EFFECTS OF pH CONTROL WITH PHTHALATE BUFFERS ON HOT-WATER EXTRACTION OF HEMICELLULOSES FROM SPRUCE WOOD
The extraction of galactoglucomannans (GGMs) from ground spruce (Picea abies) sapwood was studied using pressurised hot water with different phthalate buffer additions, providing different and fairly constant pH-levels in the range of 3.8 ~ 4.4. The primary aim was to extract GGMs from spruce wood in high yield and with high molar mass. The extractions were carried out in an accelerated solvent extractor (ASE300) at 170℃ with extraction times of 20,60 and 100 minutes. Addition of phthalate buffers enhanced the extraction of GGMs from wood compared to extraction with plain water. Higher yields of dissolved carbohydrates than with plain water were obtained with buffers at pH 3.8 and 4.0. With these water solutions, about 60％ of the total non-cellulosic carbohydrates were extracted in 60 min. About 70％ of the total dissolved solids (TDS) were non-cellulosic carbohydrates, i.e., hemicelluloses in polymeric or oligomeric form with GGMs as the main group. About 75％ of the GGMs in the wood, i.e. about 12％ based on original wood, was extracted with the pH 3.8 buffer solution in 60 min. Extractions with buffers at pH 4.2 and 4.4 gave lower yields of carbohydrates, but both hydrolytic depolymerisation and deacetylation of GGMs were less extensive at these pH levels. It is concluded that pH control to a level around 4 provides optimal conditions for extraction of GGMs in polymeric form from wood.
acetyl groups galactoglucomannan hemicelluloses hot-water extraction molar mass non-cellulosic carbohydrates phthalate buffer Picea abies spruce wood xylan
Tao Song Andrey Pranovich Bjarne Holmbom
Laboratory of Wood and Paper Chemistry, Process Chemistry Centre, (A)bo Akademi University, Porthansgatan 3, FI-20500, Turku/(A)bo, Finland
国际会议
16th International Symposium on Wood,Fiber and Pulping Chemistry(第十六届木材、纤维及制浆化学国际会议)
天津
英文
408-412
2011-06-08（万方平台首次上网日期，不代表论文的发表时间）