78. Kumar, Sandeep; Kothari, Urvi; Kong, Lingzhao; Lee, Y. Y.; Gupta, Ram B. Hydrothermal pretreatment of switchgrass and corn stover for production of ethanol and carbon microspheres, Biomass and Bioenergy (2011), 35(2), 956-968
Pretreatment of biomass is viewed as a crit. step to make the cellulose accessible to enzymes and for an adequate yield of fermentable sugars in ethanol prodn. Recently, hydrothermal pretreatment methods have attracted a great deal of attention because it uses water which is a inherently present in green biomass, non-toxic, environmentally benign, and inexpensive medium. Hydrothermal pretreatment of switchgrass and corn stover was conducted in a flow through reactor to enhance and optimize the enzymic digestibility. More than 80% of glucan digestibility was achieved by pretreatment at 190 °C. Addn. of a small amt. of K2CO3 (0.45-0.9 wt.%) can enhance the pretreatment and allow use of lower temps. Switchgrass pretreated at 190 °C only with water had higher internal surface area than that pretreated in the presence of K2CO3, but both the substrates showed similar glucan digestibility. In comparison to switchgrass, corn stover required milder pretreatment conditions. The liq. hydrolyzate generated during pretreatment was converted into carbon microspheres by hydrothermal carbonization, providing a value-added byproduct. The carbonization process was further examd. by GC-MS anal. to understand the mechanism of microsphere formation.