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Quantification of lignin-carbohydrat...

Nicholson, Daniel J.

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Quantification of lignin-carbohydrate complexes (LCC) in sugar maple (Acer saccharum) pulps and their role in lignin removal.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Quantification of lignin-carbohydrate complexes (LCC) in sugar maple (Acer saccharum) pulps and their role in lignin removal./
Author:	Nicholson, Daniel J.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2014,
Description:	252 p.
Notes:	Source: Dissertation Abstracts International, Volume: 76-08(E), Section: B.
Contained By:	Dissertation Abstracts International76-08B(E).
Subject:	Wood sciences. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3687348
ISBN:	9781321648799

Quantification of lignin-carbohydrate complexes (LCC) in sugar maple (Acer saccharum) pulps and their role in lignin removal.
Nicholson, Daniel J.

Quantification of lignin-carbohydrate complexes (LCC) in sugar maple (Acer saccharum) pulps and their role in lignin removal. - Ann Arbor : ProQuest Dissertations & Theses, 2014 - 252 p.

Source: Dissertation Abstracts International, Volume: 76-08(E), Section: B.

Thesis (Ph.D.)--State University of New York College of Environmental Science and Forestry, 2014.

Chemical linkages between lignin and carbohydrates (lignin-carbohydrate complexes, LCC) contribute to recalcitrance in the depolymerization of some in-situ hardwood polymers. A method to quantify the LCC in chemical pulps has been developed using cellulolytic enzymes to remove carbohydrates and isolate the lignin with very low concentrations of sugars strongly bound to it. This enzymatic lignin (EL) is hydrolyzed in sulfuric acid to liberate the bound sugars and convert them to monomers that are then quantified using 1H-NMR. SAQ pulps produce ELs which contain higher amounts of bound sugars than pulps from the kraft process. Below a value of 30, decreases in kappa number by kraft or SAQ result in slow increases in the EL bound glucan and xylan, and relatively rapid decreases in EL bound galactan (BG) and arabinan (BA). A mechanism of delignification by kraft and SAQ is proposed where both processes form BA in the bulk phase of cooking to different degrees. The BA cleavage mechanisms that are proposed are consistent with easily oxidized structures being generated in the kraft residual lignin (in the fibers), while some condensed and less reactive structures would be formed in the SAQ lignin. Oxygen and hydrogen peroxide delignification result in lower EL bound xylan (BX) content, but higher concentrations of the other sugars. Chlorine dioxide was the only treatment that reduced BA on EL, but only moderately. Hot water pretreatment (HWP) of the chips for 60 minutes before kraft and SAQ cooking resulted in ELs with no BA or BG. HWP also afforded dramatic improvements in delignification rates in subsequent kraft and SAQ cooking and in the bleaching stages. Also, HWP afforded nearly identical results for kraft and SAQ pulping and the bleachability of their pulps. Acid hydrolysis of LCC in some hardwoods may be more difficult than in softwoods. This could lead to inaccurate measurements of lignin content by the Klason Method (LCC measured as lignin). A new method is proposed in which a higher overall hydrolytic intensity is obtained from the H2SO4 treatments. The method is more accurate and also takes two hours less time than the conventional Klason method.

ISBN: 9781321648799Subjects--Topical Terms:

3168288
Wood sciences.

Quantification of lignin-carbohydrate complexes (LCC) in sugar maple (Acer saccharum) pulps and their role in lignin removal.
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300 $a 252 p.
500 $a Source: Dissertation Abstracts International, Volume: 76-08(E), Section: B.
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520 $a Chemical linkages between lignin and carbohydrates (lignin-carbohydrate complexes, LCC) contribute to recalcitrance in the depolymerization of some in-situ hardwood polymers. A method to quantify the LCC in chemical pulps has been developed using cellulolytic enzymes to remove carbohydrates and isolate the lignin with very low concentrations of sugars strongly bound to it. This enzymatic lignin (EL) is hydrolyzed in sulfuric acid to liberate the bound sugars and convert them to monomers that are then quantified using 1H-NMR. SAQ pulps produce ELs which contain higher amounts of bound sugars than pulps from the kraft process. Below a value of 30, decreases in kappa number by kraft or SAQ result in slow increases in the EL bound glucan and xylan, and relatively rapid decreases in EL bound galactan (BG) and arabinan (BA). A mechanism of delignification by kraft and SAQ is proposed where both processes form BA in the bulk phase of cooking to different degrees. The BA cleavage mechanisms that are proposed are consistent with easily oxidized structures being generated in the kraft residual lignin (in the fibers), while some condensed and less reactive structures would be formed in the SAQ lignin. Oxygen and hydrogen peroxide delignification result in lower EL bound xylan (BX) content, but higher concentrations of the other sugars. Chlorine dioxide was the only treatment that reduced BA on EL, but only moderately. Hot water pretreatment (HWP) of the chips for 60 minutes before kraft and SAQ cooking resulted in ELs with no BA or BG. HWP also afforded dramatic improvements in delignification rates in subsequent kraft and SAQ cooking and in the bleaching stages. Also, HWP afforded nearly identical results for kraft and SAQ pulping and the bleachability of their pulps. Acid hydrolysis of LCC in some hardwoods may be more difficult than in softwoods. This could lead to inaccurate measurements of lignin content by the Klason Method (LCC measured as lignin). A new method is proposed in which a higher overall hydrolytic intensity is obtained from the H2SO4 treatments. The method is more accurate and also takes two hours less time than the conventional Klason method.
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