Delignification Studies on Hot-Water Extracted Wood, 2010 TAPPI PEERS Conference

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There is a growing demand for increasing profitability of the pulp and paper industry by generating additional value-added products from wood. Consistent with these goals, a biorefinery concept based on hot-water extraction (HWE) of hardwoods has been suggested. Hot-water extract contains xylan chains, xylan-based oligosaccharides, and xylose, which, after hydrolysis, may be fermented to produce biofuels or bioplastics. Value-added chemicals such as acetic acid, formic acid, and furfural may be separated from hot-water extract. Hot-water-extracted woodchips used in kraft delignification demonstrated a significant advantage compared to unextracted woodchips: under the same conditions, extracted wood required less time than unextracted wood to produce pulps of similar kappa number. The relative ease of kraft pulping of hot-water-extracted wood may be attributed, in part, to higher porosity of the wood after HWE. These results on kraft pulping indicated that hot-water-extracted wood may be more efficiently delignified with other delignification agents including environmentally friendly alternatives. In this study, different sulfur-free agents were explored for their respective delignification efficiencies in an effort to devise effective alternative methods of lignin removal from hot-water-extracted wood. Peracetic acid was investigated as an attractive delignification agent with a potential to be produced on site from acetic acid, a projected biorefinery product. Oxygen was used in combination with acetone and ethanol, which are also designed biorefinery products.