关键词: 毛竹, 脱木质素, CO₂超临界, Klason木质素, GC-MS

Abstract: This paper researched the delignification of bamboo under the supercritical fluid of CO₂ with dioxane/water as co-solvent. The experiments were carried out by using an orthogonal experimental design for four factors in three levels. The influence of temperatures (160,180 and 200℃), pressure (16,20 and 24 MPa), reaction time (30,60 and 90 min) and co-solvent dioxane content (95%,90% and 85%) on delignification extent, pulp yields, Klason lignin content and residual holocellulose contents were analyzed. The results showed that the most important factor that affected the efficiency of delignification was the temperature and next was the pressure. The influences of reaction time and concentrations on delignification were relatively less. From the data, it can be found that the content of Klason lignin in exact liquid would be high and the pulps yield would be low when the temperature rises. Under the condition of 180℃ and 20 MPa, the high pulps yield and delignification could be obtained within 60 min with 95% concentration of dioxane/water as co-solvent and the yield run up to 84.18%. The analysis of the GC-MS of the extract liquor tested under different temperature showed that the linear chain or branch of ethoxy and alcohol, aldehyde, ketone, acid and ester of five-member ring structure were existed. Lignin's basic structure unit likes vanillin and p-hydroxyl benzaldehyde etc were found. The temperature had a great effect on the extract liquor content. There would be no furfural and benzofuran generated when the temperature was low, such as 160℃. But when the temperature increased to 200℃, the benzofuran content nearly reached to 15% and furfural content run up to more than 42%.

Key words: bamboo, delignification, supercritical, Klason lignin, GC-MS