Comparison of biodiesel yield from seed oils extracted by ultrasound-assisted chemical solvent and supercritical CO2 methods

Abstract

The seeds from Hibiscus cannabinus and Gliricidia sepium, also known as kenaf and kakawate seeds respectively, were used as sources of oil in the production of biodiesel. The oil was extracted using two methods: ultrasound-assisted chemical solvent (UACS) and supercritical fluid. The performances of two methods were compared based on their oil and biodiesel yields. Using supercritical CO2 (SCCO2), the highest oil yield recorded was 13.19% from kenaf at operating conditions of CO2 flow rate=2.5ml/min, T=70°C, P=30MPa, and 11.79% from kakawate at operating conditions of CO2 flow rate = 2.5ml/min, T=60°C, P=30 MPa. Using multi-walled carbon nanotubes and concentrated sulfuric acid under thermal decomposition, a sulfonic catalyst was produced and used in simultaneous esterification-transesterification reactions. The individual chemical compositions of kakawate and kenaf methyl esters were analyzed using gas chromatography–flame ionization detector. Higher biodiesel yields were observed for oil samples extracted using SCCO2