Biopowered - vegetable oil and biodiesel forum
Biodiesel => Chemistry and process => Topic started by: dgs on March 30, 2023, 06:31:28 PM
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A guy on the facebook group asked me to help him with making bio with ethanol (instead of methanol) so I said I would give it a go. It has worked but the reaction is really strange, here is what happened.
I used just 200 mls of new oil. I added 50 mls of ethanol (which I had dried with quick lime as the ethanol was only 96%) in which I dissolved 1gm of NaOH. This was in a laboratory graduated separating funnel. I heated it to about 30degs and after giving it a good shake I noticed the mix had darkened slightly as if glycerol had been produced.
This morning there was no visible glycerol dropout and the mix was homogenous (no visible layers and relatively clear) I did a 10/90 and used methanol, the test shows 0.5mls dropout, so I assume the reaction has worked but where is the glycerol.
Has anyone out there used ethanol, if so is this normal.
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It could simply be that the glycerol has not dropped out. Since the reaction appears incomplete you are likely to have a significant amont of mono and di glycerides which might limit how easily any free glycerol drops. If you would normally use 20% methanol, that would be 40ml, but with ethanol you would need 57.5ml, so you may be a slightly light on the ethanol side. Did you check the ethanol for acetic acid which could also use up the caustic? There is no guarantee that new oil is entirely FFA free either. I would try adding another 10ml of ethanol and 1/2g of caustic to see if that pushes it on a little further.
One simple test might be to take a sample of the mix and add a little water which might cause the glyc to drop.
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I wonder why somebody would consider using ethanol when it's approxamately twice the price of methanol?
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It could simply be that the glycerol has not dropped out. Since the reaction appears incomplete you are likely to have a significant amont of mono and di glycerides which might limit how easily any free glycerol drops. If you would normally use 20% methanol, that would be 40ml, but with ethanol you would need 57.5ml, so you may be a slightly light on the ethanol side. Did you check the ethanol for acetic acid which could also use up the caustic? There is no guarantee that new oil is entirely FFA free either. I would try adding another 10ml of ethanol and 1/2g of caustic to see if that pushes it on a little further.
One simple test might be to take a sample of the mix and add a little water which might cause the glyc to drop.
Thanks Paul, I will try it. The oil was ffa free. The expt is now back to the colour of the new oil but is 90% reacted. I wonder if glycerol from this process is clear.
Nigel, this expt is for the guy from Vegas that sent me the link about drinking biodiesel. He has been tinkering around with trying to make it with ethanol for ages and in the end asked me if I would try it. I don't think he was drying his ethanol which (like mine) had 4% water.
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I was given an IBC of Ethanol about 10 years ago from my company who had no further use of it. The would have been charged to have it disposed of ::)
Readings indicated about 96 pure, but I was unable to get it to react to both KOH NaOH and put it down to impurity.
It didn't go to waste though as I used it over quite a few years to heat the ethanol fire i bought for inside the house.
There is no way I would ever be tasting let alone drinking bio even if I could get a reaction with Ethanol. The man is crazy!
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I was given an IBC of Ethanol about 10 years ago from my company who had no further use of it. The would have been charged to have it disposed of ::)
Readings indicated about 96 pure, but I was unable to get it to react to both KOH NaOH and put it down to impurity.
It didn't go to waste though as I used it over quite a few years to heat the ethanol fire i bought for inside the house.
There is no way I would ever be tasting let alone drinking bio even if I could get a reaction with Ethanol. The man is crazy!
This is where he got the idea from.
https://biopowered.co.uk/forum/index.php?topic=3429.msg41672#msg41672
I think the last paragraph is the key. Although it doesn't say so it assumes the biodiesel is made using ethanol.
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So I added another 10mls of ethanol and 0.3gms NaOH to the mix and got the same reaction. the mix darkened slightly then returned to the normal colour (virtually looks like the new oil I started with) Still no glycerol drop and it's just a single phase. I will do another 10/90 tomorrow.
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10/90 now shows 01mls dropout after the 2nd reaction.
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Dave,
I assume you mean 0.1ml dropout in the 10/90 test since you indicated 0.5 earlier. Has any glycerol dropped? If not have you tried mixing a little of you mx with some water to try and trigger seperation?
I am wondering if when using ethanol the speed of reaction maybe different possibly resulting in more mono and diglycerides, or more hydrolysis and soap formation both of which might make seperation more difficult. Might be adding a little glycerol from elsewhere could also trigger the remaining glyc to drop.
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I remember there was a time when a few people on infopop were trying to make bio with ethanol and I seem to recall that there were a few problems then too, I think most gave up after a while. There may be something about it on Graydon Blair's (utah biodiesel) or Rick da tech's (make-biodiesel) websites.-
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Paul, I will add some water and see what happens.
Chug, I will look at Graydons info and see if it helps. The make Biodiesel site went a while ago, if you can access it please give me a shout.
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There is quite a lot of info on processing with ethanol on the JTF site. It looks as though the glycerol failing to drop is a common problem.
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Biofuels mailing list member Ken Provost, who has much experience making ethyl esters, sent us the following tips&tricks sheet.
Ethanol-based Biodiesel
1. Get plenty of experience making biodiesel with methanol before you try it with ethanol. Get comfortable titrating your oil for FFAs (free fatty acids); you’ll need to do that when you use ethanol.
2. Try to find a source of KOH (potassium hydroxide) to use instead of lye with ethanol. Lye (NaOH, sodium hydroxide) will work, but it dissolves VERY slowly in ethanol. You'll need to use more of either one -- 7g per liter of clean oil with NaOH, 10g per liter of clean oil with KOH. More as required per your titration level.
3. Your ethanol will have to be EXTREMELY dry. 199-proof or higher. "Absolute" ethanol. Any more than one half of one percent water can kill the reaction. Denaturants like methanol, isopropyl alcohol, MIBK, etc., are fine. But no water. Ethanol that dry is difficult to find cheap, especially in the US. If you want to try to make it yourself, you'll need molecular sieve, quicklime, or something else to do a "chemical" drying. Distillation alone can't get the water under 5% -- still way too much. (See below -- Anhydrous ethanol)
4. If you're interested in ethanol for environmental reasons, be careful. Even if you find anhydrous ethanol, it may come from fossil fuel. The denatured alcohols used by painters, or in other industrial applications, may be anhydrous but still derived from petroleum. In fact, since fermentation uses water, it's cheaper to make 200-proof starting with petroleum. The only way to know is to call the original manufacturer of the formula. Ask if the ethanol is "synthetic" or "fermentation". One type of denatured anhydrous ethanol that is almost always fermented is "fuel-grade", which is 199-proof denatured with gasoline. It's what they add to gasoline to make gasohol.
5. Your oil will also have to be EXTREMELY dry. Heat the oil to 120 deg C (248 deg F) and hold it there until you can turn off the flame and see the bubbling stop almost immediately. You might want to throw in some clumping cat litter (bentonite clay) and/or silica gel to scarf up any remaining water, let it settle half a day, and take the oil off the top. Sometimes that's still not dry enough. Remember -- any more than 0.5% water can kill the reaction.
6. Your oil will have to be fairly low in FFAs. You'll want to do a titration on every batch to make sure. Anything over 2 ml titration (using 0.1% NaOH solution) can cause failure of the glycerine to separate -- under 1 ml is a good idea. Most waste oil is too high, and either needs to be refined with NaOH first, or cut with clean oil to neutralize FFAs.
7. You need to use more ethanol to get full conversion. Somewhere between 275 and 300 ml per liter of oil is about right for most oils. Coconut oil will need more, maybe 350 ml. Theoretical is about 180 ml per liter, and the rest is excess to drive the reaction all the way.
8. Even when you do all the above, getting the glycerine to separate is a matter of good luck and fervent prayer. Sometimes separation occurs just like a methanol batch. Other times you won't start seeing a glycerine layer for 3 or 4 hours, or maybe overnight. Then again, sometimes it NEVER separates. Until you get separation, you haven't made biodiesel. I've heard of folks who don't wait for separation -- they just pour the whole mess right into the tank, or do some kind of water wash and think it's good biodiesel. It might burn, but it's not biodiesel. It must separate.
9. If it doesn't separate, you can sometimes force it by adding some methoxide mix. You can also make it more likely to separate by including some methanol with the ethanol right from the start. For example, you could try using an initial mix of 5 to 7 parts ethanol and 1 part methanol. Give it a few hours to separate. If it doesn't, add some straight methoxide to the kettle, using enough methanol to bring the alcohols ratio down to 3:1 eth:meth, and containing another 2g of KOH per liter of oil. That usually initiates separation within an hour. Fresh, refined edible oil might even work the first time with straight ethanol. If you use a mixture of ethanol and methanol, you can get away with 275 ml of initial mix per liter of oil.
10. If you're not scared off yet, Good Luck!
-- Ken Provost
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That ^^^ all sounds like a massive, potentially dangerous, PITA.
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That ^^^ all sounds like a massive, potentially dangerous, PITA.
Indeed, but its what I used to do when working in the labs at ICI. Experimenting is interesting.
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Since getting the glyc to drop is obviously the biggest issue, triggering that by adding a little (or a lot) of previously produced glyc may help.
This sounds very reminisant of the lecture subject about Zeta potential changes to cause solid precipitates to fall from solution - only it is now over 40 yrs since I attended those and can't remember enough about how to effect the changes. ???
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Ethanol sounds like a right pain.
I wonder if this is a case where using acetone as a co-solvent would help? There are many papers on this.
Also of interest is this paper where they used IPA as a co-solvent (this seems to be less studied, but IPA is less expensive and more easily sourced).
https://onlinelibrary.wiley.com/doi/10.1002/er.7432
Many things to try, potentially - all of which I would want to see working with Methanol first before even attempting Ethanol.
Of course if this chap is planning to consume the produced biodiesel by drinking (why - it tastes awful?) then any introduced co-solvents would be a very bad idea.
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Hi Tony, just sent you a pm asking how we now post photo's.
I've posted a photo ( facebook ) to the guy in Vegas, just waiting to post one on here then I can continue.
Paul, what about adding some pure glycerine (I'm sure this will be available to the chap in Vegas wheras he won't have any normal ex process glycerol) Even though it's clear I'm sure an interface will be visible.
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Tony, acetone may have been a good idea except the guy I'm doing the experiment for wants to drink the stuff! Hence the idea to add pure glycerine to encourage the glycerol to drop.
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You can certainly try pure glycerine, I can't see any reason why that should not work unless its the impurities in the bio-glycerine that triggers the precipitation. Luckily you should only need a small amount as the prices I've seen certainly seem to make it expensive.
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https://postimages.org/
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Here is a photo of reaction
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Thanks for the link neisel.
So, there is the photo (at last) as you can see it just looks like the new oil I started with, presumably the glycerol in the mix isn't dark coloured like our normal methanol reactions. When I added the ethoxide for each stage the mix darkened slightly then returned to the colour as in the picture, very strange.
Next step (probably tomorrow) is to add the pure glycerine to encourage the glycerol to drop.
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Just out of curiosity, what sort of oil is you are using? I can see reference to new oil, but not as to whether its rape, sunflower, olive etc.
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Just out of curiosity, what sort of oil is you are using? I can see reference to new oil, but not as to whether its rape, sunflower, olive etc.
It's rapeseed, I call it new but it's actually waste from an oil supply business, the bottoms of the big tanks they have. When I get it there are some lipids present but they settle out. The oil I used had been glyc washed and showed no titration.
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Here is a picture of the glycerol separation.
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I added 32mls of pure glycerine to the mix and gave it a good shake. After a couple of hours the dropout was 87mls. So 55mls of glycerol was in there after the 2 stages. 60 mls of ethanol had been used for the 2 stages (of course 20mls had been removed for the 2x 10/90's including some glycerol)
There is about 275mls of liquid in the tube, so 188 mls of bio from 200 mls of oil. With the amount taken for the 10/90 tests I realise things don't quite add up but I suppose its within experimental error.
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Remember the densities of oil, alcohol, glycerol and bio are different so the volumes should never balance (though weights should).
Are you going to experiment to determine the minimum amount of glycerol needed to cause the ful amount to fall? How about using the "waste" glycerol from this experiment for the next...
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I was rather hoping that there wasn't going to be a 'next' experiment Paul.
The guy from Vegas was pleased to hear it worked so he is going to try and copy it using pure glycerine to separate the glycerol.
I may try and water wash the bio I have produced just to see how it goes.