tentacles Posted November 15, 2008 Posted November 15, 2008 (edited) Arthur, Swede has an excellent test for chlorate on his blog - requires only one "hard to get" indicator. http://www.apcforum.net/forums/blog/swede/...hp?showentry=20 edit: There's another sensitive chlorate test, but it involves our dear friend, boiling HCl. But the indicator is quite a lot easier to get.. the link Mumbles provided should have information on that test. Also on page 5 of his blog he shows some very neat Hach chloride indicator strips that cost about $1 each. Hach seems to sell them in all sorts of ranges, as well.. The only real contaminant in crystallized K perc that is produced from KCl that we would worry about is chlorate, for obvious reasons. Swede's chlorate test seems to be quite sensitive enough for that. Swede, I've been wanting to ask if you would take some commercial perc and run your chlorate test on it to see what the levels are like, if you've got the time. (and if you haven't already done it). This would give us a target to shoot for, at least. I've been thinking that one recrystallization, with mild-moderate chlorate destruction performed, should produce a suitable product. Edited November 15, 2008 by tentacles
Swede Posted November 16, 2008 Posted November 16, 2008 Swede, I've been wanting to ask if you would take some commercial perc and run your chlorate test on it to see what the levels are like, if you've got the time. (and if you haven't already done it). This would give us a target to shoot for, at least. I've been thinking that one recrystallization, with mild-moderate chlorate destruction performed, should produce a suitable product. After I figured out a way to use the n-phenylanthranilic acid, I did test commercial perchlorate, and there was... nothing. No hint of any color whatsoever. The perchlorate I made in a test cell was collected and aggressively washed, which you can do with perchlorate because it is so much more insoluble than chlorate, and it exploded (pardon the pun) with color, immediately. But that was a raw, washed product, not a recrystallized product. I've been thinking of how to methodically determine which procedures to use to clean raw perc right from the cell. It can be taken in steps. With any of these, the solution must be rendered neutral or slightly basic, per Wouter's pages. Yet another reason to have a bit of KOH on hand. 1) Attempt a standard recrystallization of the perc, with the container cooled to near zero, the crystals collected and given a basic cold water wash. Test for chlorate. If that fails, try.... 2) A perc recrystallization whereby the 100C liquor is cooled to something like 15C, well above zero. Aggressive wash with slightly warmer water. More perc will be lost, but the washings can be recycled. The higher water temps are likely to retain contaminating chlorate more efficiently. Again, test for chlorate. If that fails, step 3. 3) Saturate the recrystallization vessel, and while the perc is hot and dissolved, try any number of chemical cleanups (reducing agents) on the hot solution; sulfites, sulfates, or use HCl and decompose residual chlorates. Neutralize, cool, collect and wash. If we can avoid step 3 (reducing agents) I think it would be a good thing; much simpler to do, and an overall purer product. One last option would be a 2X recrystalization, but that would be a royal PITA. Much better would be an effective reducing agent as in step 3. I'm excited and ready to move on to perchlorate production. I do have some (maybe 400 grams) raw perchlorate, and I'm tempted to try a recrystallization and testing today. An ion-selective probe for chloride would be a handy addition to a serious amateur lab. The only problem is that the samples would still have to be diluted. The annoying factor with titration strips, normal titration, or a chloride probe, is the accurate dilution of the sample. These cells run at too high a chloride content for any of these, and I have been diluting 50:1 to bring the liquor to an acceptable range. That means careful pipetting, as a sloppy technique will really skew the results. Even with normal titration, unless you want to use a gram of expensive silver nitrate each test, you need to accurately dilute.
Swede Posted November 16, 2008 Posted November 16, 2008 I re-read that old blog entry, and again, the question is begged: How much chlorate is permissible in perchlorate? It is impossible to remove all of it. 10 ppm? 1? A kilo of perchlorate contains 1 million milligrams. 10 ppm chlorate contamination is 10 milligrams (0.010 g) distributed evenly throughout the kilo of perchlorate. That is NOT MUCH... but it might be too much for pyrotechnic use. Using NPAA: I do believe that by creating a standard, such as 5ppm chlorate, you can use that as a color intensity baseline. Subsequent test samples can be ranked as greater than, or less than, 5ppm, based upon the color intensity vs. the standard. All we need to do is determine what's "OK" for pyro use. Plenty of room here for experimentation.
TheSidewinder Posted November 16, 2008 Posted November 16, 2008 This is anecdotal, but may be relevant. Jim Freeman has said many times, during his seminars and when just passing on info, that all commercial K-Perc contains "a couple percent" of K-Chlorate as an impurity, that there's very little that can be done about it, and doesn't make comps any more sensitive, or affect the colors because of it. Anecdotal, as I said, but perhaps a good starting point?
tentacles Posted November 16, 2008 Posted November 16, 2008 I can't imagine 1-2% being acceptable.. maybe .1%, and honestly even that seems like a lot to me. Clearly, from Swede's tests there, the commercial stuff is probably recrystallized twice and some reducing agent is used to further refine it. On an industrial scale, a second recrystallization is no big deal. I wonder if there's some kind of industry standard for chlorate contamination of pyrotechnic/explosive use perchlorate.
BPinthemorning Posted November 16, 2008 Posted November 16, 2008 Just wondering: for lead dioxide anodes, wont the area where the anode is no longer plated begin to flake? I am under the impression that any flaws in PbO2 plating begin to flake and fall apart almost instantly... If this is true, shouldnt the plating go up a little higher on the lugg than you made it Tentacles? That way, you could have the plating go all the way out of the lid of the cell, so the gasses and electolyte can't eat away at the seam. Little side note, I just wanted to say that anyone who is thinking about getting into makeing their own chlorate/perchlorate should take a look at Swede's MMO anodes and Ti cathodes. I just got mine in the mail a few days ago. This is "A" grade stuff at a price that just can't be beat. Its made to be idiot proof from the morons who would destroy cheap anodes when they let their pool's chloride levels drop too low, so its increadably durable. Not to mention Swede does an awsome job with the welds, and I got mine 2 days after payment. Best quality, price that you cant beat, and the best packing and shipping (I'm seriousl; no way they were getting damaged), this realy can't be beat.
tentacles Posted November 17, 2008 Posted November 17, 2008 The LD over MMO should stay adherent, and even if there are cracks and such, the MMO will survive the perchlorate cell environment.. unfortunately I don't know for certain that the oxygen overpotential of the MMO is higher than the LD. If it is, then the LD will preferentially form oxygen to the MMO. This is most likely the case, particularly in a perchlorate cell environment. Swede does a fantastic job of packing.
Swede Posted November 17, 2008 Posted November 17, 2008 Thanks for the plug, guys. My goal is simple... this process is like crack, and I want more addicts out there! I think it's worth repeating... right now those of us in the USA have unlimited access to relatively cheap and plentiful oxidizers. I think those days are numbered. There was also a time when you could buy a case of dynamite at the local feed store for busting stumps and beaver dams. Those days are long gone. Our freedom to explore pyrotechnics and energetic materials is being nibbled away, slowly. Chlorate and perchlorate are easier to make than any other oxidizer I can think of. Who wants to boil dung to make KNO3? With perchlorate, you can make just about any composition known. I think it pays to be self-sufficient, or at least have the knowledge, "just in case." I've got a mini test cell ready to go to see what this material can do, starting with chlorate and hopefully producing perchlorate. If it actually works at any efficiency better than about 40%, I think it'd be remarkable. But really, it's more of a fun test to see what happens, and how tough this MMO is. I don't anticipate significant production.
tentacles Posted November 23, 2008 Posted November 23, 2008 Almost finished building my bucket cell: PVC/CPVC fittings I made for the cell - left to right are the fill/sample port (with lid and teflon seal), 1/2" PVC pipe to lid adaptor/union, and the 1/4" OD compression fitting, with teflon seal. I don't have anything better than a good aqarium pump to supply air for circulation yet, but I do have a 20PSI diaphragm pump on the way. Next step is to whack together the power supply, and connect up the volt and amp meters.
tentacles Posted November 24, 2008 Posted November 24, 2008 (edited) Well, I've got the cell running since last night.. Started out with hot tap water (my tap water's about 65 PPM TDS) and cell current at around 18A. The PS kicked in the overvoltage while I was away at dinner and was off long enough for the electrolyte to cool considerably - turned it back on and it was at 12.0A, and this morning it had heated up enough to be at 13.8A. I may just insulate the bucket and see how that does me. Also, I might rework this lid adaptor and move the cathodes closer to the anode. I COULD just figure out what's wrong with the 5.5V/200A power supply (and I will, someday) but I'd rather be able to do this (perchlorate cell) with one PS at a lower voltage. Cell volume is about 18.5L and there's a bit over 1100g of KClO3 in there to start. 30g of NaF as additive. I'd like to reiterate, for those who don't know, that this is a lead dioxide plated MMO anode. Edited November 24, 2008 by tentacles
tentacles Posted November 25, 2008 Posted November 25, 2008 Got an update on the operation, I fixed the 5v/200A power supply and plugged it in series with the 0-6V/90A unit.. Started running the cell at 8v/30A and took a look at the anode, LD flaking off. It looked worse than it was after I took things apart.. I crumbled as much of the rest of the coating off as I could, I've decided to try plating on a proper coat of alpha lead dioxide using a lead tartrate (alkaline) bath, and then plating a serious beta LD layer over that. I was getting a considerable amount of ozone production.
Swede Posted November 25, 2008 Posted November 25, 2008 (edited) What the hell is it that prevents the LD from adhering? I'm going to try a nonionic surfactant to see if it helps. Perhaps some sort of etch of the MMO might be helpful as well, a fairly serious immersion in nitric acid or similar... something beyond degreasing the MMO. All the MMO does in this case is provide a conducting layer to protect the Ti substrate. Was there any particular region where the LB flaked worse? At the edges? Or was it a fairly universal failure? Edited November 25, 2008 by Swede
tentacles Posted November 25, 2008 Posted November 25, 2008 (edited) The beta phase lead dioxide plates sort of funny, it gets some sort of compression stress that pushes in strange ways. The alpha plates with something like the reverse of that compressive stress, so it actually destresses the material. Ideally what you want to do is plate alpha, then 1-2mm of beta, then a bit more alpha, more beta, etc. I may even go so far as to do that.. once you have the baths made up, why the hell not, right? I believe the compression stress of beta is rather unusual in a plated on material, as I recall it actually gets more compression at the bottom of the layer, the thicker the plating is, so it has a very poor ability to adhere. There are additives and plating methods to reduce or prevent the stress.. NaF dopant is supposed to help somewhat, as well as increasing the service life of the anode and the oxygen overpotential. Bi dopant is supposed to enhance perchlorate activity and increase the oxygen overpotential as well. Surfactant is also known to reduce the stress *greatly*. Alembic over at sciencemadness, successfully made LD over graphite anodes with surfactant. I think he used a nonionic pesticide surfactant. Edited November 25, 2008 by tentacles
tentacles Posted December 1, 2008 Posted December 1, 2008 Double posting madness! I'm at it again, folks.. Currently plating a new layer of LD on that test anode, I gave it a good 2 1/2 hours plating at 2ma/cm2 in the lead tartrate bath, incidentally giving my cathodes a nice lead plating... Took that bath off, and fired up the acid bath, and it's going along at about 10ma/cm2 now. The reason for the low current is I'm going to dump in some PbO and go to sleep while it plates, and I want things to happen rather slowly. The alpha PbO2 bath definitely plates a different product, it's shiny and just has a different look to it than the regular acid bath. The anode gained a good 20g in that 2 hours. Amazing!
Swede Posted December 2, 2008 Posted December 2, 2008 (edited) EXCELLENT! After reading US Patent 4038170, I have been going nuts buying certain chems and setting up my own plating rig to plate LD with perhaps Bismuth doping. He achieved repeatable success by carefully controlling the parameters of the bath, and I hope I can replicate his results. I am very interested to hear if the lead tartrate plating creates a layer that adheres. I say, go for it until those holes in the mesh close up and the sucker weighs 200 grams! I'm curious, why did you decide to use PbO rather than sheet lead as you did in the past? Edited December 2, 2008 by Swede
Ralph Posted February 1, 2009 Posted February 1, 2009 i know this for some would be harder but in countries like Australia where you cant buy perchlorates at your local chemical supplier many will sell ypou perchloric acid now if you are good with your chemistry you could work mole for mole how much perchloric acid to use and if you want k perc than how much potasium hydroxide to use (koh isnt to hard to buy) but if you want to search around at your chem supplier you can get potasium carbonate or potasium hydrogen carbonate than all you do is poor out some of perchloric acid (it may be a great idea to dilute it very very slowly also perchlorates are toxic as is perchloric acid it will also aoxidise almost anything so only use glass and also watch out it is an acid). add your bace (k2co3 or khco3) very slowly as it will bubble and you dont want it to splash keep adding it slowly till the bibbling stops when you add your bace now add a tiny bit more just to ensure your acid is nutralised now recrstalise (add to boiling water till you get a saturated solution than cool and colect the crystals) and you will have perfect perc with absolutely no chlorate impurities stay safe
WarezWally Posted February 1, 2009 Posted February 1, 2009 Good luck getting someone to sell you perchloric acid without a ABN or very good reason Expensive to buy, expensive to ship and highly dangerous to boot
TheSidewinder Posted February 1, 2009 Posted February 1, 2009 i know this for some would be harder but in countries like Australia where you cant buy perchlorates at your local chemical supplier many will sell ypou perchloric acid now if you are good with your chemistry you could work mole for mole how much perchloric acid to use and if you want k perc than how much potasium hydroxide to use (koh isnt to hard to buy) but if you want to search around at your chem supplier you can get potasium carbonate or potasium hydrogen carbonate than all you do is poor out some of perchloric acid (it may be a great idea to dilute it very very slowly also perchlorates are toxic as is perchloric acid it will also aoxidise almost anything so only use glass and also watch out it is an acid). add your bace (k2co3 or khco3) very slowly as it will bubble and you dont want it to splash keep adding it slowly till the bibbling stops when you add your bace now add a tiny bit more just to ensure your acid is nutralised now recrstalise (add to boiling water till you get a saturated solution than cool and colect the crystals) and you will have perfect perc with absolutely no chlorate impurities stay safe Ralph, At APC we require that members use correct punctuation and proper grammar, and for a very good reason. We're discussing things that, if misinterpreted during experimentation and construction, could KILL you. Spelling errors aren't so bad, if they're at least CLOSE to the right word. However, some words or phrases really DO need to be spelled correctly because there are several other words that are very similar but produce very different results. Nitrate and Nitrite, is just one example. Substituting one for the other will likely produce a failure in what you're trying to achieve. While *I* can understand your post above, many users for whom English is a second language will not be able to. Please keep this in mind for the future. Thank you.
Ralph Posted February 2, 2009 Posted February 2, 2009 sorry my spelling is shocking after i have editited (which i did with that post) english is most definatley not my strong point i think with chemicals i will stick to using formulas no3 and no2 dont require good spelling to do my teachers have been trying to teach me proper spelling and gramar all my life coming from a home in which english isnt used much i have a bit of an excuse
BigBang Posted February 5, 2009 Posted February 5, 2009 I have no idea if this has been presented ITT, but lets say we don't want to use the electrode method for KClO3. Has anyone tried bubbling chlorine gas through K2CO3? I saw it on frogfot's page a few years back, went to try it, and I mucked up on the Cl2 production. Haven't had the carbonate to try it since. It should be cheap and fast, if you can handle the gas (no lectures on the dangers please, anyone and everyone here should already know. old members moreso after the blind incident.) I'm looking for, will it work, if it fast, how's the efficiency.
Mumbles Posted February 5, 2009 Posted February 5, 2009 I thought that just formed hypochlorite, which had to be boiled to turn into chlorate. I could be wrong though.
WarezWally Posted February 6, 2009 Posted February 6, 2009 Why? Whats wrong with buying a MMO anode and a bag of KCl? My last encounter with elemental chlorine was not a good one, why go to all that effort when easy simple and safer methods exist?
BigBang Posted February 6, 2009 Posted February 6, 2009 How'd you fair with the gas and why did it happen? Why? The novelty factor. Why not?
WarezWally Posted February 7, 2009 Posted February 7, 2009 I wanted to de-galvanize some steel so I poured HCl into a bucked that contained a bit of NaClO3 (I thought it was my old sodium chloride top up bucket from my electrolytic cell adventures). Normally I would clean out any container before using it but I couldn't be bothered as NaCl was effectively inert for all intensive purposes. Naturally I remembered what I was using the bucket for a few weeks prior just as I started pouring the acid is. Bellowing green fumes evolved and I held my breath and bolted out of the garage. Took another deep breath, bolted in and drowned the reaction with water, bolted out, took another deep breath, bolted in and turned on the fan and retreated till it was safe to re enter
Swede Posted February 8, 2009 Posted February 8, 2009 Nothing like a little hit of chlorine gas to snap your glottis closed and make you run for cover!
Recommended Posts