Comparative study of the efficiency of synthetic and natural mediators in laccase-assisted bleaching of eucalyptus kraft pulp.
The natural phenolic compounds syringaldehyde and vanillin were compared to the synthetic mediators 1-hydroxybenzotriazole, violuric acid and promazine in terms of boosting efficiency in a laccase-assisted biobleaching of eucalyptus kraft pulp. Violuric acid and 1-hydroxybenzotriazole revealed to be the most effective mediators of the bioprocess. Nevertheless, laccase-syringaldehyde system also improved the final pulp properties (28% delignification and 63.5% ISO brightness) compared to the process without mediator (23% and 61.5% respectively), in addition to insignificant denaturation effect over laccase. The efficiency of the biobleaching process was further related to changes in non-conventionally used optical and chromatic parameters of pulp, such as (L*), chroma (C*) and dye removal index (DRI) showing good correlation. Adverse coupling reactions of the natural phenolic mediators on pulp lignin were predicted by electrochemical studies, demonstrating the complexity of the laccase-mediator reaction on pulp.
Moldes
D
D
Department of Textile and Paper Engineering, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain. diegomoldes@gmail.com
Díaz
M
M
Tzanov
T
T
Vidal
T
T
D001463:Barbiturates / Q000378:metabolism; D001547:Benzaldehydes / Q000737:chemistry / Q000378:metabolism; D003116:Color; D005052:Eucalyptus / Q000378:metabolism*; D007220:Industrial Waste; D042845:Laccase / Q000378:metabolism*; D010209:Paper; D010545:Peroxides / Q000378:metabolism; D010636:Phenols / Q000378:metabolism*; D011395:Promazine / Q000378:metabolism; D013057:Spectrum Analysis; D014230:Triazoles / Q000378:metabolism
D001463:Barbiturates; D001547:Benzaldehydes; D007220:Industrial Waste; D010545:Peroxides; D010636:Phenols; D014230:Triazoles; C094277:violuric acid; C069665:syringaldehyde; C011852:1-hydroxybenzotriazole; C100058:vanillin; D042845:Laccase; D011395:Promazine