Kinetic Study of Levulinic Acid from Spirulina platensis Residue

Microalgae have the potential to emerge as renewable feedstocks to replace fossil resources in producing biofuels and chemicals. Levulinic acid is one of the most promising substances which may serve as chemical building blocks. This work investigated the use of Spirulina platensis residue (solid residue after lipids extraction) to produce LA via acid hydrolysis reaction. In this study, Spirulina platensis residue was set to have a solid–liquid ratio of 5% (w/v). The effect of process parameters on the Spirulina platensis residue to levulinic acid hydrolysis reaction was observed at temperatures ranging from 140 to 180 °C under four acid concentrations, i.e., 0.25, 0.5, 0.8, and 1 M. A simplified kinetic model was also developed to describe the behavior of Spirulina platensis residue conversion to levulinic acid, based on the pseudo-homogeneous–irreversible–1st order reaction. The results showed that the proposed model could capture the experimental data well. The reaction network also considered involvement of intermediate products namely glucose and 5-hydroxymethylfurfural. The results showed that Spirulina platensis residue, with acid catalysts, can be used to produce levulinic acid, and the kinetic model can provide useful information for understanding the Spirulina platensis residue to levulinic acid hydrolysis reaction.