• 펄프종이기술
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• 제37권3호
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• pp.74-80
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• 2005

The compositions of residual extractives in woodmeal, unbleached and oxygen-delignified aspen kraft pulps were investigated with gas chromatography(GC) and gas chromatography-mass spectrometry (GC-MS) with focus on fate of extractives in kraft pulping and oxygen delignification. Steryl esters and shorter retention time (shorter than palmitic acid) extractives were main extractives in aspen woodmeal. Shorter retention time extractives were well removed in kraft pulping. Sterol esters were hydrolyzed to sterols and fatty acids. Sterols and fatty acids were two major extractives classes in unbleached kraft pulps. Linoleic acid was main fatty acids in unbleached pulps compared with palmitic acid which is generally found in aspen woodmeal. Sterolsand fatty acids were also two major extractives classes in oxygen-delignified kraft pulps. However, linoleic acid was well removed in oxygen delignification.

• 펄프종이기술
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• 제41권5호
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• pp.20-25
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• 2009

Residual extractives had a noticeable impact on the brightness of unbleached hardwood kraft pulps (trembling aspen). The brightness-impacting extractives were effectively removed by oxygen delignification. In addition, oxygen delignification was more effective in removing chromophores in hardwood unbleached kraft pulps than in those of softwood (loblolly pine). The residual extractives in unbleached hardwood kraft pulps also affected the pulp color, primarily redness and the L value. These redness-related extractives in unbleached hardwood kraft pulps were also effectively removed by oxygen delignification. There were no significant color differences between untreated and solvent-extracted oxygen-delignified aspen kraft pulps. The residual extractives in unbleached and oxygen-delignified softwood (loblolly pine) kraft pulps did not have a significant impact on either brightness or pulp color.

• 펄프종이기술
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• 제36권5호
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• pp.62-68
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• 2004

The amount of non-lignin components in unbleached and oxygen-delignified kraft pulps and their impact on lignin determinations was investigated. The lignin analyses investigated were kappa number and Klason lignin in conjunction with acid-soluble lignin. The species investigated were loblolly pine, and aspen. The non-lignin components that impacted on lignin determination were residual extractives and hexenuronic acid in unbleached and oxygen-delignified kraft pulps. In the hardwoods, significant amounts of extractives remained after kraft pulping and oxygen delignification. These residual extractives in the hardwood pulps had an impact on the lignin determination, more so on the acid lignin method than kappa number. Hexenuronic acid only impacts on kappa number determination both softwood and hardwood pulps, not on acid lignin. Hexeneuronic acid contributed as lignin content more in aspen than pine pulps, and more in oxygen-delignified than unbleached kraft pulps. Impact of hexenuronic acid on should be corrected both softwood and hardwood pulps for accurate kappa number.

• 펄프종이기술
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• 제37권5호통권113호
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• pp.50-55
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• 2005

In previous report, we investigated the impact of hexeneuronic acid and some residual extractiveson lignin determination. These non-lignin components severely interfered lignin content determination which also affect on the oxygen delignification comparison between aspen and pine unbleached kraft pulps. Very different pattern was observed whether based on uncorrected conventional kappa number or based on corrected kappa number in oxygen delignification comparison. Lower kappa number aspen pulps showed poor response to oxygen delignification when kappa number was used as lignin determination method but better response with using the acid lignin method. Phenolic hydroxyl group in kraft pulps were also compared based on uncorrected or corrected kappa numberfor lignin content. Based on uncorrected kappa number, lower kappa number oxygen-delignified pulps had lower phenolic hydroxyl group. However, lower kappa number oxygen-delignified pulps showed much higher phenolic hydroxyl group based on the corrected lignin content. For accurate comparison for residual lignin properties from different pulps, lignin determination should be corrected from non-lignin components contribution to lignin.