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| Effects of Autohydrolysis Pretreatment on the Lignin Structure of Poplar Wood Chips and the Subsequent CTMP Brightness |
| Received:October 21, 2020 |
| DOI：10.11980/j.issn.0254-508X.2021.04.003 |
| Key Words:autohydrolysis combined hydrolysis factor poplar wood lignin brightness |
| Fund Project:国家自然科学基金项目（31570574）。 |
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| Abstract:In order to explore the effect of lignin structure changes on the brightness of poplar Chemi-thermomechanical pulp （poplar CTMP pulp） during autohydrolysis pretreatment， poplar wood chips were pretreated by autohydrolysis， and the changes of lignin structure were studied by using FT-IR and nuclear magnetic resonance （1H， 13C， 2D-HSQC NMR）. The relationship between the change in lignin structure and poplar CTMP pulp brightness was established using partial least square method. The results showed when combined hydrolysis factor （CHF） was 73.63， the content of acid insoluble lignin and acid soluble lignin in poplar wood chips decreased by 4.59 percentage points and 1.21 percentage points compared with that in poplar wood chips without autohydrolysis pretreatment. In addition， more cleavage of β-O-4 bonds， β-β bonds， β-5 bonds and β-1 bonds in lignin took place in autohydrolysis pretreatment. Compared with those at the CHF of 2.78， the degree of change of the G unit structure of lignin was greater than that of the S unit structure； and the conjugated carbonyl groups number increased by 0.037/C9 and the number of quinone structure decreased by 0.104/C9. The lowest brightness of the resultant poplar CTMP pulp was 14.9%. Therefore， autohydrolysis pretreatment could affect the lignin structure of poplar wood chips， and consequently reduce the brightness of resultant CTMP pulp. The conjugated carbonyl groups had the greatest impact on the poplar CTMP pulp brightness. |
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