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Drying oil with sulfuric acid
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It appears that vegetable oil can be dried effectively using sulfuric acid as a pre treatment to Acid Esterfication. Drying vegetable oil is probably the most important step for successful results during the AE reaction but can be very onerous/time consuming and if heat drying using an electric element it can also be costly.
I have been doing some testing on oil this week to determine the effects of pre treating with sulfuric acid

Starting water content (confirmed by sandy brae test) 1700 ppm

Sample 1 3ml acid/ltr of oil, heat oil to 150f add acid and mix with magnetic stirrer for ¾ hr. allow to settle over night RESULT 700 ppm

Sample 2 4ml acid/ltr of oil, same procedure as above RESULT 390 ppm

It appears that each ml of acid/ltr of oil reduces the water content of the oil by 300 + ppm. Not sure how much acid is left in the oil but for starters I will reduce the acid amount to T *.05 rather than T *.095 for the ae of this oil stay tuned!


" 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 Biotom; So where does the water go? Does something settle out, that can be removed? Remember the law of conservation of mass. The water goes somewhere.
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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Good question, at a dose rate of 4ml/ltr of oil there is what looks to be a granular black sediment. I assume (I know dangerous) that this is comprised of microscopic junk that was in the oil; water and acid. I can post pictures.


" 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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It seems likely that 2 things are happening.

First, sulfuric acid is highly hydrophylic so it will attract water. However, if you are not recovering all of this water as heavy "foots," then this does not account for the entirety of what you are seeing.

The other thing that is likely going on is that the sulfuric acid is acting as a catalyst enabling water to react with neutral oil to form free fatty acids. The result of this leaves you in the same (soap producing) situation that you were in when you had wet oil.


Kristof Reiter

Reiter Scientific
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Location: Nationwide | Registered: April 24, 2013Reply With QuoteReport This Post
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this was suggested as a possible pre treatment of the oil to remover water prior to acid esterfication, no soap is created in that process.


" 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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Initially:

Triglyceride + H2O <----acid---> Diglyceride + FFA [Hydrolysis Reaction]

Hydrolysis means breaking or cutting (lysis) with water (hydro). In this case, water is reacting to break the ester bond between the fatty acids and their glycerol backbone.

In this reaction, H2SO4 is a catalyst. Water is the reagent. Not all the water will react, there is an equilibrium. Some will react, some may drop out with the high density hydrophilic sulfuric acid.



and then later:



FFA + Na+ + OH- --------> Na-Soap + H2O [Saponification Reaction]

or, in the case of methylate catalyst

FFA + Na+ + H3CO- ---------> Na-Soap + H3COH (methanol)

In these 2 reactions, the the NaOH or NaMe intended catalyst acts as a reagent.


In either case, sulfuric acid can be a hydrolysis catalyst. This results in FFA formation. FFA's, unless esterified then create soap during transesterification.

If you still want to use sulfuric acid for drying oil, then at least do it at lower temperature so that the hydrolysis reaction, and other sulfuric acid related reactions to no proceed as quickly.


Kristof Reiter

Reiter Scientific
http://reiterscientific.com/contact

Check out my FREE biodiesel calculators at http://reiterscientific.com/resources
 
Location: Nationwide | Registered: April 24, 2013Reply With QuoteReport This Post



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Acid plus base makes a salt plus water. That's a neutralisation reaction not saponification. Ffa plus sodium hydroxide yields soap plus water a neutralisation reaction, not saponification reaction. Saponification is something else.
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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quote:
Originally posted by WesleyB:
Acid plus base makes a salt plus water. That's a neutralisation reaction not saponification. Ffa plus sodium hydroxide yields soap plus water a neutralisation reaction, not saponification reaction. Saponification is something else.


If the acid is a fatty acid, the "neutralization" reaction where the metal (Na or K in our case) from the base combines with the fatty acid is saponification.

Have a look here:

http://en.wikipedia.org/wiki/Saponification


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Location: Moncure, North Carolina | Registered: April 21, 2001Reply With QuoteReport This Post
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From Hawley's Condensed Chemical Dictionary, 11th edition; Saponification. The chemical reaction in which an ester is heated with aqueous alkali such as sodium hydroxide to form an alcohol (usually glycerol), and the sodium salt of the corresponding ester. The process is usually carried out on fats (glyceryl esters of fatty acids). The sodium salt formed is called a soap.
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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quote:
Originally posted by Biotom:
It appears that vegetable oil can be dried effectively using sulfuric acid as a pre treatment to Acid Esterfication. Drying vegetable oil is probably the most important step for successful results during the AE reaction but can be very onerous/time consuming and if heat drying using an electric element it can also be costly.


To heat 100 gallons of oil to 212F with the starting temp at 80F takes 16 KW. At 10 cents KW it comes to $1.60. To heat it to 250F takes 21KW.

bubbling air through sulfuric acid than bubble this same air through your oil is one way sure way to dry your oil. At some point the sulfuric acid will take on enough moister that you will need to reheat it. When heating it, keep an eye on it.. Soon as a white cloud starts to fume off its ready to be used again.

This method is dangerous and probably not a good idea but it sure works.


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