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Coffee House => Coffee House Boards => CH / Science and Technology => Topic started by: WotTheFook on May 06, 2008, 09:43:50 PM
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Hi,
Your problem is perhaps you are getting an azeotrope of the alcohol and the water, the alcohol will also be hygroscopic and will gradually absorb water.
The answer (using kitchen stuff you should have around) is to heat some table salt or baking powder to make it anhydrous (to drive off the water of crystallisation).
Then you allow it to cool and add it to the alcohol. You should stand a much better chance of removing the final water content that way.
BTW, I was an industrial chemist for 25 years in the oil industry.
:-D
WTF
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^^ What he said :-)
If you can buy a big load of epsom salts (that's hydrated magnesium sulfate), then you can bake it dry and grind it into a powder. If you stick this into your alcohol it will mop up any excess water even more effectively than the above salts.
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Hi there and thanks for the comment(s)!
I've just processed about 500ml of raw isopropyl alcohol today, using just the salting-out technique followed by basic distillation. I used a water bath (Pan) for the boiling flask as suggested by another member - This enabled much better control over the temperature of the mixture and helped to prevent the flask from running dry as it did when I tried it with direct heat, however, the process took about 4 1/2 hours to finish! (Decided to re-use the cooling water from the condenser to water the garden in the process...).
About 25cm3 of initial mixture remained in the boiling flask, probably mostly alcohol, which had to be discarded due to the process slowing down unbearably towards the end. Oddly, the mixture in that flask had turned slightly brown/orange - Presumably residue from the new rubber bungs used.
Density test on the distillate to follow, hopefully.
@WTF/Karlos:
Ah, I'd read about the magnesium sulphate idea over on the instructable (And got some evaporating dishes just in case). However, im at a loss as to how to remove the hydrated/anhydrous magnesium sulphate afterwards - Simple filter paper or is another distillation step required?
How easy would it to be to reuse it?
@WTF:
Eg, just use a drying agent for the whole process? Or bake the "Salting-out" salt before use to mop up additional water?
Thanks,
Hodgkinson.
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@ Hodgkinson
I would bake the powder (whichever you decide to use) just before you use it and add it to the distilled alcohol, followed by a filtration process.
You may also be able to percolate the alcohol through a filter paper containing the anhydrous powder, although you are risking the powder caking up and blinding the filter.
Once the alcohol has flashed off the powder, you should be able to re-use it, as all you are doing is removing and adding back the water of crystallisation to the powder.
You could also pack a column with a drying agent and attach it above the distillation flask, to remove the water as it distills. The problem with this is you may not know that your drying agent is spent, unless you use something like copper sulphate or cobalt chloride, which change colour with the water of crystallisation present. Copper sulphate goes from white to blue, cobalt chloride goes from blue to pink.
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About 25cm3 of initial mixture remained in the boiling flask, probably mostly alcohol, which had to be discarded due to the process slowing down unbearably towards the end. Oddly, the mixture in that flask had turned slightly brown/orange - Presumably residue from the new rubber bungs used
During my degree I often made "intractable black tar" at the end of fractional distillation of any substance that required heating :-D
Have you ever thought of buying IPA from a proper supplier? Of course, these days you'd probably be tagged as a terrorist suspect for doing so, but...
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@ Hodgkinson
The slowing down you describe towards the end of your distillation is direct evidence of an azeotrope forming, i.e. the alcohol and water form a constant boiling point mixture (it will be below 100C) and you end up at a point where you can't separate them by distillation.
Are you planning to scale up this process? If so, I would read up about a company called Chemstar that used to be local to where I work. They had the bright idea of distilling ink to recover the solvent and sell it back to the printers, all went well until a fire started one night and the results were catastrophic :-o .
http://carrbrookvillage.users.btopenworld.com/cowbury.htm
http://www.hse.gov.uk/comah/sragtech/casechemstar81.htm
I am a Health & Safety Manager by trade; I would be negligent if I didn't urge you to be careful with what you are doing and keep a fire extinguisher handy.
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So the magnesium sulphate, even when hydrated, won't pass through the filer paper? (I'll probably try this out on the recent batch - I assume that the drying agent behaves in the same way as the videoed one on Wikipedia?)
Re the cobalt chloride paper, I've got some of the stuff already. The only problem is that it seems to be so sensitive to even the slightest bit of water present (Ah, blue to pink, ligand change, whoever said that messing about in the kitchen wasn't chemistry revision?)
I suppose we might be able to find IPA available commercially, and probably far cheaper than the combined equipment/gas/salt cost, but that’s beside the point :-D we can get the alcohol free :crazy: :lol: and the whole projects been well worth all the effort!
Re safety, yeh, gas flame + alcohol vapours = Explosion hazard. Unfortunately we don't have a fire extinguisher (Should really get one, at least for the garage), but I have arranged so that any vapours that are not condensed pass outside through a flue tube to prevent build-up of vapours within the room. I've also made an open-box arrangement of gauzes, which can be used as a safety screen when any flasks are being directly heated for one reason or another.
Btw, we might be getting about 300ml or so every couple of months of the alcohol, so there's little room for growth there!
Re the azeotrope, all the way through the process the temperature of the vapours, just above the liquid level, remained between 82-86 degrees C. Towards the end the temperature crept up a little higher (NB. The distillation isn't really to separate the alcohol from the water, it’s just to get rid of the dissolved salt).
Hodgkinson.
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Right, I now have 500g of magnesium sulphate heptahydrate to try out :crazy:
:bump: So the magnesium sulphate, even when hydrated, won't pass through the filer paper?
(Just checking ;-) )
Hodgkinson.
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It shouldn't get through the filter paper; go for it!!
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Thanks! :insane:
(Will get A2 exams out the way first...)
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Hi again!
A2 Exams are now out of the way!
I tried a little experiment earlier today. I mixed (Dissolved?) MgSO4 in excess water (Just water, no alcohol yet), filtered the solution, and evaporated off the filtrate.
No residue was left on the filter paper, and loads came out in the evaporating dish.
I guess that I have a fair amount to learn about the finer points of drying agents. How can the hydrated MgSO4 be separated from the solution by filtration, even when MgSO4 dissolved in water goes straight through the filter paper?
Photos of MgSO4 experiment (Large images):
http://www.booni.info/chemistry/recycle_project/dissolve1.jpg
http://www.booni.info/chemistry/recycle_project/dissolve2.jpg
Photos of recent tinkering to help improve the efficiency of the “indirect heating” method (Large images):
http://www.booni.info/chemistry/recycle_project/tin1.jpg
http://www.booni.info/chemistry/recycle_project/tin2.jpg
http://www.booni.info/chemistry/recycle_project/tin3.jpg
http://www.booni.info/chemistry/recycle_project/tin4.jpg
PS. I’ve arranged to test the distilled alcohol for density Monday next week. I'll post on the results.
PPS. Not sure yet if I’ll upload photos of the full setup for obvious “legal misunderstanding issues” here in the UK…Besides, it’s an ongoing tinkering opportunity…
PPPS. Anyone know where I might be able to get a hydrometer from that will go down to the density of IPA?
:-D Hodgkinson.
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Eh?
Magnesium sulphate is soluble to a degree in water, it's one of the salts that make water "hard". That test proved nothing.
MgSO4 is insoluble in alcohol and it's this property we are exploiting as the drying agent. Dry some out in the oven then add it to some alcohol, it won't dissolve, but it can be filtered out.
For a hydrometer, you will need something in the range 0.750 to 0.800 as the SG if IPA is about 0.790, if memory serves. Try the Scientific Glassblowing Company in Oldham or BDH / Fisher Scientific (easily Googled), they should carry these in stock.
If you get stuck, PM me and I'll give you my phone number.
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Thanks for the advice.
EDIT: Doh. Now I get how it works. So, when the anhydrous form is added to the alcohol, its function is to effectively mop up the water left in the alcohol. When all the water has been absorbed, no water is left to dissolve the hydrated MgSO4, so it stays as a solid (Having absorbed all the water, and as a result it has nothing left that it is capable of dissolving into) in the now ~ pure alcohol?
I was trying to figure out how the the MgSO4 diddn't dissolve in the water and go straight through the filter paper...But there isn't any water left... :-)
All this is a learning curve for me, so im figuring out these things as I go along.
Heh, I really need to get myself a pestle and mortar - I also tried dehydrating some of the magnesium sulphate today just to find a congealed mass in the bottom of the evaporating dish :-D
I follow from the previous posts that MgSO4 behaves much in the same way (Visually) as the videos on Wikipedia of Na2(SO4) ?
I'll have a look at them companies :-)
Hodgkinson.
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I've just dehydrated *loads* of the MgSO4 and added it to the distilled product. With it not being a fine powder, it’s difficult to distinguish whether any more is required or not, so I've just added the whole lot.
I'll filter it in a bit (Looks like I might need to make my own Buchner app. if I’m going to do this on a larger scale...) then test it along with the raw stuff and distilled stuff.
The results should be interesting!
PS. Did I mention I’ve applied for a Chemical and Process Engineering (With Fuel Technology) Degree at Sheffield (Starting this September)? :crazy:
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@ Hodgkinson
You could also use Sodium Carbonate (Soda Ash) as the drying agent, the anhydrous salt works just the same as Magnesium Sulphate. If I recall correctly, Soda Ash doesn't cake up as much as MgSO4.
I agree, a Buchner funnel or some sort of vacuum filtration like some Millipore kit would help things along nicely, it can get expensive though. For the vacuum side of things, get a venturi to fit onto the tap to generate the vacuum, it's cheaper than a pump and there are no parts to break.
I get the feeling your learning curve is going to get a lot steeper starting in September..... :-o :-)
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The supplier that has so far supplied all the equipment also supplies Buchner funnels, but none of the venturi's or flasks, unfortunately. I figure that I might be able to rig a Buchner-type apparatus with a normal conical flask, and simply arrange the vacuum port to also connect via the bung at the top (Hence I’m writing an email now inquiring about the size of the port on the funnels).
I've got a sort of bellows-type foot pump that I could use as the vacuum source. Since its not a *proper* vacuum pump, I guess I shouldn't have to contend with the issues that require the Buchner flasks to be stronger than normal flasks.
I filtered the alcohol (A 50ml sample) from earlier and that took long enough to do :crazy:
One of the things I’m trying to achieve with this project is to use equipment that can be bought without needing any kind of checks/licence/company (One company I contacted refuses to supply individuals - And probably for a good reason) or hit and miss Ebay auctions. That way, if I do a write-up some time, anyone can obtain the necessary gear (Errm, minus the condenser, that was a reject that was *acquired* and pressed into use for the job...)
Hodgkinson.
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:idea:
For the condenser, you could rig something up using microbore (10mm)copper central heating pipe, as long as you can connect it to the heated vessel. I am thinking along the lines of a strong metal container with a screw cap for filling, with the condenser tube silver soldered to the cap. Any DIY superstore will carry microbore central heating tubing and this can be easily coiled and put into a bucket of water for cooling.
Devices like this have been distilling "moonshine" for 100s of years....
;-)
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That's the same kinda lines along which we were thinking originally, until a *cough* much more elegant and, errrm, originally many times more expensive solution to the problem turned up. Turned out cheaper (I.e. Free, since it was slightly defective for the original application) compared to the £20 or so of copper pipe that we would have needed for any decent size of condenser coil.
On that note, you have Pmail ;-)
Hodgkinson.
EDIT: Moonshine? Dukes of Hazzard :crazy:
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Damn, I hated my Chemistry degree... :-P
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I was originally thinking of getting some sort of electronics degree (Well, as with most folks here its my hobby…); but looking at the worldwide concentration of job opportunities, and a case of oooooohhhhhh, that course looks interesting; I thought bah humbug and went for it.
Its also a case of that I've always learnt electronics in a hobby environment, tinkering with what interests me from time to time; which I therefore figured that taking a degree in it might not be my cup of tea.
As for chemistry and chemistry related subjects, its something i've only been able to learn at school, so im used to learning it in that environment. CPE is also one of the highest paid jobs and is one of the best ones to try and tackle climate change through. Besides, look around, what can you see that hasn't involved a chemist or plant engineer/designer at some point?
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@ bloodline and Hodgkinson
Science abuse it great as long as you know what you are doing, I love programmes like Brainiacs and Mythbusters for that reason.
Besides, once you have nailed the concept behind a process, you can adapt it, as you already have discovered...;-)
I blew a mate's kitchen to bits with a still once, he forgot to turn the condenser water on. His wife wasn't too impressed and neither were the Fire Brigade, mind you, the Fire Officer didn't figure out what was going on.... :-D
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:laughing:
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WotTheFook wrote:
@ bloodline and Hodgkinson
Science abuse it great as long as you know what you are doing, I love programmes like Brainiacs and Mythbusters for that reason.
Besides, once you have nailed the concept behind a process, you can adapt it, as you already have discovered...;-)
But stuff like this I find so boring... And I absolutely hated Organic Chemistry with a passion...
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I made a hydrogen/oxygen mix via electrolysis a few years back. My Dad was there; we unscrewed the top and put a match near the bottle. Nothing happened. "Oh it hasn't worked"
***###***BANG***###***
That left my ears ringing for the next 5 minutes. Probably should of stood at a distance for that one, in hindsight.
I've considered trying to scale the process up since; and produce the gases separately (For lifting antennas on balloons for ham radio) but I've repeatedly discounted the idea as errrm, yeah, slightly risky.
For anyone reading this thread, we’re perfectly sane, safety minded people here on A.org.
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Results:
Raw IPA (From the same source, but not from the batch that was distilled) = 21.74g per 25cm3 = 39% water*
Distilled IPA = 20.40g per 25cm3 = 14% water*
Distilled/Dried IPA = 20.11g per 25cm3 = 8% water*
* Assuming only water and IPA present
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Dude, you must what? 18 or 19... there is penty of time to worry about boring chemical stuff... lets talk about poon! :-D
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:-D Yup, 18 ;-)
WTF: 'Tension' would like access to the AmiBay recycle bin...
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Hodgkinson wrote:
:-D Yup, 18 ;-)
WTF: 'Tension' would like access to the AmiBay recycle bin...
You weren't even born when I got my first Amiga!! So what's the poon like up your way?
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@ Hodgkinson
Tension's access has been granted.
@ bloodline
Poon, is that like Pr0n, only different, or do you mean poontang?
LOL
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/Me thinking the same thing :-D
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WotTheFook wrote:
@ bloodline
Poon, is that like Pr0n, only different, or do you mean poontang?
Poontang natürlich! Or whatever takes your fancy... but this is the coffee house, so lets hang up boring Chemistry and have some fun!!! :-D
I'm giving you this advice as someone who has been through the whole Chemistry process... You are only young once!!!
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Now im going to be a real stick-in-the-mud, but im pretty sure that that would border on the CH guidelines... ;-)
Mind you, on the other hand, im also into Amateur Radio, I've been in the ATC and RAFARS, and I have an interest in steam locomotives and trains in general (I also have MSTS and MSFS)...
I've also recently been fitting a new sound system in my mate’s car and I've just finished my A-Levels.
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Hodgkinson wrote:
Now im going to be a real stick-in-the-mud, but im pretty sure that that would border on the CH guidelines... ;-)
I didn't get to nearly a billion posts by sticking to the guidelines!!
Mind you, on the other hand, im also into Amateur Radio, I've been in the ATC and RAFARS, and I have an interest in steam locomotives and trains in general (I also have MSTS and MSFS)...
I've also recently been fitting a new sound system in my mate’s car and I've just finished my A-Levels.
Na ja... and anything non-technical going on there?
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@ Hodgkinson
Careful mate, that sounds like a wardrobe full of anoraks you have going on there, although it could explain a lot..... :-o :-D
LOL
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WotTheFook wrote:
@ Hodgkinson
Careful mate, that sounds like a wardrobe full of anoraks you have going on there, although it could explain a lot..... :-o :-D
LOL
Hmmm... We just need to steer his mind onto more interesting subjects ;-)
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:roll: :-D You mean, like, not uploading 58 photos to A.org :lol:
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Hodgkinson wrote:
:roll: :-D You mean, like, not uploading 58 photos to A.org :lol:
Unless they are of young German women, in various states of undress...
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In that case, it makes me a data ghost - I'd of been thrown out long ago :-D
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Hodgkinson wrote:
In that case, it makes me a data ghost - I'd of been thrown out long ago :-D
There is no way I'm going to get your mind into the gutter is there? :-(
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Nope (Not on a CH forum, anyway :-D )
Hint: Pmail :crazy:
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Hodgkinson wrote:
Nope (Not on a CH forum, anyway :-D )
Hint: Pmail :crazy:
Nah! I like to air my perversions in public :-)
wow... This is a bit racy!!!
http://www.amiga.org/gallery/index.php?n=1917=5
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:-? Racy?
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Hodgkinson wrote:
:-? Racy?
Cough! An uncovered peltier... that's hardcore... I'm surprised it hasn't been taken down by a mod already!?!
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:-? Sorry but now I really am confused... :-(
Don't get me wrong, but I've got a pretty good idea what you're on about with the last couple of posts... ;-)
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It seems that bloodline isn't into hardware pr0n....
PMSL!!
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Just uploaded another photo :crazy: . Should show up in a few hours...
EDIT: Ah, that one's online. There's two more just gone in in the last couple of hours...
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All online now...Now if they aren’t some form of hardware pr0n I don't know what is...
EDIT: Ah, I see you've changed your avatar ;-) Following your youtube link, are you part of a band?
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Hodgkinson wrote:
All online now...Now if they aren’t some form of hardware pr0n I don't know what is...
EDIT: Ah, I see you've changed your avatar ;-) Following your youtube link, are you part of a band?
Yup, check out http://www.tan-hausergate.com for more noise from us :-)
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Nice :-D
I've been trying to match up your old avatar to faces on the video, but it's hard going :crazy:
What is it you actually do in the band?
EDIT: Doh, just spotted the credits*. Is it more background work you do, or do you play as well?
EDIT2: Is that an I-frame type webpage? Im trying to figure out how you got the URL to work...