Enzymatic hydrolysis of wood with alkaline treatment
2013
Oka, D. (The University of Tokyo, Bunkyo-ku, Tokyo (Japan). Graduate School of Agricultural and Life Sciences, Department of Biomaterials Science) | Kobayashi, K. | Isobe, N. | Ogawa, Y. | Yokoyama, T. | Kimura, S. | Kim, U.J. | Tokuyasu, K. | Wada, M.
Pulverized samples of wood, cedar and eucalyptus were treated with 5 N NaOH solutions at 25-150degC. Hemicellulose and lignin content in the samples decreased with increasing treatment temperatures, while the recovery of glucose was maintained at nearly 90 %. X-ray diffraction analysis showed that the content of the original cellulose I structure in the samples decreased with increasing temperature, and most of the cellulose in the sample treated at 150degC was converted to cellulose II by mercerization. Enzymatic hydrolysis of the alkaline-treated samples was carried out at 37degC using solutions comprising a mixture of cellulase and beta-glucosidase. The samples treated at higher temperatures showed better enzymatic degradability. Treatment with an alkaline solution of lower concentration (1 N NaOH) at 150degC was also used. Despite significant quantities of hemicellulose and lignin being removed, mercerization was not induced. The enzymatic degradability was much lower than that of the sample treated with a 5 N NaOH solution at 150degC. Thus, treatment with concentrated alkaline solution at high temperature led to not only the removal of hemicellulose and lignin, but also to modification of the cellulose structure, which resulted in high efficiency of enzymatic saccharification of the wood samples.
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