not enough glycerine

[theratt Biofuels Forum Newbie Find all posts View Profile Close theratt]

i managed to make a litre of biodiesel using 200 ml of methanol out of WVO but i only got about 100ml of glycerine after settling?
would this indicate not enough KOH ?

[fantom Member Find all posts View Profile Close fantom]

Re: not enough glycerine

well for starters did you do a titration test on ya oil to determine your amount of koh to use?
how many grams of koh did you use?
what purity is ya koh?

[Terry Syd Senior Member Find all posts View Profile Close Terry Syd]

Re: not enough glycerine

That sounds like a low amount, even for new canola oil.

Using WVO you will also end up with neutralised FFAs as soap in the 'glycerin'. Also, any excess methanol will also end up in the glycerin. Since around 12% methanol is the stociometric ratio for reaction (chemically correct, but you need more for a good reaction), then the glycerin level will increase as you add more methanol (like say 25%).

As fantom asked, did you do a titration?

Another question, was the WVO dry? If you have water in the WVO, the water will neutralise part of the KOH and you will have a reduced reaction.

You can take the resulting biodiesel and try another reacton with it. I expect you will find that further glycerin will drop out.

[theratt Biofuels Forum Newbie Find all posts View Profile Close theratt]

Re: not enough glycerine

i did a titration and it came in at 2ml so all up i used 7 grams
im not sure of the purity ?

[joe Moderator Find all posts View Profile Close joe]

Re: not enough glycerine

maybe drain off the glycerine, reheat the oil to around 45 - 50 degrees (but no higher) and shake it up again. It might not have been shaken enough in the first place. I'd say you 100mls of methoxide that didn't convert is mixed in with your oil.

[Terry Syd Senior Member Find all posts View Profile Close Terry Syd]

Re: not enough glycerine

theratt, I noticed that you used a total of 7 grams of KOH.

Please note that 5 grams of catalyst is the baseline for NaOH. It is 7 grams for KOH. If your titration was accurate, then your final figures were a bit light on the KOH - you should have used 9 grams of KOH.

Joe, the methanol/methoxide has more affinity for the glycerin. There would only be about 3-4% methanol in the biodiesel, the rest ends up in the glycerin.

Here is something else to know about these reactions. You can add more methoxide to a reaction, but you cannot add more oil to a reaction that has taken place.

I ran into this early on when I made up some methoxide for a batch. I then realised I didn't have enough oil. So I poured the methoxide into the batch of oil I had and went and got more oil. I heated it up, poured it in and it failed to transesterfy. I ended up with oil thinned with biodiesel.

However, you can take a failed batch and drain the glycerin. Then add a small batch of methoxide to take the reaction further. This is what theratt can do with his present batch of biodiesel.

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: not enough glycerine

Hello theratt, Terry and Joe

Neutral has shown that the NaOH/KOH is consumed in a side reaction making biodiesel.
After an hour there is likely to be no KOH/NaOH left in the biodiesel so additional NaOH/KOH mixed into a little methanol will continue the reaction.
Do remove any glycerine first.

Tilly

[theratt Biofuels Forum Newbie Find all posts View Profile Close theratt]

Re: not enough glycerine

cheers for all the good comments guys ill make up a little more methoxide
and give it a mix and see what happens
im so keen to give this biodiesel a go! im only learning and forums like these are so usefull for a beginner

[fantom Member Find all posts View Profile Close fantom]

Re: not enough glycerine

hi theratt
the purity oh ya koh is important to know as if it is say 90% then for oil that tit at 2ml then you would need a total of 10 grams per litre. if it was 99% purity then you would only need a total of 9.1 grams per litre.
cheers fantom.

[hdj80 Senior Member Find all posts View Profile Close hdj80]

Re: not enough glycerine

Can you do a Titration on the processed Bio to see if it is fully converted?

[Terry Syd Senior Member Find all posts View Profile Close Terry Syd]

Re: not enough glycerine

Try this, Tilly's conversion test -

http://biodiesel.infopop.cc/eve/ubb....7459#435107459

Most vehicles can run on a lower conversion rate than ASTM. Various tests and anecdotal evidence indicated that a 90% rate was suitable for most vehicles. If you have one of the older indirect injection engines, then they seem to get by on 85% quite well. If you had a new high-pressure common rail system, then you should look to the higher levels of conversion.

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: not enough glycerine

Can you do a Titration on the processed Bio to see if it is fully converted?

HDJ, a Titration of even poorly converted biodiesel should indicate less than 0.4mL of caustic. This is because the FFA (which is the acid being neutralised in the titration) should have all been converted to soap, prior to the biodiesel reaction taking place. So even if you only have a 20 - 50% conversion, there should be no FFA to titrate.
Tony

[theratt Biofuels Forum Newbie Find all posts View Profile Close theratt]

Re: not enough glycerine

hi all just to give a bit of feedback
i have since reprocessed my oil and bingo i got another 90ml of glycerine drop out overnight , have since washed 4 times and dried
now it looks great!!
very happy, my first litre

thanks guys