taiwanluthiers Posted July 1, 2014 Posted July 1, 2014 I just received TWO platinum coated titanium anodes. I read from Sciencemadness that you could use two anodes as both cathode and anode, and switch polarity periodically to preserve the life of the anode. Basically the idea is the eroded platinum will plate onto the cathode, so very little platinum is lost. Can anyone confirm or deny if this works?
WSM Posted July 1, 2014 Posted July 1, 2014 (edited) I just received TWO platinum coated titanium anodes. I read from Sciencemadness that you could use two anodes as both cathode and anode, and switch polarity periodically to preserve the life of the anode. Basically the idea is the eroded platinum will plate onto the cathode, so very little platinum is lost. Can anyone confirm or deny if this works?Hi taiwanluthier, I don't know if double platinum electrodes with periodic polarity changes would work to preserve the platinum, but it stands to reason if that scheme were effective, the perchlorate industry would adopt it as the standard. Are you going to try it? If so, let us know if and how it works out. Thanks. WSM Edited July 2, 2014 by WSM
Arthur Posted July 1, 2014 Posted July 1, 2014 probably the MOST important thing that could be done is to research how the big companies do the job. How did Pepcon work before the bang, someone must know maybe something is written down somewhere searchable on the web.
taiwanluthiers Posted July 2, 2014 Posted July 2, 2014 You remember the perc I made with the previously failed anode? Well I am not convinced it made any perc, or at least not a very high concentration of it. Because I dissolved the thing, and took 2ml of the solution and added 2ml of conc. HCl to it, and it turned very yellow immediately and evolved yellow gases. Also when I mixed the sample with a fuel, and added conc. H2SO4 to it, it immediately ignited. Tests with a known sample of perc yielded no ignition except for charring of the fuel... So I'm not even sure what I have here...
pex Posted July 2, 2014 Posted July 2, 2014 Just wait Longer, i made 9 kilo of it and didnt ignite with sulphuric acid. I run my cell for a couple extra days. When the ampere drops. I use a pbo2 anode and at the end of the run he was almost not damaged. Platinized titanium anode platinum will gett damaged allot. If you want to use platinum. Use platinum clad titanium much better. PbO2 will do the Job. But patience is the key.
taiwanluthiers Posted July 2, 2014 Posted July 2, 2014 How much does platinum get damaged? I dont think platinum clad anode exist, at least outside of industry. What I have is 2 2" x 3" platinum coated anodes. I read they will work. I am not sure what was up with the LD I have but it fell apart after one run.
pex Posted July 2, 2014 Posted July 2, 2014 Platinum clad does exist. Maybe you putted to much voltage trou your anode. Than it can fall appart. My anode is running now for the second runn and still no damage on the surfase. I used platinum platinized one time but after one run. The anode was so damaged that it wont work for a nother runn Pex
pex Posted July 2, 2014 Posted July 2, 2014 Look for platinum clad titanium ore nobium. And you will find. You can gett them try. Alibaba.com. But my platinum failt after one runn. Just try it out maybe it will work for you. Pex
WSM Posted July 2, 2014 Posted July 2, 2014 (edited) You remember the perc I made with the previously failed anode? Well I am not convinced it made any perc, or at least not a very high concentration of it. Because I dissolved the thing, and took 2ml of the solution and added 2ml of conc. HCl to it, and it turned very yellow immediately and evolved yellow gases. Also when I mixed the sample with a fuel, and added conc. H2SO4 to it, it immediately ignited. Tests with a known sample of perc yielded no ignition except for charring of the fuel...So I'm not even sure what I have here...I'm guessing it's chlorate. WSM Edited July 3, 2014 by WSM
WSM Posted July 2, 2014 Posted July 2, 2014 (edited) Look for platinum clad titanium ore nobium. And you will find. You can gett them try. Alibaba.com. But my platinum failt after one runn. Just try it out maybe it will work for you.PexMy understanding is that high chlorides in the running perchlorate cell causes the degradation of the platinum. The best condition is low or no chlorides there. WSM Edited July 3, 2014 by WSM
WSM Posted July 2, 2014 Posted July 2, 2014 (edited) Look for platinum clad titanium ore nobium. And you will find. You can gett them try. Alibaba.com. But my platinum failt after one runn. Just try it out maybe it will work for you.PexCladding is MUCH thicker than plating (so it should cost proportionally more). Platinum clad titanium is desirable, but it appears that plate is more available. WSM Edited July 3, 2014 by WSM
taiwanluthiers Posted July 2, 2014 Posted July 2, 2014 That other LD was run at 5 volts, so I can't think of why it failed except perhaps it was not properly made. I am hoping that I have better luck with the platinum but I guess I will need to make sure the chlorate feed stock is chloride free, not sure how I can do that honestly.
Mumbles Posted July 2, 2014 Posted July 2, 2014 Just to get your process down, I'd suggest starting with recrystallized chlorate instead of crude product. Recrystallized, whether potassium or sodium chlorate, should remove the majority of the chloride. It's best to get all the unknowns and variables out of the equation until you get things figured out. There are a few tests for chloride that you may want to run on your samples to be sure. In doing some reading it seems that the biggest issue regarding platinum is chloride. Unfortunately, starting with pure chlorate will not entirely remedy this. There seems to be an issue of the chlorate being reduced down to chloride by the hydrogen produced. I found an old thesis, which basically covers most of what we know, and discusses some issue they encountered while trying to make perchlorate from chlorate using a couple different anode materials. I do believe that the issue of chlorate reduction to chloride can be remedied with various additives, NaF specifically is the one most people seem to use. http://thesis.library.caltech.edu/732/1/Maurer_fa_1923.pdf
taiwanluthiers Posted July 2, 2014 Posted July 2, 2014 I have read about adding dichromate to prevent the reduction of chlorate into chloride, at least from what I read according to the oxidizing site. It is not suitable for LD however because it reduces current efficiency. I'm not sure what NaF does, it's probable that tap water already has some NaF in it... Here is the "perc" that I have after I've recrystalized it once. Note the hot solution before (the solution with everything dissolved) was VERY yellow with chlorine gas coming out of it, now it's only a little yellow with no gas. I dissolved a pinch into about 2 mL of water and added 2 mL of conc. HCl I now have a bunch of chlorate stock, I will recrystalize it probably once more before feeding it into the cell, not sure if it's necessary. BTW I think in Swede's blog he used plated (not clad) platinized titanium and it seems to work.
frank Posted July 2, 2014 Posted July 2, 2014 (edited) The notion that platinum will plate back onto the cathode after been eroded from the anode is rubbish. Ever heard of anyone plating platinum onto titanium by placing a piece of titanium or a piece of titanium with some platinum already on it, into a tank with a high concentration of chlorate/perchlorate dissolved in the water + a tiny amount of platinum salt (milli if not micro grams per liter) and have a platinum plate appear????????? See at the bottomhttp://oxidizing.typhoonguitars.com/chlorate/cathodes.html Platinum clad anodes exist. The core can be copper. The platinum will be perhaps half to one mm thick. Thats 500 to 1000 times thicker that the one micron coating that you see with ebay (etc) anodes.The cost will be big. F is not recommended with titanium substrate anodes. It attacks the Ti. With one micron coatings etc its has not far to go? The function of dichromate is to put a film on the cathode and this effectively decreases its surface area and there for raises the current density. Use a small cathode and you get the same effect. The voltage will go up a small amount across the cell but that is irrelevant. See the bottomhttp://oxidizing.typhoonguitars.com/chlorate/reaction.html See the tophttp://oxidizing.typhoonguitars.com/chlorate/cathodes.html Edited July 2, 2014 by frank
Mumbles Posted July 2, 2014 Posted July 2, 2014 Platinum definitely works. It's also expensive. To me, it can serve as a control, but isn't really viable long term. On the hobbyist scale, lead dioxide seems to be the answer. It's cheap and effective. If the electrode eventually fails, who cares? I'm sure MMO may also be an option. I'd be more concerned about getting something running and having a competent system before worrying about the details. If you look, the specifications for making good electrodes are available. I've attached a couple of papers. One is available from Science Madness. In it the reference to making the electrodes is given, and I attached that as well. I wasn't sure if that could be had from SM or not. The other covers some of the additives, and stuff, and is a previous publication from the same group. www.sciencemadness.org/talk/files.php?pid=98632&aid=3341 [Edit] I removed the other files. It turns out they were linked directly to my university access, and I didn't want to get in trouble with them.
taiwanluthiers Posted July 2, 2014 Posted July 2, 2014 The problem with LD is thus far there doesn't seem to be a reliable seller of good quality LD and it seems to take quite a bit of effort to plate one properly, at least judging how Swede does it in his blogs. It would be nice if someone with the setup to plate them would offer some for sale... those Chinese ones seems to be hit or miss... sometimes they work, sometimes they don't.
taiwanluthiers Posted July 6, 2014 Posted July 6, 2014 (edited) I got a platinum anode up and running. One day and no sign of any coloration to the solution or changes in the anode surface. There's obviously a strong smell of ozone but it remains to be seen if any perchlorate is produced.... I added a couple of grams of potassium dichromate to the solution to prevent chloride formation, and that solution is now yellow rather than orange due to higher PH. Current seems to be about 5 amps and solution temperature is about 40-50 degrees C. I'll let it run for 3 days and then harvest it. One thing I like about perchlorate mother liquor is that they are a lot less corrosive than the chlorate liquor. Edited July 6, 2014 by taiwanluthiers
WSM Posted July 11, 2014 Posted July 11, 2014 I got a platinum anode up and running. One day and no sign of any coloration to the solution or changes in the anode surface. There's obviously a strong smell of ozone but it remains to be seen if any perchlorate is produced.... I added a couple of grams of potassium dichromate to the solution to prevent chloride formation, and that solution is now yellow rather than orange due to higher PH. Current seems to be about 5 amps and solution temperature is about 40-50 degrees C. I'll let it run for 3 days and then harvest it. One thing I like about perchlorate mother liquor is that they are a lot less corrosive than the chlorate liquor. Possibly also due to the breakdown of the dichromate to chromate. I recall the same thing happening when treating magnesium with potassium dichromate and the residue was potassium chromate solution (sunny yellow color, rather than the orange color of the dichromate). To turn the waste product into something useful, I did a double exchange with cupric nitrate, filtered out the (brown color) cupric chromate and dried and stored it. When I get the time I plan to roast it in a crucible to form copper chromites (black color), an excellent catalyst for AP propellants or even whistle rockets. WSM 1
WSM Posted July 11, 2014 Posted July 11, 2014 I got a platinum anode up and running. One day and no sign of any coloration to the solution or changes in the anode surface. There's obviously a strong smell of ozone but it remains to be seen if any perchlorate is produced.... I added a couple of grams of potassium dichromate to the solution to prevent chloride formation, and that solution is now yellow rather than orange due to higher PH. Current seems to be about 5 amps and solution temperature is about 40-50 degrees C. I'll let it run for 3 days and then harvest it. One thing I like about perchlorate mother liquor is that they are a lot less corrosive than the chlorate liquor. Hi taiwanluthiers, How is the cell going? Anything to report? WSM
taiwanluthiers Posted July 11, 2014 Posted July 11, 2014 (edited) Nothing good... I ran the cell longer and ALL the platinum eroded from the anode. I do not know why, but I was using a computer power supply at 5 volts, and the amp was really low. No idea what was the deal here. It does not look like any perchlorate formed at all. I tried again using the old LD anode, and a KNOWN pure chlorate sample (reagent grade) to see if it was due to small amount of chloride contamination, and ran it at 12 volts, then the power supply died like within 30 minutes. It was pulling 20 amps before that. I don't know where to get a real power supply, because with a computer power supply it was either 5 volts or 12 volts, and nothing in between. The only real power supply I can find is only capable up to 3 amps so if I want to run it at 15 amps I'd have to get like 10 of those... Edited July 11, 2014 by taiwanluthiers
MrB Posted July 11, 2014 Posted July 11, 2014 Nothing good... I ran the cell longer and ALL the platinum eroded from the anode. I do not know why, but I was using a computer power supply at 5 volts, and the amp was really low. No idea what was the deal here. It does not look like any perchlorate formed at all. I tried again using the old LD anode, and a KNOWN pure chlorate sample (reagent grade) to see if it was due to small amount of chloride contamination, and ran it at 12 volts, then the power supply died like within 30 minutes. It was pulling 20 amps before that. I don't know where to get a real power supply, because with a computer power supply it was either 5 volts or 12 volts, and nothing in between. The only real power supply I can find is only capable up to 3 amps so if I want to run it at 15 amps I'd have to get like 10 of those... Use 12v as positive, and 5v as negative, and get 7v. if 3.3v you get 8.7v. If using the -12v as negative, you'd get 24v, but i'm suspecting we want to stay between 5 and 12v. By using 5v you get a new subset of alternatives available, most relevant might be and -5v you get 10v. What is the target voltage for your application?The PSU wont be quite as efficient when run like this, supposedly, and some PSU outright refuses to run like this.It should be noted, i know people to run this kind of setups for years on end, but quite honestly, they aren't drawing 10's of Amp's, so while it will work, i cant say that much for long term reliability. Try it and let us know.B!
taiwanluthiers Posted July 11, 2014 Posted July 11, 2014 (edited) I tried that, the PSU refused to output any voltage like that. I think something must be connected to the 5v before this will work, and the 5v load must be higher than the load you are drawing off of 7v. I need a new PSU in any case... I still have no idea why the anode seems to bite the dust no matter what... Edited July 11, 2014 by taiwanluthiers
MrB Posted July 11, 2014 Posted July 11, 2014 Weird. Must be down to the power-supplies in question, since i know it's been used to power lights with no additional loads. Oh well. It was a thought at least. B!
WSM Posted July 16, 2014 Posted July 16, 2014 I tried that, the PSU refused to output any voltage like that. I think something must be connected to the 5v before this will work, and the 5v load must be higher than the load you are drawing off of 7v. I need a new PSU in any case...I still have no idea why the anode seems to bite the dust no matter what... I suspect a combination of chemistry and physics. Some part of the setup must be throwing the Pt off the anode (or eroding, or dissolving it, or something). If used as a cathode, when the current is impressed cathodic protection would leave the Pt intact (in theory). If your solution, after the platinum dissappears, is kept and analyzed for platinum salts (and those salts are identified), we'll be on the way to understanding the mechanics of what's happening there. My first question is whether sodium or potassium chlorate was the starting salt?My second question is, besides chlorate and water, was anything else added to the cell (what and how much)? Knowing that much information will be a start, and prompt other questions in the search for answers as to the cause of the anode destruction. WSM
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