Hydrogen peroxide and supercritical carbon dioxide: a new bleaching stage for Eucalyptus kraft-O2 pulps
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Roberta Pacheco Francisco
,
Jorge Luiz Colodette
Abstract
Kraft pulp is currently bleached largely by the elemental chlorine free (ECF) technology with oxygen, chlorine dioxide, and hydrogen as active agents. This technology brought about significant environmental improvements in relation to standard processes based on chlorine gas and hypochlorite, but there is still need for further improvements. This study presents a novel environmentally friendly bleaching stage – the so-called ‘hydrogen peroxide in supercritical carbon dioxide’, P(SC-CO2) – that can be adapted to current ECF bleaching processes, with preference in cases where hydrogen peroxide is already used. In this study, the P(SC-CO2) stage was evaluated as a replacement to the last peroxide stage of the D(EP)DP bleaching sequence and to the first peroxide stage of the D(EP)DP sequence, for an oxygen delignified eucalypt kraft-O2 pulp. The P(SC-CO2) stage was run with 0.5% hydrogen peroxide, at 15% consistency, 70°C, and 73 bar. The reaction time was 30 min. The performances of regular P stages and the new P(SC-CO2) stage were compared. Promising results were observed with the DEP(SC-CO2)DP sequence; the P(SC-CO2) decreased kappa number from 2.7 to 2.1, and the hexenuronic acid groups from 17.0 to 12.4 mmol kg-1. The P(SC-CO2) stage showed poor performance when applied in the D(EP)DP(SC-CO2) sequence. It is concluded that the process presents potential but requires further optimization to improve selectivity and efficiency.
©2011 by Walter de Gruyter Berlin New York
Artikel in diesem Heft
- Publisher’s Note
- Publisher’s Note
- ORIGINAL ARTICLES
- Brightness reversion of eucalyptus kraft pulp: Effect of carbonyl groups generated by hypochlorous acid oxidation
- MgSO4 vs. Mg(OH)2 as a cellulose protector in oxygen delignification
- Hydrogen peroxide and supercritical carbon dioxide: a new bleaching stage for Eucalyptus kraft-O2 pulps
- Preparation and physical characterization of strongly swellable oligo(oxyethylene) lignin hydrogels
- Activation of pine kraft lignin by Fenton-type oxidation for cross-linking with oligo(oxyethylene) diglycidyl ether
- Determination of pectin content of eucalyptus wood
- Theory of transport processes in wood below the fiber saturation point. Physical background on the microscale and its macroscopic description
- The effect of galactan content on the mechano-sorptive strain in loblolly pine
- Genetic and environmental variation in heartwood colour of Australian blackwood (Acacia melanoxylon R.Br.)
- Aging of wood: Analysis of color changes during natural aging and heat treatment
- Thermal behaviour of Norway spruce and European beech in and between the principal anatomical directions
- Air-coupled ultrasound inspection of glued laminated timber
- Optical characteristics of wood investigated by time-of-flight near infrared spectroscopy
- Comparison of NDE techniques for assessing mechanical properties of unjointed and finger-jointed lumber
- Potential of pulp and paper sludge as a formaldehyde scavenger agent in MDF resins
- FT-IR imaging microscopy to localise and characterise simultaneous and selective white-rot decay within spruce wood cells
- Effects of ionic strength, monoethanolamine, copper, and pH on adsorption of alkyl dimethyl benzyl ammonium chloride in wood
- Long-term performance of fused borate rods for limiting internal decay in Douglas-fir utility poles
- SHORT NOTE
- Composition of the heartwood essential oil of incense cedar (Calocedrus decurrens Torr.)
- Meetings
- Meetings
Artikel in diesem Heft
- Publisher’s Note
- Publisher’s Note
- ORIGINAL ARTICLES
- Brightness reversion of eucalyptus kraft pulp: Effect of carbonyl groups generated by hypochlorous acid oxidation
- MgSO4 vs. Mg(OH)2 as a cellulose protector in oxygen delignification
- Hydrogen peroxide and supercritical carbon dioxide: a new bleaching stage for Eucalyptus kraft-O2 pulps
- Preparation and physical characterization of strongly swellable oligo(oxyethylene) lignin hydrogels
- Activation of pine kraft lignin by Fenton-type oxidation for cross-linking with oligo(oxyethylene) diglycidyl ether
- Determination of pectin content of eucalyptus wood
- Theory of transport processes in wood below the fiber saturation point. Physical background on the microscale and its macroscopic description
- The effect of galactan content on the mechano-sorptive strain in loblolly pine
- Genetic and environmental variation in heartwood colour of Australian blackwood (Acacia melanoxylon R.Br.)
- Aging of wood: Analysis of color changes during natural aging and heat treatment
- Thermal behaviour of Norway spruce and European beech in and between the principal anatomical directions
- Air-coupled ultrasound inspection of glued laminated timber
- Optical characteristics of wood investigated by time-of-flight near infrared spectroscopy
- Comparison of NDE techniques for assessing mechanical properties of unjointed and finger-jointed lumber
- Potential of pulp and paper sludge as a formaldehyde scavenger agent in MDF resins
- FT-IR imaging microscopy to localise and characterise simultaneous and selective white-rot decay within spruce wood cells
- Effects of ionic strength, monoethanolamine, copper, and pH on adsorption of alkyl dimethyl benzyl ammonium chloride in wood
- Long-term performance of fused borate rods for limiting internal decay in Douglas-fir utility poles
- SHORT NOTE
- Composition of the heartwood essential oil of incense cedar (Calocedrus decurrens Torr.)
- Meetings
- Meetings
