Nanomembrane that separates oil from water
When the oil is spilled or leaked, it contaminates bodies of water, but there are scientific ways to eliminate fatty substance. Some methods require the addition of other chemicals to separate the oil completely before removing it from the water; These are controversial methods because the side effects of the additional chemicals are unclear. Each time oil and water are combined, the two substances tend to mix in the form of an emulsion, which is very complicated to separate, and which tends to be highly polluting.
The proposed method consists of adding nanoparticles to the mixture with iron and then separating the oil using a magnet. The researchers indicate that it is a very simple maneuver but that it should, however, be carried out on a ship so that the nanoparticles do not contaminate the ocean. In other words, similar methods have been proposed but they had the disadvantage that it was necessary to know in advance the concentration of water and oil in the mixture. The proposed technique, by placing the magnets within the current, and not outside it, as in the previous methods, can always be applied with good results, regardless of the concentration of each component in the mixture.
This method must not only be used in spills in the ocean, but it can also be used in offshore drilling, where water is injected into the wells and therefore mixed with the oil. So far the separation process is done by separation tanks where gravity makes the oil float and leaves the water underneath, a method that works partially, since if the molecules are large the separation is complete but when an emulsion remains (with fines drops of oil stabilized in water or vice versa) the separation of this requires the use of highly polluting chemical agents.
The membranes contain what their creators call "hierarchical pore structures." These membranes are composed of a very thin layer of nanopores, and a much thicker layer of micropores that limit the passage of unwanted material, while at the same time supporting the high pressure and the passage of the liquid. A very interesting aspect is that researchers have the ability to reverse the properties of the membranes: Depending on each case, it is possible to repel water and attract oil or achieve exactly the opposite effect. The combination of nanopores and micropores solves the disadvantages that went through previous developments, with membranes destroyed due to pressure.
The best part is that the manufacture of the membranes could be elevated on an industrial scale, which in theory should lead to a large volume of production, and finally at a low price. To date, 99.99% efficiency in separation has been achieved in laboratory tests. Therefore, they should still be evaluated outside the laboratory, and for this, the researchers are working together with Shell.
This is an interesting and innovative method for separating nanoemulsions since previously it has been tried to perform but this may be probably the simplest technique at the same time scalable to manufacture these membranes. They could have a high impact, since nanoemulsions are present in a good number of industries, and these membranes could allow the fast separation of these emulsions with great purity and efficiency.