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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 59 2010. Does my biodiesel have soap in it?. No direct ASTM standard for soap 500 ppm is a good rule of thumb
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Biodiesel – analytical methodsPart 2 (to follow Synthesis) Dr Robert Elliott (Dr) David Schaller Ms Anna Paice Primary Industry Centre for Science Education Presented at CONASTA 59 2010
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 Residual NaOH Soap AOCS method “soap in oil” cc17-79 www.nrel.gov/docs/fy04osti/36240.pdf Image adapted from http://www.chemguide.co.uk/physical/acidbaseeqia/indicators.html
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 ~100ℴC for 10‘ • Viscosity test
Viscosity of biodiesels from different oils 40˚C Oils FAMEs See slide notes for data sources
Viscosity as a proxy for completion 40˚C FAMEs Fillipis et al., 1995
Ostwald Viscometer http://www.pharmainfo.net/free-books/pharmaceutical-suspensionsa-review
Relative viscosity by pipette draining Image from http://www.glassware-manufacturers.com/pipettes.html
Data collection with mobile phones (Large bore pipettes are too fast on hot days)
Relative Viscosity by Pipette Drain Time