期刊
CHEMICAL ENGINEERING JOURNAL
卷 112, 期 1-3, 页码 167-171出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2005.07.006
关键词
copper complex; pulp bleaching; 2,2 '-dipyriclylamine; 4-aminopyridine; lignin; ESR
Oxygen-prebleached kraft pulp (OKP) was bleached with H2O2 activated with a copper complex coordinated with 2,2'-dipyridylamine (dpa) or 4-aminopyridine (4-ap) under alkaline conditions. Bleaching of OKP by H2O2 activated with the Cu(II)-dpa complex decreased the kappa number (k) and viscosity (v) of the pulp by 26 and 0.7%, respectively. In contrast pulp bleaching without the coordinator resulted in a decrease in k and v values of 25 and 7.8%, respectively. Thus, selectivity for delignification, expressed by klv, was increased 12-fold by the coordination with dpa. ESR demonstrated that the coordination with dpa suppressed the production of (OH)-O-center dot by 57%. These results support the involvement of a hydroperoxo complex of Cu(II) formed by the reaction of -OOH with [Cu(II)(dpa)(H2O)(3)](2+) When the OKP was bleached with H2O2 activated with a Cu(II)-4-ap complex, selectivity (k/v) in pulp bleaching increased by 2.6-fold and production of (OH)-O-center dot decreased by 47%. We conclude that Cu(II)-dpa is a catalyst potentially applicable to totally chlorine free (TCF) bleaching sequences due to its high selectivity for delignification. (c) 2005 Elsevier B.V. All rights reserved.
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