Effect of Mass Transfer and Enzyme Loading on the Biodiesel Yield and Reaction Rate in the Enzymatic Transesterification of Crude Palm Oil

Efforts in minimizing mass transfer effects in enzymatic transesterification of crude palm oil in a biphasic system have always been the compromise between enzyme loading and agitation speed. Therefore, effect of enzyme loading and agitation speed on fatty acid methyl ester (FAME) productivity in terms of intrinsic and external mass transfer limitations and the effective reaction time were determined using factorial design. FAME yield response was significantly affected by agitation speed, enzyme loading and reaction time, whereas initial reaction rate was solely dependent on the enzyme loading. Graphical plots of experimental results revealed that the mass transfer effect for the transport of reactant from bulk liquid to immobilized lipase and within the intraparticle of immobilized lipase were absent at 150 rpm and 6.65% enzyme loading. Optimization conditions for a kinetically controlled domain proposed by the response surface methodology established 100% FAME yield in 4 h reaction time at initial reaction rate of 2.77% FAME yield per min.