Hodgkinson - the answer to your chemistry problem

[Hodgkinson]

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.

[Hodgkinson]

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.

[Hodgkinson]

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.

[Hodgkinson]

Thanks! :insane:

(Will get A2 exams out the way first...)  

[Hodgkinson]

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.  

[Hodgkinson]

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.

[Hodgkinson]

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:

[Hodgkinson]

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.

[Hodgkinson]

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:

[Hodgkinson]

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?

[Hodgkinson]

:laughing:

[Hodgkinson]

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.

[Hodgkinson]

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

[Hodgkinson]

 :-D Yup, 18 ;-)

WTF: 'Tension' would like access to the AmiBay recycle bin...

[Hodgkinson]

/Me thinking the same thing :-D