De-emulsification of Oil by heat
De-emulsification is one other practical
application of heat where mixtures of two different immiscible liquids
are separated. Emulsion is a mixture of two different immiscible
liquids, where in each liquid is made miscible by addition of
emulsifying agent or a surfactant. In this experiment, oil and water is
taken as two immiscible liquids which are mixed in different proportions
and mixed with a surfactant (generally detergent). Separation of this
emulsion is achieved by application of heat. Addition of surfactant
causes a micelle formation by hydrophilic and hydrophobic interactions
due to the polar molecules present in the mixture. Application of heat
causes breakdown of these micelles, interrupting the
hydrophilic-hydrophobic interactions. This leads to the separation of
the two immiscible liquids. The process of de-emulsification is applied
in purification of heavy crude oil in petroleum & paint industries.
Two 1000ml graduated glass
Two glass rods for stirring.
Sodium dodecyl sulfate (SDS).
Towels for clean up.
Previously we reported the temperature
profile of de-emulsification process of oil and water emulsion. The
emulsion mixtures prepared were not stable enough. Hence we prepared
stable emulsions with SDS as emulsifying agent. Emulsion solutions
containing 110ml of different concentrations of 10%, 25% and 50%
solutions of water in oil with SDS as emulsifying agent. The amount of
SDS added was proportional to the percentage of water added. In case of
10 % water, the amount of SDS used was about 0.05 g while in case of 25
% water, 0.1g of SDS was used and in that of 50 % water, 0.2g of SDS was
used. The solutions were heated at every interval time in order to
determine the amount of water separated. Heating the solution every
minute the volume of water separated was recorded.
Results and Discussion
Figures 11 (a) and 11(b) show
the amount of water separated by hotplate in case of 10 % and 25 % in
comparison with microwave. At lower percentage of water, hot plate
hardly separated the water from the mixtures. As it required more amount
of energy to break down the micelle bonds. In case of microwave
radiation, the direct heat applied by it was sufficient enough to break
down the strong micelle bonds formed at lower percentage of water
content. Higher the percentage of water, more unstable the micelle bond
becomes, hence it requires less energy to break down the micelles in
order to separate the emulsion. Thus from the Fig 11 (c) we see that for
a 50 % micelle mixture a substantial amount of water separated by
hot plate heating too. But for the same period of time the amount of
water separated by microwave was comparatively higher than that of
conventional heating. The amount of water separated by both methods of
heating for separation of 50 % oil in water mixture, and their
respective energy consumption is tabulated below.
(a) Volume of water separated versus time for 10 % emulsion mixture, (b)
Volume of water separated versus time for 25 % emulsion mixture, (c)
Volume of water separated versus time for 50 % emulsion mixture.
(d) Volume of water separated from 75 % emulsion mixture.
The amount of water separated by both
methods of heating increased with increase in amount of water content.
The energy consumed
the concentration of iron extracted by different heating methods.
Power Rating (KJ/min)
Actual Energy Consumed (KJ)
Amount of water separated (ml)
Difference in Calculated and Recorded
Energy = Power x Time
Energy Consumed = 51.0 KJ/min
x 3 min = 153 KJ
Hot Plate: Energy
Consumed = 51.9 KJ/min x 3 min = 155.7 KJ
The percentage of error for microwave
and the percentage of error for hot