Re: How could you seperate a small amount of oil from a large amount of water?

We perform an oil and grease extraction for our wastewater treatment plant. In the days of old, our extraction process used Freon. Freon is no longer used at our facility because chlorofluorocarbons are environmentally detrimental to the ozone layer and have been discarded for alternate methods. The gravimetric method that has taken the place of the freon method is the hexane extraction method. Hexane is light enough to evaporate while leaving the heavier oil and grease behind for measurement. The hexane is shaken with a known quantity of water in a separatory funnel. The water is withdrawn into the collecting vessel. The hexane is filtered through water absorbant salt like MgSO4 and collected in a tared vessel. The process is repeated 2 or 3 times. The hexane is evaporated over a hot plate while nitrogen stream flows over the hexane. I'm not sure that this would be a "home" type of method for extraction of the oil. Hexane is flammable and I'm not exactly sure the availability for home purchase.

My suggestion would be to allow the oil to separate on its own. Try to select a vessel shaped with a very narrow neck and fill your sample to the neck and allow the oil to separate from the water. Withdraw the oil layer from the narrow neck and repeat the procedure a few times to collect enough oil. Since you didn't mention the oil sought and didn't specify the accuracy of the work required, I'll assume the measurements will be ballpark. Increased accuracy would require expensive equipment not practical for home use.

Keep up the good work and stick with it.

Good Luck.