KCl from KOH

[kingkama]

Well just for a Challenge I decided to make my kcl from KOH and hcl, KOH costs less than kcl and also summing the hcl there is a bit of money savings, using a reaction calculator I have been able to find the reaction ratio to obtain the complete transformation in water and kcl. I charged the reactor and a Violet/black deposit start to accumulate on the jar wall, at the same time a brown particolate forming and start to precipitate. I thinked an iron impurity fecl2 and fecl3, can be instead the the mmo anode starting to disintegrate? Which is your opinion?

Thank's.

Edited September 26, 2020 by kingkama

[WSM]

Well just for a Challenge I decided to make my kcl from KOH and hcl, KOH costs less than kcl and also summing the hcl there is a bit of money savings, using a reaction calculator I have been able to find the reaction ratio to obtain the complete transformation in water and kcl. I charged the reactor and a Violet/black deposit start to accumulate on the jar wall, at the same time a brown particolate forming and start to precipitate. I thinked an iron impurity fecl2 and fecl3, can be instead the the mmo anode starting to disintegrate? Which is your opinion?

Thank's.

 

 

A few questions:

 

What was the pH of the KCl solution you produced?

 

What was the quality of the source materials (reagent grade, technical or agricultural grade or some other grade)?

 

Without more information, it's not possible to give a worthwhile answer. I'm sure you need more than uninformed guesses.

 

WSM

[kingkama]

PH well I don't have litmus paper but I discovered that the pigment is derived From a specie of lichens, that are similar to one who grow near my lab, so I used them, Violet for basic green for acidic, no change lightly acidic or neutral, I know it's not perfect but the production of chlorine gas in the first hours make me mind that it's acidic (lichens Confirm the thought).

Reagents were bought in a Hardware Store, KOH is sold 90% minimal, HCl from 30 to 33 % both seems clean (when KOH is in solution is clear as the acid when poured in bottle).

I used for the first batch a steel spoon that seems corroded and electrolyte is a bit yellow greenish, so I thought that the problem could be a iron contamination, is the Violet black deposit on the wall of the jar that Worries me a lot, when current is on is much visible when I turn off tends to fade off, so I start to don't understand what's happening, if electrode are disintegrate or is an iron contamination.

[Arthur]

The electrode materials are important and not cheap and sometimes hard to find. The full process to perc is still hard, until you have enough toys to be able to just play then I'd suggest that you use the best available current best practises. Most times you can buy a material cheaper than you can make it, and at greater purity.

[kingkama]

@Arthur all this is obvsly a game, in the littlest proshow i made, my 2 month production is used in the first 5 shells, this is an hobby, so researching for new way, is a stimulus, if i like to buy few kilos of chlorate or perchlorate is faster and cheaper indeed. So if you havr an idea of what is the violet/black material is very welcome.

[markx]

Given the setup I suspect that ferrate might have evolved in the cell. The compound has a purple violet appearance much alike permanganate solutions. It often arises under alkaline conditions in electrochemical systems that involve iron contamination. E.g. in alkaline electrochemical steel passivation cells that are intended to grow a magnetite layer (black oxide) onto anodic electrode in hot caustic electrolyte:

 

https://en.wikipedia.org/wiki/Ferrate(VI)

 

https://en.wikipedia.org/wiki/Potassium_ferrate

 

Potassium ferrate is soluble in highly alkaline media, so perhaps that might explain the deposition on cell walls (the electrolyte not being alkaline enough to dissolve the substance). I might be wrong though, but it is a possible explanation for the phenomenon that was observed.

Edited September 30, 2020 by markx

[kingkama]

I think that you can be right, the solution ph changed a lot cause the substances I'm using, maybe that potassium ferrate was in solution then at ph change it would became to precipitate. Many thanks, a new point of wiew is like fresh water for the desert mouth of the unknown.

Readings the Wikipedia articles, if your supposition are right, the formation of this substance is obtaining something like unobtanium.

Edited September 30, 2020 by kingkama

[kingkama]

After a bit of researching, the contamination of electrolyte is a mix of iron clorides and iron hydroxide, which in a electrolysis environment had the tendency to decompose in irox oxide 2 and 3 and precipitate. The particles are insoluble so they can be easily filtered away in recristallization process. In the process a lot of precursor of iron oxide are formed, also the ferrate contaminations proposed by Mark.

By now the whole procedure is working good the iron contamination is minimal and without big interference, so, the KOH to KCl procedure is fairly economical and is a good solution for place where is hard to buy KCl or the purity is too low. 300 grams of KOH produce 400 of KCl using 200 grams of HCl.