How Do You Separate a Mixture of Oil and Water?

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How Do You Separate a Mixture of Oil and Water?

Although oil and water are two compounds that do not mix, it will be quite difficult to separate them once they come together. However, because of the high demand for finding ways to break these two apart, a lot of methods have been developed over the years that effectively separate a mixture of oil and water, according to SWA Water Australia, who are experienced in water and oil separator methods. 

But before we discussed the different methods that are used to separate oil and water, let us first examine the reasons why these two compounds do not mix together. 

Why Oil and Water Do Not Mix?

According to Wikipedia, water is a chemical compound that is made up of two hydrogen atoms and one oxygen atom. It is a simple structure that has partial negative and positive charges which makes it polar in nature. 

The polarity of the water molecules enables it to form a strong bond between the positively charged (hydrogen) and the negatively charged (oxygen) atoms. These charges on both ends force other compounds like salt and sugar to dissolve when mixed due to the attraction to its polarity.

On the other hand, based on the information provided by the Scientific American website, oils are non-polar making it unattractive to the polarity of water molecules. In fact, the hydrophobic properties of oil repel water molecules causing it to separate when mixed together. 

Moreover, because oil has a lesser density than water, it tends to float on top of it creating a layer of oil on the surface of the mixture.

Different Methods Used to Separate a Mixture of Oil and Water

Now that we know why these two compounds do not mix, let us now discuss some of the methods that are used to separate oil and water.


One of the easiest ways to separate oil and water is by freezing. As we all know, water becomes ice when it is subjected to low temperatures. Even though this is not a practical approach when it comes to a larger scale, freezing the mixture of water and oil will turn the water to ice which will make it easier to separate the two compounds.


Bioremediation is an emerging technology that is used to separate oil from water. It is one of the most sustainable approaches in getting rid of environmental pollution such as cleaning an incident of an oil spill in the ocean.

This method uses microorganisms like Pseudomonas to get rid of oil by consuming it. Although this method is less expensive, easy to implement, and environmentally friendly, using it will eliminate the oil mixture, leaving only the water components behind. 


Another method that is used to separate oil from water is absorbance. This method separates oil from water by using absorbent materials to soak up the oil.

One of the most common materials used for this oil and water separation method is polypropylene. This type of material is ideal for this approach due to its water repelling nature (hydrophobic).

This method involves using the absorbent material to suck up all the oil from the mixture leaving just the water compound behind.


Decantation is the method used to separate liquids with different densities. It is done by pouring the less dense liquid (in this case the oil) out of a container to separate them. 

Although this method is effective, it often produces an incomplete separation because it is quite difficult to pour out all the oil from the mixture without including some portion of the water compound. On the other hand, a separatory funnel apparatus can be used for better separation results.


Distillation is the process of eliminating vapor from a mixture. It utilizes the condensation process by boiling the mixture to get rid of the water compound. This process may result in complete or partial separation of water and oil.

The distillation method is often used by the petroleum industry to reduce the vapor in crude oil. This is necessary to eliminate water from the mixture so that the oil will be safe for transport and storage purposes.

Centrifugal Separation

The last method for separating a mixture of oil and water that we are going to include in this article is the centrifugal separation method. This process is the separation of various substances through their difference in gravity levels.

Centrifugal separation uses centrifugal force to separate substances like oil and water. Using centrifugal force on the mixture will separate the compounds through means of natural sedimentation.

Final Words

Separating oil and water can be done easily if you have the proper knowledge and the right equipment to accomplish it. Using any of the oil and water separation methods mentioned above such as absorbance, bioremediation, centrifugal separation, decantation, distillation, and freezing can definitely help you accomplish your goal of separating any mixture of oil and water quickly and more conveniently.