citric acid

A couple of weeks ago I made a mix of citric acid from powder , I used it for cleaning some copper parts before I soldered them . Today I took the lid off to use it again and found it contaminated with a lot of small black balls of something . I would have thought that the mildly acid solution would kill off any fungus etc Any ideas what this might be ?

Phil

Probably fungus... citric acid a.k.a. vitamin C isn't very toxic and in dilute form it's probably even food source for some things.

Neil

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Really ?

MichaelG.

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https://www.uwhealth.org/files/uwhealth/docs/pdf/kidney_citric_acid.pdf

Edited By Michael Gilligan on 23/09/2019 18:03:19

Vitamin C is ascorbic acid.

Fungus and bacteria having a feast probably. Citric Acid is common in many fruits and edible. The crystals are fairly resistant to hungry bugs but add water and Citric Acid goes off just like a rotting Lemon or Lime.

'Acid' always sounds a scary but most of them are weaklings. Citric is one of the mild organic acids: it's not in the same league as Sulphuric, Hydrochloric, or Nitric which are strong mineral acids.

Dave

So should I dump this and mix some fresh , or carry on using it , Will it still have the cleaning effect ? Should I have made a stronger mix ?

Phil

I would guess it is a fungus or some form of lower life. These can turn up in unexpected places such as in petrol and aviation fuel.

Why don't you just try using your citric acid. It will either work or not work. What ever it is will not eat your copper.

Fungi are more likely to be killed by copper than citric acid.

JA

Edited By JA on 23/09/2019 19:05:47

Amazing where fungi will grow.

At school, we found that the winchester of fuming sulphuric acid had a white fungus growing in it. In THAT environment?

Try out your solution on a some metal. If it works satisfactorily, use it.

If it doesn't, dispose of it safely

Howard

If it tastes mouldy it probably is

Like humans?

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Possibly aspergillus niger, which [oddly enough] is used in the production of Citric Acid

Photos, or a rough estimate of size might help.

MichaelG.

I used citric acid to pickle copper a lot a while ago. It regularly grew mould on the surface, irrespective of the strength of the solution. However, it worked just as well with or without the fur coat. It just looked a bit grim.

James.

Adding a small amount of bleach fixes the mould problem for me.

Edited By Clive India on 24/09/2019 07:58:27

Nah, add a double Vodka in there, it'll be fine...

D'oh! Engage brain before keyboard...

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Sulking ... Why does Michael Cox get the credit ?

If it just citric acid I guess you pour it down the sink.

My pickling acid, made from powder bought from CuP Alloys, is now a nice green colour since used acid is returned to bottle. I guess the green is copper citrate. I would think the powder I bought contained a biocide since I never had anything grow in the liquid.

JA

I wonder if the 'mould' seen by Howard Lewis was actually crystals of SO3, and not a fungus at all. Fuming H2SO4 is so eager to combine with the tiniest speck of water that it would not make a good environment for anything living - mould, germ, or virus. Just because it looked fluffy, do not be misled.

Cheers Tim

Just a reminder