I processed the last 120 litres of canola oil i had using KOH rather than NaOH.

I got good separation - only about 10 litres glyc but not suprising as the oil was quite clean.

I think i've way over titrated - as soon as I started my normal wash it was creating way too much soap which didnt seem to settle out properly even after being left overnight. I added more water, mixed it too agressively and now have a massive emulsion. The whole lot now looks like cream.

I've now heated the mix to 60 degrees and will circulate overnight and see if that improves things at all. I've noticed that some of the emulsion that spilt on the top of the tank has had the water evaporate in the heat and it now looks like oil again.

Is this simply a patience game while the water evaporates out?

Am I on the right track here? Recommendations welcome!

Thanks.

Read this:

Breaking Emulsions - Collaborative Biodiesel Tutorial Website

Or try adding acid (vinegar or HCL) or salt. (Not both at the same time).

But definitely do some more searching as this subject has been discussed a thousand times especially on the infopop forum.

I managed to rescue my emulsified bio by adding a LOT more water to the mix and it seemed to virtually force it to separate

__________________
Regards,
Richard

1999 Hilux

Let it settle and drain off as much water as you can. If it's all emolsion and no water sitting at the bottom then drain about 1/2 of the emolsion off into anything you can find. Then work on 1/2 first.

Hit it with heaps of water. That will dilute the soap.
One of two things have happened.
One you over titrated and have made heaps of soap. OR

Two, Your seperation wasn't complete. Let stand longer, or you have let glyc get into the wash tank with the bio.

Either way heaps of water will fix this problem for now.

Ok thanks I will try that. I'll drain half off and work on one half with heaps of water and let sit for a few days.

Thanks for the advice - much appreciated.

I made an emulsion recently but managed to fix it by heating - cooked out the methanol at around 80 degrees and then the water and biodiesel separated.

WFD,
Te small amount og byproduct separated points to the possibiluity that you didn't add ENOUGH caustic, so rather than making mainly biodiesel, you didn't react far enough and created mono- and di- glycerides.

I have read that these increase the likelihood of causing emulsions during washing.

Please get a sample of your separated oil and so a 3/27mL bio/methanol test to see how much unreacted oil remains in the biodiesel.

Please let us know how you fare in the separation and testing.

Note:

While many people are concerned that adding an acid to a water - biodiesel emulsion will cause a revarsal of the reaction, a WEAK acid like Vinegar or citric acid should not have any impact on the biodiesel as the transesterification was catalysed by a STRONG Base. A STRONG acid could cause the reversal, it all of the reaction products were present.

In the washing phase, the vast majority of the byproduct has been removed, any remaining methanol is dissolved in the water, and mainly soap remains in the biodiesel.

Thus, adding vinegar or citric acid should not adversely affect the quality of biodiesel affected by an emulsion, when added to help break down the emulsion.

As these acids are carried in water, they will be removed by the washing process.

Regards,
Tony

I agree with Tony- it sounds like you might not have used enough methanol or caustic, or you might not have had a complete reaction for some other reason. You didn't say what the oil titrated at, nor how much caustic/methanol you used, so it's hard to say. I use 22% methanol, and get that percentage or slightly more back as byproduct.

Tony is right in suggesting a 3/27 test, to test how complete your reaction was. If it wasn't complete, you'll then have to figure out why.

On the other hand, if your reaction was complete, and all you have is an emulsion, I know of an excellent way to break it (I believe someone on this forum gave me this idea). Pour some glycerine into your emulsified bio, and mix it up. It'll start to separate immediately. To find out how much glycerine you should use, you should first try with a small sample.

Justin

Thanks for the replies.

I used about 17% methanol (120 oil / 20 methanol) - which is on the lower limits but has worked fine with previous batches and lets me squeeze out an extra 20 litres of bio in the batches I do.

With 1 litre tests using this oil I got about 10% glycerine (using 20% methanol) - which is consistent with the glyc I drained from the large batch (10-12 litres).

I will try some salt on a 20 litre batch and see how this responds.

I take it I can just sprinkle and mix in?

Hello Tony

Adding acid to the wash does not run the reaction backwards, it converts soap back into FFA's.

Removing the methanol while the glycerine and biodiesel layer are together runs the reaction backwards. Neutral's testing suggested it only goes back as far as mono or di glycerides.