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Acid turns oil to dark color
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I had oil that looked good, and had a nice gold color but titrated high....20. I added methanol plus acid using the common formula. After circulating oil mixture (oil methanol, acid)with heat my oil changed to a dark brown color and titrated even higher than original. Any thoughts ???
 
Location: yes | Registered: July 16, 2011Reply With QuoteReport This Post
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your oil will titrate higher once you add the acid. for every ml of acid/ltr of oil the titration will initially increase about 2 points. All biodiesel made after acid esterification will be darker than what you where used to.
You don't indicate how long after the addition of acid/methanol the sample was taken.


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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I took samples every hr. for 3 hours. No reduction in T. Shut it off and let it settle overnight, drained off bottom 1" of tank (nothing bad found). Started heat and mixing next day, and no positive changes evidenced after mixing and checking hourly. Added a bit more methanol and acid and still no changes. Errr I'm starting to hate a&e
 
Location: yes | Registered: July 16, 2011Reply With QuoteReport This Post
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When you shut it off was the heat left on? when you drained from the bottom what color was the drainage? how much methanol(%) did you use? how much acid/ltr? what is the strength of the acid?
Are you doing ae in the same tank as transesterfication?


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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Used the "common" formula. T - 3 X .16 per ltr. 98% acid No heat after 3 hr "heated" mix. Used 60% of required total methanol. Drainage was same color and consistency of the rest of the batch. Oil was Totally dry before start. I do use the same tank for "good" oil and "high titrating oil". Perhaps this is the root of my problem ?????? Thanks for you help
 
Location: yes | Registered: July 16, 2011Reply With QuoteReport This Post
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Just an afterthought......... does my reactor tank need to be covered, vented, left open or...........? Thanks again
 
Location: yes | Registered: July 16, 2011Reply With QuoteReport This Post



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when you loose the heat the reaction stops. Normally all that is required is to reheat and agitate to get it working again. The process will take about 16 hours.
if there was no difference in color I have to wonder if the methanol /acid is floating on top. Is there any way to check what the top couple inches looks like?
Your using DK's formula, did you also use the 12% methanol? I like to use only 10% this assures me that the junk will fall to the bottom, too much methanol and it floats on top.
look closely at the plumbing and pump configuration on your processor, ever pipe joint will hold biodiesel after the batch has been drained. Biodiesel is also found in the pump flute and on the bottom of the processor if the bottom fitting extends into the tank. Contamination left from the previous transesterfication batch is probably the most common reason, aside from wet oil, for this reaction to be problematic.
To overcome the caustic contamination in the processor tank one has to add more acid, how much more is simply a trial and error thing as it will be different for each processor design.
I highly recommend to do AE tank used for that purpose only as this will make the process much more predictable/reliable.
the tank should be closed to prevent the methanol from venting off.


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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Biotom is right; if the oil was wet to start AE will not work. The Fischer esterification requires dry conditions.
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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the reaction does not move forward if the heat is removed! I have let the AE sample sit for up to 30 days with not reduction in titration once the sample was reheated and mixed the reaction restarted. Chemistry may say otherwise but I encourage you to test the theory before making comment.
the pressure in the reactor will depend on the amount of heat you use, as Ronny stated the reactor should not be sealed tight. a length of copper pipe at the top will act as a condenser and allow the methanol to drip back into the mix. My comment to close the reactor was a poor choice of words and in fact could be dangerous. If you seal a tank you need to install a blowout safety device which could be as simple as a column of water, that's what they use at the crown royal distillery up the road.


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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quote:
Originally posted by BuilderBill:
I had oil that looked good, and had a nice gold color but titrated high....20. I added methanol plus acid using the common formula. After circulating oil mixture (oil methanol, acid)with heat my oil changed to a dark brown color and titrated even higher than original. Any thoughts ???



LOL
That is expected. Use no less than 3 liters methanol to 1 liter oil. Use 5 ML acid for each liter methanol. IN 100 gallon tank you can do 33 Gallons at a time. Each batch takes under a couple hours if you use heat. Some of your methanol will stay in your oil. So you will need to add more acid and methanol with each batch. Do several batches and than start processing your oil to biodiesel as you normally would. Depending on temp your oil and type and how long you let it settle out, it may have as much as 15% methanol in your oil. Keep that in mind. Better check it and allow for it. If oil titrates at 20 and you use the standard 10% methanol and 2 to 3 ML acid per liter oil it is very likely not to work and it will darken your oil. There is no way to get around that unless you use a lot more methanol.

Good luck.


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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post
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If oil titrates at 20 and you use the standard 10% methanol and 2 to 3 ML acid per liter oil it is very likely not to work and it will darken your oil

your joking right? this is absolute BS


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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Hello, if I use 3 liter methanol to 1 liter oil I would be making some Very expensive bio!

I would like to get more info on the condenser you use for your processor. (I would love to see a sketch or picture) Is this similar to methanol recovery systems? I am using a plastic cone tank (50 gals) for my processing. It has a plastic screw on lid. I'm thinking that a loss of methanol due to an open tank cover and a "contaminated " tank may be my problems.
 
Location: yes | Registered: July 16, 2011Reply With QuoteReport This Post



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wow Ronny sounds a lot like tilly, we have had this discussion before.

BB caustic contamination is most likely the problem you are having. do you have a means of testing the ph of the titration sample? the ph needs to be 1 or less for a good reaction,


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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There is nothing unusual about AE and your giving people incorrect information does not help anyone


I process 7000 ltrs of oil per year all oil is pretreated using AE. The information I give is based on my hands on experience, I am not a chemist, nor do I care to be! The ph of the titration sample after acid has been added to the mix must be 1 or less for AE to work well. Your information is correct for transesterfication, not AE.


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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thank g for the ignore button! congrats, you make the list


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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BuilderBill; You might read up on the Fischer-Speier Esterification on Wikipedia and elsewhere. That's the reaction that AE uses. Mixing during the reaction is necessary, I think. As a general rule of thumb an organic reaction proceeds two times faster for each ten degree centigrade increase in temperature. The presence of water hinders the reaction proceeding. Thanks
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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sorry to have created a "flaming" environment. I do not have a ph tester. any suggestions on where to get one? do you have any additional info on venting? Can I just put a copper pipe tapped into the plastic cover of the tank. If so, how long should it be, any modifications to it?
 
Location: yes | Registered: July 16, 2011Reply With QuoteReport This Post
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to each his own I guess, I only mix for a short time 1/2 to 1 hour, I turn off the pump keep the heat on, next morning t is nicely .75 - 1, who can argue with that! You will note on the ae thread that buckeye did some testing on the mix or no mix question and all samples that where mixed throughout the reaction ended up with higher T than the samples that where mixed initially then allowed to sit. This result matches what I have witnessed myself.


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post



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quote:
Originally posted by Biotom:
quote:
If oil titrates at 20 and you use the standard 10% methanol and 2 to 3 ML acid per liter oil it is very likely not to work and it will darken your oil

your joking right? this is absolute BS


Absolutely not. Titrating at 20 using lye is very high and if you got wet oil it wont work well if not at all. I have done a lot of testing in this area. BuilderBill did not state he was using dry oil. Even with dry oil using 10% methanol and 2 to 3 ML acid per liter oil, it takes a long time to process and the acid will severely darken your oil. Its been a while since i tested but if i recall right, i could not get the titration less than 2 using 10% methanol and 2 to 3 ML acid per liter oil for oil that titrates at 15.

If one would be doing 110 liter batches and use 3 ML per liter oil and 10% methanol they would be using 300ML acid. For the same amount of oil I would use 1600ML to 3200ML Acid and the method i use doesn't darken the oil when using around 1600ML. When using 3200ML acid per 100 liter oil and 300 liter methanol it may darken it a little.


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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post
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quote:
Originally posted by BuilderBill:
Hello, if I use 3 liter methanol to 1 liter oil I would be making some Very expensive bio!



Its not expensive at all because you don't lose any methanol. Most of the oil will settle out. The top layer of methanol and acid can be reused over and over again. Drain off the oil and reuse the methanol and acid. You may need to add a little methanol and acid each time but not that much. This is because some methanol will remain in your oil.

Even if 10% of the methanol stayed in your oil layer this is still not bad. You will need to take that into consideration when you do your lye methanol step. IN the end when your biodiesel is done you will not have used any more methanol than when you do the acid stage using the 10% methanol and the 2-3ml acid to liter of oil.

The method I use will allow you to use up to 5 times more acid per liter of oil and doesn't darken your oil. You can use up to 30ML acid per liter oil and still not darken your oil by much. But you must use no less then 3 times methanol by volume of oil.

I have a black test tank that holds 100 gallons and high speed agitator. I will try to post pictures later.


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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post
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