Biodiesel – analytical methods Part 2 (to follow Synthesis) Dr Robert Elliott (Dr) David Schaller Ms Anna Paice Primary Industry Centre for Science Education Presented at CONASTA

Does my biodiesel have soap in it? No direct ASTM standard for soap 500 ppm is a good rule of thumb Shake test – how long does water take to settle Titration test (in acetone or alcohol)

Titrating soap in a biodiesel-acetone (or biodiesel-isopropanol) solution Image adapted from Residual NaOH Soap AOCS method “soap in oil” cc

How do I get rid of soap? Use cleaner reagents and do it again... Water washing removes the soap [Be careful: wash gently in the early stages to prevent the formation of an emulsion (unless you are doing a salt wash or a vinegar wash)]. Water washing removes the alcohol, which helps the soap to stay in the biodiesel (also helps get rid of glycerol, which can make your biodiesel cloudy) Let the biodiesel stand and clarify

Did your reaction go to completion? Assaying glycerides in your biodiesel Monoglycerides, diglycerides, trigylcerides 9/1 Test - solubility in alcohol Re-reaction test – reaction at ~100 ℴ C for 10‘ Viscosity test

Viscosity of biodiesels from different oils See slide notes for data sources Oils FAMEs 40˚C

Viscosity as a proxy for completion Fillipis et al., 1995 FAMEs 40˚C

review Ostwald Viscometer

Relative viscosity by pipette draining Image from

Data collection with mobile phones (Large bore pipettes are too fast on hot days)

Relative Viscosity by Pipette Drain Time