Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: thedoc on 18/08/2014 15:30:01

Title: What is this black sludge?
Post by: thedoc on 18/08/2014 15:30:01

George asked the Naked Scientists:
   
I am producing about 2 cubic foot of Hydrogen /oxygen per six hours. I am increasing that, but what I am finding is a BLACK sludge near the positive plates. I don't know how to ask the question as to what this sludge may be. I am using water, salt, muriatic acid on 305 stainless steel plates. 6 amp, 12 volt.
What do you think?

Title: Re: What is this black sludge?
Post by: chiralSPO on 18/08/2014 18:57:54

If you are using muriatic (hydrochloric) acid and salt (sodium chloride), your going to be generating a lot of chlorine (maybe instead of oxygen). This chlorine is formed at the anodic (positive) plates, and will corrode them quite effectively.

Please tell me more about this cell. Amps and volts is a start, but how many electrodes are you using? And what is their surface area? And are they connected in series or parallel? ie what type of electrolyzer are you using, and how big is it?

With stainless steel plates, I would recommend you use sodium hydroxide or potassium hydroxide instead of the salt and acid mix--it will be more efficient and the electrodes will last much longer.