Mechanochemical Treatment of Plant Biomass for Soluble Sugar Release and Bioethanol Production

Fossil fuel depletion and the struggle for a safer and greener environment have led to the necessity of developing alternative energy sources for transportation, such as bioethanol. Bioethanol is a renewable and environmentally friendly biofuel, which does not contribute to the greenhouse effect. When bioethanol is produced from the plant biomass of argicaltural wastes and surplus products, it does not compete with agricultural plants over growth areas. This study focuses on the lignocellulosic biomass of Eichhornia crassipes (water hyacinth), the cactus Opuntia ficus-indica, grape spurs and grass (Gramineae) which can serve as a source of sugars for bioconversion into bioethanol. Hydrolysis of polysaccharides to soluble mono- and di-saccharides was performed by single-stage mechanochemical processing. The results showed that hydrolysis of the polysaccharides occurred due to the mechanochemical activation, without addition of any external catalyst. The treated biomass was characterized by FTIR, TGA-DSC, SEM and HPLC. Mechanochemical biomass treatment was scaled-up and a general scheme of biomass processing was suggested. Extracts from the mechanochemically treated biomass were used as complete media for yeast fermentation and bioethanol production.