CAROATE DELIGNIFICATION ENHANCEMENT BY HALIDES

Citation
Rc. Francis et al., CAROATE DELIGNIFICATION ENHANCEMENT BY HALIDES, Tappi journal, 77(7), 1994, pp. 135-141
Citations number
20
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Materials Science, Paper & Wood
Journal title
Tappi journal → ACNP
ISSN journal
0734-1415
Volume
77
Issue
7
Year of publication
1994
Pages
135 - 141
Database
ISI
SICI code
0734-1415(1994)77:7<135:CDEBH>2.0.ZU;2-5
Abstract
A process is described where conventional or extended delignified kraf tpulps are further delignified to low kappa numbers by an oxygen stage followed by a caroate stage (OKE). The highly delignified pulps can b e brightened by conventional chlorine dioxide treatment or by a high c onsistency hydrogen peroxide stage. A halide, preferably chloride, is added to the caroate stage. The chloride at accelerates lignin degrada tion and simultaneously retards cellulose depolymerization. In the pro cess, the chloride is oxidized to chlorine by the peracid. The involve ment of chlorine results in an effluent containing 0.5-0.7 kg of adsor bable organic halogens (AOX) per ton of pulp. If the Cl2 can be replac ed by another strong electrophile, such as dimethyldioxirane or ozone, then elemental chlorine-free (ECF) or totally chlorine-free (TCF) seq uences can be projected.