Selective hydrolysis of hexenuronic acid groups and its application in ECF and TCF bleaching of kraft pulps

Tapani Vuorinen, Pirjo Fagerström, Johanna Buchert, Maija Tenkanen, Anita Teleman

Research output: Contribution to journalArticleScientificpeer-review

164 Citations (Scopus)

Abstract

During kraft pulping a major part of the 4-0-methylglucuronic acid groups of the native wood xylans are converted to 4- deoxyhex-4-enuronic acid groups (HexA). Because of its ene functionality, HexA reacts with several bleaching chemicals, such as chlorine, chlorine dioxide, ozone, and peracids, thus consuming these chemicals. Also permanganate attacks HexA which therefore contributes to the K-number of the pulps, We now report a method for selectively removing HexA through a mild acid hydrolysis of kraft pulps. The potential of the method as a part of ECF and TCF bleaching sequences was studied with several Finnish companies. During the selective hydrolysis HexA was converted to furan derivatives that could be quantified from the hydrolyzate by UV spectroscopy. The amount of the furan derivatives correlated linearly with the decrease in K-number of both unbleached and oxygen bleached softwood and hardwood pulps. Depending on the type of the pulp, the selective hydrolysis removed 20-60 meq HexA per kg of pulp and reduced the K-number by 2-7 units. Relatively speaking the change was biggest for oxygen bleached birch kraft pulps the K-number of which was reduced, as an average, by 50 %. The treatment reduced the chemical consumption in all bleaching sequences. In ECF bleaching of birch kraft pulp the reduction was 30-40 %. Because the selective acid hydrolysis removed a major part of the metal binding sites from the pulps, their transition metal contents were after the treatment as low as after an alternate treatment with complexing agents. Thus their use was unnecessary in TCF bleaching sequences. The selective hydrolysis had no profound effects on the paper technical properties of the fully bleached pulps but it significantly improved the brightness stability of oxygen and peroxide bleached pulps.
Original languageEnglish
Pages (from-to)155-162
Number of pages8
JournalJournal of Pulp and Paper Science
Volume25
Issue number5
Publication statusPublished - 1999
MoE publication typeA1 Journal article-refereed

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Kraft pulp
Bleaching
Pulp
Hydrolysis
Bleached pulp
Acids
Oxygen
Chlorine
Derivatives
Kraft process
Xylans
Softwoods
Hardwoods
Ozone
Peroxides
Binding sites
Ultraviolet spectroscopy
Transition metals
Luminance
Wood

Cite this

Vuorinen, T., Fagerström, P., Buchert, J., Tenkanen, M., & Teleman, A. (1999). Selective hydrolysis of hexenuronic acid groups and its application in ECF and TCF bleaching of kraft pulps. Journal of Pulp and Paper Science, 25(5), 155-162.
Vuorinen, Tapani ; Fagerström, Pirjo ; Buchert, Johanna ; Tenkanen, Maija ; Teleman, Anita. / Selective hydrolysis of hexenuronic acid groups and its application in ECF and TCF bleaching of kraft pulps. In: Journal of Pulp and Paper Science. 1999 ; Vol. 25, No. 5. pp. 155-162.
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abstract = "During kraft pulping a major part of the 4-0-methylglucuronic acid groups of the native wood xylans are converted to 4- deoxyhex-4-enuronic acid groups (HexA). Because of its ene functionality, HexA reacts with several bleaching chemicals, such as chlorine, chlorine dioxide, ozone, and peracids, thus consuming these chemicals. Also permanganate attacks HexA which therefore contributes to the K-number of the pulps, We now report a method for selectively removing HexA through a mild acid hydrolysis of kraft pulps. The potential of the method as a part of ECF and TCF bleaching sequences was studied with several Finnish companies. During the selective hydrolysis HexA was converted to furan derivatives that could be quantified from the hydrolyzate by UV spectroscopy. The amount of the furan derivatives correlated linearly with the decrease in K-number of both unbleached and oxygen bleached softwood and hardwood pulps. Depending on the type of the pulp, the selective hydrolysis removed 20-60 meq HexA per kg of pulp and reduced the K-number by 2-7 units. Relatively speaking the change was biggest for oxygen bleached birch kraft pulps the K-number of which was reduced, as an average, by 50 {\%}. The treatment reduced the chemical consumption in all bleaching sequences. In ECF bleaching of birch kraft pulp the reduction was 30-40 {\%}. Because the selective acid hydrolysis removed a major part of the metal binding sites from the pulps, their transition metal contents were after the treatment as low as after an alternate treatment with complexing agents. Thus their use was unnecessary in TCF bleaching sequences. The selective hydrolysis had no profound effects on the paper technical properties of the fully bleached pulps but it significantly improved the brightness stability of oxygen and peroxide bleached pulps.",
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Vuorinen, T, Fagerström, P, Buchert, J, Tenkanen, M & Teleman, A 1999, 'Selective hydrolysis of hexenuronic acid groups and its application in ECF and TCF bleaching of kraft pulps', Journal of Pulp and Paper Science, vol. 25, no. 5, pp. 155-162.

Selective hydrolysis of hexenuronic acid groups and its application in ECF and TCF bleaching of kraft pulps. / Vuorinen, Tapani; Fagerström, Pirjo; Buchert, Johanna; Tenkanen, Maija; Teleman, Anita.

In: Journal of Pulp and Paper Science, Vol. 25, No. 5, 1999, p. 155-162.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Selective hydrolysis of hexenuronic acid groups and its application in ECF and TCF bleaching of kraft pulps

AU - Vuorinen, Tapani

AU - Fagerström, Pirjo

AU - Buchert, Johanna

AU - Tenkanen, Maija

AU - Teleman, Anita

PY - 1999

Y1 - 1999

N2 - During kraft pulping a major part of the 4-0-methylglucuronic acid groups of the native wood xylans are converted to 4- deoxyhex-4-enuronic acid groups (HexA). Because of its ene functionality, HexA reacts with several bleaching chemicals, such as chlorine, chlorine dioxide, ozone, and peracids, thus consuming these chemicals. Also permanganate attacks HexA which therefore contributes to the K-number of the pulps, We now report a method for selectively removing HexA through a mild acid hydrolysis of kraft pulps. The potential of the method as a part of ECF and TCF bleaching sequences was studied with several Finnish companies. During the selective hydrolysis HexA was converted to furan derivatives that could be quantified from the hydrolyzate by UV spectroscopy. The amount of the furan derivatives correlated linearly with the decrease in K-number of both unbleached and oxygen bleached softwood and hardwood pulps. Depending on the type of the pulp, the selective hydrolysis removed 20-60 meq HexA per kg of pulp and reduced the K-number by 2-7 units. Relatively speaking the change was biggest for oxygen bleached birch kraft pulps the K-number of which was reduced, as an average, by 50 %. The treatment reduced the chemical consumption in all bleaching sequences. In ECF bleaching of birch kraft pulp the reduction was 30-40 %. Because the selective acid hydrolysis removed a major part of the metal binding sites from the pulps, their transition metal contents were after the treatment as low as after an alternate treatment with complexing agents. Thus their use was unnecessary in TCF bleaching sequences. The selective hydrolysis had no profound effects on the paper technical properties of the fully bleached pulps but it significantly improved the brightness stability of oxygen and peroxide bleached pulps.

AB - During kraft pulping a major part of the 4-0-methylglucuronic acid groups of the native wood xylans are converted to 4- deoxyhex-4-enuronic acid groups (HexA). Because of its ene functionality, HexA reacts with several bleaching chemicals, such as chlorine, chlorine dioxide, ozone, and peracids, thus consuming these chemicals. Also permanganate attacks HexA which therefore contributes to the K-number of the pulps, We now report a method for selectively removing HexA through a mild acid hydrolysis of kraft pulps. The potential of the method as a part of ECF and TCF bleaching sequences was studied with several Finnish companies. During the selective hydrolysis HexA was converted to furan derivatives that could be quantified from the hydrolyzate by UV spectroscopy. The amount of the furan derivatives correlated linearly with the decrease in K-number of both unbleached and oxygen bleached softwood and hardwood pulps. Depending on the type of the pulp, the selective hydrolysis removed 20-60 meq HexA per kg of pulp and reduced the K-number by 2-7 units. Relatively speaking the change was biggest for oxygen bleached birch kraft pulps the K-number of which was reduced, as an average, by 50 %. The treatment reduced the chemical consumption in all bleaching sequences. In ECF bleaching of birch kraft pulp the reduction was 30-40 %. Because the selective acid hydrolysis removed a major part of the metal binding sites from the pulps, their transition metal contents were after the treatment as low as after an alternate treatment with complexing agents. Thus their use was unnecessary in TCF bleaching sequences. The selective hydrolysis had no profound effects on the paper technical properties of the fully bleached pulps but it significantly improved the brightness stability of oxygen and peroxide bleached pulps.

M3 - Article

VL - 25

SP - 155

EP - 162

JO - J-FOR: Journal of Science & Technology for Forest Products and Processes

JF - J-FOR: Journal of Science & Technology for Forest Products and Processes

SN - 1927-6311

IS - 5

ER -