CELLULOSE DEPOLYMERIZATION TO GLUCOSE AND OTHER WATER-SOLUBLE POLYSACCHARIDES BY SHEAR DEFORMATION AND HIGH-PRESSURE TREATMENT

The simultaneous action of shear deformation and high pressure (SDHP) creates changes in the structure of wood and its main components (cell ulose, hemicelluloses, lignin). The formation of water and alkali solu ble polysaccharides under SDHP action, proceeds in seconds in the soli d state, without the use of any reagents and solvents. Therefore, SDHP seems to be a technologically safe method and friendly to the environ ment. The amorphization of cellulose crystallites and depolymerization of cellulose chains were observed under a wide range of pressures (1- 6 GPa), both for cellulose samples and the cellulose part of wood. Sim ilar depolymerization occurs in the hemicellulose part of wood. The de composition of polysaccharides under SDHP causes the formation of the water soluble part, whose content increases with pressure and the appl ied shear deformation. A maximum solubility of 40% and 55% was registe red at 6 GPa following treatment of cellulose and birch wood samples. A higher output in the case of wood can be explained by a specific rol e of lignin under SDHP, which acts as a 'grinding stone' during cellul ose and hemicelluloses destruction. As shown by high-performance size exclusion chromatography, the water soluble fraction obtained from cel lulose contained glucose (2.6%), cellobiose (9.6%), cellotriose (16.6% ) and other higher water soluble oligomers (71%). Almost complete diss olution (98%) of the treated cellulose sample can be achieved by extra ction with 10% NaOH solution. The SDHP treated birch wood was subjecte d to submerged fermentation (with Trichoderma viride), and a 13% outpu t of proteins was obtained. In this case, the water soluble part playe d the role of the so called 'start sugars'.