Free and conjugated sterols are among the main compounds responsible for pitch deposition in the manufacture of wood chemical pulps, making difficult the implementation of totally chlorine free bleaching (TCF) and closure of bleach plant circuits. In this work, the suitability of oxidative enzymes in efficiently removing sterols from eucalypt pulps is revealed. The enzymatic treatment was appli...

Kraft pulp and wood powder from Acacia spp. were selected for the development of rapid, minimally-destructive, and environmentally friendly predictions of kappa number and pulp yield, by means of near infrared reflectance (NIR) spectra. The models, based on Partial Least Squares Regression (PLS-R), were established with fifty-four calibration samples selected by Principle Component Analysis (PC...

Previous work has shown that Trametes (Coriolus) versicolor bleaches kraft pulp brownstock with the concomitant release of methanol. In this work, the fungus is shown to produce both laccase and manganese peroxidase (MnP) but not lignin peroxidase during pulp bleaching. MnP production was enhanced by the presence of pulp and/or Mn(II) ions. The maximum level of secreted MnP was coincident with ...

The aim of this work is to prove the suitability of a new alkaline and halotolerant bacterial laccase (SilA) produced by Streptomyces ipomoea CECT 3341 to enhance the conventional chemical bleaching process of an industrial eucalyptus kraft pulp. The laccase used for this study was a recombinant laccase obtained from cultures of E. coli BL21 (DE3) grown in LB liquid medium. The biobleaching exp...

The enzyme involved in hexenuronic acid (HexA) removal from kraft pulp was identified in Paenibacillus sp. strain 07. Extracellular and intracellular enzymes of Paenibacillus sp. were assessed for their hexenuronosylxylotriose (∆X3) degradation activity. First, ∆X3 was obtained from hardwood kraft pulp by enzymatic hydrolysis using three commercial enzymes. Crude extracellular and intracellular...

Rice straw was cooked with three levels of alkali content (12, 14 and 16%) in cooking liquor by soda-organosolv (ethanol, diethylene glycol, dimethyl formamide) process. The effect of alkali addition on yield, kappa number, brightness and viscosity of organosolv unbleached pulps was studied. The TCF bleachability of these organosolv pulps and kraft pulp was carried out using a simple three stag...

In recent years there has been an increasing interest in using high-yield pulp (HYP) as a partial replacement for hardwood bleached kraft pulp (HWBKP) in the production of high-quality fine papers as a cost-effective way of improving the product performance. This study investigated the substitution of HYP for HWBKP and its effect on the Alkenyl Succinic Anhydride (ASA) sizing performance. The r...

Barrier paper, which is made of bleached absorbent kraft pulp, is a significant layer of decorative laminates, since it controls the see-through of brown color of saturating kraft paper and its opacifying effect usually is achieved by a heavy loading of TiO2. The TiO2, due to its very small particle size, passes between the cellulosic fibers and drains into the white water. To overcome this pro...

Steam explosion has been proposed for a wide range of lignocellulosic applications, including fractionation of biomass, pre-treatment of biomass for ethanol production, or as an alternative to conventional mechanical pulping. Nevertheless, a steam explosion process could also be used as pretreatment before chemical pulping, expecting a reduction in cooking time due to the open structure of the ...

Biobleaching of hardwood unbleached kraft pulp (UKP) by Phanerochaete chrysosporium and Trametes versicolor was studied in the solid-state fermentation system with different culture media. In this fermentation system with low-nitrogen and high-carbon culture medium, pulp brightness increased by 15 and 30 points after 5 days of treatment with T. versicolor and P. chrysosporium, respectively, and...