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Measuring Oil presence in water

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Junior Member level 3
Mar 27, 2010
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I am working on a project to separate out oil and water.I asked the same question in my previous thread and found many useful answers.

I had decided to use IR, but now I need to make decision for separation by measuring oil level in water oil mixture. If the oil is less than 15 ppm (parts per million) , It needs to be ignored. In other case I need to separate it to another container.

My idea is to take a sample of mixture in a specific volume container and then carry out test. Can resistance test be used to determine oil level. What are other solutions.

Please help.

I already noticed a system to measure oil+water relation just placing a plastic matherial in the recipient, whose floatage characteristics was intermediate bwtween both fluids.
The solid piece was better behaved than turbulent fluids, and measurement reflexion were performed in it.

Thanks andre. Your idea seems interesting. Can you please explain/elaborate it further. I am unable to grab it.

If you need a threshold measure of 15 ppm (i.e., approx. 1 mg/L), you need to tell us more about the oil. Is it mineral or vegetable? What is its chemical composition (e.g., pure hydrocarbon or ester?). What is its solubility on water?

I am leaning toward using near infrared, not so much by refrative index, but maybe simple absorption.


Hi, I got busy in following method to measure resistance of the mixture, but it did'nt work well. The resistance of a sample of water seems to be changing when measured. What is your idea jpanhalt?

The oil is mineral, its crude oil actually. Please help.

In my experience monitoring water, small amounts of organics in the water, such as oils, do not affect its resistivity much. That is why we used chemical methods to remove oils before purifying the water.

In your case, since you mention crude oil, I suspect the water is not a know entity either. In other words, it does not appear you are mixing crude oil with a characterized sample of "reagent grade" water and monitoring the change. Therefore, I still think IR (or maybe Raman) is your best bet. Water does not have carbon-hydrogen and other organic bonds; oil does.


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