Enhanced Enzymatic Hydrolysis of Steam-Exploded Douglas Fir Wood by Alkali-Oxygen Post-treatment

摘要

Good enzymatic hydrolysis of steam-exploded Douglas fir wood (SEDW) cannot be achieved owing to the very high lignin content (>40%) that remains associated with this substrate.Thus,in this study,we investigated the use of alkali-oxygen treatment as a posttreatment to delignify SEDW and also considered the enzymatic hydrolyzability of the delignified SEDW.The results showed that under optimized conditions of 15% NaOH,5% consistency,110 deg C,and 3 h,approx 84% of the lignin in SEDW could be removed.The resulting delignified SEDW had good hydrolyzability,and cellulose-to-glucose conversion yields of over 90 and 100% could be achieved within 48 h with 20 and 40 filter paper units/g of cellulose enzyme loadings,respectively.It was also indicated that severe conditions,such as high NaOH concentration and high temperature,should not be utilized in oxygen delignification of SEDW in order to avoid extensive condensation of lignin and significant degradation of cellulose.