thermal transesterifi cation of triglycerides requires a multiple
step process with one or more batch reactors. Initially, TG and alcohol form
two immiscible liquid phases. As the reaction proceeds, two separate liquid
phases form, one containing the newly formed FAAEs and the other glycerol,
with the excess alcohol, catalyst and feed oil being dispersed into both
phases. Even the most effi cient of the traditional processes requires several
hours to process each batch of feed. Additionally, serious problems arise in
the separation steps. Signifi cant quantities of glycerol left in the alkyl esters
diminish the quality of the diesel fuel and likewise contaminated glycerol
also loses much of its value compared to pure uncontaminated glycerol. It
should be stressed that the methyl esters derived from methanolysis are not
biodiesel until the proper specifi cations are met. Excess alcohol must be
recycled and the unused catalyst typically must be neutralised. Traditionally,
the separation procedures necessary to adequately clean the two product
streams produce large quantities of wastewater thereby creating additional
process complexity and cost. Alternatively, particulate and/or adsorbent