Effects of extraction parameters on the yield of oils from non-edible seeds of Bauhinia variegata and Pachiraglabra

Abstract

The influence of extraction temperature, seed age, and extraction time and their interactions on the Bauhinia variegata seed oil (BVSO) and Pachira glabra seed oil (PGSO) yield was studied using the response surface methodology (RSM). The BVSO and PGSO obtained were characterized to determine their suitability for use as biofuel. Numerically predicted optimum values for the extraction process using the RSM model proved to be a one-week-old seeds, a 10 h extraction time and a 60 °C temperature with a 47.05 % PGSO yield, and a one-week-old seed, a 6.5 h extraction period and 60 °C temperature, with a 23.1 % BVSO yield. Performance evaluation of the models by coefficient of determination (R2), Adjusted R2, and absolute average deviation (AAD) showed that the RSM model (R2 = 0.99, Adjusted R2 = 0.99, AAD = 0.07 % for BVSO yield, and R2 = 0.99, Adjusted R2 = 0.99, AAD = 0.01 % for PGSO yield) was satisfactory, reliable, and flexible. The physicochemical properties of BVSO and PGSO, i.e. acidity index (4.63 mg KOH/g and 27.21 mg KOH/g) and kinematic viscosity (3.24 mm2/s and 12.45 mm2/s), reveal the need for post-treatment of oils for use as additives to conventional fuels. Other physicochemical properties obtained, such as oxidative stability, higher heating value, cetane number, flash point, iodine value, and saponification value, demonstrate that these oils are excellent potential sources for biodiesel production.