Effects of surfactant on biochemical and hydrothermal conversion of softwood hemicellulose to ethanol and furan derivatives

This study was to explore the effects of surfactant on biochemical and hydrothermal conversion of hemicellulose into biofuels and value-added co-products. It was found that extraction of loblolly pine with 0.4% H2SO4 (w/w) at 150 °C for 2 h can dissolve most of hemicellulose. The addition of surfactant (0.4% w/w) showed significant improvement on hemicellulose extraction, hemicellulose yield increased from 8.14 ± 0.16% to 10.15 ± 0.02% (w/w) based on raw biomass. Pre-extracted hemicellulose was fermented to ethanol by Saccharomyces cerevisiae. In the presence of 0.4% surfactant, the glucose consumption rate in the hydrolysate fermentation increased from 0.28 g g−1 h−1 to 0.46 g g−1 h−1, and mannose consumption rate increased from 0.30 g g−1 h−1 to 0.35 g g−1 h−1. The final ethanol concentration increased from 7.45 ± 0.18 g/L to 10.68 ± 0.26 g/L. It was also observed that the hemicellulose extract could be effectively converted to levulinic acid at low pH (∼2) by a hydrothermal process. Under the condition of 200 °C for 45 min, 38.61 ± 1.06% of hexoses from the hydrolysate extracted by 0.4% of sulfuric acid converted to HMF, and 64.48 ± 1.20% of pentoses to furfural. The addition of surfactant (0.4% w/w) significantly increased the selectivity of furan by 41% for HMF and 30% for furfural.