| 摘要 |
A bleaching process for cellulosic pulp contg. transition metals, esp. manganese, which have not been removed by washing comprises(1) ozone bleaching of highly conc. pulp (greater than 20% dryness) in an acidic medium at a max. temp. of 50 deg C; (2) diluting the pulp with water hotter than 50 deg C (e.g. 80 deg C) to give a mean pulp concn. of 10-20% dryness or lower, whilst at the same time adding complexing agent to reduce the transition metal content of the pulp; (3) neutralising the pulp to pH 4-10 (pref. 7-9); and (4) washing the pulp. Magnesium is pref. added immediately before or after step (4). |
