Rheokinetics of microalgae slurry during hydrothermal pretreatment processes

Abstract Hydrothermal pretreatment is an efficient process for improving the productivity of biofuels from wet microalgae biomass. The rheological behavior of microalgae slurry is a significant parameter affecting the performance of hydrothermal pretreatment reactors. Herein, the dynamic rheological behavior of microalgae slurry during hydrothermal pretreatment was investigated for the first time. The results revealed that the insoluble organics released from microalgae cells was the main factor affecting the rheological behavior of microalgae slurry. The denaturation and hydrolysis of starch and protein in liquid phase at different temperature regions caused the increasing and decreasing of viscosity of the microalgae slurry, respectively. The rheokinetics equations were established based on four-parameter cross-linking rheokinetics equation to describe the variation of viscosity with reaction time in different temperature. The variation of the rheokinetics model parameters with temperature revealed that the temperature has an obviously positive influence on the hydrothermal pretreatment process of the microalgae slurry.