Sciencemadness Discussion Board

Sodium bisulphate & acetone

amaurer - 1-8-2012 at 12:36

I need to extract the sodium bisulphate from a saturated aqueous solution. Evaporation is too slow and I can't heat the solution over ~50C. This is related to my fabric etching question from earlier - I can't heat the fabric up.

Can I crash it out by adding a bunch of acetone to gobble up the water? I seem to recall separating solutions like this in chemistry class once...?

I can't find any data on sodium bisulphate solubility in acetone, or if there is a reaction I need to worry about. Same question for alcohols.

EDIT: looks like its decomposed by alcohol, so thats out.

[Edited on 1-8-2012 by amaurer]

zoombafu - 1-8-2012 at 12:49

What do you mean by 'gobble up' water? Acetone is miscible with water. And if you cant find info on it get a test tube, put some sodium bisulphate in it along with some acetone. If it dissolves then it is soluble, if it doesn't it is not.

I'm not entirely sure what you are doing ( I did read your original post though). Is the aqueous solution on the fabric? If so aren't you supposed to let it dry and then heat it to eat away a hole?

amaurer - 1-8-2012 at 13:02

I'm trying to scale the process up. I apply my aqueous solution to the fabric, but, say, if I want to do 50 pieces I've got a serious problem because hanging up 50 pieces of fabric takes a lot of room.

I can stack the fabric, but then it takes forever to dry. It also tends to wick the bisulphate to the edges of the stack.

I could also build some crazy apparatuses to compactly stack and ventilate the fabric... but that doesn't scale without spending $$$.

So I'd like to be able to take the fabric, soak it in bisulphate, and then give it a dunk in acetone (for example) to pull the water out and leave the bisulphate behind. Then acetone dries in mere moments.

Back to the question - the solubility in acetone is easy to find, as you say... but the question is also whether is possible to crash the bisulphate out of the water with acetone as I describe? Also are there any side reactions of bisulphate with the acetone?

amaurer - 1-8-2012 at 16:58

Looks like anhydrous sodium bisulphate is insoluble in acetone.

However I attempted to crash it out of an aqueous solution with an excess of acetone... what I got was a two phase liquid - upper layer apparently wet acetone, the bottom layer was something thicker and oily-looking. Perhaps some sort of icky sodium bisulphate hydrate+acetone slurry?

I'm try to evaporate it now.

EDIT: the remaining acetone came off easily and whats left has no acetone (or any other) odor and is not evaporating easily.

[Edited on 2-8-2012 by amaurer]

[Edited on 2-8-2012 by amaurer]

amaurer - 2-8-2012 at 07:31

Just to update, looks like the acetone will dissolve all the easily-available water but the sodium bisulphate apparently like to hold onto a lot of water itself.

The lower phase is aqueous sodium bisulphate, very near to or at the saturation point.

So this isn't of any use to me. Bummer.