[wolfpackengineer]

My facility works with a high volume of DMSO-Water solution, where the DMSO concentration is only about 2% of the liquid (other 98% is DI water). We want to responsibly dispose of the DMSO, but removing such a high volume of liquid is costly. Does anybody have recommendations for how to potentially concentrate the DMSO and separate it from the DI water? By having a higher concentration, the amount of volume we would have to remove could be greatly reduced.

Any thought or recommendations are greatly appreciated!

[Arkcon]

Distilling that much water is going to be energy intensive, therefore expensive.  I don't know if there's some sort of misting under vacuum apparatus that can help, but its likely capital expensive.

What your left with is process controls -- what can you change so this solvent isn't so diluted in water so that your waste is easier to discard or cheaper to remediate.

[ramana143]

Add THF to this solution. THF and water forms azeotrope at 65°c. After the distillation you can get the pure DMSO because of it has the boling point of 189°c.

[wolfpackengineer]

Thank you for the recommendations. Yes the energy consumption is an issue for distilling the mixture, but if it is cheaper than frequently removing a high volume of liquid then it is certainly a potential option.

As far as THF, this is an interesting idea. However, wouldn't evaporating the THF pose a possible hazardous waste concern?

Thanks again for the replies.

[Enthalpy]

If sunlight is reliable enough where you work, it can provide cheap heat. Fractional distillation, using the heat several times, needs only pumps for the liquids, especially of done at >1atm.

Degrading the DMSO in water with an oxidizer, UV and photocatalysts, or both, looks like the standard method:
http://www.tandfonline.com/doi/abs/10.1080/01919510701573418?journalCode=bose20
maybe some CaO finishes the job. I ignore whether some intermediates are toxic.

[Enthalpy]

Reverse osmosis of course
https://en.wikipedia.org/wiki/Reverse_osmosis
especially if the mixture is (or can be made) reasonably clean.

The operation only needs pressure, <100bar, which consumes less than 1/200 of the power needed to evaporate water.