Hydrogen peroxide and supercritical carbon dioxide: a new bleaching stage for Eucalyptus kraft-O2 pulps

Holzforschung ◽  
2011 ◽  
Vol 65 (3) ◽  
Author(s):  
Roberta Pacheco Francisco ◽  
Jorge Luiz Colodette ◽  
Antonio Aprigio da Silva Curvelo
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Supercritical Carbon Dioxide ◽  
Kraft Pulp ◽  
Poor Performance ◽  
Kappa Number ◽  
Elemental Chlorine ◽  
Chlorine Gas ◽  
Hexenuronic Acid ◽  
Supercritical Carbon

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.

ECF Bleaching of Pre-Hydrolyzed Larix Kraft Pulp for Production of Dissolving Pulp

2013 ◽  
Vol 634-638 ◽  
pp. 386-390
Author(s):  
Zhi Li ◽  
Jun Li ◽  
Jun Xu
Keyword(s):  
Hydrogen Peroxide ◽  
Chlorine Dioxide ◽  
Kraft Pulp ◽  
Kappa Number ◽  
Alkaline Extraction ◽  
Polymerization Degree ◽  
Oxygen Delignification ◽  
Elemental Chlorine ◽  
Pulp Properties ◽  
Ecf Bleaching

Elemental Chlorine Free (ECF) bleaching sequence of O1/O2D0EOPD1D2 was adopted to bleach the pro-hydrolyzed Larix kraft pulp, where O1/O2 was two-stage oxygen delignification without interstage treatment, D was chlorine dioxide bleaching, EOP was pressurized alkaline extraction strengthened by hydrogen peroxide. Keeping bleaching temperature and time unchanged, sodium hydroxide charge(NaOH) in O1 stage, chlorine dioxide(ClO2) charge in D0 stage and D2 stage were studied, pulp properties such as brightness, kappa number, alpha-cellulose, pentosan and polymerization degree were measured and compared to establish optimal bleaching conditions. Results show that the optimal charge of NaOH in O1 stage is 2.5%, ClO2 in D0 and D2 stage are 2.5%, 0.6%, and the pulp gained at the optimal bleaching conditions has the properties of 93.9% of alpha-cellulose, 2.60% of pentosan, 375.5 ml/g of viscosity and 86.6%ISO of brightness.

Antioxidant property of TCF pulp with a high hexenuronic acid (HexA) content

Holzforschung ◽  
2013 ◽  
Vol 67 (3) ◽  
pp. 257-263 ◽  
Author(s):  
Cristina Valls ◽  
M. Blanca Roncero
Keyword(s):  
Kraft Pulp ◽  
Antioxidant Property ◽  
Kappa Number ◽  
Raw Material ◽  
Antioxidant Power ◽  
Elemental Chlorine ◽  
Enzyme Pretreatment ◽  
Extraction Stage ◽  
Hexenuronic Acid ◽  
Oxidized Products

Abstract Totally chlorine free (TCF) pulp with a high content of hexenuronic acids (HexAs) was found to possess a high antioxidant power. The contribution of HexA to kappa number in unbleached Eucalyptus globulus kraft pulp was estimated to be 1.05 units per 10 μmol of HexA. The variation of HexA and lignin contents in enzymatic elemental chlorine free (ECF) and TCF sequences was monitored, and interesting effects were observed during the TCF XLE sequence, where X denotes an enzyme pretreatment with xylanase, L a laccase-mediator stage, and E an alkaline extraction stage. Thus, HexA removal during L stage was strongly enhanced after the X stage; also, the HexA content was decreased by the alkaline stage. None of these effects was observed in the ECF sequence with chlorine dioxide. The antioxidant power detected in HexA makes TCF pulp an excellent raw material for manufacturing packaging for easily oxidized products.

High-consistency ozonation of hardwood kraft pulp

Holzforschung ◽  
2006 ◽  
Vol 60 (6) ◽  
pp. 685-690 ◽  
Author(s):  
Ai Van Tran
Keyword(s):  
Kraft Pulp ◽  
Kappa Number ◽  
Second Phase ◽  
Residual Lignin ◽  
Two Phase ◽  
Elemental Chlorine ◽  
Ozonation Time ◽  
Shrinking Core ◽  
High Consistency ◽  
Hexenuronic Acid

Abstract At present, ozone is one of the main chemicals in elemental chlorine-free (ECF) and totally chlorine-free (TCF) bleaching sequences. High consistency (HC) and medium consistency (MC) technologies are in use. This study shows that HC ozonation of hardwood kraft pulp, as expressed by the overall kappa number encompassing both hexenuronic acid groups and residual lignin, is a two-phase path. The reaction rate of the first phase is two- to three-fold higher than that of the second phase. We propose that the first phase is due to ozonation of both hexenuronic acid groups and residual lignin, whereas the second phase involves only residual lignin. The fiber width and wall thickness were relatively unchanged during ozonation. These results are in contrast to the “shrinking core kinetic model” frequently discussed in the context of HC ozonation. The development of pulp brightness and the decrease in pulp viscosity with the ozonation time are well correlated with the overall kappa number or the kappa number due to residual lignin alone.

Olefin Epoxidations Using Supercritical Carbon Dioxide and Hydrogen Peroxide without Added Metallic Catalysts or Peroxy Acids

2002 ◽  
Vol 41 (3) ◽  
pp. 316-323 ◽  
Author(s):  
Shane A. Nolen ◽  
Jie Lu ◽  
James S. Brown ◽  
Pamela Pollet ◽  
Brandon C. Eason ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Supercritical Carbon Dioxide ◽  
Olefin Epoxidations ◽  
Peroxy Acids ◽  
Supercritical Carbon

Sterilisation of collagen materials using hydrogen peroxide doted supercritical carbon dioxide and its effects on the materials properties

2015 ◽  
Vol 102 ◽  
pp. 32-39 ◽  
Author(s):  
Michael Meyer ◽  
Ina Prade ◽  
Kathrin Leppchen-Fröhlich ◽  
Alexander Felix ◽  
Volker Herdegen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Supercritical Carbon Dioxide ◽  
Materials Properties ◽  
Supercritical Carbon

scholarly journals Effects of supercritical carbon dioxide on morphology of apocynum venetum fibers

2015 ◽  
Vol 19 (4) ◽  
pp. 1279-1282 ◽  
Author(s):  
Shi-Hui Gao ◽  
Chong-Wen Yu
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Scanning Electron Microscopy ◽  
Supercritical Carbon Dioxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Apocynum Venetum ◽  
Scanning Electron ◽  
Supercritical Carbon

This paper investigated the structures and compositions of apocynum venetum fibers treated with pectinase and mixture of sodium hydroxide and hydrogen peroxide in supercritical carbon dioxide fluid. The apocynum venetum fibers were analyzed by Fourier transform infrared spectrometry, X-ray diffraction, and scanning electron microscopy. Fourier transform infrared analysis indicated that pectinase could remove the pectin and hemicellulose and the mixture of sodium hydroxide and hydrogen peroxide could extract the lignin in supercritical carbon dioxide. Meanwhile, the results of X-ray diffraction showed that cellulose crystallinity index and crystallite sizes of treated fibers increased in comparison with that of untreated fibers. The studies of scanning electron microscopy also revealed a complete removal of non-cellulosic gummy material from surface of treated apocynum venetum fibers. Small gummy on the surface of apocynum venetum fibers would be removed by supercritical carbon dioxide, which can be verified by bubble dynamics.

Sign in / Sign up

Export Citation Format

Share Document