A Novel Oxidative Pretreatment of Loblolly Pine, Sweetgum, and Miscanthus by Ozone

Abstract

Three biomass feedstocks (Loblolly pine, Sweetgum, and Miscanthus) were subjected to a novel, two-step ozone pretreatment to enhance the enzymatic digestibility of cellulose. The results show that ozone pretreatment alone did not significantly reduce recalcitrance of the three feedstocks. However, the ozone pretreatment was capable of generating oxidative biomass fragments that can be utilized in a subsequently conventional pretreatment without the need for exogenous acid to be added. For example, employing a dose of ozone followed by an ethanol organosolv pretreatment led to significant delignification and preserved most of the carbohydrates in the three biomass feedstocks. Likewise, ozone treatment followed by autohydrolysis gave higher solubilization of hemicelluloses and distinctive results in terms of enzymatic glucose release and fermentation yields for both Sweetgum (14.00 g ethanol/100.00 g biomass) and Miscanthus (11.10 g ethanol/100.00 g biomass) feedstocks. Although ozone treatment followed by organosolv pretreatment gave low enzymatic glucose release yield for Loblolly pine, a two-step ozone pretreatment has been shown in this study to be a very promising strategy for Sweetgum and Miscanthus feedstocks.

Keywords:

• Ozone pretreatment
• Loblolly pine
• Sweetgum
• Miscanthus
• ethanol

Acknowledgments

The authors wish to acknowledge financial support from Chevron Technology Ventures for these studies. The authors are also grateful for financial support from the Paper Science & Engineering (PSE) Fellowship program at Institute of Paper Science & Technology (IPST) and the School of Chemistry and Biochemistry at Georgia Institute of Technology.