Increased bio-oil yield from Swietenia macrophylla seeds through microwave pretreatment and ultrasonic-assisted solvent extraction

Abstract

Low recovery coupled with intensive energy requirement due to long processing time makes the potential of bio-oil production not seamlessly appreciated. In this study, the optimization of bio-oil yield from non-edible Swietenia macrophylla seeds through microwave pretreatment before ultrasonic-assisted solvent extraction was investigated. Central composite design of response surface methodology was employed to analyze the effects to the bio-oil yield of the irradiation time (4–8 min) and irradiation power (90–450 W) as pretreatment variables using a microwave oven at 2.45 GHz frequency. Results showed that microwave pretreatment significantly increased the bio-oil yield by 5% with optimum recovery of 43% at shortened pretreatment time of 7 min instead of 6 h in the conventional oven heating method. The bio-oil yield increased when the irradiation time was increased, while irradiation power showed no significant effect. Analysis of the produced bio-oil through Fourier Transform Infrared Radiation spectroscopy identified similar functional groups present both in the extracted bio-oils from the microwave and the conventional pretreated seeds indicating that the former pretreatment, like the latter, did not destruct the compounds present in the seeds. The study demonstrated that the seeds of S. macrophylla have strong potential for bio-oil production and poise huge implications to the future of liquid biofuel and chemical industries.