Rubber seed sample were peeled. The seed kernels was macerated, blended and dried in an oven at
55°C for 2 hours. One hundred grams of samples were introduced into flask equipped with mixer (see Fig.
2). Aqueous methanol and H2SO4 were added and then heated and mixed. The solution was heated to
60o
C at atmospheric pressure. The in situ process (extraction-reaction process) was done for 120 minutes.
The product was filtered and methanol was separated with distillation. Biodiesel product was analyzed for
weight, viscosity, density and concentration. Concentration of methyl ester in biodiesel product was
analyzed by GC.
The experiment was divided into three stages. The first stage (preliminary study) was carried out to
obtain reaction time for in situ processing. In this step, response variable was analyzed on density and iscosity. The experiment was done at H2SO4 0,5% (v/v) and ratio of raw material to methanol (1:2) and
every 15 minutes was analyzed until constants condition. In the second stage, the experiment was
investigated with catalyst concentration of H2SO4 about 0.1; 0.25; 0.5; 0.75 and 1% (v/v). The experiment
was done in variable ratio of raw material to methanol (1:2) and 120 minutes reaction time. In the third
stage, the experiment was conducted about effect of ratio of raw material to methanol i.e; 1:1.5; 1:1.75;
1:2; 1:2.5 and 1:3 (w:v).
Weight of product was used to calculate the biodiesel yield. Yield of FAME was calculated using this
equation (1) [17,18] :