I am performing a filtration experiment using some filter media where i need to find the upstream and downstream concentrations of oil in water. So, I was wondering if COD content of water sample can indicate the respective oil concentration in that sample.
2006-07-19 05:21:48 · 4 answers · asked by curious 1 in Science & Mathematics ➔ Chemistry
As mentioned above, disolved/suspended oil, of any kind will contribute to COD. Lil oil = lots COD. in a pure solution (i.e just oil and water) the correlation will be very good. However in a true waste water stream, your results will not correlate as well -- esp if the nature of the oil can change.
If you desire to determine the amount oil in water, use the EPA oil and grease method - either solid phase extraction (lots of money in setup) or hexane extraction in a sep funnel (cheap but more work). The recovery of vegetable oil - like corn oil - in this procedure is darn near 100%, with about a 2 PPM lower limit for a 1 liter sample. Need a scale measure at least to 1mg resolution, hexane, and an extraction flask.
2006-07-19 08:03:21 · answer #1 · answered by imabiggles 2 · 1⤊ 0⤋
there won't be enough to extract. think of what you're trying to do. unless there are surfactants aplenty in the water oil won't mix with the water, so you can filter than use a separatory funnel to allow the layers to settle out so you can separate them. if there's surfactants in the water good luck on extracting the oil cuz you're gonna have to break open the micelles and that will take time and energy.
COD is from lots of stuff and ammount of oil in water could change the number. set up a scale of samples you made yourself to see if there is a relationship, and you can apply this to the sample you'll take
2006-07-19 06:38:12 · answer #2 · answered by shiara_blade 6 · 0⤊ 0⤋
The molecular composition of water allows more mass to pack into an equal volume. So the real issue is the amount of mass a substance can pack into a given volume. This is density; density is a function of weight per a volume. Even though the molecular weight of a hydrocarbon oil is greater than the molecule of a H2O, it cannot pack as tightly into the same space.
2016-03-26 23:55:13 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Yes, but other organic matter would have a COD also. You could extract the oil with chloroform or some other solvent.
2006-07-19 05:31:18 · answer #4 · answered by Fredrick Carley 2 · 0⤊ 0⤋