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Title: Highly bleachable wood fibers containing less condensed lignin from acid hydrotropic fractionation (AHF)

Source: ACS Sustainable Chemistry & Engineering. 8(24): 9046-9057.

Author(s)Ma, Qingzhi ; Hirth, Kolby ; Zhai, Huamin ; Zhu, J.Y.

Publication Year: 2020  View PDF »

Category: Journal Articles
Associated Research Project(s):   FPL-4709-3B

Abstract: This study evaluated the bleachability of wood fibers from acid hydrotropic fractionation (AHF) of birch using ptoluenesulfonic acid (p-TsOH) at low temperatures below 90 C. The wood fibers had varying amounts of lignin after AHF under different conditions using both batch and flow-through configurations. The extent of lignin reprecipitation in batch mode was evaluated by extended washing with p-TsOH. 2D 13C?1H nuclear magnetic resonance (NMR) spectroscopy indicated that residual lignin on fibers from batch reaction was significantly more condensed than that from flow-through under equivalent conditions. Furthermore, condensation substantially affected oxidative bleaching by reducing the reactivity of the residual lignin. Even a little variation in the extent of lignin condensation showed a marked effect on sample bleachability. Specifically, oxygen bleaching at 110 C removed 79% of residue lignin from a batch fractionated fiber sample with 7% ?-O-4 aryl ether linkage and resulted in 55% ISO fiber brightness. The same oxygen bleaching removed 87% of residue lignin from a flow-through fractionated fiber sample with almost the same lignin content but with a higher ?-O-4 of 16%, or lower degree of lignin condensation, and higher brightness of 59% ISO. The 4% increase in brightness with the same loading of bleaching chemical translates to significant cost reduction. Furthermore, a brightness of 70% or more can be achieved with single stage peroxide bleaching for the flow-through AHF fibers

Keywords: acid hydroytrope fractionation; fiber bleaching; lignin condensation; NMR lignin analyses

Publication Review Process: Formally Refereed

File size: 5,120 kb(s)

Date posted: 08/21/2020

This publication is also viewable on Treesearch:  view
RITS Product ID: 98645
Current FPL Scientist associated with this product
Zhu, JunYong
Research General Engineer

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