Sciencemadness Discussion Board

Electrochemical ozone generation

 Pages:  1  

madscientist - 18-10-2002 at 12:52

I wasn't sure just where this thread would belong, but since the reaction that produces the final product isn't electrochemical, I thought I'd put it here.

This method of preparing ozone that I just thought of relies on the following reaction:

3H2O + 3F2 ----> 6HF + O3

This method would involve electrolyzing a solution of HF with a copper cathode, and a graphite anode. The cell would be divided into two sections so that they have seperate atmospheres; the side with the anode would be air-tight, with a teflon tube to lead away fluorine, ozone, and oxygen gas; the side with the cathode would just be open, to allow hydrogen gas to escape. The gasses produced at the anode would be bubbled through water, and the resulting gas (hopefully mostly ozone) stored.

Obviously the hydrogen fluoride is regenerated, so this process would cost as much as the electricity.

rikkitikkitavi - 18-10-2002 at 13:14

If you electrolyze a aqeous solution of HF, O2 will of course be formed at the anode instead of F2.

The eletrochemical for the reaction

2H2O=>4 H+ + O2 + 4 e- is 1,23 V

2F- => F2 + 2 e- : 2,83 V.

/rickard

Why this method?

Polverone - 18-10-2002 at 13:16

Even if it does work, this sounds like a pretty complicated setup. If you're going to build a complex device, why not build a device for silent high-voltage discharge? That's how most ozone generators work, I believe. You might want to inquire about this at PowerLabs. They do a lot of high voltage electronics stuff.

madscientist - 18-10-2002 at 13:18

I hear that ozone generators that work by electric discharge in oxygen give poor yields and concentrations of ozone.

rikkitikkitavi - 19-10-2002 at 07:06

yeild can be up to 15 %, based upon energy consumed,if prechilled,cleaned oxygen is used. yield is normally around 5-10%

The reaction F2+H2O => HF + O3 + O2 doesnt show high yield either. Plus that the reaction between F2 and H2O is extremely violent (like most compounds reacting with F2)

/rickard

IodineForLunch - 19-10-2002 at 07:34

Madscientist's first reaction given will work without electricity if hot water is used.

However, I don't know of many amateurs that have the want or the way to make fluorine...

David Hansen

Marvin - 19-10-2002 at 20:35

I'm a fan of weird reactions, particulaly ones that dont follow obviosly from the chemistry.

You can make ozone by electrolysis of dilute sulphuric acid. The best conditions are, Pt/Ir electrodes, sulphuric acid between 1.075 to 1.100 density, the solution of the anode must be very cold, -14C is suggested and the current density must be as large as possible so long as it doesnt cause too much heating, so a small thin electrode is better. With a Pt electrode 0.1mm by 11mm embedded in glass (so the surface 0.1mm by 11mm long is the only surface exposed to the solution) the oxygen that comes off contains up to 28% of ozone.

In hindsight you can see why, oxygen radicals form at the anode to give oxygen and ozone molecules and the higher the concentration, the more ozone.

Ozone is extremely nasty, allthough I know most of you know that, not everyone reading this thread will.

S.C. Wack - 29-1-2006 at 23:41

An article on the H2SO4 process that I stumbled upon:

Attachment: iec_44_2207_1952.pdf (651kB)
This file has been downloaded 1636 times

S.C. Wack - 30-1-2006 at 01:35

Might as well also upload these JACS articles while I'm here. One talks of the other so here are both 51, 2676 (1929) and 47, 1844 (1925). These are also articles that I stumbled upon (not looking for lab ozonizers in the literature) earlier, so maybe there is something better out there that has been published but no one has uploaded here. Your turn.

EDIT: BTW, these JACS articles are off-topic and probably best posted in some other existing thread as these are a standard sort of ozonizer, unlike the IEC device above. But no one is going to make it anyways so oh well IMHO.

[Edited on 30-1-2006 by S.C. Wack]

Attachment: O3.zip (563kB)
This file has been downloaded 1180 times

stygian - 30-1-2006 at 08:49

http://freepatentsonline.com/4316782.html

12AX7 - 30-1-2006 at 10:09

Quote:
Originally posted by madscientist
I hear that ozone generators that work by electric discharge in oxygen give poor yields and concentrations of ozone.


So? Bubble it through some liquid nitrogen. Filter out the ozone crystals.

:P!

Tim

Marvin - 30-1-2006 at 12:15

Hmm, just because its solid doesn't mean it won't dissolve. Sure it won't?

Theres also the little problem of the crystals tending to detonate when they warm up. Solid and liquid ozone is a bit... unpredictable.

12AX7 - 30-1-2006 at 13:35

Well, eventually either by adding enough O3 or evaporating enough N2, it'll precipitate, you're right it might dissolve to a pretty good amount in the mean time though.

Explosiveness is just semantics. Hence the :P :D

Tim

Fleaker - 30-1-2006 at 19:48

If kept at LN2 temperatures, the black/purple crystals of ozone can be filtered from the LN2. Even cold like that, the fumes are really aggressive and it sublimates rapidly. IIRC, it is soluble to a degree in liquid oxygen not so much nitrogen? If I remember where I placed the literature and my lab book I'll post it up.

Ozone is a rather fleeting substance, even in a strongly basic solution (say pH of 14) it doesn't last too long as the dissolved gas. Rather apt to forming hydrogen peroxide too :-P.

O3 by electric discharge

Flip - 6-3-2006 at 13:05

Quote:
I hear that ozone generators that work by electric discharge in oxygen give poor yields and concentrations of ozone.


This is far from the truth. I built an ozone generator three or four years ago that was capable of turning methanol blue at -40 deg C by complexing with the solution. I used a 75 kV neon sign transformer, copper wire, and a borosilicate glass tube as my dielectric. Also, I managed to give myself ozone poisoning with is *not* fun. Let's see, what else could it do? Oh yeah, the thing dissolved rubber and all manner of surgical tubing making my bubbler a huge challenge to construct. Of course, I have an O2 tank and regulator. If you try electric discharge through ordinary air, the O3 yeild will not be high, but will still be enough to smell from several feet away (ppm range).

If you're interested in building one I have a design that works exceptionally well and puts out a great yeild of ozone. My only concern was that the output would be TOO big.

garage chemist - 6-3-2006 at 14:18

I'd be interested.
I have tried to build an ozone generator myself, by taking glass tube (7mm outer diameter) and inserting a wire, and coating the outside with Aluminium foil.
It worked extremely well with a flyback, and not so well with a neon transformer.
With the flyback, hissing blue discharges were formed and the tube became hot quickly, this rapidly diminished ozone yield since high temperature is very detrimental to ozone.

I overcame this by bending the glass tube in a W shape and immersing it in salt solution which served as the outer electrode.
This worked best. However, the glass tube broke because the setup was too fragile.

The output of the thing, directed at a piece of paper soaked with KI solution turned it DEEP BLACK instantly. No starch was added to the KI.

I'd like to hear about your setup!

[Edited on 6-3-2006 by garage chemist]

Flip - 6-3-2006 at 16:20

I'll see if I can describe it without illustrating any pictures...

The basic idea is a borosilicate tube with thin gauge copper wire threaded tightly around the outside, and a heavy gauge wire suspended through the center.

The output can be modified by adjusting how "threaded" the outside of the tube is, or how much spacing is between each coil. My coil had spacing of about 1 cm/coil. The coil is taped down at both ends with electric tape, but you'll have to make certain that the ends of the tube are far enough away from the wire to prevent arching from the inside of the tube to the outside on the ends.

The most important part of this setup are the end-pieces, and my setup used a PVC pipe fitting with a threaded cap at each end. You'll have to bore a small hole in the outside of the fitting on one side, in order to thread some of the outside wire through the hole so you can attach the alligator clip from the generator. Now, the reason the threaded caps are important, you'll need to make sealed end pieces... I accomplished this by cutting round pieces of plexiglass to fit on the inside of the end caps. You'll take your heavy gauge copper wire and heat it up so you can stick it through the plexiglass. This way, the wire will be suspended in the center of the tube from end to end, and the system will be sealed.

So in order to fit with the PVC fitting, you'll need a much wider diameter tube. I used one of those long lightbulbs for my prototype, but they are too easy to break to be worthwhile, the borosilicate tube should, however, be of similar diameter. It's better to err by getting a tube too small, because you can always wrap the tube with electric tape until it seals perfectly with the PVC fitting. You can order the borosilicate tube from any glass-blower's supply catalog, they use the tubes to blow into other shapes.

When it's finished and turned on, it looks rather like a purple lightsaber with two handles. ;)

So you then need to bore two more holes into the plexiglass end pieces, and get double sided hose fittings (plastic) to stick through them so you can attach hoses for input and output.

You can get an O2 tank and regulator for about 150$ total from Holox or a similar company. You can get the transformer from a neon sign company. When you wire the transformer, make sure you use a cord with a ground, or you could get yourself in big trouble. Then all you need is some alligator clips to run from your transformer to the exposed parts of each wire (taking care that there isn't any arching around the sides) and you're good to go.

The output of this design is incredible, and my main concern was that it would be so strong that it would tear benzene rings as well as double bonds, but it didn't seem to effect the aromatics. You can calibrate the output with a known molar amount of an alkene in a DCM/methanol solution in acetone/dry ice. When the alkene is completely cleaved (1-1 molar ratio here) the O3-methanol complex will begin to form and the solution will turn a light shade of royal blue... it's kind of self-indicating. Once you know the moles O3/min, you can utilize it as a precise instrument of organic synthesis.

Just don't try to use neoprene hosing like I did, because O3 will corrode right through it, effectively melting it, and O3 will be released in huge volumes into your workspace, giving you ozone poisoning, making your breating unbearably painful, and confining you to your bed for days. (I didn't realize at first that the hose was neoprene).

All the same though, you should be able to complete the construction of it for about 250 USD. If you need any more specifics you can PM me, i'd also be happy to draw a picture or two if I'm not really clearly expressing my design.

Flip - 6-3-2006 at 18:08

Forgive the crappy illustration, but here's a picture that should give you a rough idea of what i'm talking about. If anyone here is serious about building one, though, it is fairly simple and I can walk you through the construction.

(picture attached)

dischargetube.JPG - 17kB

S.C. Wack - 8-4-2006 at 18:13

[low yielding]
Microscale Production of Ozone

http://jchemed.chem.wisc.edu/Journal/Issues/2005/OctACS/ACSS...
http://jchemed.chem.wisc.edu/Journal/Issues/2005/OctACS/ACSS...

Natures Natrium - 18-11-2006 at 14:29

Hmm, I have a quick (and relatively uninformed) question. I was wondering how feasable it would be to use a length of copper tubing instead of a rod for the center, so as to pass cold water through it continously and increase ozone yields. If one could skip the tank/regulator and just use CaCl2 dried air that would reduce the overall cost quite a bit (although Flip's design is still about US$500-5000 cheaper than the commercial designs I have seen). Hmm, I wonder how it would affect my aquarium pump, which is a sealed design? I thought about running water through a condenser, with rod inside and coil outside, but my gut instinct (without any real knowledge to back it up) says the water would interfer heavily with the corona discharge. Maybe use cold salt water through the condenser and forgo the coil altogether? I guess I am just brainstorming here on alternate design routes.

Oh yea, Flip, is that 75kV mentioned a typo for 7.5kV, or did you really use 75000V for your design? Oh, and did you attempt to use braided PVC tubing, and if so how well did it stand up to the O3?

Does anyone else have anything to report on this interesting project?

-NN

roamingnome - 18-11-2006 at 15:04

Flip Said: I built an ozone generator three or four years ago that was capable of turning methanol blue at -40 deg C by complexing with the solution.



Im a bit behind as im putting the finishing touches on my first ozone generator now ..only 5 kV but with pure oxy im sure ill get something... so what else was in the methanol ... huh....:P i hope to be turning methanol blue soon as well...

maninly cuase i want to open a bakey that sells almond muffin cakes... ya know the regular reasons

roamingnome - 18-11-2006 at 15:18

As far as reporting in general,, im basically copying a design from a web page

a parralell plate setup 2mil thick glass, The gap is spaced by microscope slides 1 mil thick.

im hoping that some clear silcone to seal the apparatus between random thicker glass will hold up for a while

the thing that i dont know is how the discharge region or path length affects production. who cares right

12AX7 - 18-11-2006 at 18:34

A mil thick? I didn't know you could get glass in that size; that's like film!

Of course you know how the discharge will effect production. It needs to be a glow discharge, but not spark. Corona between two closely spaced plates, supplied AC of any frequency or DC, is the ideal method.

Tim

[Edited on 11-19-2006 by 12AX7]

Natures Natrium - 18-11-2006 at 19:39

I just finished scouring the boards of anything with "Ozone" in the thread, and as an aside I found quite a few reactions that I was not aware were capable with O3. Even more reason to make this work. :-)

Anyways, the thread I think I learned the most from is this one: https://sciencemadness.org/talk/viewthread.php?tid=1774&...

If I am understanding this correctly, the best method for Ozone production while still using a NST would be to NOT have a glass layer between the electrodes? So the goal would be to get them as close together as possible without inducing an arc.

This flyback circuit looks interesting, and if I understand Martin correctly, a higher frequency output is very beneficial to producing ozone with a glass insulator. I just have to wonder, how beneficial?

I would like to be producing at least 5g O3/hr with my setup. I may have to opt for the pure, dry oxygen source after all.

Also, MODS, maybe this thread should be moved to technical? I didnt mean to dredge up an old thread, but even O3 derived from the electrolysis of sulfuric acid solutions seems more like a tech thread than a chem thread to me. *shrugs*

-NN

Natures Natrium - 20-11-2006 at 15:17

Though I know it to be folly to expect replies when posting upon on internet forum, still I pine for encouragement.

I was looking through my collection of resources (read:piles of crap), when I realized I have two objects in my possession that might be used for this project.

1. .002" (.05mm) thick 99%+ copper foil
2. a 30cm long, 2.5cmID pure alumina catalyst tube

The first was bought for making a home made capcitor, I think. The second was purchased for attempting to produce PCl3 from a phosphate/carbon mix in the presence of pure diatomic chlorine at 650C. However, I was never able to figure out a design which I felt would comfortably contain the stream of 650C Cl2, PCl3, and PCl5 exiting the tube. It was to be heated with NiCr wire and a 600w cieling fan dimmer, but I digress.

I am thinking that the alumina tube would make an excellent dielectric for this project, using tight fitting PVC caps (covered in PTFE) sealed with rubber tape.

My questions are: would it (probably) be more effective to use a thin wrap of wire around the outside or the copper foil covering the entire outside, and two, is the 2mm thick walls of the alumina tube plus the 1.25cm gap to the center rod going to be enough to prevent actual arcing (10.5kV, 30mA)?

Of course, the one MAJOR disadvantage to this design is that I wont get to see the cool purple corona. :(

Any help, either fact or speculation, would be appreciated, as this is actually my first high voltage project. As always, I am most interested in the information which will let me draw my own deductions, i.e. how to calculate how far apart two metal objects must be to prevent arcing at a specific voltage.

Many thanks,
-NN

franklyn - 22-11-2006 at 00:28

Quote:
Originally posted by Flip
I built an ozone generator three or four years ago that was capable of turning
methanol blue at -40 deg C by complexing with the solution, the O3-methanol
complex will begin to form and the solution will turn a light shade of royal blue

Is this a good idea, how safe is this ?
CH3OH and oxidizers don't usually play nice together,
even at the temperature of dry ice.

.

roamingnome - 24-11-2006 at 15:22

These links might be intersting for ozone use

I was most happy to find Lindlar's Catalyst preparation, which at first seems off the point but bear with me.


www.uni-leipzig.de/~nmr/STB/Publications/ozon.pdf

www.freepatentsonline.com/5039737.html

http://www.ch.ic.ac.uk/local/organic/12.html


Excerpts from the above:

EXAMPLE 2

156 g of styrene in approximately 850 ml of methanol were treated with ozone as described in Example 1, whereby approximately 1 liter of a 1.5 molar peroxidic ozonolysis solution was obtained; this solution was treated with hydrogen in a device as depicted in the illustration at a temperature of 30.degree. to 40.degree. C. and a pressure of approximately 0.12 MPa in the presence of a metallic monolith catalyst coated with a Lindlar catalyst basic substance. The absorbed hydrogen amounted to 31.9 normal liters, or 94.9% of the theory. After completion of the reaction, the diluting agent was evaporated and the residue was vacuum-distilled. At a boiling point of 119.degree. to 120.degree. C./14 mm of Hg, 149.3 g of benzaldehyde, or approximately 94% of the theory in relation to the employed styrene, with a purity of virtually 100% were obtained.


Lindlar's Catalyst (5% Pd on CaCO3, poisoned with Pb)6

Stir calcium carbonate (precipitated, light; 1.1 g) in water (10 ml) in a flask which is fitted with a thermometer and mounted on a magnetic stirrer/hotplate. Whilst continuing the stirring, add palladium chloride (90 mg) to the suspension and after 5 min., raise the temperature to 80deg.C for a further 10 min. Cool the mixture and transfer it to a hydrogenation flask, using ~ 10 ml of water for rinsing. Hydrogenate the mixture until hydrogen absorption (10-20 ml) is complete (ca. 15 min); the hydrogenation procedure is described below. Collect the reduced catalyst on a small 'Hirsch' funnel (Whatman filter paper No. 1) and wash the catalyst with distilled water (20 ml). Add the damp catalyst to distilled water (10 ml) in a flask on the magnetic stirrer/hotplate. Switch on the stirrer, add a 5% (w/v) solution of AnalaR lead acetate in water (2 ml) and, after 10 min., raise the temperature to 90deg.C for 40 min. During this time, add distilled water, as necessary, to compensate for evaporation losses. Cool the mixture, collect the catalyst on Whatman No. 1 paper in a small 'Hirsch' funnel and wash the catalyst with distilled water (total, ~ 50 ml). Transfer the catalyst to a clean, tared, specimen tube and dry the catalyst in a pistol at 40deg.C to constant weight (~ 1-3 h). Crush the dry catalyst to a powder with a clean spatula or glass rod and stopper and label the tube (catalyst yield: 0.9-1 g).

And for the truly inquizitive

Towards the catalytic application of a monolithic stirrer reactor

http://repository.tudelft.nl/file/321784/202260


methanol some how becomes formaldehyde, but im not totally sure yet. theres a level of danger in most things

[Edited on 24-11-2006 by roamingnome]

Natures Natrium - 25-11-2006 at 10:02

http://www.valdosta.edu/~tmanning/research/ozone/

A wonderful site with a motherload of presifted US ozone related patents, sorted by type of ozone production (electrochemical, UV, discharge, etc).

roamingnome - 25-11-2006 at 11:46

acording to this page Natures Natrium
http://www.valdosta.edu/~tmanning/research/ozone/

Does only one plate of the ozone device need to be gaped?

My NST transformer does not designate + or -
Can a cheapodepoto voltage tester be used on high voltage becuase its low amps?

Natures Natrium - 25-11-2006 at 13:49

Quote:
Originally posted by roamingnome
Does only one plate of the ozone device need to be gaped?


-I'm not sure what you mean. The gap is the relative distance between two objects, you only have two plates (right?), so how can one "be gaped" and not the other?
Quote:
Originally posted by roamingnome
My NST transformer does not designate + or -
Can a cheapodepoto voltage tester be used on high voltage becuase its low amps?


-I have no idea, but I would guess yes. I havent touched a multimeter since I was a child. I really need to pick one up one of these days. It does matter though if using a design like Flip's, as you want a "negative corona" discharge which produces more ozone than the "positive corona" discharge.

http://en.wikipedia.org/wiki/Corona_discharge

This is where my understanding gets fuzzy though, as it seems that oxygen should make contact with the negative, so the negative should be the rod in the center, but it also seems like all the information I have implies that the type of corona is decided by the coiled electrode.

This is all a moot point though, when using plates, and that strikes me as yet another powerful advantage over the tube type. Im not really willing to mess with trying to build a flyback driver, expecially if that will only bring the efficiency up to the same level as a system with no dielectric, which it seems to me would be easier to contruct with plates rather than tubes.

If some of you electrohobbiests out there could chime in and correct any mistaken notions you see, I would be ever so grateful.

-NN

EDIT: DO NOT USE YOUR CHEAPO METER. I was at the hardware store, and it looked like most of them could not take over 660V.

[Edited on 26-11-2006 by Natures Natrium]

Natures Natrium - 27-11-2006 at 16:54

Weee! :-)

Silly I know, as all I have done is make a simple corona discharge, but it was somehow extremely exciting to smell that ozone smell, and it is my first time working with HV. Also, I now know my transformer works just fine. :-D

Im also starting to think that using the alumina tube was a fantastic idea, although I will need to rework my center "rod", as I used a piece of 10 gauge solid core copper wire stuck through a stopper. I straightened it the best I could, but there was a noticeble difference in strengths of corona along its length. For the outside I had intended to use a thin wire coiled about 5mm apart, but I actually had trouble finding wire small enough. So for this proof-of-concept run I just used some aluminum foil, and it worked extremely well. I think I may just use my copper foil for the outside wrap on the next run. For the inside I might go ahead and find some larger diameter copper tubing, once I am confident of where my arc gap is, if it can even arc through the alumina at all.

This was a real "jump up and down and clap with glee" kind of thing for me. Reminds me why I love science so much. And so much more to do and learn as well! :cool:

-NN

EDIT: Moving the solid core wire around with a plexiglass handled screwdriver covered in rubber tape, I was unable to get an arc formed, and there was a noticeble change in the sound of the corona that made it sound more intense (louder). I think I might try to leave a gap between the copper tube and the aluminuma sheath of ~1-2mm to pass the O2 through, if I can find convient enough parts to do it. Thoughts? Anyone have any?

[Edited on 28-11-2006 by Natures Natrium]

roamingnome - 28-11-2006 at 12:10

Well it looks like you got yourself some ozone production. Getting that gap where you want it sounds tricky though. I finally got to the point of just plugging my apparatus in as well.

To clarify my other point, you are correct in saying that between to plates there is only one gap. In the parallel plate ozone setup two “electrodes” are sandwiched between a piece of glass creating two gaps. I decided to air gap one and sandwich the other.

At first nothing was happening and it appears that my over all surface area for electrodes was too large for the NST. So I took some scrap pieces and crudely clipped them to the NST between glass and presto… purple coronas with lime… of course the uneven surface quickly heated up and cracked the glass, but I got proof of concept.

Using that alumina tube for a molten sulpher battery might even be a cooler use, since that’s what they actually use for those high temp yet powerful batteries.

Natures Natrium - 30-11-2006 at 20:18

Quote:
Originally posted by roamingnome
To clarify my other point, you are correct in saying that between to plates there is only one gap. In the parallel plate ozone setup two “electrodes” are sandwiched between a piece of glass creating two gaps. I decided to air gap one and sandwich the other.


Ah, I see what you are getting at, unfortunately I still do not have an answer. :(

I have been playing around with the electrode inside the tube, trying different materials and shapes to try and create the largest amount of corona discharge without it actually arcing. My understanding is that a discharge is a purple streamer that tends to appear to be a steady "flame", whereas an arc is a bright blue-white "bolt" that tends to dance a lot. Note that there is no airflow in the tube, it is sealed at one end and open at the other for observation.

The thin, 10 gauge copper wire provides nothing but steady, small purple jets that do not reach the alumina tube. The overall quantity of jets and individual size is relatively small, and the set-up produces a light buzzing noise. (All the sounds are amplified greatly by the open-ended ceramic tube).

I took some ultra-fine steel wool, and rolled it up (like making easy clay snakes), and pierced it lengthwise with the copper wire. This gave the length of the wire an effectively fuzzy physical diameter of about 2 cm (inside the ~26mm ID tube). The effect of this was quite drastic. The sound increased 4x, and looking into the tube the number of jets had increased by about ~20x, although the intensity had not changed much. A strong smell of ozone became apparent much more quickly than with the wire alone. There was, however, an occasional dancing bolt, particularly close to the center where the alligator clip was on the outside electrode (more on that IAM). Whereas the wire produced almost zero heat, this slowly became warm within a minute.

Next I tried wrapping aluminum foil tightly around the fine steel wool, shortening its physical diameter to ~16mm. With this setup the sound dimmed a bit, and the number of jets lessened, but the intensity of the jets seamed to increase a bit, and there were several that I had trouble differentiating between arcs and streamers. They werent terribly bright, and they were purplish, but they tended to flicker back and forth between one or two points.

Last, I tried drilling a hole through a new stopper, and shoved through it an old 3/8" masonary bit I have. I shoved it through so that the tip of the bit was outside the tube and made a convient place to clip on to. The supposition I had in mind was that a smooth, larger analogue to the copper wire would be ideal. I was suprised to see that number of jets appeared to be less than the copper wire, although they were much more intense individually, particularly where the bit ended in the tube, as the bit was marginally wided there.

So, I still havent found an ideal inner electrode, and the best I have come up with seems like a bad choice both intuitively and logically (the ultra-fine-steel-wool wrapped copper wire). At the very least, I can imagine that it will have to be replaced on a regular basis, although it showed no signs of oxidation or decay from my brief experimentation. On the other hand, the rubber stopper is faring less well, as the surface that is inside the tube during operation is already cracked (though oddly it is still very flexible and rubbery).

Oh yea, and for the outer electrode I switched to very carefully and tightly wrapped copper foil, secured down with rubber tape both at the ends and along the outside seam (two layers of copper total). This alone lead to a very observable increase in both number and intensity of the jets coming off the 10 gauge inner electrode wire.

I keep finding myself questioning whether or not I am actually creating a real "corona discharge", as it is called the "silent discharge method" and my setup doesnt seem very silent to me.

I think, based on these observations, the ideal inner electrode would a 6mm wide solid copper rod with a very fine, high thread-count spiral carved into its surface.

It also occured to me that higher pressures probably favor this reaction, since 3O2 -> 2O3 produces a drop in pressure, but I dont know how that would effect the corona discharge, if at all.

Again, if anyone has any input or advice, please share.

-NN

12AX7 - 30-11-2006 at 21:57

Higher pressure insulates better.

The smaller the radius of any surface, the higher the electric field at that point (assuming it's open to opposing charge, of course). This is easily seen with Gauss' law, since for some regular charge enclosed inside a spherical Gaussian surface, the shape of it does not matter. Similarly, the force of gravity at the distance from Earth's center to its surface is the same regardless of whether the Earth's mass is in the form of a huge spherical rock or a compact ball of neutronium. However, at the surface of the object, the field is much more intense. Air breaks down at a certain (if variable!) electric field. You can put 20kV on a big smooth sphere without any breakdown whatsoever, or you can put 20kV on a sewing needle and get a big flame of corona (but obviously, no bigger than the smallest sphere that won't break down!).

Since you want breadth as well as electric field, some smooth plates (possibly perforated, but mind that they are deburred), stacked and charged alternately, with air/oxygen flow across or through them, should get you there. With high frequency (FBTs with HV diodes need not apply), you can also use insulators, which tend to prevent arcs, or form millions of low-energy sparks, which is fine enough for the goal.

Tim

Natures Natrium - 2-12-2006 at 07:17

Ok, so if I may use extrapolation as a means to verify my understanding...
Quote:
Originally posted by 12AX7
Higher pressure insulates better.


For my situation, high pressure is more likely to be detrimental than helpful, not to mention it would add to design complexity. I can imagine large power sources (30kV+) could take advantage, but I am only using a 10.5kV NST.
Quote:
Originally posted by 12AX7
The smaller the radius of any surface, the higher the electric field at that point (assuming it's open to opposing charge, of course). This is easily seen with Gauss' law, since for some regular charge enclosed inside a spherical Gaussian surface, the shape of it does not matter. Similarly, the force of gravity at the distance from Earth's center to its surface is the same regardless of whether the Earth's mass is in the form of a huge spherical rock or a compact ball of neutronium. However, at the surface of the object, the field is much more intense. Air breaks down at a certain (if variable!) electric field. You can put 20kV on a big smooth sphere without any breakdown whatsoever, or you can put 20kV on a sewing needle and get a big flame of corona (but obviously, no bigger than the smallest sphere that won't break down!).


Alright, there are a lot of factors to take into account here. So it seems that the electrical field generated by a specific voltage is independent of electrode size, as long as the electrode maintains the same shape (and maintains the same distance from opposing charge?), but the field is still more intense at the surface as long as the largest possible size for the electric field hasnt been exceeded by the physical size of the electrode.
Quote:
Originally posted by 12AX7
Since you want breadth as well as electric field, some smooth plates (possibly perforated, but mind that they are deburred), stacked and charged alternately, with air/oxygen flow across or through them, should get you there. With high frequency (FBTs with HV diodes need not apply), you can also use insulators, which tend to prevent arcs, or form millions of low-energy sparks, which is fine enough for the goal.


This also appears to confirm what Martin was saying about the need to use a flyback. Im not neccesarly opposed to the either the use of a flyback or the removal of the diaelectric, but I was trying to avoid any sort of plate design. The use of plates introduces a number of basic design complexities, including the need for a non-conductive, ozone resistant, and very probably rectangular enclosure. The only materials that are available for me that meet the criteria are glass, lucite, and PVC. I am not capable of working with glass that well, and lucite and PVC have limited tolerence to ozone (plus PVC is hard to find around here except in tube form).

However, my bottom line goal for this project is to create a device capable of outputting >5g O3 per hour. To this end I will modify my approach as needed.

As an aside, has anyone ever calculated the amount of ozone that the "commercial unit" depicted in Vogel's 3rd ed. produces? 170mL of O2/min @ 7% (maximum) O3 content = 10.2L/h = 714mL O3/h = 31.9mmol of O3 or 1.53g/h O3. At that rate it would take 33 hours just to reach one full mole of O3. OTOH, some of the modern models being hawked on eBay make claims of 28g O3/h, which would reach one full mol of O3 in about 1h45m! It is my sincerest hope that 5g/h is not an unreachable goal for a home built apparatus.

I am going to go play around a bit more, maybe test how close two sheets of flat aluminum foil can get before they arc. Not to say I am giving up on the tube design just yet. I cant help but wonder how using a sheet of copper instead of a tightly wound copper wire as the outside elctrode effects the discharge. Will try variations on that too. Last, I need to find a convienent source of a pure alkene (I was thinking about isolating some leaf alcohol for the purpose, but it became winter too quickly) to use as a means of determining the efficiency of the design.

-NN

EDIT: Hmm, this plates with no dielectric thing could be tricky. There was a distance where I noticed a physical hum-like vibration, but no arc was drawn. The aluminum foil covered pieces of cardboard clearly moved a bit due to thier attraction to each other. However, keeping the plates as close to each other as possible without drawing an arc produced NO smell of ozone. Considering this stuff is blatently pungent in the ppb range, I am not convinced that using an uncovered plate is a viable method at all. OTOH, tilting on plate about thirty degrees away from the top edge and drawing an arc on the bottom edge produced a rather neat Jacobs Ladder effect. BzzzzZZZT! :P

[Edited on 2-12-2006 by Natures Natrium]

Natures Natrium - 2-12-2006 at 16:38

Essentially finished contruction of tube design. Using a water aspirator to draw air through the inlet, and through a small RBF containing a spatula tip of NaI in tapwater (used HDPE tubing through-out, is supposed to be as good or better than lucite ... hmm), the ~30mL of water quickly turned amber orange in a matter of 20s or so, and ceased any other visual changes despite another 5m or so of "ozoning". On pouring down the drain (diluted with running water), the smell of iodine was evident. Now I know what I already knew, that this setup is producing some ozone. Now to try a positive pressure setup using pure O2. Oh yea, and the rubberstoppers at either end are coated with teflon tape now, dont know how well that is going to work out yet.

After the five minutes or so, even with an airflow of RT air, the tube became quite warm. This is something I kind of expected to happen, but hoped would not. It seems some sort of cooling is absolutely essential to making a design such as this work. Ideally the coolant would function as an electrode (as per garage chemists work), but I am not too comfortable with a bucket of (salt) water with a 10kV charge on it. The only other thing I can think to do would be to draw (or push) the O2 through a copper tube coiled at the bottom of an acetone/dry ice bath. Not exactly condusive to easy, portable, and continual operations, but might be necessary to reach that 5g/h goal.

EDIT: Ive not seen any specific design elements used to reduce the heat problem in a multi-plate system. Is it not an issue?

[Edited on 3-12-2006 by Natures Natrium]

garage chemist - 3-12-2006 at 04:52

If you want to determine the ozone output of your design, you can do it with iodide solution. Just remember that it has to be acidified with at least 1 mol HCl per mol iodide, as the oxidation of iodide with ozone produces hydroxide ions which will react with your iodine as soon as their concentration becomes high enough.
A NaI solution without acid added is not suitable for ozone determination!
The liberated iodine can be titrated with sodium thiosulfate or sodium sulfite solution, making possible the direct calculation of the output in mol O3 per measured gassing time.

In my setup, the salt water was of course grounded, and the wire inside the glass tube was the live electrode. I also wouldn't like to have a bucket of electrified salt water on my table. But with an NST which has a center-tapped secondary that's not possible.

You see, with a flyback as the HV source you have the advantage of added safety.
Also, with the flyback the ozone output of my setup was very much increased in comparison to the NST I also tried. It seems that the ozone production increases with increasing frequency of the HV source.
I used the Powerlabs flyback driver, it's the best one I've ever used, much better than any IC-based oscillators.

I recommend that you try the tube design with 7mm OD tube (or slightly larger) in saltwater and flyback as power source.
The ozone concentration at the output of my setup was so high that it burned my nose and eyes like bromoacetone vapors.
Do you have a supplier of glass tubing?

Natures Natrium - 3-12-2006 at 19:13

Quote:
Originally posted by garage chemist
If you want to determine the ozone output of your design, you can do it with iodide solution. Just remember that it has to be acidified with at least 1 mol HCl per mol iodide, as the oxidation of iodide with ozone produces hydroxide ions which will react with your iodine as soon as their concentration becomes high enough.
A NaI solution without acid added is not suitable for ozone determination!
The liberated iodine can be titrated with sodium thiosulfate or sodium sulfite solution, making possible the direct calculation of the output in mol O3 per measured gassing time.


*nods* The raw NaI was meant as a qualatative test.

Quote:
Originally posted by garage chemist
In my setup, the salt water was of course grounded, and the wire inside the glass tube was the live electrode. I also wouldn't like to have a bucket of electrified salt water on my table. But with an NST which has a center-tapped secondary that's not possible.


Hmm, by center tapped secondary, do you mean the secondary ground fault protection, or something else relating to the actual transformer? Sorry, my knowledge of electrical engineering is severly limited, but I am working on that.

Quote:
Originally posted by garage chemist
You see, with a flyback as the HV source you have the advantage of added safety.
Also, with the flyback the ozone output of my setup was very much increased in comparison to the NST I also tried. It seems that the ozone production increases with increasing frequency of the HV source.
I used the Powerlabs flyback driver, it's the best one I've ever used, much better than any IC-based oscillators.


Well, I just spent money on a NST, and I think I will finish experimenting with that first. I have never really built a circuit before short of the one I just did, (get it? :P), so I had some hesitancy about messing with this. However, I am now sure it is something I could do, but it requires more parts, and my budget is pretty limited right now. For one thing, there is no way in hell I am straight up using a battery, I will find a mains to 12+V DC converter first. Second, the majority of flybacks, at least on 'ole ebay, dont appear to be ones suitable for this task. You say you used the powerlabs design, but were you able to procure a flyback like that monster he was using? Given more time and money I will probably build one, but right now I am going to seek to enhance my current design (get it? :P) until I reach a good balance of ease of use and optimum efficiency.
Quote:
Originally posted by garage chemist
I recommend that you try the tube design with 7mm OD tube (or slightly larger) in saltwater and flyback as power source.
The ozone concentration at the output of my setup was so high that it burned my nose and eyes like bromoacetone vapors.
Do you have a supplier of glass tubing?


Most of the stuff I have is smaller diameter, from a local shop. I also know a neon sign artist that could probably hook me up for a reasonable price, if I were to inquire. I wonder, would my ceramic tube hold up against water? I am somewhat inclined to believe that it would not, although I have never even gotten it wet.

Also, there is a (relatively small) part of me, the empirical part you could say, which is demanding some hard numbers for comparison. I think I will have to run a battery of tests (get ... nm), and see what sort of ephemeral conclusions I can come up with. I wonder, you mention that your design had a very high output, higher with the flyback, but did you ever quantify an actual value from either design? Im not trying to put you on a "hot seat" or anything, I am just curious.

As an aside, I have never smelled or seen bromoacetone, but I am willing to bet it couldnt be too much worse than the time I accidentally gassed my lab with methylchlorosulfuric acid. :(

-NN

Natures Natrium - 3-12-2006 at 21:05

Wow, ok, I found out what I wanted to know:

"In general, when an alternating current voltage is applied to a sample of oxygen, ozone production doubles as the frequency of the current is doubled. The amount of ozone generated varies exponentially with the applied voltage." Ref at bottom.

The design they used was capable of producing 2mmol of O3/h (~.1g), however even knowing what they knew they still used a custom circuit with a frequency of only ~60hz @ 15-25kV. When they cooled the electrode to -20C and chilled the feed O2 to ~-150C, they were able to pass the O2 through much quicker (if that isnt a typo) and still reach concentrations of up to 10% v/v, which equals roughly 400mmol O3 per hour, or 19.29g. Thats a damn big difference, which again makes me wonder about typos.

Thier design is also noteworthy, and I am looking to see how I might incorporate it into my own build.

Primary factors:
Temperature: The colder the better.
Voltage: The higher the better
Frequency: The higher the better.

Nothing I didnt already know technically, but at least I have some idea HOW much better, and it looks like high frequency is the only way to go.

Now, anyone know an easy way to build a 50kV@30kilohertz transformer? :P Oh, and a really cheap liquid nitrogen maker would be great too.

-NN

REF is attatchment.

Attachment: ozone_generator.pdf (48kB)
This file has been downloaded 1413 times

12AX7 - 3-12-2006 at 21:38

Be careful around that LN2, don't want explosive crystals of ozone around. At least not in Technochemistry, but the forum below it :D (Big OB% explosive, eh?)

For expense, you might cool the gas/apparatus with ice or refrigeration or dry ice, rather than CO2.

Tesla coil (F >> 100kHz) is pretty easy to rig up, a solid or vacuum state one is pretty nice too, efficient and quiet. Lots of sites out there on the subject.

Tim

Natures Natrium - 4-12-2006 at 08:31

Quote:
Originally posted by 12AX7
Be careful around that LN2, don't want explosive crystals of ozone around. At least not in Technochemistry, but the forum below it :D (Big OB% explosive, eh?)

For expense, you might cool the gas/apparatus with ice or refrigeration or dry ice, rather than CO2.

Tesla coil (F >> 100kHz) is pretty easy to rig up, a solid or vacuum state one is pretty nice too, efficient and quiet. Lots of sites out there on the subject.

Tim


Yea, I decided some time ago I was too sloppy to properly mess with the energetic materials. Neat stuff though, I do enjoy reading others exploits. :-)

Indeed, I think Ice/Salt Water is the way I will go, also using it as electrolyte. Solves many problems with one go, but creates a new one: I am probably going to need a custom glass apparatus, unless I come up with a brilliant innovation on the equipment I have.

I would love to build a tesla coil someday, but one step at a time, I think. I would have to say (IMHO) I think it to be a 50/50 tie between tesla coils and lasers for the ultimate electric-orientated home built project.

By the way, as a source of power for the flyback, is there any reason I couldnt use an ATX PC power supply (350W)? It says right here the 12VDC line is capable of supplying 16A, and since there is two seperate lines I am guessing 8A per each. If this worked it would sure be a cheap, convienent means of getting that DC power I need.

-NN

12AX7 - 4-12-2006 at 11:52

On the PSU, the yellow, red, orange and black wires all go to the same respective points on the circuit board, you can look for yourself. They're all too flimsy to handle rated current alone, so you should parallel them when running a heavy load. Indeed, the output should be capable of rated load, but remember it also expects an even load between the outputs. The 5V output is regulated the tightest, which means the 12V output will sag perhaps a volt or two under heavy load (not an issue for a cheezy flyback driver, of course).

Come on... a Tesla coil is too damn easy to pass up. It's little more than the flyback driver you have already.

Remember to put a nice big film cap across the power leads to the flyback driver...nothing worse than a spongy power rail, at high frequency!

Tim

Natures Natrium - 4-12-2006 at 12:34

Quote:
Originally posted by 12AX7
On the PSU, the yellow, red, orange and black wires all go to the same respective points on the circuit board, you can look for yourself. They're all too flimsy to handle rated current alone, so you should parallel them when running a heavy load. Indeed, the output should be capable of rated load, but remember it also expects an even load between the outputs. The 5V output is regulated the tightest, which means the 12V output will sag perhaps a volt or two under heavy load (not an issue for a cheezy flyback driver, of course).

Come on... a Tesla coil is too damn easy to pass up. It's little more than the flyback driver you have already.

Remember to put a nice big film cap across the power leads to the flyback driver...nothing worse than a spongy power rail, at high frequency!

Tim


*nods*, Awesome, DC power supply found.

I managed to find a flyback with an exposed ferrite core, but it is pretty small, and the secondary is entirely cased in white plastic insulator, and there are no less than 3 different leads coming out of the thing. I will post a pic as soon as I can find a digital camera. Also, the ferrite core appears to be two distinct halves, with a long screw down the center holding them together. The item was manufactured in '89.

I managed to also find the transistor, and the 1w 270Ohm resistor, but the only 5w resistor I can find thats even close is also 270Ohm. Im assuming that the difference in resistance here is very important, and cannot be substituted.

So much fundamentally I dont understand yet, it makes it difficult for me to do anything other than follow the design precisely, as I havent a clue what substitutions might do to the overall system.

I will get around to a tesla eventually, but it is better to finish one project before starting another (which of course by me saying makes me the worlds biggest hypocrit.)

Ok, and what exactly is a film cap, do you have a part number for a good one?

-NN

12AX7 - 4-12-2006 at 14:44

http://www.digikey.com/scripts/DkSearch/dksus.dll?PName?Name...

Or any similar part from junked electronics. There's a lot of them in things with switching supplies, for the same reason. Film means plastic film stores energy. Either vaporized metal (i.e. metallization) or fine foil moves the charge to and from the plastic.

What schematic are you working from? Powerlabs'? That calls for 240 ohm 5W and 27 ohm 1W (the junction between the two resistors should also have a capacitor to GND or +V). 270 ohm is close enough (for run of the mill electronics, figure 10% variation is okay). Since the two resistors form a voltage divider, you might likewise increase the 27 to 30-33 ohm instead. In this particular case, anything from 10 to 47 ohms (like, give or take a factor of 2-3) might work, mostly depending on supply voltage. You can parallel and series-connect resistors to get different resistances. (Power in each distributes according to the resistance, if they are equal then Rtot = R / n (parallel) or R * n (series) and Ptot = P * n (either way).)

Tim

Natures Natrium - 4-12-2006 at 16:52

Quote:
Originally posted by 12AX7
http://www.digikey.com/scripts/DkSearch/dksus.dll?PName?Name...

Or any similar part from junked electronics. There's a lot of them in things with switching supplies, for the same reason. Film means plastic film stores energy. Either vaporized metal (i.e. metallization) or fine foil moves the charge to and from the plastic.

What schematic are you working from? Powerlabs'? That calls for 240 ohm 5W and 27 ohm 1W (the junction between the two resistors should also have a capacitor to GND or +V). 270 ohm is close enough (for run of the mill electronics, figure 10% variation is okay). Since the two resistors form a voltage divider, you might likewise increase the 27 to 30-33 ohm instead. In this particular case, anything from 10 to 47 ohms (like, give or take a factor of 2-3) might work, mostly depending on supply voltage. You can parallel and series-connect resistors to get different resistances. (Power in each distributes according to the resistance, if they are equal then Rtot = R / n (parallel) or R * n (series) and Ptot = P * n (either way).)

Tim


Ah, awesome, thanks for the help. I have a couple of caps off the circuit board that the flyback came attatched to, round small ones rated at 3.3microF, 50v. These should work as well, yes?

As for the resistors, I ended up with a 270ohm 1W and a 240ohm 10W. I was informed by the helpful clerk that it would work just as well, and he explained that the wattage was just the max the resistor could dissapate.

I learned I cant solder for shit, it really is an artistic technique.

The transistor has me unsure of myself. The dude from powerlabs talks like you have to insulate the transistor from the heatsink, but isnt the case of the transistor point C (collector) in the design? It sure as hell looks like it upon examination, which means the return from the primary coil should be able to be hooked to the heat sink as long as the transistor is not insulated from the sink.

Beh, I am starting to hit my saturation point for today, may have to kick back and play some video games for a bit, to let all this sink in.

-NN

12AX7 - 4-12-2006 at 17:05

Yes exactly, but then the heatsink is live. In grounded equipment you have to insulate the transistor or the heatsink, so the transistor is usually insulated, for which hardware is made anyway. If you don't intend on licking it I suppose it's fine, but do mind stray wires as well!

That cap will work, if not better since it's bigger. 3.3uF is also a good size for tweeter crossovers, and mylar film is a whole hell of a lot lower distortion than the bipolar crap usually used. :D

Tim

Natures Natrium - 4-12-2006 at 17:18

Oh good, one less thing I need to purchase. :-)

Hmm, any idea how high the voltage coming back off the primary gets? My understanding is this side of the circuit is relatively low voltage, and the wiring that is soldered to the transistor is fairly standard 12 gauge rated to 600V. I will have to make sure my resistors keep thier distance, though.

Im actually almost finished with construction, but because I am unsure of where the output on this flyback actually is, I will wait to power it until I can snap a shot of it and post it here. I will have to borrow a friends digital camera in order to this, which probably wont happen until later tonight.

Again, thanks for all your help, it has been invaluable. :cool:

-NN

12AX7 - 4-12-2006 at 22:06

Depends, a resonant winding will peak out at about double the supply, you don't have a capacitor to reign it in so you'll certainly get more than that. I wouldn't expect more than about 20 times, or a few hundred volts peak (for a period of maybe ~10 microseconds, each cycle).

Output is always the thickest wire...it's the highest, eh? You can arc around to other pins (naughty, but...eh...) and see which gets the best discharge.

Tim

Natures Natrium - 4-12-2006 at 22:48

The whole setup, minus the PSU.



The end of the flyback.



Hmm, I dont think overvoltage on the primary side of the flyback will be an issue then. I am going to have to go and pick up a cap after all, as the one I salvaged not only had very short leads, but appeared to be cracked as well. I dont think I would have fired it up anyways, too tired.

I will say this though, considering I knew nothing about transistors, resistors, flybacks, or even soldering I still managed to buy and put this together inside of a day. Of course, if it doesnt actually work, then that doesnt mean much. Will find out tomorrow.

-NN

garage chemist - 5-12-2006 at 01:45

The flyback you have looks really good, definately better than mine (and yes, the monster flyback from Powerlabs is overkill for an ozone generator. You don't need more than 10kV at those high frequencies to make a very efficient ozone generator).
Even the modern flybacks with dozens of different leads can be used, as long as enough of the ferrite core is exposed to wind the new primary on.

To find out which lead on your flyback is the second lead to the secondary, measure the resistance between the thick HV lead and all the other leads. If there is a few hundred ohms, it's the right one.

[Edited on 5-12-2006 by garage chemist]

Natures Natrium - 5-12-2006 at 09:06

Cool, I was somewhat worried I might have gotten a POS, still might, wont know until I fire it up.

Heh, I uh, still havent gotten around to getting a multimeter. So, are you thinking the main lead off the secondary is the thin red wire, or that plug that comes off the side? I am unsure, as the red wire seems to come from the center of the secondary, but looks way too thin to support any kind of high voltage. The plug on the other hand looks stout enough and the metal connector inside is actually deep enough to be inside the resin block, but it appears to be coming off the bottom of the secondary. Any thoughts?

Here, a pic of the other side should help:



-NN

Natures Natrium - 7-12-2006 at 12:28

Well, I got something at least. After messing with the PC power supply for a bit (and figuring out how to trigger it to "ON" status), I tried my circuit out. At first I got absolutely nothing, and then I realized I had wound my feedback coil exactly opposite of my primary. Took it off, rewound it. Now I am getting juice through the system, but it appears to be pretty damn low power.

The NST would start an arc between two pieces of aluminum foil at about a cm, which would then grow to a white arc of ionized air at about 3cm before it would pop out. With this setup I am barely getting 5mm of arc. The good news is it does sound like a MUCH higher frequency than the NST, but I have to figure out a way to get more power out of it than this. Hooked to my alumina tube setup, I get no observable effect.

Also, I was very confused about the ground lead, the one than comes off the other side of the HV arc. Does it ground to someplace on the secondary, or does it ground to the ferrite core itself? Powerlabs doesnt makes this specifically clear, and I am as of yet too ignorant to deduce the correct action.

EDIT: Alright, realized I was one wrap short of the powerlabs design on my primary, did that, it did help some. I still cant really get these coils really tightly wound and close to each other, that solid core stuff just has too much memory.

Also, did some math:
NST: 30mA @ 10kV = 300W, it uses 316W @110V to produce this.

ATX PS: 16A @ 12V = 192W, so @10kV, the theoretical A= 19.2mA, or not suprisingly 2/3 the power.

However, I realized something else, that the 16A rating on the PS apparently only is valid for the +12V (yellow wires). The only -12V line is a single blue wire, and its maxmum rating is just .8A, or 9.6W, ie 3% the power of the NST.

The bottom line is that despite the convience of it (I even put a CPU fan on that CPU sink, since the transistor was getting warm, and it was convient to tie into the 12V lines with it), I dont think this PS is going to work.

What I really need is about 25A@-12VDC. (Equals 300W.) Does anybody else think that will make my transistor a heating element for a very short period of time?

-NN

[Edited on 7-12-2006 by Natures Natrium]

12AX7 - 7-12-2006 at 16:33

Yeah that's a good point at which to use MOSFETs and a good squarewave circuit to drive them.

Tim

Natures Natrium - 7-12-2006 at 17:05

Quote:
Originally posted by 12AX7
Yeah that's a good point at which to use MOSFETs and a good squarewave circuit to drive them.

Tim


*Sigh* Know where I can buy one? Or a relatively simple way to frequency double 10.5kV AC a couple of times?

I think I will go back to working on the actual ozone tube design, as I am flat out of "play time" money for at least a month.

-NN

garage chemist - 7-12-2006 at 17:39

No! You don't need a more powerful 12V power supply, and you certainly dont needs Mosfets!

The flyback driver draws about 3-5 Ampere of current from a 12V supply when under full load. There is no way you can make it more powerful using 12V.

What you need is a 24V power supply! 10A of current output capability will be plenty there.

It is the same with my flyback driver: with 12V I get only thin 5mm arcs, but with 24V I get at least 1cm and they are much hotter.

Natures Natrium - 7-12-2006 at 18:58

Wow, I just typed up a whole bunch of stuff, and then lost it when I mysteriously could not connect to scimad for a bit. Hmm, reminds me of the mid-90s and the whole AOL scene.

First, thank you for setting me straight on some misconceptions, I do so ever appreciate it. :)

Second, I think borosilicate glass might be too conductive when using a system like that in the paper I uploaded. I tried wrapping the outside of a 300mm condenser with aluminum foil (a 100mm area, centered in the middle), and using the NST I found I had corona on the wire clear at the top, well away from the aluminum foil area. I question the effeciancy of a system which utilizes two salt water electrodes, both of which are in direct contact with a piece of glass that is eventually contiguous (as in the paper I uploaded). Maybe this is why Vogel was saying that borosilicate is not satisfactory for an ozone generator? Still, in that paper they reported ok results, and were using 20kV, 60Hz, @ ~500ma.

Third, I am still trying to think outside the box in terms of design, and see if I cant come up with something original, easy for the hobbyists, and relatively efficient.

-NN

PS I still wonder if that guy really had a 75kV transformer or not. :P

12AX7 - 8-12-2006 at 07:50

Quote:
Originally posted by garage chemist
The flyback driver draws about 3-5 Ampere of current from a 12V supply when under full load. There is no way you can make it more powerful using 12V.


Nah, sure you can. Fewer primary turns (and fewer feedback turns to compensate) and more amplification (i.e. current handling) will draw more current with the basic circuit.

Up into the 10-20-50-100A range at low voltage, the 1-3V forward drop of BJTs starts looking real infuriating, so you also want to use MOSFETs, which reach very low ON values (a chunky 0.003 ohm Rds(on) MOSFET drops less than a volt at 30A) and heat less, using more of your supply voltage as well.

But yeah, really, anything with more amps than volts is impractical. You could do worse than rectify line voltage and run 160V at a couple amps instead! Heck, you could even use IGBTs for that (albeit at little advantage to more robust MOSFETs or more so BJTs). Easy enough to put on a whole bunch more turns and run that sort of voltage.

Of course, at this point you have to consider the size of your FBT. Even the biggest in use are designed for perhaps 30kV at 1-2mA, or 30-60W. More than 100W for much time will certainly burn it out, and that's if it's a bigger one.

You can quite easily step up voltage: if you have an AC source, you can use a transformer to produce higher AC, or a voltage multiplier to create DC. If you have DC already, you're SOL on that end. If you want to do this with glass insulators, you obviously need AC, anyway.

Tim

Natures Natrium - 9-12-2006 at 15:52

Study study, learn learn. Could anything be better?

Well, I have been playing around with a small U-tube I have. I found a way to get a fantastic amount of corona in it, but the damn secondary ground fault on my transformer keeps tripping it off. >_<

What I did was wind 3 seperate pieces of a single strand of copper wire from my 12-gauge stranded around a length of the still insulated 12-gauge. I wound them in such a way as to form a triple helix. Then I pushed the wrap through the U tube, grabbed onto the 3 wires at the other end, and pulled the core wire out, leaving a cool looking triple helix of 3 very thin wires. Application of the NST to this setup (the U-tube dipped in a salt bath attatched to the other end of the transformer) produces a bright purple glow that fills the tube completely... for about 3-5s, max.

Midedit: Just messed with it some more, got it to work properly. The discharge must be heating up the air, as on application one end of the U-tube feels like it has a small fan behind it since it is emitting quite a lot of air.

If I get a couple more of these U-tubes and set them up in series (as regards O2 flow), I think a pretty damn efficient generator could be made. The U tubes each have two air flow nipples as well as the usual testtube-like tops, so the wires come in through teflon-coated rubber stoppers, and the hoses hook onto the air flow nipples.

So far this is looking promising; cheap, easy to build, solves cooling issues, and hopefully turns out fairly efficient. Any work on the flyback driver is halted, as I clearly need a higher voltage DC source, and I wont be able to afford one until probably after the New Year.

-NN

Natures Natrium - 15-12-2006 at 16:56

I have been thinking pretty frequently lately about how to implement an efficient design, as well as spending some time just playing around to get a feel of the characteristics of high voltage discharge.

This is what I came up with (so far):



I came up with the idea of solder-filled glass tubes after I considered that silver plating the inside of one of these would make an excellent electrode. While having two layers of glass, one on each electrode does work, I notice a considerable drop in overall intensity. Rather than simply have a wire inside the glass tube, which probably wastes minute amounts of energy, I wanted to fill the tube with a conductive metal. Silver containing solder seemed like the best choice from given that low mp, good conductability, and ease of acquisition were all valid factors.

The outside being made of "hard" plumbing copper is convienent both by the fact that it is very conductive and its easy to assemble into whatever shape I need.

I cant decide whether or not to make the cooling bath brine or not. It would allow lower temperatures, but it seems to me from my observations and playing around that larger amounts of salt water tend to drain a bit of energy from the system. I wonder how much better tap water would be as an insulator as compared to brine. I know they used to make large, barrel sized resistors this way.

The bath itself would be in a styrafoam cooler, setting on top of an inverted cooler of the same type. Distance and insulator to help prevent wasted dispersion of charge.

The gap between the electrode and the copper tubing will be on the order of 1-2mm. A rather slow feed of gas will be necessary, since there wont be much volume inside the system, but this way all the O2 moving through is constantly exposed to the corona, save for the bottom "U-joint". If necessary (or helpful), I dont think it would be too much harder to set up a series of these (Im thinking 6, max). It would depend on whether or not my PS can power a larger system without overall loss on yields. Also, once I get a 24VDC source, I want a system that wont overwhelm my flyback driver.

Please, if you have any helpful ideas or comments, or can point out grievious mistakes, feel free to do so.

-NN

EDIT: Oh yea, length of glass electrodes should be ~30cm, so outer copper tubing beneath water should be ~25cm.

[Edited on 16-12-2006 by Natures Natrium]

12AX7 - 15-12-2006 at 17:12

Sounds reasonable. Be sure those capillaries are sealed! ;)

Don't worry about resistance; connected to the copper, the HF current will travel mostly along the inside surface of the copper (most of the copper at 20kHz, but a few mils of the surface at 200kHz, say).

Tim

Natures Natrium - 23-12-2006 at 17:54

Got it all built. I wanted to take a picture, but I dont have a digital cam (still). I will get pics up as soon as I can.

Pretty much everything was built to spec. I used a few tricks I had read about a long time ago regarding glass blowing, and sealing the tubes was a cinch. I wasnt aware that solder had an organic component in it, a high bp glue-like stuff which I was informed by a friend was that "flux" stuff I am always hearing about. Filling the tube was easily accomplished by feeding the silver solder (62/36/2) into the tube while keeping the glue like stuff right on the edge of boiling. A 10-gauge solid-core copper wire was bent into a C-shape, and the ends were inserted into the two seperate electrodes by heating the solder to liquid, inserting, then cooling, one at a time. I have to admit it was pretty neat to create glass covered solid metal electrodes so easily.

Unfortunately, during operation the glass covered electrodes are still getting way too hot. Too bad too, it was really cool to look into the copper tubing from a side port and see all the air inside lit up a glowing, deep purple color. The first electrode broke pretty quickly, allowing an arc to form through the crack. I figure it was because I had to force the rubber stopper on with too much force, so I made a third electrode and drilled out the stopper a bit more. However, the 3rd one broke as well, and this time the glass was a bit frosted in a circular shape where it broke, making me think it was more a product of heating than physical mishandling. I havent tried running the setup with just the remaining in-tact electrode, as I dont want to overheat and break it as well. I am currently thinking that the 300W of power that the 10.5kV NST is providing is simply overwhelming any sort of cooling that the water, or air being pulled through the system, provides.

(On a side note, when I made the third electrode I broke apart the glass on the first and recovered the solder. Feeding this into the new glass tube proved to be far more hassle than it was worth, however if anyone is wanting a smallish lead/tin rod-shaped electrode for something, this might be a good way to do it.)

When I get my 24v PS, and if my output from the flyback is in the neighborhood of 20kV @ 3mA, then the 60W total power should provide much less heat to the system, as well as providing a large increase in yield thanks to the high frequency of the AC current.

Even though any trail is a success regardless of whether or not the actual setup worked as expected, assuming that data is acquired which leads to an even more likely construct, I could not help but to feel a but bummed out when I ended up with two broken electrodes. Still, I want to continue foward until an easily achievable means of acquiring molar amounts of ozone is obtained. There is just WAY too much neat stuff that can be done with it. :-)

Finally, my necessary QUESTION for the day: Can someone explain to me why it is easy to find a 24V @ >5A PS that only has a positive terminal, but all the ones which have both positive and negative terminals at that ampreage are usually twice as expensive? At least, thats the impression I have gotten while searching ebay and online stores. Thoughts?

-NN

EDIT: Oh yea, is there a way to double voltage while halving current? Like making one of those old style transformers you see in the B&W pictures. Say, 20 wraps of 10-gauge solid core on the outside and the inside coil being 40 wraps of very thin, enamal coated magnetic wire? Does it work by powers (ie 20 wraps outside, 400 inside to get 2xV, and less than .5xA)? websites links for me to learn more? (Wikipedia has a bit, but I found more historical refs than actual useful info, which is neat but not helpful to my projects.)

[Edited on 24-12-2006 by Natures Natrium]

UnintentionalChaos - 23-12-2006 at 21:17

The conversion for transformers is a simple ratio, though of course, this is the real world, and losses occur for various reasons. In theory (and a perfect world):

Voltage in / Voltage out = # wraps in / # wraps out

Nevermore - 2-1-2007 at 05:23

i built and ozone generator a few years ago for deodorizing purposes..
i do not need a very strong concentration of ozone for those purposes so i went for the easy way by photocatalitic reaction:
i took a mercury light and removed the bulb carefully exposing the inside mercury bulb, then i placed it inside a box, with a big computer fan blowing tru, and build a labyrinth so that is impossible to see the lamp directly.
when turned on it created enough ozone to deodorize my garage in 20 minute..leaving for longer increases the concentration up to the point which u can't breat and your eyes water..

roamingnome - 3-1-2007 at 11:59

simple is better.... simply by taking of the glass of a mecury bulb!? what was the wattage like 50-100..or 1000

why the heck am i fooling around with cracking pyrx glass every secound...

Nevermore - 3-1-2007 at 14:24

exactly.
the power i used was barely 70W, and luckily i didn't buy anything more powerful..otherwise it could have been quite a bit of a problem..the important is having a nice big box (mine is approx 25liters, with insides covered with tin foil..
this way u will maximize the UV exposion of air..

The_Davster - 3-1-2007 at 15:18

Potentially stupid question to those in the know but...
I have a vaccuum leak detector, in otherwords a small handheld tesla coil, it makes inch or so sparks to a ground. Whenever I play with it there is a noticable ozone smell, however, would this work well in the tube type of ozone generator as the power source? A couple pages back someone said the higher the voltage and frequency the better, so is this an ideal power source?

The_Davster - 3-1-2007 at 21:42

Why yes it can. Even in a world class shitty rigged-together-in 10-min-setup!
It oranged the KI solution in about 20s
Air was drawn through with an aspirator. Just a copper tube in the centre of a leibig condenser, filled with .3ishM CaCl2, copper fibers taped on the outside.

In the background is a smaller, failed ozone tube.

I tried with tinfoil instead of the copper fibers, and it did work better, but I used the copper fibers so I could see the tube glow blue in the dark.:P

[Edited on 4-1-2007 by The_Davster]

OZONE.JPG - 50kB

The_Davster - 4-1-2007 at 17:23

Ok, triple post, but I have a cool picture:P

All I need is some ozone proof tubing for the output, and a water pump for cooling(I hate using the tap to run cooling water), the pump I origionally bought does not have the power to pump though all those coils.
Even without cooling there is much ozone smell at the output right after turning it on.
I also plan to build a clear plastic box around it, I attempted to keep the HV isolated as best as I could(note the electrical tape:P), but more is better.

EDIT: AARG...tested it on KI solution....the first crappy generator I rigged up worked better than this. I think I have too much foil surface area.

[Edited on 5-1-2007 by The_Davster]

[Edited on 5-1-2007 by The_Davster]

ozone machine.JPG - 42kB

Natures Natrium - 19-2-2007 at 14:58

Hmm, I recently resumed expirementation on this project, but I have been having some spots of trouble.

First off, I found an 18.5v, 6.25A power supply in the form of a power brick for a laptop. Got a good deal on it too.

Then, I promptly burned through 3 2n3055 transistors in a row when attempting to use this power supply. Hmm. The third time I actually drilled two holes in the bottom of the AMD stock cpu heatsink, mounted the transistor with arctic silver, and attatched the stock fan that came with the sink. Still burned it up.

Mounted a 4th transistor (I looked around for some higher power handling alternatives that powerlabs recommended, but couldnt find any), also a 2n3055, and ran the PC PS supply, which supplied its 12V@800mA, and I was suprised to find that the aluminum block got warm and the transistor was almost too hot to touch after just a few minutes of drawing (very small) arcs.

I am really at a loss, as I feel that something is causing the transistor to heat up much too quickly, but an examination of this simple circuit compared to the powerlabs tutorial showed that, as near as I can tell, it is set up exactly as he had his.

If anyone has a clue or idea, please feel free to share.

Also, I had an idea, while I was examining how speaker amps work, and suddenly realized its not so different from my setup, and if I understand how speakers work correctly, is capable of generating high frequency current (15-20kHz) pretty easily. Some sound gurus on another forum (which I forgot to bookmark, damnit) were suggesting that a 200W amplifier often put out (with certain sounds) as much as 24V, which simple math would indicate was about 8A (unless the 200 is an indication of the power used, not power outputted, which I dont think it is). Could probably get away with a 100-150W amp at max volume, playing a CD that is a 70-minute track of a continous 20kHz pitch. This would be the input into the flyback.

I thought this was a rather novel idea, which immeadiatly made me think it probably wouldnt work because there is too much I dont understand about electronics to be coming up with novel ideas.

Anyhow, what do all of you think?

-NN

not_important - 19-2-2007 at 15:36

Why not just use a simple signal generator? Even a 555 with some low pass filtering and a buffering op amp will give an OK sort of sine.

The 555 might be better, if you're running the transistor as a switch or class C or D amp. The square wave out of a 555 is going to reduce the time spent between on and off states, which reduces power disappation in the switch. You'll still want snubber diodes if you're driving an inductive load.

12AX7 - 19-2-2007 at 17:17

Self-excited is fine.

How did you wire it? I was talking to someone just last week who connected the base directly to a tap on the winding! How silly!

The 3055 is such a POS transistor. Tough as nails and an old standby, for sure. Above say, 10kHz, it's worthwhile to invest in some better transistors. Give Digikey and Onsemi a browse (Onsemi has samples, although shipping is not free).

Tim

Natures Natrium - 19-2-2007 at 18:22

Quote:
Originally posted by 12AX7
How did you wire it? I was talking to someone just last week who connected the base directly to a tap on the winding! How silly!


Hmm, if you are refering to the secondary, it is encased in a polymer of some sort, and I have read that it is very difficult to make the secondary winding on a flyback since it uses 40-gauge wire and many thousands of wraps. I have not altered it at all.

By base do you mean ground? I am using the black wire as my ground, since it produced the largest arcs when using the PC PS.
Quote:
Originally posted by 12AX7
The 3055 is such a POS transistor. Tough as nails and an old standby, for sure. Above say, 10kHz, it's worthwhile to invest in some better transistors. Give Digikey and Onsemi a browse (Onsemi has samples, although shipping is not free).


Hmm, if it is tough as nails, then why have I burnt through 3 of them? Given what the powerlabs dude claimed he did with his, I really dont understand why they keep frying out on me. Isnt the 3055 rated at ~70v and several hundred watts?
Quote:
Originally posted by not_important
Why not just use a simple signal generator? Even a 555 with some low pass filtering and a buffering op amp will give an OK sort of sine.


Well, to be honest, because I dont really know what any of that is. A 555 is a mosfet transistor, yes? How do I do low pass filtering and what is a buffering op amp? Would trying to build a circuit like this be cheaper and easier than rewiring a cheap stereo, and attempting what I mentioned earlier?
Quote:
Originally posted by not_important
The 555 might be better, if you're running the transistor as a switch or class C or D amp. The square wave out of a 555 is going to reduce the time spent between on and off states, which reduces power disappation in the switch. You'll still want snubber diodes if you're driving an inductive load.


Alright, I am going to do some more research to educate myself on all these terms and meanings, as I really have no idea what you are talking about.

Thanks for the replies guys, I do so appreciate any and all help I can get. If there is a simpler and more dependable way to create a ~20kHz freqeuncy than trying to depend on the feedback winding to trigger the transistor off and on, I would definetly be willing to take that route.

-NN

not_important - 19-2-2007 at 18:33

Try

http://www.uoguelph.ca/~antoon/gadgets/555/555.html

http://en.wikipedia.org/wiki/555_timer_IC

for starts. A cheap way to get an oscillator (astable mode) when you don't need really tight control of the frequency. It's output is husky enough that it often can directly drive power transistors.

Natures Natrium - 19-2-2007 at 19:10

Hmm, ok, if I am understanding this correctly, wiring up a 555 to the flyback circuit in place of the feedback winding would be a way to control the transistor state. But, it looks as thought the 555 also needs a control for starting/stopping its timer (applying current to pin 2 (TR)), which means I still need something to create a high frequency. It also seems to me that whatever I use to create the high frequency pulses might as well be directed at the transistor in place in my circuit (unless those things dont generate enough power to trigger a transistor state?). It all seems rather redundant, since that transitor is the primary problem I have been having. (Hmm, afterthought, unless the voltage applied to pin 2 can be left on continous, so that everytime the 555 triggers off it immeadiate starts to cycle again? Then the frequency would be soley determined by the capacitor/resistor combination. Hmm.)

I still am wondering, would using the leads normally going to a speaker work to drive the flyback primary directly?

I looked through digikeys catalogues, but 99% of it was greek to me. I did notice that some oscillators had frequencies in the 100's of MHz range, too bad the secondary on the flyback probably wouldnt have time to collapse before the next field pulse from the primary formed. (Yes?)

This 555 thing looks very interesting, but I think I need something simpler and more direct. Actually, thinking about it, triggering a transistor through the feedback winding probably IS the simplist way to do it, too bad its not working out for me.

Still, in my pursuit to create ozone, I have realized how cassette tapes, power transformers, car detectors (at stoplights), and a whole bunch of other stuff works. Those sudden revelations are always fun. ;)

As far as replacing the transitor in the existing circuit goes, I could definetly use some suggestions.

Again, many thanks, if I can get a good source of power to my ozone design, I am fairly confident it is going to work quite well. :D

-NN

[Edited on 20-2-2007 by Natures Natrium]

not_important - 19-2-2007 at 19:33

Running a 555 in astable mode is a pretty simple way to get an oscillator. Using a varible resistor in the frequency control part of it would allow for fine tuning of the frequency; this can be done with a pot that's 10 or 20 percent of a the needed value and a fixed resistor for the rest.

The 555's output would drive a power transistor, you're switching a fair amount of current with it. Likely you will need diodes to shunt the reverse inductive kick of the flyback. If you drive the flyback at frequencies too far from it's designed one, too much current can be pulled from the driver transistor, overheating it, so you'll need to run near normal flyback frequency; trying to use the feedback winding is more direct, but a bad design can result in either or both running at the wrong frequency, or not driving the transistor hard enough. Whe the transistor is driven properly, it spends much of the time in the full conduction state of full off, when the drive is too low it spends more time in the partially on state, where it works like a resistor and generates more heat.

Natures Natrium - 19-2-2007 at 19:46

I think I see where you are coming from with the 555, it does sound doable.

As for power transistors, I was thinking of getting a 2N5684 (80V, 50A, 300W), that ought to be overkill enough that even if my circuit is running improperly the transistor wont fry.

Which, actually, brings me to my next question (I got a million of 'em! ;-) ), do you suppose that an extra winding or two on the feedback coil might alleviate my problems? I was thinking initially that too much feedback was what was frying the transitor, but if the transistor is staying in a partially on state too much of the time and resistively heating, that would explain why I have been frying transistors left and right.

As for diodes for absorbing the reverse inductive of the flyback, any model numbers jump to mind? Wouldnt plain ole' resistors do this job as well?

-NN

[Edited on 20-2-2007 by Natures Natrium]

[Edited on 20-2-2007 by Natures Natrium]

Natures Natrium - 1-3-2007 at 16:12

I tried adding an extra winding on the feedback coil, and got the following results:

On the 12V PC PS: the arcs were significantly longer, a darker purple in color, and the frequency was so high I couldnt hear it unless I brought the two arcing electrodes so close they were almost touching each other. Hmm, I thought, this is promising. Also, the transistor seemed to be heating up a lot slower.

On the 18.5v laptop PS: The instant I connected the power the transistor fried, without a sound or smell. It didnt even get hot or anything, it just instantly stopped working, even when I reconnected the 12V supply.

While I have sourced some much beefier transistors, I am not sure they would do much good at this point. There seems to be something fundamentally flawed going on here, and my guess is that it somehow is related to the laptop PS. Not really sure what I can do about, except buy yet another PS, and I dont have the budget for that right now.

On the other hand, I was reading through the DIY particle accelerator thread, and I got to wondering how effect a Van de Graaf generator would be in powering an ozone producing system. Obviously the current would be DC, but I have to wonder if using a quater million volts would be detrimental or helpful in the production of ozone. Certainly the ultra-low current would be nice, as just a few microamps would produce relatively little in the way of heat.

I havent had much luck in producing a model which would be good for continous operation, but I will be damned before I give up on this idea. :D

Despite all the difficulties, I cannot help but feel that getting this flyback circuit working properly would be the way to go. Anyone got any suggestions, other than building solid state timers or buying tougher transistors? Can anyone imagine why the laptop PS keeps frying the transistor?

-NN

Twospoons - 1-3-2007 at 22:33

I've built a self-resonant inverter like this, but it was the two transistor push-pull version. Works flawlessly and I can pull an arc an inch long. The single transistor circuit on powerlabs has some rather fundamental flaws mostly in terms of there being no protection for the transistor for excess volts on the collector, or excess negative volts on the base, or excess current when the transformer core saturates or an arc "shorts out" the secondary. I'd guess your transistor died because your extra feedback winding put too much reverse voltage on the base. especially given the extra boost from the 18V supply.

Have a look for the two-transistor circuit.

S.C. Wack - 7-3-2007 at 04:07

FWIW, back to the topic of electrochemical ozone generation, and another article from someone who seemed pleased with it, after taking some trouble to get it right. From Recueil des Travaux Chimiques des Pays-Bas.

Attachment: rec_trav_67_217_1948.djvu (219kB)
This file has been downloaded 823 times

franklyn - 14-3-2007 at 23:21

A good overview of what's involved for production
http://www.scielo.br/pdf/qn/v26n6/a17v26n6.pdf

Simple enough to make yourself
http://www.emanator.demon.co.uk/bigclive/ozone.htm

.

Bander - 20-3-2007 at 22:59

Interested in low frequency atmospheric ozone production by glow discharge around 20kV? These guys have a novel barrier discharge setup using flowing deionized water as the dielectric; http://www.center.bg.ac.yu/plasma/DBD.htm

An example of usage, Removal of phenol and chlorophenols from water by new ozone generator
Quote:
Depending on the experimental conditions, the new ozonizer after approximately 1 h of work provided the concentration of dissolved ozone in water of 7–40 mg/L. These values were onsiderably higher than 0.2mg/L obtained by authors using the reactor based on corona needle-toplate discharge.

(after thinking about this for a while it occured to me that this would make a kickass pre-ionization system for atmospheric pressure nitrogen lasers)

[Edited on by Bander]

ozone generator for ozonolysis

Dr.3vil - 18-4-2007 at 15:29

would something like the device linked below be suitable for the production of ozone used in ozonolysis reactions

http://cgi.ebay.com/High-Power-Water-Ozonator-300-mg-hr-Ozon...

- dr.3vil

franklyn - 18-4-2007 at 17:57

dr.3vil
While I researched this some and posted about it , I have not used
such a method myself. Note that 300mg is just a third of a gram
assuming you get good yield from your reactions , obtaining just
a few grams of product will be an all night affair , any meaningful
amount would take a week. This may well try your patience.

Ozonolysis also must be done using pure dichloromethane solvent
also available and known as methylene chloride, at the temperature
of dry ice if ozonides are being produced ,since these will decompose
over 20° C and are hazardously explosive.

.

[Edited on 19-4-2007 by franklyn]

seb - 18-4-2007 at 20:29

The Metropolitan water District of Southern California is building several 5 MW ozonators at water treatment plants as well as other units, such as coal removal and water treatment (one facility is called Lake Skinner), and these will have liquid O2 tank farms. The plants already have Cl2 gas in tanker trailers onsite. Chlorine treatment is supposed to be phased out. The project cost was originally $680 million.
Obtaining some ozone is admirable, but I mention this because a different focus might be what happens in theory when heretofore unheard-of quantiies become available. I am not saying we can get our hands on any, which is too bad. A technician will get his job handling all that material and never be allowed to conduct any experiments with it. Of course, the Chernobyl accident was supposedly the result of experimentation, but the full story is that this design of reactor can have a runaway power buildup. I read about it in a "Dictionary of Scientific Ethics". All the "experimentation" had to do with was how you do a low-power startup, since a no-power startup takes days to get going. In the ozone case, if you ozonate water, you have to have an ozone destructor downstream. It would be nice to position objects in the stream just to develop the chemistry of rubber that could resist ozone damage, maybe to make rubber hoses to use in biodiesel engines. I feel that MWD should be encouraged to to do research with some of that cheap ozone.

Matchheads - 19-4-2007 at 19:22

Let's change our thinking and get rid of this kind of science. Isn't school a game? Okay, "300 mg is a third of a gram" (Franklyn). I was thinking that if you are trying something with independent events, like answering test questions, even if you get two out of three, that is only 66%, not passing. I think back in the day, they noticed this and said, "we are not letting ppl get away with competence. We are setting passing ABOVE the best two out of three. I am only doing something 3 times, maximum. I am not going to get it all three times. Let's have school be just three test questions and only promote those who get them all.

franklyn - 20-4-2007 at 01:46

In scientific notation rounded off to one one significant digit
how do you write one third of a matchhead :D

.

Matchheads - 11-5-2007 at 10:09

I am still unamused. The Nineties were a washout as far as Mars exploration went, a) The coloring books you men grew up on had no recent data on Mars, therefore our trips to the library were heavily influenced by the likes of Dr. Martin Luther King, b) Oh, wasn't that a question of mere UNITS, on the order of "Let's assume everone is using the metric system". c) That was "Mars Observer" failing an orbit insertion. Funny?

1/3 (mh), mh/3, 0.33333... x (mh), and 33.333...% of a matchhead, or a pinch.

Why would you go from something you can write in two figures, and w/o splitting a line, and's correct, to something you exaggerated a skosh?

Franklyn, you didn't even go "Franklin", so we could be talking about Benjamin Franklin. Aw.

Benjamin Franklin never gave up. That's why we have heard of him, see?

Note that we want to see all big numerals and zero plus the decimal point (because there's no 'Q'), unless you want to be a slave to a computer screen and not really work in labs, and use a bar to offset information, then you'll get an "ADEQUATE" in NOTES, what we call, "legible". Also, use superimposition to condense double letters. Thus, "Matchheads" or "mh" will come out like this: ,|,,.

[Edited on 11-5-2007 by Matchheads]

Pulverulescent - 2-2-2008 at 09:14

Hi anyone, My first post, and I'm putting it here because I have a "thing" about ozone.
Some time ago, I produced ozone (apparently?) by passing unsmoothed dc through a plat/ir wire. The wire was to be used as anode for perchlorate synth and I'd been checking its conductivity the lazy way.
The idea had been to pass currents of increasing density through the alloy to see how many watts I could get without burning the bakelite cell-cover.
The psu was two battery chargers in parallel and all switches were out of their housings. The alloy wire was 500mm in length and 0.5mm thick. Intending to begin with the lowest density current, I connected the wire to the terminals which were fairly thick copper wires twisted round the ends of the alloy wire so that the wire was stretched horizontally between them. Because of the confused arrangement of the switches I inadvertently selected max power, and swiched on.
The wire instantly went whitely incandescent and sagged visibly so I dived for the off-switch. I reset the psu for min density and again switched on.
No glowing this time but visible convection currents were seen rising from the wire.
Suddenly there was a strong smell of ozone and it seemed as intense as that from a generator I'd made years before from an nst, small window-panes and ulufoil.
On smelling ozone, my heart sank, thinking I'd got an arcing short in a primary coil.
On not finding any arcing, I put my facial ozone-detection sensor close to the alloy wire and found that the smell was coming off the wire itself. My reaction then was, "this is interesting but there's a rocket waiting for nh4clo4 and you can get back to this ozone thing later. I had to turn it off quickly anyway,because the rectifiers were at, near or above their operating limits. Setting up the e-cell required cutting the alloy wire into short lengths and so, the ozone thing went on the back-burner for yonks.
When, later, I got to thinking about the anomaly I realised I might have stumbled on something useful. I purchased a new (expensive) alloy wire to reproduce the "effect". If I'd succeeded you'd've heard all about it, already.
Basically, my lack of knowledge destroyed the second wire. I used steel croc-clips on the alloy and this caused fe ions to migrate onto the alloy surface, causing extensive black staining, and poisoning the catalyst. I'd figured that ozone was produced by electron-induced desorption of oxygen adlayers as 0, forming ozone by recombination.
The only other way ozone could have been produced would be by reduction of mixed oxides of plat/ir, formed by the high temps, but in that case only traces of ozone would be expected and I remember the smell being quite intense, and sustained. Around this time, while browsing, I found a paper, titled, "Electron-induced Synthesis of Ozone in a Dioxygen Matrix" by Lacombe, et al. The abstract is still available under that title.
The inferences in that paper seemed to suggest that ozone *can* be produced efficiently by a form of electro-catalysis---on platinum crystals. The work had been done under uhv and low temp conditions to investigate the occurrence of ozone in spectra from some asteroid or satellite.
I haven't, yet, been able to reproduce the effect, but I'm not done trying.
I'll have another alloy wire sometime this year, but a variac is also needed.
Any similarities to junk-science are unwelcome and unavoidable.
Ozone synthesis by e-catalysis would be efficient (c/d generators are inherently inefficient), use low voltges (<10v), eliminate the nox problem in air and allow the production of any concentration of ozone.
The entire thing may hinge on the fact that dioxygen is paramagnetic.
So, have I "sparked" interest in any cranial receptacles out there?
After this, thoughts of patents are well and truly out-the-door! But, C'est la vie!

12AX7 - 2-2-2008 at 17:58

"Dioxygen matrix" means, they put something inside of frozen crystalline O2 (a matrix, bound by dispersion forces -- brr cold!), then did some sort of reaction to it. Matrix reactions are done in a suitable medium (e.g., Ar, Kr, N2, etc.), frozen solid. Not amenable to producing things.

Ozone can be produced by the decomposition of permanganate in acidic solution, electrolysis of a nonreactive or, more commonly, strongly oxidizing solution (e.g., peroxydisulfate, perchlorate, etc.), and I think fluorine and various compounds of it (CoF3?).

Tim

Pulverulescent - 3-2-2008 at 10:09

Thanks for the insights,12AX7. 'At risk here of stating the fairly bleeding obvious, but, all electrical discharges in air or oxygen produce some ozone. Ozone is produced when atomic oxygen interacts with dioxygen by forming weak bonds---the resulting triatomic form owing its thermal instability to the weak bonding of the third atom. Atomic oxygen can be produced by chemical and electrochemical action, electron bombardment, thermal desorption of chemisorbed oxygen or by high temperatures.
Oxidation of S02 at PGMs relies on the formation of ozone as a transient intermediate.
Ammonia is oxidised catalytically by a somewhat different mechanism because hydrogen reacts directly with adsorbed oxygen on the PGM surface.
A recent process generates ozone by bubbling air or oxygen through a water/phosphorus slurry; oxidation processes within the mass produce atomic oxygen but the ozone formed is heavily contaminated by various oxides of phosphorus.
Corona-discharge generators produce ozone more efficiently than electrochemical methods but they themselves have efficiencies of only around 5%.
I don't know if my "observed process" is reproducible, but if it is it would produce ozone without most of the losses that occur with other processes.
Lacomb's process used ultra high vacuum as well as cryogenic temperatures. Atomic oxygen was produced in his experiment by electron-beam bombardment of condensed oxygen layers on platinum crystals. Desorption occurred at electron energies of around 7.5 ev which coincidentally is roughly the output in volts of a 6v battery charger. The extra 1.5v is there to overcome the cell-resistance.

Pulverulescent - 5-2-2008 at 10:46

Tim, asking pertinent questions won't make you look gullible as you might think!
I could have made the entire thing up, obviously, but I didn't; there's a possibility I'm terminally delusional, though.
Ozone, like its stable allotrope is odourless; it has *no* smell whatsoever. When inhaled, ozone attacks nasal mucus, producing odourous volatiles.
In a nut-shell, or matrix, you smell burning snot(ugh!)when ozone's around.
That Lacombe paper is now pay-per-view, unfortunately, and the abstract skimpy.
If you find a chink in your scepticism anytime soon and you've excess cash, you could check it out.
Ozone used to be made by a lab-curiosity by dipping a red-hot platinum wire into lox, withdrawing it and allowing the residue to evaporate. It would seem that desorption of O produced ozone and the low temperature prevented its decomposition. If oxygen is blown though heated porous platinum ozone is formed by the same mechanism in the interstices. In confined spaces it cannot decay thermally at its normal rate because of the limited number of molecules available for reaction.

-jeffB - 5-2-2008 at 11:40

Quote:
Originally posted by Pulverulescent
Ozone, like its stable allotrope is odourless; it has *no* smell whatsoever. When inhaled, ozone attacks nasal mucus, producing odourous volatiles.
In a nut-shell, or matrix, you smell burning snot(ugh!)when ozone's around.


No offense, but this seems like a silly distinction. One could argue on the same grounds that chlorine is odorless, because when inhaled it chemically combines with mucus (and water) to make odorous HCl and HOCl. The fact that it chemically attacks tissue does not mean it "has no smell" of its own.

I remember long ago seeing a claim that ozone doesn't actually have any odor, and that what people think of as the "ozone smell" is actually the oxides of nitrogen formed in electric discharges through air. This claim is easy enough to debunk; pass a discharge through a stream of pure oxygen, and see what the product smells like.

I do see a number of Google matches claiming that ozone is a "colorless, odorless gas". They're wrong on both counts, unless they really mean it's colorless and odorless in sufficiently low concentrations. By that definition, iodine is colorless, and hydrogen sulfide is odorless. :P

Pulverulescent - 5-2-2008 at 14:52

None taken, jB, but dioxygen is determined to be odourless because our first breaths at birth are all too easily forgotten and we're breathing a mixture, anyway.
On a more serious note, you must have noticed the similarities in smell between ozone, nitric acid and chlorine. The smell of ozone is that of a pure oxidiser, but the other two have nitrogen and chlorine along with their reactive oxygen.
When I made a simple ozoniser, on switch-on the smell was all ozone, but running it for a time caused an extra pungency as the condensing moisture within the discharge-gap caused increasingly hotter discharges bringing nitrogen in on the act.
At the time it got me thinking that an ozoniser running on air could be fine-tuned to produce n2o5 from ozone and no2. Bubbling it through water could lead to hno3 of almost any concentration or the n2o5 could be condensed using dry ice.
As far as as semantics goes one *can* say that since oxygen has no odour, being oxygen ozone has none either.
Back to angels on pin-heads!

Pulverulescent - 6-2-2008 at 04:23

So...Anyway, who's going to be first to put their head over the parapet to tell me my first post is pure wishful thinking, or worse. . .?

Pulverulescent - 6-2-2008 at 14:50

(sigh. . .!)Here's what I think might have happened---heating the plat/ir wire close to its mp. "reordered" in some way the alloy surface allowing the formation of more complete oxygen adlayers. There's a strong possibility that the rectifiers(two)were damaged by the current used in heating the alloy and ac might subsequently have been superimposed on the dc pulses.
I'd assume that the heating step produced at least a "clean" alloy surface ready for adsorption.
On switching on the ("operating current?"), oxygen, being paramagnetic, would have been attracted to the metal surface where under the influence of the rising first pulse fast adsorption/chemisorption would occur. As the voltage/energy in the pulse rose desorption(breaking metal/oxygen bonds) might occur at a point near peak-voltage(~7.5v).
The desorbate would be unlikely to come off in triatomic form, but it's just possible.
It'd, more likely, be single atoms "ejected" into surrounding dioxygen, forming ozone by recombination and leaving the surface ready for the next electron-induced adlayer to form.
Ozone, being diamagnetic, would be repelled by the weak field surrounding the wire, thereby escaping the heated zone close to the wire surface without decomposing.
Each 50hz. pulse would produce a small(ish) amount of presumably pure ozone which would quickly leave the reaction-zone(platinum decomposes ozone).
As Parthian Shot---the mechanisms behind adsorption/desorption reactions are *still* poorly understood because hard information is hard to come by in the field of catalysis.
Surface reactions can't easily be observed.
BTW, academia basically told me to eff' off. Don Kennedy(retired) admired my persistence and then told me to eff off. Out-of-hand dismissals to me are water off a... blah, blah!

Pulverulescent - 7-2-2008 at 04:26

If not an interrogation, I'd expected a *few* questions at least!
Isn't there anyone who'll engage me on this? (sniff...!)
P

Pulverulescent - 10-2-2008 at 05:20

This is very odd; I may, and I *stress* "may", have stumbled upon a new, more efficient process for ozone synthesis, and no one's interested enough to muster a serious comment one way or the other.
And yes, I'm I'm all too aware that I may be holding myself up to ridicule, at some point, but the only thing worse than ridicule is indifference.
It may, if you'll pardon the pun, be fall-out from the cold-fusion debacle.

Pulverulescent - 10-2-2008 at 10:25

This may be of some slight interest to someone messing with PGMs as anode material.
When I was fiddling around with plat/ir something a bit unexpected happened.
70/30-pt/ir is fairly brittle and its electrical conductivity only moderate, so to tweak the cell to enhance productivity, I found myself trying to solder copper wire to a piece of alloy which had been sealed into the closed end of a short glass tube(soda glass).
I was using multicored solder and an ordinary iron.
Within seconds of the molten solder making contact with the alloy, a eutectic of some sort was formed.
Several millimetres of the alloy became liquid so that solder and alloy seemed to coalesce.
I realised that nh4cl in the flux must have been oxidised to aqua-regia, which dissolved the alloy, possibly allowing some mixing with the metals in the solder.
IIRC, the melting point of 70/30-plat/ir is close to 2000*C.
I found too, that repeated vigorous heating of the alloy causes it to degrade fairly rapidly.
A marked roughening is noted at first, further heating exacerbates this, producing little nodules along the length of the wire which grow in size with further heating steps to the point where the wire between the nodules becomes so thin and fragile that the least pressure (or high temperature) causes breakage.
I found out subsequently, that this phenomenon is caused by agglomeration of various oxides produced, into clumps which enlarge each time the metal is heated to redness.
The effect is called "bambooing", for fairly obvious reasons!
P

12AX7 - 10-2-2008 at 13:05

Soft solders are well known to dissolve and pit noble metals.

The copper tip on your soldering iron typically survives thanks to a plating of iron; when that wears through, the tip isn't long behind.

Tektronix, a famous test equipment manufacturer, used to (and may still) use ceramic terminal strips, which have evenly spaced divots metallized with silver. Older oscilloscopes using them often had a small roll of silver-bearing soft solder clipped inside the chassis, so repair technicians would realize that ordinary solder would dissolve the silver, loosening the connection from the terminal strip!

I have a book centered primarily on making jewelry; a mixture of acids is suggested to remove soft solder from noble metals to prevent pitting on further handling (which often involves silver brazing, diffusion, forging, etc., all high temperature processes).

Finally, tin tends to form intermetallics as well as oxides. A browse through my phase diagram database suggests both Pb and Sn form numerous intermetallics with Pd at least. I don't have data on Pt-Pb, but Pt-Sn does. (Interestingly, Zn-Pd looks like a clean system; zinc can probably be used to strengthen palladium, making something analogous to German silver, a Ni-Cu-Zn alloy. But alas, I digress.)

NH4Cl does NOT hydrolyze, pyrolyze OR oxidize to anything near aqua regia. NH4Cl <--> NH3 + HCl with heat -- it appears to sublimate.

Tim

Pulverulescent - 10-2-2008 at 15:14

Tim, you make some good points(while continuing to studiously ignore the large trunked pachyderm in the room).
My old Weller, though, has been through many coils of solder without noticeable damage, of any kind, to the copper tip.
Anyway, the molten blob of of mixed metals was a bit larger than a match-head and I lost it, in more ways than one, when it hit a fairly cluttered and unswept floor.
And you're, with respect, incorrect in thinking nh4cl won't oxidise on pt. to aqua-regia. Nh3 from dissociated nh4cl is obviously oxidised to no at pt..
The wisps of smoke from molten solder in contact with the hot tip normally contain some sublimed nh4cl, but a significant portion, in this case, also oxidised to form hno3. Surface pitting is one thing, formation of liquid eutectic blobs, quite another.
Iridium, interestingly enough, isn't itself, attacked by aqua-regia, possibly because of its extreme density.
What I saw was a eutectic formed at a relatively low temperature(~400*), and hot solder of whatever lead/tin ratio doesn't normally attack pt/ir in this way.
This is all peripheral to ozone generation by any means, and I'd prefer you to concentrate on the "main dish", if that's okay
 Pages:  1