testerman said:
Thanks again for all the info. This is very interesting and enlightening. I'm going to take all the advise given and I'm going to talk to a local battery supply store here that's not far from me and they recycle car batteries, and they sell them too. I should get some good results from them.
Kevin
The sulfuric from batteries is much too weak to be used in a sulfuric stripping cell. To be of use, the sulfuric should be at least 90% and, therefore, most of the water would have to be eliminated by evaporation on a hotplate. As the water evaporates off, the sulfuric gets stronger and the boiling point (B.P.) gets higher. As I mentioned before, the B.P. of 90% sulfuric is about 500F. Therefore, the sulfuric will get hotter and hotter as the water evaporates and the only limiting factor is the boiling point at whatever strength it happens to be at that particular time.
There are huge safety problems in doing this. They can be moderated somewhat by accurately measuring the temperature continuously and keeping it at some lower point.
Firstly, the hotter the solution, the easier it is to break beakers. To evaporate safely, you definitely need a container under the beaker to catch the acid in case the beaker breaks. The most reliable catch container is a 5 liter Corning Ware Pyroceram dish, which costs $50-$60 new.
Secondly, hot sulfuric is one of the most dangerous things on the planet. It will cause severe burns instantly.
Thirdly, the more concentrated and hotter it gets, the more it will tend to splatter.
Fourthly, if you over-evaporate the water and the sulfuric gets over-concentrated, you can get copious (a lot of!) white fumes of toxic SO3 gas.
http://www.google.com/search?num=10&hl=en&site=imghp&tbm=isch&source=hp&biw=1024&bih=503&q=sulfuric+acid+burns&oq=sulfuric+acid+burns&gs_l=img.3..0j0i24l3.1719.10828.0.11750.19.13.0.6.6.0.344.3609.2-10j3.13.0...0.0...1ac.1.PQHNcHwo6mE
I know that some people on the forum evaporate battery acid to make the sulfuric stripper. This has always seemed very stupid to me. Why put yourself in harm's way when you can buy readily available concentrated sulfuric acid, in the form of commercial drain cleaner, inexpensively? Concentrated sulfuric, at room temperature, is dangerous enough. Why magnify this danger, maybe 100 fold, by heating it up hundreds of degrees? Stupid!