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C. C. Walker, T. J. McDonough, R. J. Dinus, K.-E. L. Eriksson

Selectivity and Efficiency of Biomimetic Catalysts in a Model System for Pulp Bleaching

Three biomimetic systems were evaluated for their selectivity in a model system for pulp. FeSO₄, Fe-EDTA and hemoglobin, in the presence of H₂O₂, constituted the biomimetic systems. Sodium lignosulfonate and hydroxyethyl cellulose (HEC) were used as a model system to represent lignin and carbohydrate fractions in pulp. A simple kinetic model was used to determine kinetic parameters for depolymerization of each substrate. Point selectivities at two different H₂O₂ concentrations were evaluated on the basis of the resulting expressions. Hemoglobin demonstrated superior selectivity for lignosulfonate degradation at a high H₂O₂ level. The production of hydroxyl radicals from each of the biomimetic systems was measured using a chemiluminescence assay. For the FeSO₄ and Fe-EDTA systems, depolymerization was related to the amount of radicals generated. The fate of reacted H₂O₂ was evaluated using a specially designed reactor to measure H₂O₂ consumed by reaction and that decomposed. To achieve a given number of chain scission in lignosulfonate, the hemoglobin system consumed the least amount of H₂O₂.

Holzforschung, Walter de Gruyter

Print ISSN: 0018-3830
Volume: 55, 06/2001
Pages: 391 - 396

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