KINETIKA TRANSESTERIFIKASI BIODIESEL JARAK PAGAR

Abstract

Biodiesel were produced by trans-etherification of castor oil with alcohol in the presence of NaOH catalyst. The
reaction mechanism and model of castor oil trans-etherification is
A + 3B C + 3 D
A, B, C, and D were castor oil, alcohol, glycerol, and ester. The reaction rate equation was r=-dCA/dt =
k1(CA)(CB)3–k2(CC)(CD)3. In this study was used two measurement method of free fat acid as the rest content of
castor oil with SNI 01-3555-1998 and AOAC (Association of Analytical Chemist). It found that SNI 01-3555-
1998 method was the easier and the acurate measurement. The classification of alcohol used was methanol and
ethanol to compare the action both of them. Methanol produces the higher conversion than ethanol. The reaction
in a batch reactor with temperature 40, 50, and 60°C in atmospheric pressure as the operation condition to
looking for kinetics parameter of trans-etherification. Coefficient reaction rate and activation energy were look
into kinetics study. Reaction rate was a mathematics model as a function of concentration and time which solved
by Runge-Kutta, multivariable optimization and SSE (some square error) method using Matlab. The activation
energy (Ea) and impact factor (A) obtained by linier regression method. The result of study obtained the kinetics
parameter of trans-etherification with methanol k1=1.9313x1031exp (-41.940/RT) average error 0.0010 and
k2=2.7678x1025exp(-37.362/ RT) average error 0.0003. While kinetics parameter of trans-etherification with
ethanol obtained k1=1.168x1019exp(-24.588/ RT) average error 0.0306 and k2=4.9966x106exp(-10.328/RT)
average error 0.1589. It means, more reactive alcohol then bigger the value of kinetics parameter.