Applications of ultrasound for lignocellulosic bioethanol production

High intensity ultrasound was studied as an adjunct to chemical pretreatment of biomass from Miscanthus x giganteus. The physical and chemical effects of ultrasound originate from acoustic cavitation: the formation, growth, and implosive collapse of bubbles in a liquid. Cavitation causes intense localized heating, high pressures, and enormous heating and cooling rates which enhance the chemical pretreatment. In heterogeneous systems (i.e. solid-liquid slurries), asymmetric bubble collapse at an extended surface results in high velocity microjets and shockwaves which cause surface deformations and particle fracture. These physical and chemical effects of ultrasound increase the porosity of the Miscanthus biomass and thus increase the accessibility of cellulose, as shown by SEM, Simons' Stain method, and enhanced glucose production from enzymatic saccharification. We have optimized the important parameters of ultrasonic treatments such as ultrasound power, time of sonication, temperature, solvent, slurry wt.%, and pH.