My experience with acidbase biodiesel has been interesting. When I first started using Aleks Kac’s acid-base biodiesel method I found that it solved a washing problem that many of us had in this area with a certain source of oil. This was a weird waste oil, low moisture, low free fatty acid content, which came from a junk food plant that we (about 10 users) couldn’t make good quality fuel with, at least not when we were using 20% methanol. It had conversion issues and they turned up as washing problems- major emulsion. I tested it pretty thoroughly and I'm pretty sure that soap was not the cause of the wash problems either.

I had the oil itself lab tested and there was no real explanation for why this was so. The only solution that eventually worked to solve the conversion problem was to use higher amounts of methanol (higher temperatures helped too, but higher catalyst quantities didn’t do much for ease of washing).

For some bizarre reason, using acid-base, I was able to get easier washes on this fuel finally, which doesn’t quite make sense as the problem with the oil wasn’t FFA content and acidbase doestn' affect conversion. I never tested in a lab the actual fuel produced this way.

I was driving home last night thinking about acid-base biodiesel and had a revelation (I think) about what was causing the easier washes.

I am a big believer that washing is a good indicator of quality (see http://www.journeytoforever.org/biodiesel_bubblewash2.html ). It’s somewhat difficult to exactly pinpoint what causes poor or easy washes without further testing. The wash is usually affected by one of two biodiesel-related things and one water-related thing.

The biodiesel factors are either excess soap (including if you got some glycerol/soap byproduct into your wash tank by accident) or, to some extent, monoglycerides and diglycerides.

The water factors that influence washing can include the levels of salts or minerals in the water.

If you have fuel with excess soap and/or excess monoglyceride or diglycerides present, you can make emulsion more easily than if your fuel was more pure to start with.

If you have certain salts or minerals in the water, you water won’t pick up soap as well and your wash won’t emulsify as badly.
That is to say, if there's salt in the wash water, it looks like an easier wash, but the washing is in fact not doing it’s job quite as well. Salts in the water will look like you have biodiesel that contains less soap, when in fact that soap is just not dissolving into the water as well as normal.

Most homebrewers don’t do further testing of the easy wash/ difficult wash to pinpoint whether it’s poor conversion that causes emulsified washes or if it is excess soap that does so.

There has been a debate about Aleks Kac’s acid-base method for a couple of years now, I’m part of this debate, and currently it’s focusing on quality. Todd Swearingen’s main proof for why he thinks his version of Aleks’ method is producing quality biodiesel, seems to be that he has emulsion-free washes. In my case I was also producing emulsion-free washes with this method, but had doubts about why this should be the case- why acid-base should have made difference, with my low-FFA oil.

But I noticed that when washing or wash testing the acid-base samples, something looks odd. The wash test is when you place some biodiesel into a jar, add some water, shake like mad until it emulsifies, and wait and see how fast it separates out. It helps you predict what will happen in the wash. Last summer I was noticing that my wash tests of acid-base biodiesel behaved differently than the wash tests of singlestage made with the same oil and washed with the same water. This difference was as follows: the acidbase would separate out into biodiesel and water and leave no intermixed emulsion layer and this separation happened rather quickly, and the water that settled out was less white than normal. So far, so good. But the biodiesel portion of the wash test was a lot more turbid and hazy than the corresponding tests on some singlestage biodiesel. The singlestage might have a thin layer of emulsion or might take longer to separate completely, but the biodiesel would also look a lot more clear, quicker, than the two-stage acid-base would. I struggled to interpret these differences.
In acid-base biodiesel, there is a salt, sodium sulfate, formed when sulfuric acid is neutralised by the NaOH in the base stage. It is water soluble and you are supposed to wash it out.

I thought at first that the turbid biodiesel layer in my acidbase wash tests and washes had something to do with the sodium sulfate- that it was somehow retaining water in the biodiesel portion of the jar.

Last night I started thinking that the sodium sulfate might act similarly to table salt in inhibiting the washing out of soap- that essentially the washes might look ‘easier’ (as in, less white water coming out which looks like there’s less soap (same thing happens with NaCL salt too), also that there’s less or no emulsion formation) but that this might be an 'easier wash' in the same sense that adding salt to a soapy biodiesel in a wash makes it look like you have an emulsion-free wash. In fact with a salted wash, there's no emulsion because the salt is interfering with the washing out of soaps.


When you do a salted water wash (ie rock salt or table salt), I noticed that it takes longer to get the biodiesel and the water to clear and look done afterwards- more washes that is. My theory is that the salt is retained in the water that's in the biodiesel layer between washes, and goes on to interfere with multiple washes besides just the one that you added the salt to (I"m talking batch style bubblewashing here). I think I was noticing a similar thing in the acidbase- I wasn't getting emulsification as badly, but it was taking longer than I would have predicted to wash out the hazing of the fuel itself.

The turbidity I saw might be caused by the same problem that caused the emulsification in the first place- the poor conversion I was getting because something is wrong with the oil (which caused a wash problem that wouldn't be as affected by salts in the wash). The acidbase might have just masked the 'wash problem' feedback in the same way that salt wash might mask wash problems. I was pretty impressed by the lack of emulsification, but thought it took longer to clear the biodiesel than I could have expected with such an emulsion-free wash. I wonder if it was the sodium sulfate salt?

This message has been edited. Last edited by: girl mark,

Re Acid-Base and Washing'
Have been doing the Acid/base process lately, Looking to pick up some extra yield. Have noticed several differences also.

1/ Soap SLOW to let-go during washing, ( bubble or Mist.)

2/ Acid/Base Bio giving same S.G Bio, as Base Bio, but Acid/Base Bio Viscosity WAY slower than base only.Bio.

3/ Normal Cat requirement (based on normal Bio Tit formula) insufficient to achieve ok conversion
( ie; to avoid starting material dropout) As witnessed following Chill/Thaw settling test.

Also suss about if Acid/base Bio might be holding extra Meth prior to Washing as Finished Yield is a bit off too, maybe ??

Hows this Jive with you guys..???

Airborne, are you uisng the "Foolproof" Acid/Base method

If you are following the Foolproof method you are lucky to be making any biodiesel. The Foolproof Method as written on Journey To Forever is a dud and cannot make high quality fuel.
If you look at the test I posted yesterday you will see that when using the "Foolproof" method with new oil it only produced a low quality fuel which still contained in excess of 12% un-reacted and partially reacted glycerin in the biodiesel.
Using WVO with the Foolproof method gives an even lower quality fuel than this as your viscosity tests are pointing out. When the WVO hits a titration of between 3 and 3.5 the Foolproof method does not even achieve seperation.

I found that if You follow the FATTA Acid/Base Procedure which Aleks dummied down to produce the "Foolproof Flop", you will should get a high quality fuel.
In particular you need to titrate at the beginning of the base stage and use the amount of NaOH as shown in the titration +5g NaOH per litre WVO.

If you have not read this Esterfication forum for a while I would strongly urge you to look at all the posts from the last 6 months or so.
There is a lot of good info here.

Rev Tilly KE

Girl Mark

I too have noticed that acid/base biod gives a very clear wash initially but it never dawned on me why this was so. I think you are exactly right. There is no doubt that addition of ordinary salt, so useful to break emulsions in bad batches and in badly managed batches, slows down the removal of soap. Sodium sulphate would do so the same.

I wonder whether the Uni Idaho idea of adding a bit of water to the glycerine and stirring a bit more before draining the glycerine would help. It might help more with acid/base than it does with base only.

Thanks Tilly,
Nup, gave up on the Fools/method ages ago.And am glad someone (you) have finally exposed it for the dud it is. Am going ok with the Fatta method so just adding my observations thus far.

Typical Batch...Tit 3 ish.
Acid 1ml to 1ltr Oil. Acid stage Meth 10%. Run Time at 55 oC 3-4 hrs. Rest overnite, Tit comes down to 1.0. Drain off usual small amout of Water ( couple of ltrs) created during Acid run.(1200 ltr Batch)

Base stage next ...currantly 13gms koh per Ltr Oil(previously useing less but got too much Dropout of starting material !!)(just a few percent but still too much !!) Meth 13% then run 2hrs at 50-55 oC ( useing covered Reactor,not totally sealed though..)

Leave to seperate, and then Ester off for Washing and Gly off for Meth recovery.Yields <90% but still bit better than Base only, but not that much!!??

Cheers

I'm about to go on the road for two weeks so I won't have time to follow this thread, but...

There are easy experiments that can be done to figure out if the clear water is due to the process producing less soap, which should be the case anyway (this is what I originally figured was the cause of the appearance of the wash) or if it's due to sodium sulfate salts inhibiting the wash (what I now suspect). anyway, once again, there's a titration that will do this. I will try and get around to posting exact instructions for the soap titraiton as specified by American Oil Chemists Society while I"m traveling or in a few weeks. It's the titration of unwashed biodiesel against hydrochloric acid solution, with bromophenol blue as an indicator and isopropyl or acetone/water as a solvent. It's easy and tells you exactly how much soap you've made, and knowing the soap answers all the other quality testing questions as it eliminates one of the two main variables in backyard quality control.

mark

quote:

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Originally posted by neutral:
Girl Mark

I too have noticed that acid/base biod gives a very clear wash initially but it never dawned on me why this was so. I think you are exactly right. There is no doubt that addition of ordinary salt, so useful to break emulsions in bad batches and in badly managed batches, slows down the removal of soap. Sodium sulphate would do so the same.

I wonder whether the Uni Idaho idea of adding a bit of water to the glycerine and stirring a bit more before draining the glycerine would help. It might help more with acid/base than it does with base only.

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Neutral/chemist types: won't a salt-water wash still pull out residual methanol, releasing whatever glycerin and soap it was keeping dissolved? Is that enough of an effect to be useful, or even noticable? I agree that it seems to take a lot more washing once salt has been used. The water continues to feel slimy for several rinses after it runs clear.

The comments about some wvo being more prone to emulsify rings very familiarly to me. Since I converted my truck to WVO, I've been observing interesting accumulations of a high melting point fraction during the WVO filtering process. It's consistantly from the same low-titration source oil that gave me emulsion troubles, which is why I now dedicate it towards WVO use. I've been assuming it's from the bacon, beef, and other "tallow" producing meats. The "tallow" is solid at least as hot as 80degF, and possibly as high as 90F to melt. I may try to make a 1-liter batch of biodiesel from it, to see what it's characteristics are like.
I've wondered if the tallow esters are in "solid" phase during the wash, leading more easily to really difficult emulsions, and clearing instantly with a hot water wash.

Yes the salt water wash will be just as good at getting methanol out as fresh water. The salt water resists removal of soap because the salt is ionic and uses up the capacity of the water for other ionic material such as soap. Shifting the methanol out will make the soap less soluble in the esters but this effect will be minor compared with the resistance created by the salt.