Nice Work and nice pictures...

Does anybody know if it would make a difference if one used prufied glycerine instead of the crude glycerine mentioned in the article, by purified I mean crude glycerine that has had it's content of FFA and soaps released by adding acid until the soaps breaks and then settled and neutralized to a ph of 7 with a base?

I think that by using purified glycerine you could combine the 'emulsion break' part with a 'glycerine wash' part in one easy step, and possibly not wash with water at all. The dirty glycerine can be treated with acid once more and be reused until the water content becomes to high, but because we always have more glycerine that we need this is not an issue :-)

Have anybody tried to break a heavy emulsion with 'pure' glycerine instead of the crude glycerine mentioned in the above article?

/Morten

It has been tried as a wash and seems to work very well but not perfectly. I favour it in theory. Do a search here on the site and you will find info on it.

This has been discussed under waterless wash. The thing about washing is that it apparently doesn't need to be done all that well as there are plenty of people using biod unwashed. One would think that a single wash with desoaped glycerine would be pretty satisfactory. It has the great advantage that no water is introduced and should lower the content of residual soap enough to ensure that it would not come out in the vehicle tank.

The total alternative to washing is of course to just add a little extra alcohol to offset evaporation of methanol and keep everything in solution. The best alcohol to add is isopropanol. It is a better solvent and doesn't evaporate as readily as methanol

While mentioning the topic of avoiding water and jumpinf off on a tangent.

Neutral, are you aware of using KOH creating more water in the reaction than using NaOH?

Since I changed over I seem to be getting a fine cloud of soap I wasnt getting before. I still dry the oil at high heat.

What do you think?

There is no chemical explanation for this. Perhaps your KOH is not as dry as your NaOH.

Don't know where I picked this up but my impression is that soap from koh is much harder to wash out. Something to do with the chrystaline structure.

The KOH is 90% pure anhydrous and I keep it well sealed when not in use. And open it very briefly to use it.

Perhaps Dropout is right or perhaps the different qualties of the byproduct (eg always liquid for one)don't settle the soap out as well as the NaOH byproduct.

However it happens it seems to be a noticable effect.

And my pump has a started to play up after using KOH. It is a 240v diesel transfer pump that was once used to fill lorries etc from a storage tank. could be a coincidence but...

Anyone else noticed any of these things happening.

Anhydrous was a figment of my faulty memory. What is the other ten percent anyway? Water?

Still only amount to about 5g of water. Insignificant.

Tried really, really drying the oil today.

130deg C for a sustained period until steam had died down to a whisper.

Will see how it turns out in the morning.

seems clearer this time

Perhaps it is more sensitve to water content and needs drier oil to avoid soap haze.

Will check it tommorrow to see if it is still clear

Nope, white soap haze settling at the bottom.

Seems to be a result of using KOH but I'll perservere as I value having a liquid byproduct.

Get some good KOH and avoid speculation.

What do you mean by good?

This is 90% bought in a sealed 25k sack direct from a chemical supply house.

Decanted straight into a wide mouthed hdpe drum which has an inner and outer lid. Well sealed from air or moisture.

If this isn't good then what is?

I'm going to try a purified glycerine wash to see if that takes all the soap out better than filtering.

I'm also going to try one of my better, drier, oil sources.

90%? I repeat, try a small sample with good KOH and see if it different. If it isn't then it is not the KOH.

KOH is usually 85%. I thought 90% was good for KOH. That is one of the factors we usually convert for when using more I thought? They don't sell better than 90% where I buy it.

OK after further experimentaiton it seems that the KOH is more inclined to produce soap haze with badly wet oil that the NaOH can cope with once it has been through my normal drying cycle.

When used with good nominally dry oil that has also been through my drying cycle then the KOH also produces clear bio.

I think it is something to do with the different solubilities of the soaps produced by KOH and NaOH.

On further thought the titration value may be a factor too. None of the oil was very high. The oil I got the haze with titrated at less than 2 using NaOH. The oil that was clear titrated less than 1 using the same solution.

Shouldn't be a big difference I would have thought. But in the interests of complete information.