Comparative study of the efficiency of synthetic and natural mediators in laccase-assisted bleaching of eucalyptus kraft pulp

Moldes, Diego; Díaz, María José Moreno; Tzanov, Tzanko; Vidal, Teresa

doi:10.1016/j.biortech.2008.04.002

Cited by 85 publications

(47 citation statements)

References 41 publications

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“…The advantage of using natural enhancers resides in the low cost and lack of toxicity since they are obtained from natural, renewable sources. Some natural compounds, mostly phenols, involved in the synthesis and degradation of lignin have been recently revealed as efficient enhancers for laccase catalyzed oxidation of kraft lignin [7,20,23], polycyclic aromatic hydrocarbons [22], recalcitrant dyes [21] and also for removal of lipophilic extractives from paper pulp [24]. The purpose of the present study was to evaluate by means of electrochemical techniques the efficiency of 16 phenolic compounds, of which 14 are naturally occurring, as mediators/enhancers in laccase-assisted bleaching of pulp, using veratryl alcohol as a lignin model compound.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Study of Phenolic Compounds as Enhancers in Laccase‐Catalyzed Oxidative Reactions

2009

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Sixteen phenolic compounds, twelve of which derived from lignin, were evaluated as potential mediators for laccaseassisted bleaching of pulp. The electrochemical behavior of these phenols, alone and in the presence of the lignin model compound veratryl alcohol, was studied by means of cyclic voltammetry. All phenolic compounds showed catalytic effect on the veratryl alcohol electrochemical oxidation. However, they could not be considered as mediators, since their oxidation products are not stable and regeneration of their reduced forms was not observed. The redox potentials of the phenolic compounds seem to have a negligible effect on their catalytic efficiency, supporting a H-abstraction oxidation mechanism. This mechanism was also confirmed by electrochemical studies of 2,4,6-trimethylphenol in acetonitrile and in the presence of benzyl alcohols.

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Section: Introductionmentioning

confidence: 99%

Electrochemical Study of Phenolic Compounds as Enhancers in Laccase‐Catalyzed Oxidative Reactions

2009

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“…However, this process is not fully developed due to the availability of efficient and stable in industrial conditions enzymes, the high cost and potential toxicity of the mediators and the long reaction times involved [2,3]. Moreover, oxidative enzymes have scarcely been used to bleach non-wood pulp [4][5][6][7][8]; also, most kinetic studies on their effects have focused on the action of laccase mediator systems (LMS) in reactions with lignin model compounds for short times [9,10].…”

Section: Introductionmentioning

confidence: 99%

Biobleaching of high quality pulps with laccase mediator system: Influence of treatment time and oxygen supply

Fillat

Roncero

2009

Biochemical Engineering Journal

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In this study we examined the influence of the treatment time and addition of oxygen on the efficiency of a laccase mediator system (L) applied to flax pulp at atmospheric pressure. The redox potential and the dissolved oxygen concentration during L tests are measured. After L stage, an alkaline extraction (E) is carried out. The pulp properties (kappa number, brightness and viscosity) and the effluents properties (color and COD) were measured in order to evaluate the environmental impact of this enzymatic treatment.The biotreatment involves two distinct stages in both L and LE sequences; in the beginning the pulp exhibits a fast delignification and a slow viscosity decrease that is followed by slow delignification in the second. Pulp brightness changed differently during L stage and LE sequence.Initially brightness after the L stage decreased with respect to the initial pulp; then, it increased rapidly and eventually leveled off. After the LE sequence, brightness increased rapidly in the beginning and more gradually afterwards. The results show that supplying the medium with oxygen and increasing the oxygen concentration in it, influence the kinetics of the process.Based on CIE L*a*b* color coordinates study, the enzyme treatment not only removes lignin, but also alters the structure of the pulp by causing the formation of chromophoric groups giving color.Such groups are removed in an E stage.

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“…Given the high cost of HBT and the tendency of the HBT oxidant to inactivate laccase, other mediators, both synthetic and natural, have been sought [39,52,53,[56][57][58][59][60][61][62]. For example, the synthetic mediator NHA has been described as both cost effective and biodegradable, with another particular advantage that laccase retains about 80% of its initial activity in an LMS stage with this mediator [63].…”

Section: Laccase and The Mediator Systemmentioning

confidence: 99%

Mixed Enzyme Systems for Delignification of Lignocellulosic Biomass

Woolridge

2014

Catalysts

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Abstract:The application of enzymes such as laccase and xylanase for the preparation of cellulose from lignocellulosic material is an option for those industries seeking to reduce the use of chlorine-containing bleach agents, thus minimizing the environmental impact of their processes. Mixed hydrolytic and oxidative enzyme systems have been well described in the context of biopulping, and thus provide good precedent regarding effectiveness, despite the susceptibility of xylanase to inactivation by laccase-generated oxidants. This paper examines the progress towards development of sequential and simultaneous mixed enzyme systems to accomplish delignification.

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Comparative study of the efficiency of synthetic and natural mediators in laccase-assisted bleaching of eucalyptus kraft pulp

Cited by 85 publications

References 41 publications

Electrochemical Study of Phenolic Compounds as Enhancers in Laccase‐Catalyzed Oxidative Reactions

Electrochemical Study of Phenolic Compounds as Enhancers in Laccase‐Catalyzed Oxidative Reactions

Biobleaching of high quality pulps with laccase mediator system: Influence of treatment time and oxygen supply

Mixed Enzyme Systems for Delignification of Lignocellulosic Biomass

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