Optimization and kinetics of biodiesel production of Ricinus communis oil and used cottonseed cooking oil employing synchronised ‘ultrasound + microwave’ and heterogeneous CaO catalyst

Abstract

Current novel work investigates synchronized ultrasound and microwave (MW + US) applications with an appropriation of Ricinus communis oil (RCO) and used cottonseed cooking oil (UCCO) blends for biodiesel production. The study aims at process optimization, kinetic and energy analysis of biodiesel production where fuel properties improved. The effect of oil/methanol proportion, CaO %, RCO + UCCO blend ratio, and reaction time is examined using Box-Behnken investigational design. The appropriation of blended oil proportion as a process parameter has been deliberated for the first time. The optimized conditions were methanol:oil ratio: 9.7:1; CaO wt%: 2.8 wt%, reaction time: 12.3 min, and 59:41 of RCO:UCCO blend proportion with highest biodiesel yield of 92.11 ± 0.06%. The blended oil transesterification kinetics followed the pseudo-first-order, with activation energy 1.8 times lower than the conventional process. Blended oil biodiesel showed ∼7.5% enhanced calorific value and two-time viscosity reduction than RCO biodiesel. Fuel properties found equivalent to ASTM-D6751 biodiesel standards.