The use of impregnated perlite as a heterogeneous catalyst for biodiesel production from marula oil

In this study, biodiesel was produced from marula (Sclerocarya birrea) oil using impregnated perlite with potassium hydroxide (KOH) as a heterogeneous catalyst. The effect of experimental variables such as temperature (°C), reaction time (h), methanol to oil ratio (mass %), and catalyst to oil ratio (mass %) on the transesterification process were investigated. Using a central composite design (CCD), a mathematical model was developed to correlate the experimental variables with the percentage yield of biodiesel. The model showed that optimum conditions for biodiesel production were as follows: catalyst to oil ratio of 4.7 mass %, temperature of 70.4°C, methanol to oil ratio of 29.9 mass %, and reaction time of 3.6 h. The yield of 91.4 mass % of biodiesel was obtained. It was also possible to recycle and reuse the modified perlite up to three times without any significant change in its catalytic activity. The X-ray diffraction (XRD) and the Brunauer-Emmett-Teller (BET) surface area showed no modifications in the perlite structure. The results show that the important fuel properties of marula biodiesel meet the American Society for Testing and Materials (ASTM) biodiesel standard properties.