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Dave Kenny's method- catalyst factor if titrating with NaOH?
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There was a great question in another part of the forum - how to calculate the amount of acid needed for Dave Kenny's method if you had done the FFA (homebrew) titration using NaOH instead of KOH.

Anyone want to take a crack at it?
 
Location: Pittsboro, North Carolina | Registered: March 07, 2001Reply With QuoteReport This Post
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ok.

if I worked the math correctly..
I converted the KOH titration to %FFA using netrual's formula
%FFA = 0.546 x t
then I converted the %FFA into Naoh titration
using his other formula
%FFA = 0.766 x t

using 13 as the starting titration...
starting %FFA = 7.1 or 9.27 NaOH
(3) %FFA = 1.64 or 2.14 NaOH
9.27 - 1.64 = 7.13

now the multiplier...
for KOH we need 2ml/liter
2/7.13 = 0.28 ml/liter

since I don't use NaOH not sure how well this will work. if someone who uses NaOH and bad oil would give it a try..and lets all know how it works out.

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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Dkenny

Going back to my spreadsheet and useing a multiplier of 2.8 that all works out to within about .01ml/L. That is the math tho which aint saying what it will be in the real world.

I just got 275 gallons of oil that is supposed to be around 7% FFA, but I have not tested yet, If it is that high ill be working out Acid/Base useing NaOH. After I work out the pitfalls ill let folks know.

Trc


If you can't dazzel them with brilliance, then baffel them with bullchit.
 
Location: north of houston, south of dallas, east of austin | Registered: August 31, 2006Reply With QuoteReport This Post
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um...using a multiplier of 2.8 or 0.28..?

if you want to try some on a smaller scale use 0.25ml/liter instead of 0.28..if anything it should mean that you didn't use enough acid the ending titration will be slightly higher.

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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oops .. sorry .. .28 i ment. Its been long day fighting Houston traffic. Yes I was thinking of creeping into the Multilier number probably useing .22 or so to start with and see how its working out with the math.

Trc


If you can't dazzel them with brilliance, then baffel them with bullchit.
 
Location: north of houston, south of dallas, east of austin | Registered: August 31, 2006Reply With QuoteReport This Post
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I am always nervous when people start doing KOH homebrew titration, then converting to theoretical %FFA, and here we're converting back to NaOH and then getting some twice-removed theoretical results on what to do about sulfuric acid catalyst with this.

The reason is that the KOH we use in the titrating solution seems to be as much as 15% impure straight out of the bag, and if you made your titrating solution with some stuff that sat around for a while, it might have carbonized and become part potassium carbonate and be even less pure KOH.

I've been meaning to order some known, standardized .1N KOH solution so as to do %FFA tests correctly for research.
 
Location: Pittsboro, North Carolina | Registered: March 07, 2001Reply With QuoteReport This Post



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Girl Mark

Yes it is a mess when trying to convert around 3 or 4 different things. But need some sort of starting point to then fine tune the results, and to see maybe whats expected. That is why with a theroetical multiplier of .28 I would first start out with around .2 or .22 and see if it does lead me sort of the target. If it does then next time around ill bump up the multiplier a tab and see what happens.

Anyway I just tested the oil got from render, its not as bad as I thought or what he said it be. He said MUI of aound 2%-3% and FFA of around 7. I just tested it at .48% water and 6NaOH which is ~4.6FFA. Bit high for single stage base but doable, Ill have to decide if can live with the yield loss.

Trc


If you can't dazzel them with brilliance, then baffel them with bullchit.
 
Location: north of houston, south of dallas, east of austin | Registered: August 31, 2006Reply With QuoteReport This Post
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Mark,
that is exactly the reason behind my suggestion on using a lower multiplier to start with...
also if you look at neutral's thread
%FFA

I have some questions to the accuracy of the numbers because of molecular weights of varoius oils. I am not suggesting his math is off just the change in molecular weights of the oil might cause an error.

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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I think it's simple math to get the right amount for NaOH. I did test it, and seem like it's very simple.

KOH is 1.4 times more than NaOH

so (start NaOH titration)*1.4 - (desire NaOH titration)*1.4, then multiply the result by 0.2 will get u the right amount of sulfuric acid needed per liter of WVO.

It's very logic if you think about it.
 
Registered: November 08, 2008Reply With QuoteReport This Post
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The formula should be:

(NaOH start titration - NaOH desired titration)*0.28 = sulfuric acid needed for 1 liter wvo
 
Registered: November 08, 2008Reply With QuoteReport This Post
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you are correct about the numbers.

What I was referring to is that in the US, our KOH is usually NOT very pure, and it seems to vary from one supplier to the next.


-Dave worked out the .2 recommendation based on testing with our 'homebrew' titration with the impure KOH.
-It'll be a little bit different for NaOH and that'll be more than just a math conversion, since the NaOH tends to be relatively pure and the KOH tends to be much more impure, at least what we buy in the US.
 
Location: Pittsboro, North Carolina | Registered: March 07, 2001Reply With QuoteReport This Post
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quote:
Originally posted by girl mark:
KOH is usually NOT very pure, and it seems to vary from one supplier to the next.
I standardize KOH via a titration of KHP; once the KHP is dried (in an oven), it will donate one proton per molecule, so it's easy to standardize your base with standard titration equipment and a reasonably sensitive scale.


"Political language... is designed to make lies sound truthful and murder respectable, and to give an appearance of solidity to pure wind."

George Orwell
 
Registered: June 09, 2006Reply With QuoteReport This Post



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quote:
Originally posted by girl mark:
Or you can buy exceedingly cheap 1M KOH solution from an educational or lab chemicals supplier. I bought 1N HCL and it was about $5 for enough to make thousands of soap tests happen. Similar price for 1N KOH. It's standardized to KHP I think.
Premade solutions will degrade over time (carbonation occurs in solution, apparently), so their given value may not match the actual value. If you use and repurchase frequently and maintain good storage techniques (and your supplier does as well), then this isn't a problem.

Highly concentrated acids will lose some of their value over time as well (in the formation of hydrogen gas). In general, very dilute solutions will not see these effects.


"Political language... is designed to make lies sound truthful and murder respectable, and to give an appearance of solidity to pure wind."

George Orwell
 
Registered: June 09, 2006Reply With QuoteReport This Post
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Erik,

I like your suggestion of KHP.

quote:
Premade solutions will degrade over time (carbonation occurs in solution, apparently), so their given value may not match the actual value.


This is true. However, the rate of degradation is surprisingly slow, at least under the conditions we have tested. In the lab at the winery, we have tested 6 month old solutions 2 different times. Both times it has lost just under 1% of it's strength. Granted, the lab is pretty stable in terms of temp. since it is in a cellar, and we close the bottle after each use pretty quickly, but the loss of potency is still less than I had expected.


Andrew

http://biodieselcommunity.org
03 Dodge 2500 B100 homebrew
79 Rabbit B100 homebrew
 
Location: Northern California | Registered: February 27, 2006Reply With QuoteReport This Post
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quote:
Originally posted by Andrew M:
In the lab at the winery, we have tested 6 month old solutions 2 different times. Both times it has lost just under 1% of it's strength.
I've been measuring the purity of our anhydrous KOH we bought in bulk. It's dropped from 91% to 89% pure over the span of a year*. If you measured such a small change with a standardized solution that changed 1% every six months, your results would indicate no appreciable change in purity even though there was.

*Actual results - we use KOH briquettes which have much less surface area. I suspect this may slow carbonation.


"Political language... is designed to make lies sound truthful and murder respectable, and to give an appearance of solidity to pure wind."

George Orwell
 
Registered: June 09, 2006Reply With QuoteReport This Post
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I suspect that flakes carbonize more rapidly than that based on the fact that people can't seem to get the same transesterification results with KOH as they do with NaOH even though they adjust for purity.


I also suspect that quality control is somehow lower for the KOH manufacturing process than for NaOH.
 
Location: Pittsboro, North Carolina | Registered: March 07, 2001Reply With QuoteReport This Post
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Some important points about %FFA titration that this brings up:

-the homebrew titration, essentially an acid value titration using .25N NaOH solution, gives results in the format "amount of the specific alkali you have on hand that is needed to neutralize the FFA in the oil you're testing"

-like Neutral always said here, the homebrew titration is ideal for it's purposes (which are to answer the question 'How much alkali do I need'- as opposed to working from a lab method titration assumed to give results in percent FFA. Homebrew titration is more ideal because it will account for small variations in the fatty acid profile of the oil you're working with (I think) and it will definitely account for differences in purity or degradation of the KOH itself assuming your KOH solution is relatively fresh (the solution itself will carbonize also over time or with exposure to air).

-all titrations that are assumed to tell you a result in terms of 'percent FFA' are guessing/estimating

-You can convert from our homebrew acid value titration to 'percent FFA' ONLY as long as you know the actual purity of the KOH or NaOH you're using, which we almost never do in a homebrew environment. It can be as much as 10%-20% off because the KOH can be as low as 80-85% pure out of the bag. Usually it's a bit better than that and is usually sold as 90%. Who knows if or how much a bag actually degrades before you've bought it.

-Dave Kenny's method is based on tests he did that tracked the sulfuric acid percentage needed, based on the results of his homebrew titration using cheap KOH, which is exactly what the homebrew community needed. No one's done a similar 'tracking' process for 'sulfuric acid needed compared to %FFA' using regent grade KOH for the %FFA titration, or NaOH

-granted the instructions to use "titration-3 times .2 ml H2SO4" is not a magic number, a little less or a little more also works, somewhat less well.

-There may be some optimizing needed to really tie the method to %FFA or to a homebrew NaOH titration
 
Location: Pittsboro, North Carolina | Registered: March 07, 2001Reply With QuoteReport This Post
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