Bio-oil from microwave pretreated microalgal biomass using supercritical carbon dioxide (SCCO2) system / Siti Nurhanis Ibrahim

Chlorella vulgaris is one of the promising microalgal strains that can produce high yield of bio-oils. Chlorella vulgaris has higher growth rate which was 0.9288 day-1 compared with Neochloris oleoabundans was at 0.7369 day-1. Furthermore, C. vulgaris has high lipid content compared with N. oleoabundans. The selected microalga, C. vulgaris was pretreated with microwave irradiation prior to extraction using supercritical carbon dioxide (SCCO2). Fourier transform infrared spectroscopy (FTIR) analysis showed microwave irradiation pretreatment does not affect the material composition of C. vulgaris. Scanning electron microscopy (SEM) of the microwave irradiation pretreated microalgae showed agglomeration of distortion and rupturing of microalgae cell walls. Optimization of the SCCO2 process parameters (pressure, temperature and CO2 flow rate) was conducted by using response surface methodology (central composite design, CCD). Two factors significantly affect the extraction yield comprising of temperature and pressure.