[Ren]

Hi, I have this bucket of ~15% citric acid solution which I use to strip metal parts of rust and general cleaning of iron parts (mostly motorbike parts). It's so dark now, after many uses, nearly black and it's effect is obviously very weakened. Sure, I can send it down the drain and prepare a new solution but I was thinking, wouldn't it be possible somehow easily clean the solution and keep it "forever"? I was thinking about electrolysis, but I guess it won't clean the liquid itself, considering electrical current flows directly between two metal electrodes. So what about chemical way? I frankly have no idea, what form the iron in the liquid is now. Does it bond somehow with the acid molecules, or is it just a mixture now? Considering it doesn't create any sediment at the bottom of the bucket I believe the former is right but I have only general chemical knowledge. Any pro tips here?

[Borek]

What you have is (more or less) a mixture of unreacted citric acid, iron citrates (including complexes) and suspended iron oxides. Trying to clean up and reclaim the acid would be quite difficult and would definitely not make any economical sense.

[Ren]

What you have is (more or less) a mixture of unreacted citric acid, iron citrates (including complexes) and suspended iron oxides. Trying to clean up and reclaim the acid would be quite difficult and would definitely not make any economical sense.

Ah, that's a pity. But thanks a lot for the info.