I mixed 100ml ethanol with 200ml water and another 100ml of ethanol with 200ml of castor oil. Then the oil mixture was added on top of the water mixture.
I set up the camera but the pictures are coming out with horizontal stripes and overexposed looking. I tried new batteries but no luck, so I guess it bit it.
I took the cook pan and filled it with water and heated it up on the hot plate. I put the experiment (in a 4 cup measuring glass) into the pan of hot water.
I set a fan nearby on low to remove the ethanol vapor away from the surface and expedite evaporation. The pan water was 120 F when I first measured it.
After a while, I remeasured the pan water and it had dropped to 115 F, so I cut up pieces of a plastic shopping bag and laid them on top of the water.
After a few minutes the water was at 130 F.
The contents of the measuring cup have reduced from 600ml to 500ml as I type this.
I hope to see it continue to drop to 400ml and then halt.
If there is no more drop after that then I can hope the ethanol has successfully been driven off without any significant amount of water vapor having been driven off with it.
I will then measure the remaining water under the oil and weigh a volume of it comparing it to fresh tap water to see that the specific gravity indicates there is little to no ethanol remaining in the "wash".
I will edit this post with the results.
EDIT (Results):
1st edit:
The water bath topped out at about 145 to 150 F. There are tiny bubbles that form in the water below the oil. These rise to the interface where they collect to rise through the oil layer. They may be ethanol but they may have significant water vapor content as well. Here may be the failure of this concept. What ever water vapor there would normally exist above the water for a given temperature and pressure is blocked by the oil BUT being a vapor it is lighter than both the water and the oil and rises through the oil to escape as it normally would anyway.
So I suspect the original concept is going to prove a failure. There is the possibility remaining of taking advantage of the diffusion of ethanol from the water into the oil which requires no energy input. Then separating the oil from the water and supplying sufficient energy to drive the ethanol out of the oil. I tried this with a blender previous to this experiment and the two layers did separate but the water layer turned white like milk and the oil layer became opaque as well but less so with a tan color. But in theory it should work. No energy wasted evaporating water.
2nd edit:
The oil took over some real-estate at the bottom of the measuring cup. A little later the water rose and took over some of the surface area. When the water broke the surface a strong ethanol smell was evident. So the ethanol diffusion across the boundary between oil and water is not very good apparently. Makes a cool lava lamp though..
3rd edit: After the water broke the surface and released the ethanol it sank again below the oil layer. It still hasn't evaporated down to 400ml yet so I will let it continue to run for awhile to see what happens.
4rth edit: Reached 400ml just after midnight. Letting it continue to see if the water keeps evaporating or not..
WOW shock.. 8 more hours have gone by and the level remained at 400ml while about 90% of the pan water evaporated away! Looks like it does work despite the temporary lava lamp phase, which apparently occurs just to release the ethanol.
5th edit: never assume... yeah evaporation stopped at 400ml but apparently not for the reason I thought to be the case.
I measured the specific gravity of the remaining "water" to be 0.96. (The same as that for castor oil.)
I could smell ethanol in it.
0.96 = x(1.0) + (1-x)(0.79) solving for x gives x=0.81
So the residual water mix is about 81% h20 and 19% ethanol.
So for the "wash" :
ethanol: 38ml left and 62ml driven off
water: 162ml left and 38ml driven off
Vapor driven off was 62% ethanol averaged. (from the water mix - the additional ethanol mixed with the oil at the start is not considered in this. It was added to make sure the oil mixture would float on top of the water mixture)