Acid hydrolysis conditions for the production of fine chemicals from Gracilaria birdiae alga biomass

Abstract

Gracilaria birdiae is a tropical agarophytes species of red seaweed that is rich in carbohydrates and presents a great potential for mariculture and economic use. However, it is still understudied as a potential renewable resource. In this study, the hydrolysis conditions of G. birdiae algal biomass, reaction time, and sulfuric acid concentration for obtaining monosaccharides, organic acids, and furanic compounds were optimized. Glucose and galactose concentrations were found to be more affected by algal biomass concentration, while the production of 5-hydroxymethylfurfural (5-HMF) and organic acid were most affected by sulfuric acid concentration. The most suitable conditions to produce glucose (28.56 ± 0.72 g·L−1) and galactose (108.03 ± 1.32 g·L−1) were at 121 °C, with sulfuric acid 1.3 mol·L−1, 841.59 g·L−1 of algal biomass and time of 20 min. For cellobiose (25.39 ± 0.43 g·L−1), the condition was sulfuric acid 0.6 mol·L−1, 680 g·L−1 of biomass, and 10 min. For 5-HMF (19.82 ± 0.43 g·L−1), it was sulfuric acid 0.6 mol·L−1, 680 g·L−1 of biomass and 30 min. Finally, for levulinic (38.88 ± 0.58 g·L−1) and formic acids (26.75 ± 0.54 g·L−1) and, the best conditions were sulfuric acid 2.0 mol·L−1, 680 g·L−1 of biomass and 30 min. Thus being, Gracilaria birdiae is a promising renewable resource to produce fine chemicals and fermentable compounds by optimizing its acid hydrolysis conditions.