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Kinetics of delignification and diff...

Li, Jianghua.

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Kinetics of delignification and diffusion of soluble lignin out of chips during magnesium bisulfite pulping.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Kinetics of delignification and diffusion of soluble lignin out of chips during magnesium bisulfite pulping./
Author:	Li, Jianghua.
Description:	112 p.
Notes:	Source: Masters Abstracts International, Volume: 40-04, page: 1033.
Contained By:	Masters Abstracts International40-04.
Subject:	Engineering, Chemical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=MQ65501
ISBN:	0612655016

Kinetics of delignification and diffusion of soluble lignin out of chips during magnesium bisulfite pulping.
Li, Jianghua.

Kinetics of delignification and diffusion of soluble lignin out of chips during magnesium bisulfite pulping. - 112 p.

Source: Masters Abstracts International, Volume: 40-04, page: 1033.

Thesis (M.Sc.E.)--The University of New Brunswick (Canada), 2000.

The thesis focuses on the fundamental aspects of the kinetics of delignification and that of diffusion of soluble lignin during magnesium bisulfite pulping.

ISBN: 0612655016Subjects--Topical Terms:

1018531
Engineering, Chemical.

Kinetics of delignification and diffusion of soluble lignin out of chips during magnesium bisulfite pulping.
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100 1 $a Li, Jianghua. $3 1929872
245 1 0 $a Kinetics of delignification and diffusion of soluble lignin out of chips during magnesium bisulfite pulping.
300 $a 112 p.
500 $a Source: Masters Abstracts International, Volume: 40-04, page: 1033.
500 $a Adviser: A. R. P. van Heiningen.
502 $a Thesis (M.Sc.E.)--The University of New Brunswick (Canada), 2000.
520 $a The thesis focuses on the fundamental aspects of the kinetics of delignification and that of diffusion of soluble lignin during magnesium bisulfite pulping.
520 $a The kinetics of delignification during magnesium bisulfite pulping were modeled as the sum of three modes of attack: nucleophilic cleavage of alpha-ether bonds, nucleophilic cleavage of beta-ether bonds, and homolytic cleavage of the free phenolic beta-ether bonds. The activation energies, obtained by comparison of the model results with the experimental data, are 157, 147 and 99 kJ/mol for the three modes, respectively. This shows that delignification via the homolysis reaction has a lower temperature dependency than the other two. In general, however, the relative rates of delignification of the three pathways are comparable under normal bisulfite pulping conditions.
520 $a The diffusion of degraded, soluble lignin in wood chips during magnesium bisulfite pulping was simulated numerically by solving the unsteady, one-dimensional diffusion with reaction equation. The effective diffusion coefficients of lignin at cooking temperatures of 155, 165 and 175°C obtained by fitting the simulation results to the experimental data are 1.97 x 10 -10, 4.85 x 10-10 and 9.72 x 10-10 m2/s respectively. These values are of the same order of magnitude as the bulk diffusion coefficients calculated using the Stokes-Einstein equation. However at the highest cooking temperature the simulation gives a higher value than that predicted by diffusion theory in porous solids. Possible reasons for these deviations are presented. The implications for controlling magnesium bisulfite cooking by measurement of the dissolved lignin concentration in the cooking liquor are discussed.
590 $a School code: 0823.
650 4 $a Engineering, Chemical. $3 1018531
650 4 $a Agriculture, Wood Technology. $3 1031154
690 $a 0542
690 $a 0746
710 2 0 $a The University of New Brunswick (Canada). $3 1253304
773 0 $t Masters Abstracts International $g 40-04.
790 1 0 $a van Heiningen, A. R. P., $e advisor
790 $a 0823
791 $a M.Sc.E.
792 $a 2000
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=MQ65501