How do I remove H2O from H2SO4.H2O mixture? 1

[mikeolesen]

I am using heated (~140C) concentrated (98%) sulfuric acid to clean a part of organic films. I follow this by rinsing with hot deionized water. I end up with a mixture of H2SO4.H2O, with > 10% H2O. My need is to remove as much of the water as possible by heating the mixture. I would like to achieve < 10% H2O in the H2SO4.
I originally thought I needed to get to 98%, however, that may not be possible by heating only.

I can calculate the amount of wattage required to evaporate, for example, 1 liter of water per hour. Using the same calculations, can I assume to be able to evaporate the same 1 liter/hr? Or do the rules change, since I have a mixture where the temperature can be much hotter than water only?

I am considering two methods to do this, one would be to heat the full volume of acid and water mix and evaporate the water from the surface. There would be a nitrogen flow above the bath to carry off the moisture. The other would be to use heated plates where a thin film of the mixture would flow across the plate in the nitrogen atmosphere into a pool below at the correct concentration. Give me your thoughts.

If someone can shed some light on this please do so and respond.

Thanks, Mike Olesen

 

[25362]

Since both acid and water have vapor pressures (however small) nitrogen stripping + heating could create an emission problem.

Depending on the size of the plant and the related economics, one should check:

Reabsorbing SO[sub]3[/sub]
SAR
Dehydrating by chemical reactions
Dehydrating with other chemical agents
Chilling to separate a richer hydrate as a solid. See fig. 1 in

http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1739.pdf