Influence of Oxygen Derived Chemicals on Bleachability of Non Wood Fiber, 1996 Pulping Conference Proceedings

Bindu Dhasmana & Jeffery S. Hsieh

Georgia Institute of Tech.

In recent years, due to the restriction on forests cutting and shortage of wood pulp people have certainly directed their attention towards Kenaf (Hibiscus Cannabinus), a nonwood fiber. Currently very little information is available on its pulp behavior towards oxygen derived chemicals. In present study Kenaf was cooked with soda-AQ pulping process and bleached with oxygen derived chemicals such as oxygen, and hydrogen peroxide. Effect of total chlorine free bleaching sequence OQPP, OQPQP and elemental chlorine free bleaching sequence DEDED were studied for both core and bast pulp. Beating of bleached bast and its blending with bleached core pulp were studied. Results indicate that unbleached Kenaf bast has higher pulp yield than the unbleached core fiber. To reach same kappa fiber. Unbleached bast has 700 Canadian standard freeness and 55.5 cP viscosity while core has 430 CSF freeness and 28.7 cP viscosity. Bast showed better bleachability in compare to core fiber during ECF and TCF bleaching sequences. Final brightness and final viscosity of bast fiber was about 6 points higher then the core fiber during ECF bleaching process.. Higher delignification (43% ) and significant reduction (32%) in viscosity was observed for bast fiber during oxygen delignification in compare to core fiber (30% delignification and 9% reduction in viscosity). TCF bleached pulp at +83% ISO brightness with less degradation of carbohydrate can be obtained from Kenaf bast and core fiber using oxygen and hydrogen peroxide with proper pretreatment. TCF Bleached bast had very high freeness in compare to TCF bleached core. To reach desired freeness bast pulp need significantly lower refining while core pulp need little or no refining compare to wood pulp. Core can be blended with bast at higher ratio without adverse effect on freeness.