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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

   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




  Fillipis                 FAMEs
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

				
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