Introduction: Build a Lab Quality (ish) Distillation Apparatus.
First Prize in the
The Mad Science Fair
There are a few Instructables out there on how to create stills for various purposes. Usually these include a large amount of small diameter, flexible copper refrigerator tubing. While these stills can be quite effective, there is just something a little hokey about them. Especially the part where you run a large amount of expensive copper tubing through a bucket of standing water to cool the condensate. Then there's the issue of a high surface area on the interior of the tubing, which makes small volume distillations difficult to impossible. Plus they're bulky, unwieldy, and they look like a meth lab. I do have to give the authors of these projects some credit however, since DIY is typically about getting the job done, form follows function, etc etc. BUT...
I say there is a better way.
By using a small amount of 1/2" and 3/4" copper pipe, it is possible to build a lightweight, compact, collapsible, interchangeable, universal distillation apparatus for anything you could possibly hope to distill. The apparatus featured here is capable of efficient low to medium volume distillations and could in principle be scaled for use in high volume applications. It is constructed from relatively inexpensive parts which are available at any hardware store.
UPDATE 10/27/2011: If you find the start-up costs for this project to be prohibitive, I recommend this instructable.
I was inspired to build a distillation apparatus during an organic chemistry lab where we were required to identify an unknown organic solvent by IR spectroscopy. The samples they gave use weren't pure and we had to distill them first so the IR machine could get a good spectrum. This apparatus is modeled after the one I used in that lab. In the lab the apparatus was made of lab quality glassware. Since I don't know how to work with glass, and I DO have experience remodeling houses, I decided to combine my experiences to make an affordable, clean, safe, glass alternative distillation apparatus.
So. Now I've got your attention. Read on, my friend.
Step 1: Safety, Legality, and Disclaimer.
Ugh. I really hate this part. Can't I just ask you guys to be smart and leave it at that? Ok, here we go!
This project requires the use of tools and equipment that may be HAZARDOUS if handled improperly. Soldering of copper pipe requires the use of an open propane flame that can cause severe burns and fires. Never point a propane jet at anyone or leave one unattended for any period of time. HOT metal looks like COLD metal.
Distillation is a method of separating liquids that are in solution together, often as a form of purification. However, only proper, professional testing can positively identify the constituents of a given distillate. If you are purifying comestibles, DRINK AT YOUR OWN RISK.
DO NOT use lead solder.
DO NOT use this to distill hydrogen peroxide or any other potentially explosive chemical.
DO NOT allow blockages to form in the distillation pot outlets.
DO NOT use radioactive materials as fractionating column filler.
RESEARCH aluminum and decide for yourself whether it poses any danger.
In my own backwards country where the vestiges of prohibition are still rampant, it's illegal to manufacture certain distillates without a permit for the still in question. We'll just leave it at that. I don't think it's a problem to distill anything else, but I haven't checked so don't take my word for it. If you're in a country that allows it, then I highly suggest the HomeDistiller where you will find the finer points of ethanol production described in beautiful detail. The same principles apply to ethanol used for fuel, but as mentioned in the comments section, a still must still be registered to distill fuel. Still.
Please visit TTBgov for more information about US law regarding the use of a distillation apparatus. Basically, they make it impossible for a regular person to distill liquor. Producing fuel ethanol is somewhat do-able. All other distillations are ok.
This Instructable is provided for entertainment only and should not be used as a source of official information by anyone. Any and all damages incurred by the implementation of the information in this publication are the sole responsibility of the end user.
Step 2: Distillation Theory.
Figure citation: Techniques in Organic Chemistry by Mohrig, Hammond, Schatz. ISBN 978-1429219563.
Imagine you have a big stack of differently colored marbles. For whatever reason, you want to sort your marbles into different piles based on their color. So you begin to go though and pick out the colors one by one. If you have a small number of marbles this won't take long. But now imagine your marbles are about a billionth of a meter in diameter and there are so many of them it would make Avogadro, er, I mean your head spin. Well, it wouldn't be very practical to go through with a very small tweezers, picking out all the marbles that are the same color. Indeed, color loses its meaning at those scales anyway. So we have to use some other method to sort them, hopefully a method that doesn't involve much manual sorting.
I'll return to the realm of not insulting your intelligence now.
Distillation is a method of separating two or more liquids by taking advantage of their differences in vapor pressure. Vapor pressure is the pressure exerted by the gas above a compound. All compounds have vapor pressure, even solids. Granted, the vapor pressure of steel is much less than that of, say, water. Given this fact, it would be fairly easy to separate water from steel, yes? Vapor pressure is exerted by ice. This means ice can evaporate, and in fact this is what causes freezer burn. But what if we have two liquids that have relatively similar vapor pressures (but still different) and we can't just use some sort of filter to separate them?
Let's say we have two liquids A and B. A and B have a vapor pressure at room temperature of 22Torr and 40Torr, respectively (Torr is a unit of pressure). Let's say we have exactly the same amounts of A and B in a container. This means that the composition of the liquid is 50%A and 50%B, but the vapor ABOVE the liquid has a composition of 22/(22+40)=35%A and 40/(22+40)=65%B. There is significantly more of compound B than compound A in the vapor! By the way, this is probably a horrendous oversimplification of the proportions, and I COULD flip though my O-chem book to find the correct relation, but I'm sure you get the general idea. Now, if we can collect this vapor and turn it into a liquid, we would have a liquid of composition 35%A and 65%B. We would be one step closer to separating our compounds.
In fact, we CAN collect the vapor and turn it into a liquid by cooling the vapor down so that it condenses. And as luck would have it, as we remove vapor, it is replenished constantly by the liquid below. Unfortunately, this process will be EXTREMELY slow because the vapor pressures are so low and very little vapor can escape from the liquid in the container in a given amount of time. It could take days or weeks to separate them. If only there was a way to raise the vapor pressure... Well there is. And we do that by adding energy, in the form of heat, to the system. By adding heat, we can raise the total vapor pressure within the container to exactly 760Torr, but no further. This is because 760Torr is the pressure of the Earth's atmosphere, and it is at this point that the liquid in the container begins to boil.
Now we can collect the vapor above the liquid and it will be replenished VERY quickly. The boiling will actually push the vapor out of the container, and as long as we channel the vapor through something cold, thereby reducing the vapor pressure once again, we can condense it and collect it as a liquid with a high concentration of compound B.
This is what a distillation apparatus does, and one distillation step is referred to as a "simple distillation". A mixture of liquids is placed in a pot that is heated to boiling. The temperature of the vapor is measured by a thermometer at the top of a vapor column, as an indication of relative purity. Condensate (distillate) is usually collected over a certain temperature range, which is indicative of the purity of the result. The vapor travels through a condenser that cools the vapor, returning it to a liquid state that is a different composition from the starting liquid.
If we do this over and over again, we'll eventually get a liquid that is nearly pure B, and almost no A. Note that purification actually takes many repetitions of distillation. Well, that's kind of a pain. What if we want to completely purify something very quickly?
That's where fractional distillation comes in. A fractional distillation column is a device wherein MANY distillations occur in ONE step. The fractional column is a long tube that is packed with a material high in surface area but low in volume. Glass beads, chambers separated by plates, and various shredded materials work well as packing. As vapor travels up the column, a temperature gradient is created (higher temp on bottom, lower temp on top). This causes vapor to condense on the packing as it rises. The condensed material is higher in purity than the starting material. Then more vapor travels up the column, heating this condensed liquid to its new boiling point and vaporizing it, with the vapor being one step higher in purity than the last step. As the composition skews further toward B, the boiling point drops, reinforcing the temperature gradient as the material travels up the column. This occurs many times as vapor travels up the column, with the lower vapor pressure liquid separating out and dripping back down the column and flowing back to the original container. Fractional columns are often referred to as reflux tubes for this reason.
The use of a perfect fractionating column would result in very sharp jumps in temperature readout on the thermometer. As each pure compound is exhausted in the container and the next lowest boiling compound climbs the column, the temperature will rise quickly, indicating the change in compound.
Performing a distillation using a fractional column is referred to as "fractional distillation" and results in a highly purified liquid.
This project allows for the use of both types of distillation, since many raw products to be distilled contain organic solids that can contaminate the packing of a fractional column, and MUST be simply distilled first to remove these impurities.
Step 3: Parts List.
First of all, an apology: I really despise the British Imperial system of measurement. As a scientist that values accessibility and universality, I would rather do away with a system that has more conversion factors than is even remotely necessary. Unfortunately, the hardware stores don't feel the same way. So for those of you in the non-US/UK portions of the planet, I'm sorry.
I've included the prices of the things I had to buy, but I had most of the tools laying around already. That was the beauty of this project for me, but as I write this I realize it's a bit inaccessible to anyone without a well-stocked garage. The other drawback to this project is that even though we're not using much copper, copper ain't cheap. But it really is the best thing you can use other than glass. Plus, all these things can be found at a hardware store.
For this project you will need:
Small propane tank with torch attachment
3/4" or larger diameter copper pipe cutter $7
Spool of copper solder
Soldering flux with brush
3/4" and 1/2" inside and outside joint brushes.
120 grit sandpaper
A vice, or something to hold parts while you're soldering
Small metal file
A drill (preferrably a drill press but any will do)
1/4" Drill bit.
3/4" Hole saw
Accurate thermometer, preferably digital with a metal probe.
1/2" Rubber or cork stopper.
~1' 3/4" Copper pipe $4
~3' 1/2" Copper pipe $6
Four1/2" Male adapter
Two 1/2" Female adapter
Two 1/2" Tee
Two 3/4"x1/2" Adapter
One 1/2" 45
Two 1/2" Coupling
~3" ~1/4" Outer diameter Refrigeration tube
~15' 3/16" Inner diameter flexible plastic hose $0.20/ft
1ea Copper pot scrubber $1.50
You will also need some method of getting water from your kitchen sink to go into the 3/16" plastic hose. This really depends on your sink so it'll take some thought on your part. I found that my kitchen faucet has a non standard end thread so I was forced to connect directly to the wall outlet. I used:
1 3/8"x3/8" sink supply line (the size will depend on the valve you have)
1 3/8" male thread to 1/4" pex adapter
Ah, AND you will need some kind of distillation pot. This can be anything that seals, can handle high temperatures, and that you can install a 1/2" Female adapter into. I used an old 1 gallon aluminum pressure cooker I found at Goodwill for $5.
Step 4: Preparation.
So. You have a pile of raw materials sitting in front of you, patiently waiting for you to turn them into something amazing. Get to it.
Cut the pipe to length. You will need the following sections:
Two 1" long 1/4" refrigeration tube.
One 18" long 1/2" pipe.
One 12" long 1/2" pipe.
One 6" long 1/2" pipe.
Two 3/4" long 1/2" pipe.
One 12" long 3/4" pipe.
You need to put a slight bend at one end of the 18" long 1/2" pipe. This is tricky, and it's what the 1/2" couplings are for. Use the metal file to file away the pipe stops on the inside of one of the couplings so it can slide freely over the 1/2" pipe. Place the slide coupling about 3" from the end of the pipe. Place the other coupling on the end of the pipe. Now find some way of bending the pipe gradually WITHOUT KINKING IT. This is hard to do. Kinking it will result in liquid build-up behind this raised section. It's not the end of the world, but it represents a loss of distillate, which is bad for efficiency. Denting the pipe first with a brass hammer where you want it to bend helps. The couplings help prevent the circular diameter from distorting at those points so you won't have problems joining things to those points later.
Alternatively, you could use the easily bendable 1/2" pipe that comes in rolls that is made from soft copper, but this may make the whole apparatus weaker in the end.
Using the file again, file away the stops on the 3/4"x1/2" adapter so it can slide freely over the 1/2" pipe.
Using the drill, drill two holes in the 3/4" pipe section, 1" from each end, on the same side of the pipe. The 1/4" refer tube needs to fit into this hole snugly. A small pilot hole helps overcome the frustration of drilling into a curved surface.
Step 5: Proper Soldering Technique.
Now everything is ready to solder together! If you've done your prep work properly, this step is easily the most fun.
If you've never soldered copper before, I suggest starting with the columns that will end up vertical, since these don't involve non-standard joints. Use the joint brushes to thoroughly clean the areas to be joined. The copper should be bright and lustrous before you solder. Use the flux brush to apply flux to all surfaces you want to bind together with solder. This means the inside of the fitting AND the outside of the pipe. Then place the pipe inside the fitting, make sure it goes in all the way. Place the part in a vice (wrap it in a towel to avoid marking the beautiful copper) or on the edge of a table. Remember, this copper is about to get VERY HOT.
I've found that trying to flux and solder joints that are far from each other in one soldering run is a bad idea. When flux is heated and not soldered it loses is flux-iness. The joint will need to be re-fluxed or the solder won't flow correctly. If joints are literally right next to each other this isn't a problem.
Fire up the torch and adjust the knob so that the bright blue cone of flame within the outer flame is about an inch long. Touch the tip of this inner flame to the joint, preferably near the lower surface (heat rises). Touch the solder to the OPPOSITE SIDE OF THE JOINT from the flame. The ENTIRE JOINT must be hot enough to melt the solder for the solder to flow, so this prevents making a bad joint. Slowly melt the solder into the joint until one drop of solder falls from beneath the joint. This ensures you have placed enough solder. If you want a clean-looking joint (no solder blobs), quickly (before the solder solidifies) brush the exterior of the joint with the flux brush AWAY FROM YOUR FACE. This will remove the majority of the exterior solder drippage.
Step 6: Solder Parts.
This step is difficult to describe in words. I think it would be best for you to examine the pictures and figure this out for yourself. Most connections are self-explanatory, with a few exceptions.
The condenser is the most complicated bit. The 18" long 1/2" pipe resides on the INSIDE of the 3/4" pipe. The 1/2" pipe is one continuous piece with the 3/4" pipe sheathed around it concentrically and held in place by the 3/4"x1/2" adapters. There is very little space between the two pipe walls by design. It is ESSENTIAL that water be able to easily flow through this outer space between the two pipe walls. This outer sheath of flowing cooling fluid is what allows the whole apparatus to be so compact. Problems arise in assembly because the water is introduced to the chamber by the 1/4" copper tubes. If the 1/4" drilling burr or the 1/4" tube itself protrude too far into the chamber, it will restrict the flow of cooling water by contacting the outer surface of the 1/2" pipe. Use the file to reduce the size of the burr (you want a little bit there to help the soldering process) and make sure when you solder the tube in place it is just barely going past the inside wall of the 3/4" pipe.
Solder the 1/4" tubes in place FIRST so you can see what you're doing. Then clean (with sandpaper on the 1/2" pipe), flux and solder the two joints made by the 3/4"x1/2" adapter NEAREST to the the bend in the 1/2" pipe. Fit the other adapter onto the opposite end but do not flux it. The second adapter is just there to keep the pipes aligned for now. ALIGN the 1/4" tubes so that they will point UP (in-line and away from the 1/2" bend). Solder the joints near the bend in the 1/2" pipe. The 3/4" and 1/2" pipes are now bound concentrically by one soldered adapter. Now flux and solder the second adapter.
When the assembly cools, make sure the cooling chamber is sealed except for the 1/4" tubes by blocking one with your finger and trying to suck air out of the other. Then try to blow air though the chamber. If you've got a good seal and good air flow then congratulations, the rest of this is a piece of cake!
So you're done soldering and making everything functional. Good for you. Now the question is, are you barbaric enough to let this piece of art go unpolished? Sand it!
Step 7: Distillation Pot.
Somehow. Somehow you will need to find a way to install a 1/2" female adapter into the top of the distillation pot. What worked for me may not work for you. Here's what I did:
I drilled a hole in the top of my pressure cooker with a 3/4" hole saw, where the little pressure release nub is. I had to remove the nub first so I could center the drill in the resulting hole. Then I tried to solder the back end of the female adapter to the top of the pressure cooker. Apparently copper solder doesn't like to bond to aluminum. I thought about making some kind of escutcheon that I could solder to the female adapter on the inside of the pressure cooker. I gave up on that idea. I tried to use a big metal spike and a hammer to widen the back of the female adapter and that didn't work, I just ended up with a big spike stuck in there. Then I got frustrated so I beat the crap out of the female adapter with a big mallet and it flattened it. That gave me an idea.
I got a new female adapter and put it though the hole in the lid (threads facing the outside of the lid) and rested the threaded end of the adapter on the anvil of my vice. Then I placed the ball end of a ball pean hammer on the soldering part of the adapter. Then I beat the ball pean hammer with the big mallet. This deformed the back end of the adapter so it had a lip. Then I beat the crap out of the adapter with the mallet directly and flattened the lip against the lid of the pressure cooker. The thing works beautifully.
My mother always told me, "If it doesn't work then don't force it."
Clearly, there are exceptions to any rule.
Step 8: Fractionating Column
This is kind of important. There are some nasty chemicals on the surface of the copper after soldering. You probably don't want those in your distillate. Dish detergent and warm water do the trick. A long thin brush helps, the kind they make for test tubes. But whatever works. This is especially important for the tube that will become the fractionating column, since that's supposed to be pure output.
Right now your fractionating column is a lot of column and not a lot of fractionating. You need to pack it. The setup in my lab looked like it was packed with steel wool. I had my doubts about this but I went and got some coarse steel wool and tried it anyway. Don't do it. Bare steel doesn't like heat and organic compounds.
Go to the grocery store. Go down the cleaning supplies aisle. Go to the dish scrubbing section. Look for the old fashioned metal mesh dish scrubbers. There are three kinds: Stainless steel, galvanized steel, and copper. Don't get the galvanized one. Zinc is good for you in small amounts, but I don't know what the solubility of zinc is in an environment like the one you're making. Go for copper. Then you can tell your homeopathic friend that it's all copper and has healing properties and therefore you should drink this.
Remove the wire/staple that holds the scrubber together and unravel it. Kind of like a sock huh? Now get a wire/cord and feed it down your column and tie it to the end of the unraveled scrubber. Pull the scrubber though the column. Use a scissors and a needle nose pliers to trim the scrubber and pull it into position. The scrubber should reach the very bottom of the column, and stop short of the first opening of the Tee. Viola, you have a fractionating column.
Step 9: Hook It All Up.
So now you have:
Long plastic tube.
Kitchen faucet connection.
Assemble the pot, condenser and one of the columns on your kitchen stove. Connect the plastic tube to your kitchen faucet (remember, YOU have to figure this one out). Find the length of tube you need to go from the faucet to the condenser with some slack. Cut the tube. Put the end of the plastic tube coming from the sink over the 1/4" copper tube at the BOTTOM of the condenser. Run the other section of plastic tube from the TOP of the condenser to your sink drain. When you turn on the water, you should get flow from the faucet to the condenser, then back to the sink. You are now water cooled. Later you'll want to experiment with the coolant flow rate to find a happy medium between wasting a ton of water and losing uncondensed vapor.
The condenser is a little heavy to be sitting way up there, floating over your stove, attached to nothing but the distillation pot. Get some wire/cord and tie it to something so it doesn't nose dive in the middle of a distillation.
Step 10: Operation.
So you spent some time and money on this project. I'm sure you're anxious to try it out on something.
One important caveat I've mentioned before: DON'T use your fractionating column on runs that have organic solids! This could contaminate the mesh. For these things you should perform a simple distillation first, then go for the fractional distillation afterwards. Save your fractionating column for the high purity runs. That being said, pot scrubbers are two for $1.50. It's not really a huge loss if one becomes contaminated, it's just something to be aware of if you're wanting something really pure.
For any compound you have that you want to purify, you can look up the boiling point to get an idea of when to start collecting distillate. Look for MSDS information at places like Sigma-Aldrich. Say you have a mixture of compounds A, B and C, and you want only B. Look up boiling points for all three compounds. Lets say they are 65C, 78C, and 100C. After performing a simple distillation over the entire range and collecting distillate from 65C to 100C, do a fractional distillation. If there is much of compound A, the temperature readout will rise until it hits 65C, where it will plateau. Discard distillate that is produced at this temperature, it's almost pure A. When A has been exhausted, the temp will rise until it gets to 78C where it will plateau again. Collect distillate from range B. This distillate is almost pure B. Then discard from range C. You have isolated a compound! You still don't really know what it is, but you can be pretty sure it's B. Stay tuned for my next Instructable, how to build a lab quality IR spectrometer.
Step 11: Beginner's Runs
I suggest starting with salt water. See if you can make it drinkable. This is where you'll need to play with coolant flow, since you can actually get slow coolant at boiling temperatures by the time it gets to the upper tube during water distillations. This only happens when you're distilling almost pure water, or in the situation where the main component of the distillation pot has a boiling temp above that of the coolant. Keep an eye on bubbles coming out of the upper tube, and check the temperature of the output coolant occasionally and adjust the flow as required. Distilling water lets you find out if there are any bad tasting residues remaining in your apparatus as well.
Next up would be isopropyl alcohol. See if you can reduce the volume of 50% isopropyl by 50%. Note: Isopropyl alcohol has approximately the same boiling point as ethanol. So be very careful about contaminating your still before trying to distill something you want to drink. Isopropyl evaporates fairly quickly though.
If you live in the US, don't do what I tell you to do in the four sentences after this one.
Next would be wine. Try to make brandy. Experiment with the flavor of "heads" and "tails" with something you know to be methanol-free. Then go to the HomeDistiller to get more ideas.
Try making perfumes or plant extracts. Many plant compounds boil at temperatures above 100C, but will azeotropically distill along with water in many cases. This is referred to as "steam distillation" and is used extensively in the perfume industry. Make concentrated peppermint extract, etc.
The possibilities are endless, and now that you have a high quality distillation apparatus you have the tools to explore the world of liquid purification to your heart's content.
Step 12: Results.
This section will be updated occasionally when I have a project involving the distillation apparatus.
10/29/2011: Attempted to put something in the carboy for later distillation. Carboy exploded due to improper use of equipment. Floor very sticky. Moral of the story: Don't assume your equipment is as purely awesome as laboratory equipment. As an unrelated side note, malted barley is freakin delicious.
11/04/2011: So I saved a little of the thing I was trying to put in the carboy on 10/29, and I distilled it today. It's definitely the right product, but it's completely undrinkable. It's vile. It's likely not a distillation problem, but an aging problem. I need a bottle with a cork to let the distillate breathe, and to put some oak shims in there with it.
04/08/2013: I tried basically the same experiment again. I fermented malted barley and some added table sugar. Regular ale yeast. Then I put something that may or may not have been the fermented product into the distillation pot and performed two simple distillations. The results were not much better than before. I removed all heads from below 85C. After obtaining something resembling ever clear from hell I diluted it doubly and put a mint tea bag in there for a few minutes. I took that out and covered the jar with two layers of coffee filter for a few days. The result is drinkable, but just barely.
06/01/2013: Ok, ok, ok. So it turns out having the right ingredients matters. Go to your local beer making shop. Get 7lbs of malt extract. Use whatever beer/bread yeast you want and ferment 5 gallons of what looks like beer. Don't put hops in there. When it's done fermenting, either throw it out or put it into your distillation pot, I don't care. If you choose to distill things, then after you get your product, put a handful of toasted american oak chips in there. These are also found in beer making shops. Actually they're for wine. If you leave the chips in for a month or so, the product becomes pretty much drinkable and distinctly delicious. In fact, it may even become a hit at your next redneck BBQ.
2 People Made This Project!
We have a be nice policy.
Please be positive and constructive.