making potassium (per) chlorate

[taiwanluthiers]

Will a Brita filter remove sufficient solids to make them safe for use in cells?

[dagabu]

I don't think so, the pitcher we use for our Keurig machine does not lower the TDS much. A quick test just now of our tap water is 181 PPM, after the Britta its 179 PPM. The filter is about 1/4 the way through its use cycle so it could be higher or lower depending on when in the cycle you use it.

 

The jug of RO/Di I have (about four days old now) measures 1 PPM.

 

The 10" carbon filter we have for drinking water measures 166 PPM (that was interesting) and the wifes brand new Zero Water pitcher reads 0 PPM after a few minutes of flushing the new filter.

 

Now that as interesting to say the least.

 

I guess that I would try the Zero Water system.

 

-dag

Edited November 10, 2012 by dagabu

[Swede]

It isn't that I can't find distilled water locally, it's more like a confusion between mineral water and distilled water in Chinese and the labeling is inconsistent.

 

Understand. I would absolutely avoid any labeling that hints of "mineral water" or any water bottled at the source. It's going to have MUCH more minerals (Ca, Na, Cl, Mg, etc) than generic "purified drinking water" which is usually (but not always) run through a reverse osmosis system and a carbon filter.

 

Will a Brita filter remove sufficient solids to make them safe for use in cells?

 

I'd say NO. Most of those are carbon filters which make water taste good but don't do jack for sediment or most dissolved solids.

 

I may have missed it, but can you explain again why your tap water isn't OK? This process needs a LOT of water, and having to pay for it would make it "less fun."

 

By the time you consider the inevitable contaminants in your NaCl or KCl, the water isn't going to add much. The only way to do a super-clean process, say for a benchtop lab experiment, would be to use 99.99% salts, RO/DI water, and both of these cost waaay too much to be practical. Lab grade KCl can be $40 for 500 grams. Ridiculous. At the (per)chlorate factory, they use pallets of the cheapest salts imaginable. If they need ultra-pure product, they gain that through recrystallization of the crude product.

[taiwanluthiers]

My MMO anode was losing coating in the test run and I was trying to figure out why. I do not know if Fluorides have been added to my water supply that might have caused that. The problem with bottled water is not only the price, but also the fact that if I needed lots of them, it will be difficult to transport. I use public transport so you can imagine that even one gallon of water is a bear to carry.

[Swede]

What was the current density of your test run? Tell us the dimensions of your anode, please, and whether it is mesh or solid. I'd be surprised if fluorides are the cause. The USA uses a crazy amount of fluoride in the public water supply, and I haven't seen problems from it yet.

 

The RuO2 which is the primary maker of chlorate in MMO can be oxidized to RuO4 at high current densities, and importantly, high pH. RuO2 is completely insoluble and inert, very tough stuff, while RuO4 IS soluble and can be lost.

 

It is not easy to remove fluoride, but again, I'd be really surprised if fluoride was the culprit.

[taiwanluthiers]

The dimension of the MMO is mesh, about 2.5" x 5", came from laserred. The cathode is equal size but solid, made from Ti.

 

Current densities shouldn't even be an issue because the current of the test run was something like 500 mA and the current of the battery run was only 4 amps, and only for seconds at the most because the battery would die quickly otherwise. After each test run (and the solution would smell like bleach) I rinsed the MMO in water and soap and lightly rubbed it with my hands. I don't think that would erode the coating.

 

I have not ran it under high current densities yet.

 

I heard the anode/cathode can erode if left in the solution without any electricity going through it, would very low current do that too?

[Swede]

Some (maybe all) of the LR MMO comes used and is coated with some compound which I haven't identified. Probably iron. I take LR MMO and cut it into desired sizes, then pickle them in a solution of about 5 molar HCl. The acid turns yellow as it strips the crud from the MMO, but leaves the MMO itself untouched.

 

Not all of his stuff comes with 100% MMO coverage. There are often areas where you can see bare Ti due to loss of MMO, but the remainder is sturdy and they generally work great. Is it possible that your trial run and hand-cleaning removed some of the crud that came with the MMO, rather than MMO itself?

 

I'd say give it another run at a proper current density and compare before and after. Pictures would help identify what is going on. I've only had one MMO anode partially fail, and that was due to soda glass being the cell... the MMO got coated with silicates which simply cannot be removed.

[pyrojig]

I have noticed a small amount of foreign matter under my electrodes ( from LR), but this was not till after many many runs. The water was city tap water, and the kcl was water softener . The electrodes seemed to degrade with a dark small amount of color on the kclo3 after a run. Now this may have been due to city tap water, or to the fact I may have run the chloride levels to a fine line.

So I too have seen this formation of what appears to be a degrading electrode.

 

P.s. As a side note:

I did notice after a few more runs that the CE was getting worst, and it may have been linked to the losses in the MMO coating . To many variables took place ( including a failing PS) that may have lead to the probs at hand. But it is a starting point to work off of.

[oldmanbeefjerky]

I have noticed a small amount of foreign matter under my electrodes ( from LR), but this was not till after many many runs. The water was city tap water, and the kcl was water softener . The electrodes seemed to degrade with a dark small amount of color on the kclo3 after a run. Now this may have been due to city tap water, or to the fact I may have run the chloride levels to a fine line.

So I too have seen this formation of what appears to be a degrading electrode.

 

P.s. As a side note:

I did notice after a few more runs that the CE was getting worst, and it may have been linked to the losses in the MMO coating . To many variables took place ( including a failing PS) that may have lead to the probs at hand. But it is a starting point to work off of.

 

This is why everyone uses distilled water or rain water, hardly any tap water is clean enough to use. Also i recall hearing that fluride of almost any quantity in water will always seriously degrade MMO, i think it was on an MMO research paper or something its been a while, but what i am totally certain of is that flurides, some calcium compounds, iron, soluble aluminium , copper and chromium reduce MMO lifetime significantly, I recall this site listing experiments done with certain chemicals in solution and recording the level of degredation.

In any case, use rain water or distilled water, those are the only ones you can be absolutely certain are clean.

[taiwanluthiers]

What about impurities in non-lab grade KCl or NaCl?

 

It just seems the cost to use only DI/Distilled water could be more than any extended lifetime you get from MMO anodes, considering that they're rather cheap from the right seller.

 

I can catch rain water but the problem is rainwater tends to be rather dirty. It picks up pollution from the air.

[Algenco]

contaminants in rain water should be easy to remove with charcoal filtration

[dagabu]

What about impurities in non-lab grade KCl or NaCl?

 

It just seems the cost to use only DI/Distilled water could be more than any extended lifetime you get from MMO anodes, considering that they're rather cheap from the right seller.

 

I can catch rain water but the problem is rainwater tends to be rather dirty. It picks up pollution from the air.

 

Not where I live, the TDS in rain water is 1-2 PPM, better than a lot of the distilled water they sell at the grocery store.

 

-dag

[taiwanluthiers]

What about water from the dehumidifier? That has got to be the same as rainwater right?

[WSM]

What about water from the dehumidifier? That has got to be the same as rainwater right?

 

Check the dehumidifier for cleanliness. I think if it's made of plastic and it's clean, it probably has clean (pure) water caught in it. If it has metal components as part of the active elements inside, I would suspect some metal ions to be in that water (unless proven otherwise with a TDS meter).

 

Try it and see...

 

WSM

[WSM]

Not where I live, the TDS in rain water is 1-2 PPM, better than a lot of the distilled water they sell at the grocery store.

-dag

 

?!!

 

That's interesting. I tested the distilled water I got from Walmart (of all places) once and got a reading of 0 PPM. That was after reading the TDS of my tap water and then the purified water from our kitchen RO dispenser.

 

What is the sensitivity of your TDS meter? Mine is from 0-999 ppm, by Hanna (pen type). Have you had it calibrated? I'm not sure how you'd do that unless you have a calibration solution in a sealed container.

 

WSM

[WSM]

contaminants in rain water should be easy to remove with charcoal filtration

 

Thanks Algenco, That's a good tip. I supose one could set up a plastic container with a refillable filter housing and replenish the charcoal occassionally with activated charcoal from one of the big box home center's garden section (the pool and pond supplies are in that section of the store where I live and I think that's where to look). A lot of the components are probably available on eBay as well.

 

Nice.

 

WSM

Edited November 18, 2012 by WSM

[WSM]

This is why everyone uses distilled water or rain water, hardly any tap water is clean enough to use. Also i recall hearing that fluride of almost any quantity in water will always seriously degrade MMO, i think it was on an MMO research paper or something its been a while, but what i am totally certain of is that flurides, some calcium compounds, iron, soluble aluminium , copper and chromium reduce MMO lifetime significantly, I recall this site listing experiments done with certain chemicals in solution and recording the level of degredation.

In any case, use rain water or distilled water, those are the only ones you can be absolutely certain are clean.

 

mmo_poison.pdf

 

I believe this is the material refered to. I got this from one of the hobbyist sites and think it changed my mind about ever using straight tap water. In my area (a major metropolitan area near the ocean), the water quality seems to change with the season (let alone the whims of the water department directors). What is "good enough" for them may not be good enough for my cell's health; so I use at least purified if not distilled water.

 

caveat emptor

 

WSM

[pyrojig]

Thank you for that file WSM.

It does shed light on the importance for a clean brine and close observation of the electrodes during runs. It does give a few good points on what industry uses for cleaning, and maintenance. Sadly, what is purchased as "water softener" is full of impurities, maybe worst than the tap water !

[WSM]

Thank you for that file WSM.

It does shed light on the importance for a clean brine and close observation of the electrodes during runs. It does give a few good points on what industry uses for cleaning, and maintenance. Sadly, what is purchased as "water softener" is full of impurities, maybe worst than the tap water !

 

That's true . We could dissolve, filter and recrystallize it if it becomes an issue (Oh Great!, more work... ). Other than that, I suppose we'll live with it the way it is.

 

You're welcome for the file. I think it should be more widely distributed (we all should read it and keep it handy).

 

WSM

[pyrojig]

LOL ... and to think we drink that stuff ( the softened water with all those impurities ) not the chlorate "cell brine"!@!

[WSM]

LOL ... and to think we drink that stuff ( the softened water with all those impurities ) not the chlorate "cell brine"!@!

 

That's also why I use an RO system for drinking and cooking water and haven't used a water softener in about twenty five years. Cell brine is for cells !

 

WSM

[WSM]

One of the final sticking points to my experimental continuous system has been overcome.

 

I realized it needs a "heat well" in the crystallizer to prevent crystal fouling of the pump and float switches, similar to a friend's continuous system. The details of my work are posted in the electronics section.

 

WSM

[taiwanluthiers]

I had a mess today...

 

I made the cell, used 6Al-4V Ti screws to hold the MMO to the extension. I sealed everything with hot glue and about 4 hours later I noticed the current stopped flowing. I opened the cell to find a thick black mess, and upon further cleanup it turned out the Ti screw used to hold the works together had completely dissolved. Nothing else was damaged though. So now I was wondering, is 6Al-4V not that good?

 

Looking back I am beginning to think that the screws that were labeled as Titanium probably wan't Titanium... there is NO way even 6Al-4V would do that and I remember the solution having a yellow/brown tinge when it first started, evidence of iron contamination.

 

There was about 10 amps going through the system, and it went up to 15 then back to 10 as the temp. stabilized.

Edited November 28, 2012 by taiwanluthiers

[WSM]

I had a mess today...

I made the cell, used 6Al-4V Ti screws to hold the MMO to the extension. I sealed everything with hot glue and about 4 hours later I noticed the current stopped flowing. I opened the cell to find a thick black mess, and upon further cleanup it turned out the Ti screw used to hold the works together had completely dissolved. Nothing else was damaged though. So now I was wondering, is 6Al-4V not that good?

Looking back I am beginning to think that the screws that were labeled as Titanium probably wan't Titanium... there is NO way even 6Al-4V would do that and I remember the solution having a yellow/brown tinge when it first started, evidence of iron contamination.

There was about 10 amps going through the system, and it went up to 15 then back to 10 as the temp. stabilized.

 

It sounds like someone mislabeled that hardware.

 

To test it, if you have more, try touching the bolt head to a spinning grinding wheel; titanium will give a shower of white sparks and iron some gold color sparks (easier to see with a dark background or at night).

 

Titanium weighs about 2/3 what iron or steel weighs, so weigh one plus a steel one of the same dimensions and compare them.

 

Try dropping another bolt in a test tube half filled with HCl and see what happens (titanium shouldn't react much if at all, iron or steel will).

 

Let us know which test or tests are used and what you find out.

 

WSM

[frank]

You need grade 1 , 2, 3 or 4 if you want a Ti bolt that will not corrode long term.

Perhaps the bolt you had was Al.

 

Obtain a piece of g1 Ti and make some bolts