This sounds great -- I added some relevant tags to connect your work with other work going on in PL. Thanks! Looking forward to following your work!

The freezing technique is genius! How did you come up with it? Like making ice wine. Are you sourcing your extraction methods from some literature you've found?

Also looping in @ernestootero who's been collecting suspected oil samples in the field, although from asphalt surfaces, not water. Thanks!

Great Jeff! Thanks for adding the tags. Isn't it awesome? I heard about the freezing separation long time ago. People do this already for some time to separate natural oils from water, but it's useful also for other things than water. Here is a Youtube video about it: https://youtu.be/uvmy4msbfFE

Super. At some point we should overhaul this wiki page with new techniques: http://publiclab.org/wiki/spectrometry-sampling

Sounds good. I'll certainly do that sometime around next week! Very useful.

Hello!

@Matej

What a wonderful need. You will be a useful person in your community if something happens.

In the latter part of your note, you mention a desire to create a safe method of separating oil from water. As a chemical engineer, I was reminded of a polymer class lab on Super Absorbent Polymers (SAP). One can find an example in most diapers now days. Such polymers are wonderful for absorbing water which is a polar molecule.

Since oil is non-polar, it separates from water nicely, which is one reason the freezing technique will work. Still, SAPs will not likely absorb much oil. So, I tried to think of an organic that might be used similarly.

I was reminded of grounded corn cob or grounded kitty litter. I once thought of grounded corn cob (no corn) as a potential kitty litter. So, I wondered how it would work to absorb oil. I know that kitty litter works decently. Anyhow, I did a search and discovered some ground corn cob product being sold for absorbing oil. I just wonder how much water it would absorb. Would it absorb more water or more oil? IS it more polar or non-polar?

One way to test this is to grind up some corn cob, without corn, and add a certain mass of the particles to a container with a specific mass of oil (Group 1), and an equal amount of particles to another container with a specific mass of water (Group 2). Agitate each by hand, and, after agitating for specified periods, separate the particles from each liquid and weigh each group of particles along with the mass of oil and water remaining--maybe a vacuum filtration step to help ensure absorbed oil is measured, but I careful use of vacuum. It would be a delicate balance.

If the mass of the oil decreased significantly and more than the mass of water, the corn cob particles might be a good environmentally safe way to remove oil from water. It could take a few tries to get particle size correct, container correct (one that does not extract significant amounts of oil onto surface area), etc. In fact, might want to, at a minimum, weigh the container before and after--some liquid will be water and some oil though.

Next, an experiment with a mixture of water/oil and particles. If the particles are more polar, they will absorb water faster than oil. If the particles are more non-polar, they will absorb oil faster and repel more water. If somewhere in between, the ground corn cob particles might absorb each. Still, they will absorb some oil!

Finally, maybe one could re-create an oil spill by using a litter box, water, and various aliquots of oil. Afterwards, a grounded corn cob could be used to absorb oil--maybe sprinkle it on top of the oil spill directly.

Also, one can look into creating Granulated Activated Carbon and use it to absorb some oil. :)

Anyhow, just a thought. You could use the spectrometer to determine the limit of grounded material to separate oil from water. What mass of oil is left in water? When doing this, be careful of "flattening."[1].

If freezing after agitation of water/oil, some water could be trapped inside oil as droplets or the opposite as well.

Flattening Example

Deviations from Beer-Lambert Law: "Solutions that are not homogeneous can show deviations from the Beer-Lambert law because of the phenomenon of absorption flattening."[1]

References:

[1] Wikipedia. Ultraviolet--Visible Spectroscopy. Retrieved (2015, Dec. 03). Wikipedia[online]. Available from: https://en.wikipedia.org/wiki/Ultraviolet%E2%80%93visible_spectroscopy