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Old 09-08-2005, 03:34 AM   #11
BarraCuda™
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I can see calcium deposits after 3hrs of electrolysis. However I'm stopping the process temp due to the fact that chlorine might be released (in my bedroom!) while I'm sleeping.

I will be starting another pc by using solar power
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Old 10-08-2005, 01:41 AM   #12
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Seems like there is too much current used. Serious precipitation occurs.
Its greenish because oxidation by the anode.
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Old 10-08-2005, 01:45 AM   #13
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Despite of all the precipitation, there is still calcium deposit after 12hrs.
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Old 10-08-2005, 01:47 AM   #14
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This is the solar cell which will be replacing the transformer. It will be providing 10VDC for the electrolysis.
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Old 10-08-2005, 08:59 PM   #15
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After getting a mixture of greenish precipitate with brown scum. I have decided to split the anode and cathode into 2 separate containers.

This is the anode container with the green precipitate and the cathode container with brown precipitate.
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Old 10-08-2005, 09:38 PM   #16
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While I'm not good with chemistry, I will try to explain whats happening here. Please do correct me if there are any errors.

The positive terminal (anode) is oxidising and will breakdown salt (sodium chloride, NaCl).

Oxidation of chloride ions to chlorine
2Cl- ---> 2Cl2 + 2e-

Chlorine + water -> hypochlorous acid + hydrochloric acid
Cl2 + H2O ---> HOCl + HCl

Both are liquid form of chlorine suitable for disinfection. The green precipitate could be any metal chlorides, maybe iron chloride (greenish)


The negative terminal (cathode) is reducing.

Reduction of sodium ions
Na+ + e- ---> Na

Reaction of sodium to sodium hydroxide (caustic)
Na+ + H2O ---> 1/2H2 + NaOH

So what if both acids(HCl & HOCl)produced at the anode react with the NaOH produced at the cathode?

HCl + NaOH ---> NaCl + H2O and,
HOCl + NaOH ---> NaOCl + H2O

The final product of electrolysis is:
NaCl + H2O ---> NaOCl + H2

NaOCl = Sodium hypochloride aka bleach! The same stuff used for bleaching clothes.

IMHO, electrolysis is not suitable for hobbyist tanks. The by products of saltwater electrolysis are far too dangerous to be used in our small tanks.


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Old 10-08-2005, 09:38 PM   #17
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hhhmmm..
this is interesting...
i assume that the steel electrode used is not inert and if so it reacts...
so the green precipitate at the anode is from the oxidation of iron to iron 2+
...precipitate being Fe(OH)2 and the brown precipitate is iron 3+ as it is being further oxidised by air to form Fe(OH)3

however i have no idea what the brown precipitate at the cathode is...

this is really interesting
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Old 10-08-2005, 09:52 PM   #18
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Quote:
Originally Posted by BarraCuda™
While I'm not good with chemistry, I will try to explain whats happening here. Please do correct me if there are any errors.

The positive terminal (anode) is oxidising and will breakdown salt (sodium chloride, NaCl).

Oxidation of chloride ions to chlorine
2Cl- ---> 2Cl2 + 2e-

Chlorine + water -> hypochlorous acid + hydrochloric acid
Cl2 + H2O ---> HOCl + HCl

Both are liquid form of chlorine suitable for disinfection. The green precipitate could be any metal chlorides, maybe iron chloride (greenish)


The negative terminal (cathode) is reducing.

Reduction of sodium ions
Na+ + e- ---> Na

Reaction of sodium to sodium hydroxide (caustic)
Na+ + H2O ---> 1/2H2 + NaOH

So what if both acids(HCl & HOCl)produced at the anode react with the NaOH produced at the cathode?

HCl + NaOH ---> NaCl + H2O and,
HOCl + NaOH ---> NaOCl + H2O

The final product of electrolysis is:
NaCl + H2O ---> NaOCl + H2

NaOCl = Sodium hypochloride aka bleach! The same stuff used for bleaching clothes.

IMHO, electrolysis is not suitable for hobbyist tanks. The by products of saltwater electrolysis are far too dangerous to be used in our small tanks.


well...seems these reactions can occur...but i believe not to a really great extent...chlorine gas still do get produced..and most prob still considerable amounts will still react...this can be another cause of worry

thanks for testing the method out...it really is too dangerous for carrying out in our tanks
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Old 10-08-2005, 10:29 PM   #19
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Quote:
Originally Posted by decentkid
well...seems these reactions can occur...but i believe not to a really great extent...chlorine gas still do get produced..and most prob still considerable amounts will still react...this can be another cause of worry

thanks for testing the method out...it really is too dangerous for carrying out in our tanks
I'm not so concerned about chlorine production but electrolysis will precipitate alot of of unknown metals and may cause the whole system to crash.

I may bring this experiment offshore and see what happens
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