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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #324347

Research Project: Improving bioenergy and forage plants and production systems for the central U.S.

Location: Wheat, Sorghum and Forage Research

Title: Microwave pretreatment effects on switchgrass and miscanthus solubilization in subcritical water and hydrolysate utilization for hydrogen production

item IRMAK, SIBEL - University Of Nebraska
item MERYEMOGLU, BAHAR - Cukurova University
item SANDIP, ANJALI - University Of Nebraska
item SUBBIAH, JEYAMKONDAN - University Of Nebraska
item Sarath, Gautam
item Mitchell, Robert - Rob

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2017
Publication Date: 11/10/2017
Publication URL:
Citation: Irmak, S., Meryemoglu, B., Sandip, A., Subbiah, J., Sarath, G., Mitchell, R. 2018. Microwave pretreatment effects on switchgrass and miscanthus solubilization in subcritical water and hydrolysate utilization for hydrogen production. Biomass and Bioenergy. 108:48-54

Interpretive Summary: Switchgrass and miscanthus are promising potential sources for bioenergy and value-added products. They are non-edible biomass materials with high total carbohydrate contents. Successful production of biofuels and other bioproducts from biomass requires pretreatment to facilitate conversion. Microwave-based pretreatment is an efficient and effective method for these feedstocks. Microwave treatment enhanced the breakdown of these two biomass feedstocks and efficiency increased as the microwave processing temperature increased. Miscanthus biomass was more vulnerable to breakdown by microwave treatment and was achieved at lower temperatures compared to switchgrass. However, untreated miscanthus biomass produced the highest gas yield. This study demonstrates that microwave pretreatment of biomass in water is a user-friendly and viable alternative to using harsh chemicals to breakdown biomass, but also indicates that all feedstocks do not respond the same to pretreatment.

Technical Abstract: Microwave pretreatment is an energy-efficient and environmentally benign technology that can be used to reduce the recalcitrance of complex biomass structure. Switchgrass (Panicum virgatum L.) and miscanthus (Miscanthus x giganteus) are perennial C4 grasses that are being developed as bioenergy crops because they have high yield potential and desirable agronomic traits. These materials are promising candidates for biofuels, bioproducts and green chemicals production from biomass. In the present study, miscanthus and switchgrass biomass were solubilized in subcritical water after pretreatment by microwave at different processing temperatures. The hydrolysates obtained were evaluated for hydrogen-rich gas production by aqueous-phase reforming (APR). Higher temperature microwave processing reduced the biomass recalcitrance resulting in microwave treated materials having 7–10% higher solubility in subcritical water than untreated materials. However, gasification of pretreated biomass hydrolysates produced less gaseous products compared to untreated biomass for both switchgrass and miscanthus. Miscanthus biomass was more vulnerable to destruction by microwave treatment and recalcitrance of this biomass was achieved at lower temperature compared to switchgrass. Miscanthus biomass that was not microwave treated produced the highest gas yield. Microwave pretreatment caused significant increases in the formation of ungasified solid carbon residue in the APR process.