How can separate oil from water
Answers
Methods for separate water from oil:
1)To separate oil from water, add a solution of soluble ionic salt to the solution. Distillation, which involves boiling and condensing the water, is another option, as well as partially freezing the oil and water combination and discarding one-fourth to one-third of the unfrozen water.
2)Changing the state of the water to either a gas or a solid is a means to cleanly remove all of the oil from the water.
3)Add some amount of copper sulphate(CuSO4) in the mixture. the water molecules get attracted to CuSO4 molecules and it will turn into blue colour.
4)Use for Separating finely mixed oil and water
MIT researchers have discovered a new, inexpensive way of getting the two fluids apart again.
Their newly developed membrane could be manufactured at industrial scale, and could process large quantities of the finely mixed materials back into pure oil and water.
In addition to its possible role in cleaning up spills, the new method could also be used for routine drilling, such as in the deep ocean as well as on land, where water is injected into wells to help force oil out of deep rock formations.
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The term “oil” is not well defined, compared to “water” which is quite specific. Is thought of typical vegetable oil (triglycerides), mineral oil (alkanes), …? However, most oil types differ from water on below 2 properties.
Firstly, the solubility of oil in water, and visa verca, is very limited, and secondly the oil density is less than that of water.
That means an oil phase would settle on top of an aqueous phase, if separation by gravity is not prevented by a strong emulsion, and the 2 phases can thus be recovered by decantation. Industrial separation often involves centrifugation in which the gravity is increased several thousand fold. A typical separation efficiency results in a residue of around 0.2% of the other phase in the main phase (besides from any dissolved matter which cannot be separated by centrifugation).
If an emulsion is holding the liquid 2 phases together in spite of applying g-force, that has to be broken. The best approach depends of which type of emulsion is present, but heating and/or adding components (acid, base, salt) which are altering the pH or electrolytic balance are typical means to break it up.
Since the vapour pressure (volatility) of water is much higher than most oils, also vaporisation (distillation) of the water is possible, however is more energy demanding and expensive process and therefore a backup choice. If a purity of better than 0.2% of water in the oil phase is required, the remaining water (down to let's say 100 ppm) is preferably removed by vaporisation. The necessary temperature can be reduced by conducting the vaporisation under vacuum.
Even lower concentrations (down to 1 ppm or so residual water) can be achieved by applying adsorption (letting the mixture pass hydrophilic molecular sieves trapping the water molecules), which again normally is a more expensive process than vaporisation.
Conclusively one can say that the required efficiency (acceptable residual concentration) determines which separation process is preferred.