification techniques are already present; these include thermal, mechanical, chemical, and electrical techniques. Crude oil and gas produced from wells originally come with water, salts, and volatile gases such as oxygen, carbon dioxide, and sometimes hydrogen sulfide, etc. Hence, the petroleum mixture needs to be refined-water, salt, and non-hydrocarbon gases to be separated from the mixture, in order to meet certain oil and gas specifications (which state the maximum concentrations of such contaminants) and make it ready for purchase and transportation. Sonication provides a cheap, simple, and harmless (as it involves mainly the propagation of sound waves) way of separating crude oils from water droplets via demulsification. In addition, if needed, it can be used for emulsification processes as well. Hence, a study of sonification as a way for crude refinement or chemical mixing has important implications for the oil and gas. This investigation proposes the use of ultrasonication as a new and cost-effective technique to aid in the demulsification of crude oil emulsion. The effectiveness of this technique was gauged through its comparison to the already present methods in the industry. Based on the investigation it was found that centrifuge served as the best demulsification method for it reduced the turbidity by 86%. In addition, the reduced turbidity achieved with proposed ultrasonication method ranges from 20%-60%.
Potential Use of Ultrasound to Produce High Solids Emulsions
2016
Ultrasound was used to obtain kinetically stable emulsions for further spray drying. Sonication time of 3, 7 and 11 minutes were evaluated at power amplitudes of 50%, 75% and 100% (in relation to the nominal power of the equipment), where energy density required for each assay was calculated. Emulsions were characterized for droplets mean diameter and size distribution, optical microscopy, zeta potential, creaming index (CI) and rheological behavior. The products presented bimodal size distribution, with D[3,2] ranging from 0.7 to 1.4 μm and CI between 5% and 12%, being this parameters inversely proportional to the variables studied, but with an apparent stabilization after the treatment at 100% power amplitude at 7 min sonication. D[3,2] showed to depend of energy density as a power function. PALAVRAS-CHAVE: sonicação, óleo de palma, emulsificação por alta energia.
BIO web of conferences, 2022
In this article, the influence of ultrasonic and mechanical dispersion on the viscosity characteristics of water-oil emulsions was studied. It was found that an increase in the duration of exposure to ultrasound leads to an increase in temperature as a result of intensive dispersed system mixing. Due to this, there is an intensification of the interaction between the particles, dispersion, and coagulation. The analysis of the results allowed to determine the optimal ratio between the time of ultrasonic exposure and the emulsifier concentration to obtain an emulsion with low viscosity and a dispersion range. Ultrasonic dispersion promotes the formation of fine particles and a wider polydispersity, which improves emulsion viscoelastic parameters and density. It was found that ultrasonic treatment for 80-120 seconds enhances the nanoscale effect, reducing the emulsion dynamic viscosity. These results are of significant importance for the control and optimization of the viscosity properties of emulsions in various industrial fields, including the food industry.
Effect of temperature on the ultrasonic properties of oil-in-water emulsions
Colloids and Surfaces A-physicochemical and Engineering Aspects, 1998
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 (w=0 to 0.5) and mean droplet radii (r=0.1 to 0.5 mm) 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.
Trends in Food Science & Technology, 2020
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