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Technology
Definitions:
Surfactant:
A surface-active substance – ORIGIN 1950’s from
surf(ace)act(ive)+ant. Surfactants act to
reduce the surface tension of a liquid. The
surface tension of water is 72 dyne/cm; a surfactant
can reduce this to a value in the range of 30-50
dyne/cm.
Surface-Active:
(Of a substance) tending to reduce the surface
tension of a liquid in which it is dissolved.
Microemulsion:
A microemulsion is a thermodynamically stable
dispersion of one liquid phase into another,
stabilized by an interfacial film of surfactant.
This dispersion may be either oil-in-water or
water-in-oil. Microemulsions are typically
clear solutions, as the droplet diameter is
approximately 100 nanometers or less. The
interfacial tension between the two phases is
extremely low. The final microemulsion state
will not depend on order of mixing, and energy input
only determines the time it will take to reach the
equilibrium state. Microemulsions are two
phase systems, in contracts to micellar solutions,
which may be considered one phase.
Emulsions:
Emulsions (or macroemulsions) are in contrast
unstable, the suspended droplets will eventually
agglomerate and the dispersed phase will phase
separate. Emulsion droplet sizes are much
larger, typically one micron or more, resulting in a
cloudy or milky dispersion. The nature of an
emulsion may depend on the order or mixing of the
ingredients and the amount of energy put into the
mixing process.
Emulsification:
The process of dispersing one liquid in a second
immiscible liquid; the largest groups of emulsifying
agents are soaps, detergents and other
surface-active compounds (surfactants).
Emulsion
Breaking:
In an emulsion, the combined sedimentation and
coalescence of emulsified drops of the dispersed
phase so that they will settle out of the carrier
liquid; this can be accomplished mechanically (in
settlers, cyclones, or centrifuges) with or without
the aid of chemical additives to increase the
surface tension of the droplets.
Surface
Tension:
The force acting on the surface of a liquid, tending
to minimize the area of the surface; quantitatively,
the force that appears to act across a line of unit
length on the surface. Also known as
interfacial force; interfacial tension; surface
tensity.
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