I responded to get 35 gallons of "free" wvo on cl. As I went to transfer the oil into my bulk tote, i noticed a funny smell - diesel. The oil looked very fresh and clear/yellow.
Not knowing how much contamination I was dealing with, I checked the sg and found it to be 0.897.
The titration was 7.5g +5, but i didnt feel comfortable with that, so I started with 8.5g total.
I ran a 10 gallon batch of oil, 2 gallons methanol with 8.5g/l naoh as a test and i didn't get any glycerin to fall out.
Any suggestions on next steps? Thanks
Why would you not go with the full titration? Petroleum doesn't produce FFA.
I was leary, since the wvo/diesel was so clean and looked like unused vege oil. I can try adding the full titration tomorrow with some more meth. Maybe I'll just try 5 of those gallons.
Hi fin reaper,
Assuming the liquid has been well mixed (homogeneous) the titration is to determine how much NaOH is required for each litre of liquid in the reactor regardless of how much diesel is in the mix.
However, the base amount of 5g NaOH is per litre of WVO only in the reaction and does not include the amount of diesel in the reactor.
I understand you do not know how much diesel is in the mix so you will just be guessing.
Also take into account that you have already added an amount of chemicals so you will need to take into consideration the chemicals already in the mix.
I also notice that you are talking in both gallons and metrics which is meaningless for the many of people on this forum.
Please convert everything to metric measure when asking questions.
Wouldn't it be this way - if the titration of 1ml of the oil mixture comes up with 7.5gm per litre of whatever was tested then wouldn't the 7.5+5gm stand? IE if the FFA in the 1ml test sample was sufficiently diluted by the diesel then it will be correspondingly diluted in the litre(s) to be converted.
Assuming the liquid is a homogeneous mixture, the titration is for every litre of liquid in the reaction.
The base amount (5g NaOH) only applies to the actual quantity of WVO in the mixture.
So, if you have a mixture that is 50 litres of WVO and 30 litres of Diesel,
The total amount of liquid is 80 litres that titrates 7.5 NaOH
80X 7.5g= 600g NaOH
The total amount of WVO in the reaction which requires a base amount of 5g NaOH per litre is 50 Litres-
50X 5g= 250g NaOH
Total amount of NaOH in this case would be 600g+ 250g= 850g
I think Tilly is correct in that the titration is correct as it measures variable amounts.
However the base amount will be incorrect as it cannot take into consideration the amount of mineral diesel present.
Seems we were posting at the same time Tilly.
Is there anything that can be gleaned from the sg - to help estimate % diesel?
I think I will run some mini-batches and start with an assumed 90%wvo/10%diesel with 1 liters batches of the total. If I don't get separation, I will move to other assumptions below. Hopefully the columns align below.
Gotcha, thank you.
Hi fin reaper,
Hi fin reaper,
It takes a bit of "playing around" to make columns line up.
Put it back on CL! ;-)
I'd burn it.
1-tank Elsbett VW TDI , 220,000 WVO miles.
and a '92 F-250 with only a FPHE
Can i re-titrate after removing the glycerin - and hit it again with another shot of meth and naoh (no base this time, only titrated amount)?
Just curious if this is doable if my guess of diesel contamination is off a bit.
Hi Fin reaper
The first thing that happens is that the FFA's are neutralized so a titration will tell you nothing important.
Some people have success performing a 3- 27 test and calculating the amount of additional chemicals required from the results.
Other people just add 1g NaOH to 35ml of methanol and see what happens.
In any case, do remove the glycerine first before performing another reaction
Possibly Tilly has already written it. Your titration of 7.5 grams of NaOH per litre indicates concentration of free fatty acids present. The 7.5 grams of NaOH makes soap where acid plus base produces salt (soap) plus one molecule of water per one molecule of free fatty acid. The 7.5 grams of sodium hydroxide is removed from being a catalyst for the transesterification reaction. But if your free waste vegetable oil is wet the methoxide ion will not form in a large enough quantity to cause the transesterification reaction to proceed. I suggest a hot pan test on the free waste vegetable oil to get a qualitatitve idea if it might be wet or not. I think you have assumed it is dry. Water could be screwing it all up.
You will not be able to titrate after doing a reaction. Not only are there no ffa's to titrate but the crude biodiesel will show alkaline properties, not acidic.
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