PEROXIDE BLEACHING OF PULP FROM AGRICULTURAL RESIDUES .2. FULL BLEACHING OF BAGASSE KRAFT PULP WITH LOW CHARGES OF CHLORINE

Bagasse kraft pulp of permangnate no. similar or equal to 7/was bleach ed by modifying the conventional bleaching sequence CEH by adding an a lkaline peroxide extraction stage CE(p)H. This enhanced the whiteness from 71.4 to 79.4 per cent. The efficacy of H2O2 was found to depend o n amount of peroxide, temperature, consistancy and additives. The ment ioned modification allows to reduce or even eliminate chlorine in both the chlorination and the hypochlorite stage. In further experiments a pretreatment with sulphuric acid (0.5-2%) based on pulp was studied. This led to an increase in whiteness from 62.5 to 67-per cent during t he alkaline peroxide stage.