Minimizing viscosity loss during totally chlorine-free bleaching of hardwood kraft pulp
By applying increasing amounts of ozone (Z stage bleaching) on eucalyptus oxygen-delignified pulps, it was observed that both lignin and hexenuronic acids (HexA) are attacked early during the treatment. While the HexA were progressively removed, however, the oxidized lignin tended to stay in the pul...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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North Carolina State University
2013-02-01
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| Series: | BioResources |
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| Online Access: | http://www.ncsu.edu/bioresources/BioRes_08/BioRes_08_1_0238_Pouyet_LDC_Viscosity_Loss_TCF_HW_Kraft_Pulp_3410.pdf |
| _version_ | 1818873262455652352 |
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| author | Frédéric Pouyet Dominique Lachenal Satyajit Das Christine Chirat |
| author_facet | Frédéric Pouyet Dominique Lachenal Satyajit Das Christine Chirat |
| author_sort | Frédéric Pouyet |
| collection | DOAJ |
| description | By applying increasing amounts of ozone (Z stage bleaching) on eucalyptus oxygen-delignified pulps, it was observed that both lignin and hexenuronic acids (HexA) are attacked early during the treatment. While the HexA were progressively removed, however, the oxidized lignin tended to stay in the pulp. An acidic stage (A stage) at pH 3 and a temperature of 90 to 95°C removed a high proportion of the HexA, which eventually reduced the ozone requirement. In spite of the negative impact of the A stage on the DP of cellulose, totally chlorine-free sequences containing A led to pulps of higher viscosity. Increasing the temperature in A to 120°C did not seem to have an effect other than increasing the rate of the hydrolysis reactions. A very efficient metal removal was observed when a chelating agent was added in A (AQ). Some trials showed that splitting the Z stage in a ZEZE-like process (E for alkaline extraction) minimized the impact on pulp viscosity, and that AQPZE-like sequences can reach a quality comparable to some commercial elemental chlorine free (ECF) pulps. |
| first_indexed | 2024-12-19T12:51:55Z |
| format | Article |
| id | doaj.art-d0f0c8b14ea04f37abb7778392385436 |
| institution | Directory Open Access Journal |
| issn | 1930-2126 |
| language | English |
| last_indexed | 2024-12-19T12:51:55Z |
| publishDate | 2013-02-01 |
| publisher | North Carolina State University |
| record_format | Article |
| series | BioResources |
| spelling | doaj.art-d0f0c8b14ea04f37abb77783923854362022-12-21T20:20:31ZengNorth Carolina State UniversityBioResources1930-21262013-02-0181238249Minimizing viscosity loss during totally chlorine-free bleaching of hardwood kraft pulpFrédéric PouyetDominique LachenalSatyajit DasChristine ChiratBy applying increasing amounts of ozone (Z stage bleaching) on eucalyptus oxygen-delignified pulps, it was observed that both lignin and hexenuronic acids (HexA) are attacked early during the treatment. While the HexA were progressively removed, however, the oxidized lignin tended to stay in the pulp. An acidic stage (A stage) at pH 3 and a temperature of 90 to 95°C removed a high proportion of the HexA, which eventually reduced the ozone requirement. In spite of the negative impact of the A stage on the DP of cellulose, totally chlorine-free sequences containing A led to pulps of higher viscosity. Increasing the temperature in A to 120°C did not seem to have an effect other than increasing the rate of the hydrolysis reactions. A very efficient metal removal was observed when a chelating agent was added in A (AQ). Some trials showed that splitting the Z stage in a ZEZE-like process (E for alkaline extraction) minimized the impact on pulp viscosity, and that AQPZE-like sequences can reach a quality comparable to some commercial elemental chlorine free (ECF) pulps.http://www.ncsu.edu/bioresources/BioRes_08/BioRes_08_1_0238_Pouyet_LDC_Viscosity_Loss_TCF_HW_Kraft_Pulp_3410.pdfPulp bleachingChlorine-free bleaching sequenceAcid hydrolysisOzoneHydrogen peroxide |
| spellingShingle | Frédéric Pouyet Dominique Lachenal Satyajit Das Christine Chirat Minimizing viscosity loss during totally chlorine-free bleaching of hardwood kraft pulp BioResources Pulp bleaching Chlorine-free bleaching sequence Acid hydrolysis Ozone Hydrogen peroxide |
| title | Minimizing viscosity loss during totally chlorine-free bleaching of hardwood kraft pulp |
| title_full | Minimizing viscosity loss during totally chlorine-free bleaching of hardwood kraft pulp |
| title_fullStr | Minimizing viscosity loss during totally chlorine-free bleaching of hardwood kraft pulp |
| title_full_unstemmed | Minimizing viscosity loss during totally chlorine-free bleaching of hardwood kraft pulp |
| title_short | Minimizing viscosity loss during totally chlorine-free bleaching of hardwood kraft pulp |
| title_sort | minimizing viscosity loss during totally chlorine free bleaching of hardwood kraft pulp |
| topic | Pulp bleaching Chlorine-free bleaching sequence Acid hydrolysis Ozone Hydrogen peroxide |
| url | http://www.ncsu.edu/bioresources/BioRes_08/BioRes_08_1_0238_Pouyet_LDC_Viscosity_Loss_TCF_HW_Kraft_Pulp_3410.pdf |
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