FORMATION OF CHLORINATED ORGANIC MATERIAL AND CHLORATE DURING CHLORINE DIOXIDE PREBLEACHING OF KRAFT PULP - EFFECTS OF SODIUM-CHLORIDE, CHARGE OF CHLORINE DIOXIDE AND PH
Pi. Gunnarsson et S. Ljunggren, FORMATION OF CHLORINATED ORGANIC MATERIAL AND CHLORATE DURING CHLORINE DIOXIDE PREBLEACHING OF KRAFT PULP - EFFECTS OF SODIUM-CHLORIDE, CHARGE OF CHLORINE DIOXIDE AND PH, Journal of pulp and paper science, 22(12), 1996, pp. 457-463
The presence of sodium chloride in the chlorine dioxide stage affects
the formation of chlorinated organic material (AOX) as found in spent
bleach liquor from a D(EP) bleaching sequence of oxygen-predelignified
kraft pulp. It is shown in this work that the effect of chloride to a
large extent interacts with the effect of the amount of charged chlor
ine dioxide. At a high charge of chlorine dioxide, AOX tends to decrea
se but, at lower charges, AOX tends instead to increase. The formation
of chlorinated organic material in the pulp (OCl) is increased by the
presence of chloride under all conditions and is decreased only by us
ing a higher end pH (pH 4). The chlorate formation is decreased by the
addition of chloride and also by a higher end pH. The mechanisms of t
hese effects of chloride and pH on AOX, OCl and chlorate formation are
complex and involve several reactions which are discussed.