Getting Started - Espaņol
How It's Made
Titrating Oil
Making A Small Batch
Washing A Small Batch
3/27 Conversion Test
Carboy Methoxide Mixer
'Dixie Cup' Scale
Fueling Station
Oil Collection Tank
Scales For Biodiesel
Standpipe Wash Tank
Titration Station
Biodiesel Safety
Buying Methanol
Storage Considerations
Testing Oil For Water
Quantitative Water Test
Negotiating For WVO
Filtering Oil
Pretreating Oil
Solar Preheat Oil
Bubblewashing Biodiesel
Drying Washed Biodiesel
Breaking Emulsions
Testing For Soap
Titrating with Turmeric
5% Water Prewash
Acid/Base Processing
Base/Base Processing
Online Resources
Tutorial Page Forum
Yahoo Biodieselbasics
InfoPop Biodiesel

Breaking Emulsions
by Jack Jones of Riverstones Biodiesel
Questions? Comments? Feedback? Click Here

Here is a method for breaking emulsions that Jack Jones stumbled upon in late 2004. This method uses biodiesel glycerine by-product as the emulsion breaking ingredient, a readily available ingredient for anybody that makes biodiesel.

Biodiesel emulsions sometimes occur during the wash phase. This can occur for several reasons relating to unreacted oils, poorly separated biodiesel/by-product, etc. However, all these situations have one thing in common; aggressively washing biodiesel in the presence of water and soap. Soap molecules (a by-product of the biodiesel reaction created when free fatty acids are neutralized with the catalysts) are long chain molecules that have one end that is attracted to polar molecules (such as water) and the other end that is attracted to nonpolar molecules (such as dirt, grease, biodiesel, etc.). These long molecules will attach themselves to dirt, grease, biodiesel, etc. and then bunch together forming a "bubble" around the dirt, grease, or biodiesel so that the ends of the soap molecules that are attracted to water form the outside surface of a sphere with the dirt, grease, or biodiesel at the center of the "bubble".

Emulsions occur during aggressive biodiesel washing because the biodiesel becomes "imprisoned" in these soap spheres. These soap spheres can be broken apart by pushing them tightly together by freezing the whole emulsion. Or we can break the emulsion by lowering the surface tension between the soap molecules using a solvent like alcohol. The alcohols (methanol and glycerin) in the biodiesel by-product are a readily available solvent to break emulsions; much easier than freezing a large emulsion solid.

This page provides a pictorial walk-through for creating and breaking a small biodiesel emulsion. We start with clean biodiesel. Since clean biodiesel will not emulsify with water alone we must also add soap to the biodiesel. The soap we add is, ironically enough, provided by biodiesel by-product. With the combination of clean biodiesel, soap (biodiesel by-product), water, and a very aggressive mixing of the liquids we easily create a biodiesel emulsion.

With the biodiesel emulsion created we then break the emulsion by adding the solvents (the biodiesel by-product). We add small amounts of the by-product to determine how much is really needed to break our emulsion. It is important not to mix these solvents too aggressively or their emulsion breaking power will be halted by the emulsion creating power of the soap that is present. A thorough mixing is all that is needed. It is also important to have the mixture a little warm at this point. We heated the mixture up to 90F.

Start with 500ml of nice clean biodiesel
clean biodiesel

Add 50ml of biodiesel by-product (glycerin, soap, methanol etc.)
add soap

Notice the layer on the bottom
soap layer

Add 100ml water
add water

Now notice the layer of water/by-prodcut on the bottom
soap/water layer

Shake it

And shake some more until it emulsifies
emulsified biodiesel

Remember what it looked like before the emulsion?
emulsion comparison

Add 50ml by-product and gently mix
first break attempt

That didn't break the emulsion so add another 50ml by-product and gently mix
second break attempt

It's starting to work but we need another 50ml by-product and gently mix
final break attempt

A total of 150ml by-product broke the emulsion
break emulsion

Re-clean the biodiesel
re-cleaned biodiesel

Collaborative Biodiesel Tutorial - © Copyright 2005 - All Rights Reserved