I am a newbie here, so if these questions are stupid please forgive.
Would FFA's tend to float to the top of a drum. I assume they are lighter due to the lack of Glycerol molecule.

We only need a small amount of lye as catalyst but add extra to compensate for FFA. Is there something else that could be used to neutralize the FFA's that doesn't make soap.

With very high FFA oil would it be possible to make soap to split the FFA from the glycerides and then use acid to convert the soap back into FFA's and then esterify.

Hello sinbad

No, FFA's do not seperate out in the same way alcohol and water do not seperate out once they are mixed.

Sinbad,

Settling your WVO is a good thing. WVO will usually have water in it unless you specifically only collect water free WVO. Settling it for long enough and you will usually see the oil separate into two layers. The oil layer on top is what you use to process into biodiesel. The creamy layer on bottom needs more time settling.

To you question on FFA reduction, If you titrate oil when you get it from the restaurant, then again after settling, the oil after settling will often have a lower titration number. That's mostly because the water soluble acids go with the water in the creamy layer. I don't know if the creamy layer on bottom is also attracting FFA. It might be.