J. Rutkowski et K. Perlinskasipa, DELIGNIFICATION AND BLEACHING OF HARDWOOD KRAFT PULP WITH HYDROGEN-PEROXIDE AND NITROGEN-DIOXIDE, Cellulose Chemistry and Technology, 28(1), 1994, pp. 35-45
The influence of both H2O2 charge and of the time of hardwood kraft pu
lp delignification on the technological and water-effluent indices of
the process was investigated. It was confirmed that definite two-stage
pulp delignification sequences with application in one of the stages
of hydrogen peroxide or nitrogen dioxide generated in situ from acidif
ied sodium nitrite, may decrease the kappa number to half of its initi
al value, thus improving the brightness of pulp. The impact of convent
ional multistage bleaching in GEHDED sequence, as well as in sequences
with hydrogen peroxide or nitrogen dioxide, permitting to obtain pulp
s of over 88% brightness, on the technological and water-effluent effe
cts, were determined. The influence of replacing elemental chlorine by
the mentioned chlorine-free delignification agents, on the decrease o
f pollution load in effluents, including the AOX index and shortening
of the time of bleaching process, was established.