Brine Electrolysis: Why Is the Solution Turning Yellowish?

[asamaid1]

Hi,
i have been trying to electrolyze brine having carbon as anode and cathode as well;; but i don't understand why the solution is turning yellowish. Can anyone explain it ? thanks.

 

[Borek]

My bet is that what you see is just effect of electrode decomposition, either very fine carbon particles or just the binding.

 

[mrjeffy321]

You say that you are using carbon [graphite] electrodes for both the anode (+) and cathode (-) of you cell. What current are you passing through the cell? How are the electrodes holding up? Is the anode disintegrating at all? Fine graphite particles should be flaking off the anode and making the solution turn gray (or black after a long time).

How are you making your electrical connection to the graphite electrodes from your power supply? Are these wires completely isolated from your electrolyte solution? Do the wires show any signs of corrosion? The graphite electrodes can be porous and a small amount of electrolyte can be absorbed up into the electrode and migrate up toward you wire leads.

 

[asamaid1]

Hi,

i used carbon rod as electrode, and a 9 volt battery was used, and connecting wire does not touch the solution,,,,,,,,,, so why the solution s turning reddish yellow. thanks.

 

[wazani]

hi
here the correct reason:
the product of the reaction is chlorine at anode and hydrogen gas at cathode and sodium hydroxide solution .the yellowish color produced because some of yellowish chlorine dissolved in the alkali solution .
forgive me all...

 

[Borek]

the product of the reaction is chlorine at anode and hydrogen gas at cathode and sodium hydroxide solution .the yellowish color produced because some of yellowish chlorine dissolved in the alkali solution .

No. Dissolved chlorine is colorless, especially at low concentrations. You will not get high concentrations of chlorine using simple setup like the one described by the OP.

 

[gerrardz]

possible either Cl₂ produced or presence of NaOH to cause corrosion on the conducting wire esp it contains Fe and iron(III) compound is reddish/brown/yellow ? Can carry out simple analytical test on iron(III) ion ? hopefully this will help

 

[asamaid1]

Hi,

see this you tube link

http://www.youtube.com/watch?v=OoIuDPI5GQs&feature=related


the same thing happens when i do this, but i used carbon for electrodes, and conecting wires do not touch the solution. thaks

 

[mrjeffy321]

Hi,

see this you tube link

http://www.youtube.com/watch?v=OoIuDPI5GQs&feature=related


the same thing happens when i do this, but i used carbon for electrodes, and conecting wires do not touch the solution. thaks

The cause of the color change observed in the video is very different from the situation you are describing. In the case of the video, the color change is easily explained by the oxidation of the iron (stainless steel spoons) into Fe+2 (aq) ions in solution. But you claim that you are not using iron, you only use copper and carbon, and the copper is not even touching the solution (If the copper was being oxidized to Cu+2 and put into solution, it would turn blue by the way).

As Borek said, with only a 9 volt battery as your power supply, it is unlikely that you were generating significant quantities of chlorine. Otherwise, that would have been my next guess...that you are generating chlorine that then dissolves in the water, changing its color to a pale yellow (like clorox bleach). But with the setup you describe, I do not think that is happening.

 

[asamaid1]

Hi,

if i disconnect the battery, and leave the solution still , the yellow stuff precipitates at the bottom, and i don't see any sodium hydro oxide, souldnt there be some white sodium hydrooxide at the bottom?thnks.

 

[mrjeffy321]

Sodium hydroxide is highly soluble in water; it will all remain in solution (and also react with the Cl2 that you are producing, none will precipitate out.

How much of that powder do you get? Enough to do a couple of experiments on it? You could try filtering it out and drying it. Then see what acids will dissolve it, and / or what happens when you heat it up to a high temperature in air.

 

[nismaratwork]

Hmmm... You're producing some caustic soda in solution, but not a lot of chlorine...

... What's the material you're using as a container for your electrolyte, and what kind of sealant did you use? Do you have direct means of agitation, or indirect?

 

[asamaid1]

How much of that powder do you get? Enough to do a couple of experiments on it? You could try filtering it out and drying it. Then see what acids will dissolve it, and / or what happens when you heat it up to a high temperature in air.

Hi,

thnks for the reply, I did filter it, and tried to dissolve the powder in accetic acid, it does not dissolve. any other ideas? thanks.

 

[sohel2012]

Hello everyone,

you same thing happened to me too, i used a becker for the container, carbon as electrodes, a 9 volt battery, and table salt. Then i saw the solution becoming yellow. Is it something with the salt? because i used table salt, which is iodised. the salt packing says 40 ppm of potassium iodide is mixed with the salt. can anyone shed some light on it? thanks.

 

[Borek]

As it was already said - most likely what you see is some junk from the graphite electrode.

 

[nismaratwork]

Hello everyone,

you same thing happened to me too, i used a becker for the container, carbon as electrodes, a 9 volt battery, and table salt. Then i saw the solution becoming yellow. Is it something with the salt? because i used table salt, which is iodised. the salt packing says 40 ppm of potassium iodide is mixed with the salt. can anyone shed some light on it? thanks.

I can't think of anything except what Borek said... the amount of potassium iodide wouldn't have that effect anymore than dumping a load of sea salt into clear water would.

 

[mrjeffy321]

Where did you get the carbon for the electrodes? I presume you scavenged it from somewhere, which could hint at what the contamination might be.

 

[nismaratwork]

Where did you get the carbon for the electrodes? I presume you scavenged it from somewhere, which could hint at what the contamination might be.

Oh... if that's the case I'm going to be pissed... that up front would have answered a LOT.