# Vacuum evaporating.



## qst42know (Jun 14, 2009)

Is vacuum evaporating as in concentrating sulfuric acid, faster or just more energy efficient?


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## Anonymous (Jun 14, 2009)

I am not sure it is either, since a small quantity of water will make a tremendus volume of vapor and the dryer the sulfuric gets the harder it hold on to water, or takes water from anything it can.

Jim


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## qst42know (Jun 14, 2009)

I understand the idea behind a hard vacuum is you can boil things at a much lower temperature. Under vacuum some solutions will boil even at room temp. However I don't know if this is faster or a savings in heat energy or both?


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## Platdigger (Jun 14, 2009)

It would save heat energy. I built a vacuum still, just for that reason once.

Water will boil at normal room temperatures or even lower, with a high enough vacuum.

I was just shooting for 25 inches with an old automotive airconditioning compressor.
Randy


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## leavemealone (Jun 14, 2009)

Hey randy,your vacuum idea would work fine if you utilized two containers capable of withstanding the boiling temperatures(distilling flasks) connected by a noncollapsable hose or tube.One could be used as your boiling aparatus,the other for vapor condensation,with the pump and filter on that one.That would allow most of the vapor to condensate before entering the filter.If you could install a heat resistant valve you could close off the connection when you've reached your desired pressure,then turn it back on as the air explands,giving your pump intermitant rests.Just a thought.


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## Platdigger (Jun 14, 2009)

Hi Johnny, 
mine was just to distill fuel alcohol. But, those are good ideas.

Randy


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## leavemealone (Jun 14, 2009)

Hey bud,I am not too familiar with that.I have what you need but They are going to jack this week.I boiled mine down and you are so right,it took so long,especially as the concentration started to slow the boiling.Jack has a pump now,if I do it again I will certainly get his and make a condensing container.
Hope you had a good weekend


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## Lou (Jun 14, 2009)

I'm somewhat familiar with vacuum evaporation. :lol: :lol: 

It saves time, yes, but does it really save energy? Well, I suggest you review thermodynamics--the energy to make that vacuum has to come from somewhere. No escaping it.

It will go quicker, but really, I wouldn't recommend vacuum evaporating sulfuric acid unless perhaps you were using a recirculating aspirator--any acidic vapors would quickly destroy a pump unless it had a beastly foretrap.


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## qst42know (Jun 14, 2009)

Hi Lou.

My goal is to pursue the silver plate thing. With the quantities out there if I can get my efficiencies in line I suspect I can make a go of this. Diluting and concentrating the sulfuric seems the largest hurdle. Any suggestions?


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