Creaming rate of emulsion

Calculation of the rate of creamingsedimentation in dilute emulsions. Creaming is usually a precursor of coalescence and is followed by phase separation and its extent in OW emulsions can be described using the creaming index.

A simple calculation of HoursHeightVelocity is shown.

Creaming rate of emulsion. The rise of dispersed particles to the surface of an emulsion is referred to as creaming and is due to density differences between the dispersed particles and the serum phase. The creaming rate of particles in a dilute system follows Stokess law and is given by. Creaming rate Cr R 2 ρ c ρ o η c.

In addition to the velocity the approximate time taken for the emulsion to cream ie. A simple calculation of HoursHeightVelocity is shown. The calculation on creaming tells you what will happen with drops of a given size it also suggests that particles of less than say 1000nm radius would not cream significantly.

It doesnt tell you why the drops are that size and how that size might change. It was found that the creaming rate of the emulsion could be presented by the equation Uχ Uο exp A η φ for a wide range of φ where η is the intrinsic viscosity of the emulsion and A is a correction coefficient for the individual intrinsic viscosity for emulsions with different radius. Calculation of the rate of creamingsedimentation in dilute emulsions.

Influence of increase of the volume fraction of the disperse phase on the rate of creamingsedimentation. Balance of the density of the two phases reduction of droplet size and effect of addition of thickeners. The results indicate that creaming kinetics has a complex dependence on caseinate content.

At low protein content 1 wt corresponding to less than half that required for saturation monolayer coverage the emulsion is destabilized by bridging flocculation accompanied by some coalescence. At higher protein content 2 wt where individual droplets are fully protected against protein bridging or coalescence by the thick adsorbed protein layer the unflocculated emulsion. Emulsion and is typically the precursor to actual coalescence.

The creaming rate or settling rate for disperse phases that are more dense than the continuous phase can be estimated from the Stokes equation. Where is the creaming settling rate r is the droplet. I prepared wo emulsion consist of water dichloromethane and span 80 as emulsifier.

Mechanical stirring at 2000 rpm was used. But for a few seconds after I stopped stirring creaming. 18 Zeilen Calculation of the rate of creamingsedimentation in dilute emulsions.

Creaming is usually a precursor of coalescence and is followed by phase separation and its extent in OW emulsions can be described using the creaming index. The creaming index gives insight into the extent of droplet aggregation that has occurred as such the higher the index the more droplets have agglomerated. Creaming can be measured by visual observation or by optical imaging.

Emulsion with very large droplets 10pm. This emulsion is then inverted to-an oil-in-water emulsion using a colloidal mixer Moritz BF 50. Finally this emulsion is diluted with pure water under mixing during a few minutes.

The average droplets size may range from 02 to a few microns. Let first consider the behavior of typical polydisperse emulsion oil volume fraction 4l 10il upon SDS concentration. Creaming stability of emulsions formed with calcium caseinate determined after storage of emulsions at 20 C for 24 h increased gradually with an increase in protein concentration from 05 to 20.

Further increases in caseinate concentration had much less effect. In contrast the creaming stability of sodium caseinate emulsions showed a decreased with an increase in protein. Creaming is the principal process by which the disperse phase separates from an emulsion and is typically the precursor to actual coalescence.

The creaming rate or settling rate for disperse phases that are more dense than the continuous phase can be estimated from the Stokes equation. The creaming and rheology of fine n-tetradecane oil-in-water emulsions at pH 68 containing the commercial protein sodium caseinate and the ionic surfactant sodium dodecyl sulfate SDS have been studied and an overview diagram relating surfactant composition and creaming stability has been constructed. The presence of both SDS and sodium caseinate in an emulsion system increases the overall stability with respect to creaming.

The results indicate that creaming kinetics has a complex dependence on caseinate content. At low protein content 1 wt corresponding to less than half that required for saturation monolayer coverage the emulsion is destabilized by bridging flocculation accompanied by some coalescence. At higher protein content 2 wt where individual droplets are fully protected against protein bridging or.

31 Creaming rate of an isolated spherical particle can be predicted by Stokess equation. Gravitational Separation In general if creaming rate 1 mmday the emulsion is considered stable toward creaming. 2gr2 ρd ρc 9 η1 vStokes Emulsion Stabilization Abd Karim Alias 2013.

A stable emulsion is one in which the globules retain their initial character like mean size and size distribution and remain uniformly distributed throughout the continuous phase. During storage of emulsions instability is endorsed by creaming cracking reversible aggregation andor irreversible aggregation etc. Coalescence is a growth process during which the.