Question:
Can you please give us some EASY ways of separating oil
and
water?
Replies:
It is possible to reduce the solubility [and the suspension] of oil in a
water phase several ways:
1. Add a soluble ionic salt, preferably a polyvalent salt like MgSO4
[epsom salts] available at a pharmacy. This both reduces the solubility of
the oil, and coagulates any oil emulsified in the water, which frequently
happens.
2. Distillation. Boiling and condensing the water vapor should be pretty
effective since the components in "oil" usually have a low vapor pressure
compared to water.
3. Partially freeze the oil/water, throw away about 1/4 to 1/3 of the
unfrozen water.
Repeat this 2-4 times, discarding the 1/4 to 1/3 unfrozen water. The
principle here is that the crystal structure of water [ice] with all those
hydrogen bonds is complicated and doesn't allow impurities to "fit" into the
lattice spaces. A "cool" example of this is to freeze some distilled or
deioized water in your frig. You will find about 1/2 of the ice cube is
crystal clear -- pure water -- the other half will be opaque, because the
water becomes saturated with atmospheric N2 and O2. Repeat this experiment
with freshly boiled water (de-gassed) and note the difference.
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