Modification of hydrothermal liquefaction products from Arthrospira platensis by using carbon dioxide

This study mainly reports that utilizing CO2 as a reaction medium in hydrothermal liquefaction of Arthrospira platensis, as a model feedstock of microalgal biomass, provides a means for modifying the chemical constituents in microalgal bio-oil produced via hydrothermal liquefaction. Prior to hydrothermal liquefaction, the total lipid content of A. platensis was measured as ~ 3.5 wt% (dry basis). Thermal degradation of A. platensis and the major pyrolytic gases from the thermal degradation of A. platensis were characterized to gain an insight into the physico-chemical influences of CO2 in hydrothermal liquefaction. Based on the experiment's findings, hydrothermal liquefaction of A. platensis was conducted to evaluate the influence of CO2. Hydrothermal liquefaction of A. platensis in CO2 decreased the composition of N-containing species from 63 to 59% and that of O-containing species from 31 to 27% in the bio-oil, significantly suggesting that using CO2 improves the quality of bio-oil as a transportation fuel.