so i have made some dillute sulfuric acid by copper sulfate electrolysis. now i have boiled the solution to get that small amount of concentrate, but
it is dirty (probably from makeshift boiling chips that i used)
how or what do i filter it with that would survive the concentrated acid?JJay - 29-10-2017 at 09:25
A porous glass frit can withstand concentrated sulfuric acid:
is there any other perhaps a bit cheaper alternative?hissingnoise - 29-10-2017 at 12:48
Smaller fritted funnel, perhaps ─ or if you'd concentrated the acid in an open pyrex dish, boiling chips wouldn't have been needed...
Gardeners rockwool works if done correctly; uncoated fibreglass is another option and Whatman papers will filter very dilute acid.
Use distilled water for dilution, if you do go that route.
BTW, what type anode did you use?
LearnedAmateur - 29-10-2017 at 12:57
That's a lot for a fritted filter.. I paid £10 for a 60mL filter with integrated vacuum port, shipped from China.
Aside from a fritted filter or funnel, you could pack some glass wool into a regular funnel. Won't be nearly as good but it should get some of the
larger particles out. If you've got the time, then let it sit for a few days to a week and then decant off the acid - any remaining
discolouration/visible contamination is due to a small amount of tiny particulates that would pass through a filter anyway and usually looks a lot
worse than it is.XeonTheMGPony - 29-10-2017 at 14:08
good plastic gas rated funnel and some fiber glass wool.macckone - 29-10-2017 at 18:55
polypropylene funnel, glass wool and top it with water filter grade diatomaceous earth. Only trick is finding glass wool without binders.Hector - 31-10-2017 at 14:15
i used a carbon rod. it gets pretty messy after long exposurehissingnoise - 1-11-2017 at 07:59
Graphite rod is cleaner and better than carbon ─ linseed-oil-impregnated graphite is better still...
Graphite is grey rather than black and sports a slight metallic sheen!
Would using Diatomaceous earth work to filter out the very fine particles?
I had a mess of CuCl2 and very fine graphite in about 3 gallons of KCl solution. I used cotton swabs (flat square ones) rolled into a cylinder then
ran the liquid through it 3x. The first pass there was a lot of graphite left, second pass, there was a slight grey color, third pass it looked
crystal clear (24 inches deep and was clear to the bottom). The graphite builds up and removes more each layer, but it will slow down each pass.
I've used the same setup with H2SO4 at 30-40% concentration. The filter material turns into a solid mass clump as the acid dehydrates it, but it
holds up pretty well if the cotton cylinder is pressed into the neck of a funnel so it is wedged into it, especially at the bottom.
If trying any of this you have to wet the cotton before adding any liquid you want to filter or it may never soak through due to the compression (and
other issues probably). LearnedAmateur - 3-11-2017 at 21:33
Diatomaceous earth should work, although I think that pure silica/crushed silica gel powder would be a lot better. DE can contain some metal oxides,
principally alumina and iron oxides which may interfere with some filtrations, so it's best to go with a brand specifically designed for filtration as
opposed to any old one off the shelf.macckone - 4-11-2017 at 09:51
Good quality diatomaceous earth is practically pure silica. Metal oxides are
usually tested for because they stain pools if they are in the filter material.
You can buy sodium silicate and then treat it with hydrogen chloride gas.
That will yeild a very pure silica product after repeated washing with distilled
water as the only impurity will be sodium chloride but if you need sulfuric acid
that pure, you should probably distill it as the copper sulfate method is going
to leave more copper than the diatomaceous earth will contain iron.
Commerical sulphuric acid is likely to contain lead or iron or both dissolved
from the handling equipment.
PS. yes diatomaceous earth will filter extremely fine particles.
