Notes for GL's Biodiesel Quiz #2
Methanol or methoxide are less dense than oil, so will tend to float on the oil surface unless they are vigorously mixed in.
Methanol cannot be effectively filtered from air, so the safest approach it breath fresh air from an outside source. Don't use a standard industrial air compressor to feed air to a face mask, because the compressor can introduce a fine oil mist into the air stream , which can be very damaging to lungs.
The glycerides in under-reacted biodiesel (as mono-glyceride, di-glyceride or tri-glyceride) are more viscous or thicker than biodiesel, and can over-stress your engine's injection pump, especially in cold weather.
You can reduce the heat power from an electric heating element by running it on a reduced voltage. If you run it on half its rated voltage it will give 1/4 its rated heating power.
It is imposiible to tell how 'good' used oil is, by looking at it or smelling it, because there are so many different oil types which look different to each other. The food which has been cooked in the oil can give it a darker colour and a different smell too, and this may have little effect on the oil's quality.
Lye will firstly be used up in neutraling FFA and creating soap. This is a wasteful part of the process. The remaining lye will then act as a catalyst to help strip the long chain fatty acids from the glycerol 'backbone' of the oil. The reason we titrate is to know how much extra lye needs to be added for the first wasteful 'sacrifice' when the FFA is neutralised.
The full procedure for carrying out a titration is given here.
Pure methanol boils at 65C. Methanol in the biodiesel reaction boils at a somewhat higher temperature, but if you use 65C as your upper limit you should avoid excessive loss of methanol.
The 3 main ingredients are glycerides, alcohol and catalyst.
It appears from numerous posts on the forums that the biggest contributor to good biodiesel reaction success is good mixing, all other things being equal.