Quality Improvement of Rayon Grade Bamboo Pulp by Modified Bleaching

The presence of high silica in bamboo hinders the use of this material for production of rayon grade pulp. Research has been carried out to overcome this deficiency and improve quality of rayon grade pulp with the modification in pulping and bleaching process. Effect of acid boosted water prehydrolysis, sulphuric acid pre-treatment of unbleached pulp, chlorination stage at lower pH and treatment of bleached pulp with SO₂ water were evaluated. Acid boosted water prehydrolysis of chips reduces prehydrolysis time by 50 minutes as compared to water prehydrolysis. Treatment of unbleached pulp with sulphuric acid reduces ash, acid insoluble, silica, calcium and iron contents of the pulp by 56, 31, 82, 84 and 60% respectively. The addition of acid, increase in kappa factor in C D stage and combination of both were effective in removing silica in the pulp. Treatment of final bleached pulp with SO₂ water removes silica to a great extent and improves optical properties of the pulp as compared to H₂SO₄ or PAA. Pretreatment of the pulp with acid and modification in the bleaching process can reduce silica substantially and improve the quality of rayon grade bamboo pulp.