Electrochemically mediated bleaching of pulp fibers

Electrochemical delignification is a promising approach for the development of environmentally friendly processes in pulp bleaching. In the process described here an electrochemically generated organic radical is used to oxidize the lignin selectively. This molecule has low molecular weight and a ra...

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Bibliographic Details
Published in:Electrochimica acta 2001-12, Vol.47 (5), p.799-805
Main Authors: Kim, H.-C, Mickel, M, Bartling, S, Hampp, N
Format: Article
Language:English
Subjects:
Applied sciences
Delignification
Electrochemical
ESR
Exact sciences and technology
Half-life
Paper, paperboard, non wovens
Polymer industry, paints, wood
Pulp manufacturing
Radical
Wood. Paper. Non wovens
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Summary:Electrochemical delignification is a promising approach for the development of environmentally friendly processes in pulp bleaching. In the process described here an electrochemically generated organic radical is used to oxidize the lignin selectively. This molecule has low molecular weight and a radical-lifetime in the tens of minutes range when generated in water at temperatures between 50 and 70 °C. A favorable mediator molecule, which is consistent with most of the demands for a technical process, is violuric acid. Delignification of about 35% is obtained with 4 kg/ton pulp. The mediator violuric acid is not fully reversible in this process. The mechanism of the degradation of the mediator is still under investigation. The products generated from violuric acid during the delignification process are alloxan, parabanic acid and oxaluric acid. A demonstration setup, which allows studying the possible technical implementations of this electrochemical process, is described.
ISSN:0013-4686
1873-3859
DOI:10.1016/S0013-4686(01)00760-5