Overview of ozone bleaching
Conference
·
OSTI ID:214638
- Institute of Paper Science and Technology, Atlanta, GA (United States)
The potential impact of the pulp and paper industry on the environment may be reduced by replacing chlorine-based bleaching reagents with ozone. The reactivity of ozone coupled with the heterogeneity of pulp allows many types of reactions to occur during pulp bleaching. Ozone cleaves the aromatic rings and side chain double bonds in lignin in Criegee-type mechanisms. Activated carbon-hydrogen bonds are fragmented in lignin side chains, as well as Cl carbons of {beta}-glycosides, by way of a 1,3 dipolar insertion forming a hydrotrioxide intermediate. Ozone also attacks carbohydrates at acetal oxygens, depolymerizing at the glycosidic bond. Unsaturated sites are ozonated before aliphatic sites resulting in a predominance of lignin reactions over carbohydrate reactions until lignin is substantially removed from the pulp. Important factors in the successful application of ozone bleaching include minimizing ozone decomposition and other secondary reactions, reducing exposure of cellulose to high concentrations of ozone and radicals, and promoting uniform exposure of ozone to lignin. The quantity of chlorinated organic compounds in effluents can be drastically reduced by replacing chlorine-based bleaching reagents with ozone; less organochlorine is formed and there can be greater recycle of bleach plant wastes back to the recovery cycle. Recycling of bleach plant waste also reduces total organic loading in the effluent. The toxicity of ozone filtrates is variable compared to conventional filtrates and depends on several parameters including bleaching conditions, biological treatment, and target organisms.
- OSTI ID:
- 214638
- Report Number(s):
- CONF-950801--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Use of xylanase in the TCF bleaching of eucalyptus kraft pulp
Recycling of bleach plant filtrates by electrodialysis removal of inorganic non-process elements.
Management of nonprocess elements in low-effluent bleached kraft pulp mills
Conference
·
Tue Oct 01 00:00:00 EDT 1996
·
OSTI ID:370073
Recycling of bleach plant filtrates by electrodialysis removal of inorganic non-process elements.
Technical Report
·
Sun Mar 03 23:00:00 EST 2002
·
OSTI ID:793088
Management of nonprocess elements in low-effluent bleached kraft pulp mills
Conference
·
Sat Dec 30 23:00:00 EST 1995
·
OSTI ID:214631