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Black WVO after adding Sulfuric Acid
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I typly titrate a 2.5 - 3 KOH. The oil have titrated a 8 KOH. Added 1 gallon of Sulfuric Acid to a 175 gallons of WVO. It has sat for 2 days and it still is an 8 KOH. But very dark to black. Is there any hope or get neew WVO and start over?

Dave
 
Registered: May 07, 2008Reply With QuoteReport This Post
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Did you use methanol in your acid esterification? Sulfuric acid adds to the double bonds in fatty acids in a reaction called electrophilic addition, even at lower temperatures. I made biodiesel using AE then followed by base catalysed transesterification from new corn oil. Another time I made the biodiesel from new corn oil and base catalysed transesterification. The biodiesel produced using AE was darker in color. From what I've read others use 10% methanol by volume in AE. BioTom might be able to answer this.
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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not enough info, plse state proceedure how many ml of acid per ltre of oil; how much methanol; what temp and for how long did you react; how did you determine the water content of the oil prior to adding chemicals in any event, you stated with T8, you added acid which raises the titration by 2 point for every ml of acid/ltr of oil. you started at 8 you ended at 8 so some ffa where converted. the only things that stands in the way of acid esterfication are caustic contamination in the processor (from previous base stages, wet oil or lack of heat!


" 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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also did you add the h2so4 to the oil or mix it with methanol first. adding concentrated h2so4 to the oil will 'burn' it and create a red or black product that will clog filters downstream
 
Registered: July 06, 2004Reply With QuoteReport This Post
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I know I read somewhere here that it didn't matter which went in first.
Recently told to add methanol first to keep from discoloring the oil.
I did it the other way for 2 years and made good fuel and yes it was darker than
fuel made with out AE. IMO the most important thing is dry oil and much safer to add the acid to the oil in the processor rather than adding the acid to the methanol. For me the methanol has gone in the processor before and after the acid with the same end result.
Never add methanol to acid.
Good luck
regards
Tom


1999 K3500 Dually with a new AMG 6.5TD turned up a bit by John Kennedy
Chevy DMax Totaled thanks to a 20 year old in a Mustang
Mercedes 300CDT
John Deere
On B99.?
 
Location: Decatur, Al | Registered: September 03, 2009Reply With QuoteReport This Post
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I talked with a guy in Fl sometime back who said the darker color can be removed by passing the biodiesel through a resin tower. not sure if woodchips will work for this. As far as filter clogging with the darker fuel, it hasn't been an issue for me ever!


" 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:
I talked with a guy in Fl sometime back who said the darker color can be removed by passing the biodiesel through a resin tower. not sure if woodchips will work for this. As far as filter clogging with the darker fuel, it hasn't been an issue for me ever!


We have seen the oil turn darker in the processor where acid was added before the Methanol.
Pretty sure certain feedstocks are more sensitive to the acid than others.
We have on two occasions though had fallout from the AE process that looked black
like Glycerin. It definitely had methanol and I believe water in it also, with a PH of 2.
Would love to know what it is. This particular batch started @ T10 and ended up @ 3.
Factor in the Acid leaves oil @ 1 so the reaction was close to perfect ??
Low yeild though of 90% ( we'll recover another 3-4% from the glycerin tank )
Thanks and regards
Tom


1999 K3500 Dually with a new AMG 6.5TD turned up a bit by John Kennedy
Chevy DMax Totaled thanks to a 20 year old in a Mustang
Mercedes 300CDT
John Deere
On B99.?
 
Location: Decatur, Al | Registered: September 03, 2009Reply With QuoteReport This Post
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the dropout after AE should always be black, lighter colours tan to creamy are an indication that the oil was wet.


" 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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Hamlin205; You wrote "Would love to know what it is." That was relative to the black fallout in AE. So, Alkenes react with concentrated sulphuric acid in the cold to produce alkyl hydrogensulphates. For example; Ethene reacts to give ethyl hydrogen sulphate. In vegetable oil some of the fatty acids have double bonded carbons. At these locations concentrated sulphuric acid can react/bond to the carbons at or about next to the double bond. I would have to do more study to write a better explanation. The sulphuric acid can bond to the carbon chain in long fatty acids with double bonds. Thanks
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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Thanks Wesley;

Your time and help is appreciated !!
regards
Tom


1999 K3500 Dually with a new AMG 6.5TD turned up a bit by John Kennedy
Chevy DMax Totaled thanks to a 20 year old in a Mustang
Mercedes 300CDT
John Deere
On B99.?
 
Location: Decatur, Al | Registered: September 03, 2009Reply With QuoteReport This Post
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quote:
retty sure certain feedstocks are more sensitive to the acid than other


I don't know why anyone would add the acid to the oil before the methanol. This always darken the oil. Not only does it darken it i believe some of the acid gets used up and no longer available for its intended purpose. Sometimes I put the methanol in than the acid. But normally I put the acid directly in the methanol, so that its diluted with the methanol before coming in contact with the oil.


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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post
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quote:
Originally posted by WesleyB:
Hamlin205; You wrote "Would love to know what it is." That was relative to the black fallout in AE. So, Alkenes react with concentrated sulphuric acid in the cold to produce alkyl hydrogensulphates. For example; Ethene reacts to give ethyl hydrogen sulphate. In vegetable oil some of the fatty acids have double bonded carbons. At these locations concentrated sulphuric acid can react/bond to the carbons at or about next to the double bond. I would have to do more study to write a better explanation. The sulphuric acid can bond to the carbon chain in long fatty acids with double bonds. Thanks


Interesting.


Biodiesel for cleaner air and fuel independence!
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Location: Indiana | Registered: June 13, 2005Reply With QuoteReport This Post



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