ALKALINE PULPING OF HEMP WOODY CORE - KINETIC MODELING OF LIGNIN, XYLAN AND CELLULOSE EXTRACTION AND DEGRADATION

The kinetics of alkaline degradation of lignin, xylan and cellulose in relation to pulp yield were studied for hemp woody core to support de velopment and optimization of a non-polluting alkaline pulping process . Shavings of hemp woody core were impregnated at room temperature wit h various sodium hydroxide concentration (0.25-2 M NaOH) and delignifi ed isothermally at various reaction temperatures (150-180 degrees C) i n a flow-through reactor. Extraction and degradation of xylan from hem p woody core was strongly depending on the NaOH concentration used. Co nsequently, to attain a certain lignin content, lower NaOH concentrati ons result in higher pulp yields. Extended pulping diminished the diff erences in pulp yields, due to further xylan degradation. The kinetics of lignin, xylan and cellulose degradation were modelled as a functio n of reaction time, temperature and NaOH concentration. The combined m odels resulted in a pulp yield model for hemp woody core, suitable for process optimization purposes. Degradation kinetics of perennial wood can be modelled similarly, which was illustrated using literature dat a on spruce and poplar.