Production and characterization of biodiesel obtained from Sapindus mukorossi kernel oil

• Produced biodiesel from high acid value Sapindus mukorossi oil using two step transesterification.
• The product formation is confirmed using NMR spectroscopy.
• Properties are obtained using standard ASTM techniques and most of these are found to conform to the existing norms.

Sapindus mukorossi is a tree available in northeastern region of India. Fruit of S. mukorossi has some traditional usage and its kernel contains 39% (w/w) oil. Prospect of S. mukorossi oil for biodiesel production is investigated with reference to some relevant properties. The fatty acid profile of oil extracted from S. mukorossi is found comparable with similar seed oils attempted for biodiesel production in this region. Since the acid value of S. mukorossi is found to be 15.6 mgKOH/g, so biodiesel is prepared using two stage transesterification. In the first step, alcohol to oil molar ratio of 6:1 with 1 wt% of H2SO4, results the maximum reduction in acid value (acid value 1.89 mgKOH/g) within 60 min. In the second step, 10:1 alcohol to oil molar ratio and 1wt% NaOCH3 gives the optimum yield of biodiesel. Finally, the biodiesel is confirmed by the peaks appeared in 1H NMR and 13C NMR. The properties of the biodiesel are obtained using standard ASTM techniques and found to conform to the existing norms.