Abstract
Eucalyptus globulus wood chips were decayed by the lignin-degrading fungus Ceriporiopsis subvermispora as a pretreatment step before kraft pulping. Weight and component losses of wood after the biotreatment were the following: weight (5%), glucans (1.5%), xylans (4.3%), lignin (5.7%) and extractives (57.5%). The residual amount of lignin (expressed by the kappa number) in pulps from biotreated wood chips was lower than that of pulps from the undecayed control. Depending on the delignification degree, kraft biopulps presented similar or up to 4% increase in pulp yield and 20% less hexenuronic acids (HexA) than control pulps. The extended delignification with O2 decreases approximately 50% of the kappa number of the pulps and increases brightness, but had no effect in HexA reduction. The bleaching steps with chlorine dioxide (D0ED1 sequence) decreased the kappa number up to 97%, increased pulp brightness up to 84% ISO and decreased HexA amount up to 91%. The use of C. subvermispora in biopulping of E. globulus generated important benefits during the production of kraft pulps that are reflected in a high pulp yield, low residual lignin content, low HexA amount, high brightness and viscosity of the biopulps as compared with pulps produced from untreated wood chips.
Highlights
Biopulping is the pretreatment of wood chips with lignin-degrading white-rot fungi (WRF)
We reported the evaluation of the biotretatment of Eucalyptus globulus, the main hardwood species used by the Chilean pulp and paper industry, with the biopulping fungus Ceriporiopsis subvermispora and its effects in the kraft delignification and elementary chlorine free (ECF) bleaching of pulps
The high degradation of lignin and extractives over glucan showed a preferential pattern of decay of this fungus that make C. subvermispora the main white-rot fungi used for biopulping studies (FRANCO et al, 2006; GUERRA et al, 2003; MARDONES et al, 2006; MENDONÇA et al, 2002; VICENTIM et al, 2009)
Summary
Biopulping is the pretreatment of wood chips with lignin-degrading white-rot fungi (WRF). The so-called “biotreated wood chips” were further used in mechanical or chemical pulping processes where several benefits of this biological pretreatment have been reported for both softwoods and hardwoods (AKHTAR et al, 1998; MENDONÇA et al, 2002, 2004; FERRAZ et al, 2008). Technology carried out in closed bioreactors or in open Wood chip piles, depending on the requirements of the particular microorganism would have for optimal results (AKHTAR et al, 1998; FERRAZ et al, 2008). The partial degradation and structural modifications of native lignin are considered the main characteristics that facilitate its removal and wood softening in the subsequent pulping processes. Mendonça et al (2002) showed that high-yield kraft pulps from Pinus taeda wood chips pretreated with
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