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Is water in the process our friend???
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Hey all, I need someone to explain this one. After reading U of Is research, we've all been lead to believe that our oil must be DRY, DRY...DRY, DRY, DRY or we will make nothing but glop when we use ethanol to make biodiesel. Butafter tonight, I couldn't disagree more!!!

Let begin with my tale. I've been using E85 to make biodiesel, or what I thought was biodiesel, and I've been high yielding batches with separation issues. After a while, I merely thought that ethyl ester was normally coffee colored and I've been using different acid processes to help with washing issues. No amount of washing got rid of the coffee color. Now I think that the coffee color was saturated glycerine.

Now comes to the good part...I sucked up some oil that wound up titrating very high, 5,0mg/L. After several days of drying, I could not get rid of the opaic look to it...it just wasn't dry. I knew that this high of titrating oil was going to make glop, but I had to find out for myself. Guess what, PERFECT PHASE SEPARATION AFTER 1/2 HOUR!!! I though that this was a fluke, so I made a second batch with the addition of a 1/4 cup of water...it happened again; perfect phase separation after 1/2 hour!!! In the picture, the one on the right is the first one after an hour of separating. The one on the left is the second one with 1/4 cup of water after 10 minutes!!

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Registered: November 09, 2005Reply With QuoteReport This Post
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After using the used oil, I decided to try some brand new stuff with and without water. The one on the left is a 500ml mini-batch of brand new canola oil with 2% water added to the oil prior to mixing it with E85 ethoxide. The one on the right is the same exact oil without the water, using E85 out of the same jug. The one on the left separated in 5 minutes, the one on the right is an hour old. The one on the right never did separate until I added 2% water and only after then, it separated with the same yield as the first batch.

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Registered: November 09, 2005Reply With QuoteReport This Post
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This picture is the same batches again, except I added 2% water to the one on the right to force separation...it was the dry batch.

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Registered: November 09, 2005Reply With QuoteReport This Post
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It is interesting that you haven't formed a stable emulsion. I would have expected it to form soap.

How much KOH are you adding?

I have found in my own testing, that unless the alcohol is very dry, and I ensure that as much water is excluded as possible (which involves me drying equipment in an oven, and using a guard tube (with dessicant) to prevent exposure to atmospheric water) that I do not get seperation, in fact, it appears the reaction has not gone very far to completion in those cases.

I am wondering if perhaps what we are seeing in your pics, is the effect that adding water has on the solubility of petrol in water (this is one reason e85 is anhydrous). Are you certain the top layer is biodiesel, and not just unreacted oil mixed with ethanol?
Try the same thing with no catalyst (KOH), and see what happens.
 
Location: Perth | Registered: April 17, 2007Reply With QuoteReport This Post
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The same thing with no catalyst yields no glycerin at the bottom. The top layer has the consistancy of #2 diesel and it does burn. I logically agree, E85 or ethanol must be dry in order to get successful conversion to ethoxide or the water would take up all the catalyst and will make soap when added to the oil. But I added the water directly to the oil, not the ethanol and I shook it up good before adding ethoxide. So far, I have found that adding too much water (the 1/4 cup I mentioned) will make the separation take much longer, which could be a sign of emulsion, but in my case, it's better than no separation at all. I'm thinking that 2% is enough, perhaps one...more experimenting is in order BTW, I'm using 13g/L of KOH plus titration. I would encourage you to do some mini-batch experimenting in order to confirm what I have found, which was completely by accident. Water saturated, 5.0 titrating oil should have made glop, but to my surpise made biodiesel...good thing I didn't throw it out! But next time, I will acid esterfy first to save some KOH.
 
Registered: November 09, 2005Reply With QuoteReport This Post
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BTW, I'm using 13g/L of KOH plus titration. I dry my E85 by mixing it with the KOH and throwing some aluminum foil in the mix, letting sit for a couple of days. The aluminum reacts with the KOH and water, consuming the water and giving off hydrogen gas and making potassium tetrahydroxoaluminate, which is water soluble. Before separating with high titrating oil, I add sulfuric acid to break any soap bonds and it will turn the tetrahydroxoaluminate into alum, which precipitates out with the glycerin. I then mix up more acid with ethanol to convert the FFAs from the broken up soap into biodiesel. After all that, I boil off the excess ethanol, separate, and wash.
 
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E85 should already be dry.
 
Location: Perth | Registered: April 17, 2007Reply With QuoteReport This Post
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Some if the ethanol I use is recovered from previous batches, which is bound to have some water in it...especially now.
 
Registered: November 09, 2005Reply With QuoteReport This Post
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Originally posted by Mgrant:
Some if the ethanol I use is recovered from previous batches, which is bound to have some water in it...especially now.


How do you plan on recovering the ethanol from a waterlogged mixture?

Azeotrope

In that wikipedia article, they go over some possible ways of doing it, but sounds like quite the chore.


Kumar Plocher
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Location: Ukiah, CA USA | Registered: September 19, 2001Reply With QuoteReport This Post
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MAKING BIODIESEL EXPERIMENTALLY

I had similar results to MGrant viz:

I had another go at making biodiesel yesterday ( 17th November 2007) and success! I used WVO ( chip pan oil, was originally rapeseed oil) and ethanol with NaOH as catalyst. The ethanol I used was surgical spirit and I shook this up with an excess of sodium hydroxide pellets for about ten minutes. This gave a pearly white solution/suspension which I decanted away from the remaining NaOH pellets. I added this mix to my WVO and shook vigorously for a few minutes. There was an immediate reaction - the mixture went cloudy and after another 30 seconds or so of shaking it turned dark brown again ( the starting colour) and appeared to thin a bit, but this may just be due to the heat produced in dissolving the NaOH. Anyway I let it stand for an hour. No separation. I left if for about another five hours and it had set to a pretty solid gel, about the consistency of jam -- you could invert it and it wouldn't pour. So I added about 5 % hot water and shook it up. It immediately thinned out and within a few minutes it had started to separate into a clear golden layer and some brown gunge.
I've tested the viscosity with my home made viscometer and it is about the same as the reference sample of biodiesel I have and petroleum based diesel, so I reckon I have got a pretty good sample. The yield was low, about 25% initially, so I added more water and it has doubled to about 50%, so I have added even more water to see if I can extract anymore. The colour of the biodiesel is pale yellow, slightly paler than new rapeseed oil.

Further, the dregs of the NaOH and remaining alcohol were left in a sealed jar on the windowsill ie. in sunlight. These went a salmon pink colour overnight, which is a bit of a puzzle, since both reagents were pure white/colourless to start with. I have re-mixed these with some more alcohol and used this to react with the first lot of oil, which partially decolourized, but didn't thin out.( This was an experiment I did using wood ash as the catalyst, but I don't think I gave it enough time to dissolve; I just filterd the alcohol through the wood ash.) I'm waiting for the results of that batch now.

De John G8SEQ.
 
Registered: November 15, 2007Reply With QuoteReport This Post
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There are a couple of University of Idaho papers that mention adding water to force separation after reaction. The problem is that we don't have a good way to test if the fuel is worth washing (ie conversion) if you can't get separation first.

A schoolteacher whose name I've unfortunately forgotten came up with a much better solution: adding some leftover glycerol from a previous batch, or from a methanol-based batch, to the unseparating mixture to force the ethyl esters glycerine to fall out. This means that if you then tested the esters and they needed further re-processing, you wouldn't have water in the esters to deal with.

Mark
 
Location: Pittsboro, North Carolina | Registered: March 07, 2001Reply With QuoteReport This Post
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How much glycerol do you need to force the separation?
 
Location: Gainesville, FL | Registered: November 20, 2007Reply With QuoteReport This Post



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I'm trying to find out how much glycerol is needed. I"ve been dosing it with about 20% glycerol, it seems that both ethyl-based and methyl-based glycerine works, but methyl is better. I"m currently de-methylizing (is that even a word?) a batch of glycerine to test whether that makes it work better, which it should.
 
Location: Pittsboro, North Carolina | Registered: March 07, 2001Reply With QuoteReport This Post
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Incidentally, I found the same exact phenomenon as the original poster had.

Yesterday I used some un-tested ethanol and the batch immediately made what my notes called 'murky watery hell'- it looked like it had a lot of water in it. The KOH dissolved immediately (like it had water in it) and the batch looked like a milkshake. This morning, it had actually separated, and it made some REALLY thick-looking , murky biodiesel which could be an indication of high-soap or could be low-conversion or both.

This reminds me of something that I have seen before with methyl esters when making low-quality biodiesel- sometimes it drops glycerine really rapidly. ALso, with low-quality methyl biodiesel, having a lot of water in the oil also causes the glycerine to drop rapidly. There's the obvious reason that water goes into the glyceirne layer. The question is, what effect does this have on the biodiesel layer- how full of water is it- and can it be reprocessed?

Mark
 
Location: Pittsboro, North Carolina | Registered: March 07, 2001Reply With QuoteReport This Post
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Incidentally, I was able to make good fuel out of that drum of nasty looking stuff. I suspect that the real key is to have DRY DRY DRY ethanol before we add the caustic to make ethoxide. It seems that having wet oil is not as critical...is there a reaction that takes place between ethoxide and H2O when the ethoxide is injected into wet oil? As a side note, I'm mixing 50/50% E85 with methanol for less temperamental processing. If separation still doesn't occur after an hour, I then add a gallon of methanol with about 300 grams of lye to the mix and it will separate then.
 
Registered: November 09, 2005Reply With QuoteReport This Post
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