Lignocellulosic pulp bleaching - by treating with an acid, complexing agent, a calcium and magnesium cpd. then peroxide bleaching

摘要

Lignocellulosic pulp (I) is (i) acid treated at pH upto 5 (ii) treated with a complexing agent then (iii) a calcium and a magnesium cpd. added to the pulp at 3.5-9 pH followed by (iv) bleaching with a peroxide contg. cpd. at 7-13 pH. Stages (i) of (iii) may be in any order.