Hydrolysis of lipid-extracted Chlorella vulgaris by using solid and liquid acids

Abstract

A lipid-extracted Chlorella vulgaris biomass with 12.2 % of total carbohydrate was hydrolyzed by simultaneous use of solid and liquid acids. Nitric acid at as low as 0.0075N as liquid acid catalyst and 7.6 g/L of Amberlyst36 as solid acid catalyst were used at $150 ^\circ C$ to treat 10 g/L of biomass to produce mono-sugars. This mono-sugar yield was 88.5 %. The contribution of Amberlyst36 to sugar production was increased by 91.2 % in the existence of the liquid acid clearly showing a synergy effect of simultaneous use of liquid and solid acids. Though liquid acid concentration was less related with biomass concentration to fragmentize the biomass, ratio between solid acid and biomass concentrations was a point to hydrolyze the concentrated lipid-extracted Chlorella vulgaris biomass. The use of such low amount of liquid acid was to minimize or eliminate the necessity of post-treatment steps of neutralization and desalting.