Characterization of dissolved lignins from acetic acid Lignofibre (LGF) organosolv pulping and discussion of its delignification mechanisms

Heli Kangas (Corresponding Author), Tiina Liitiä, Stella Rovio, Taina Ohra-aho, Harri Heikkinen, Tarja Tamminen, Kristiina Poppius-Levlin

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)

Abstract

Birch chips were cooked by means of the Lignofibre (LGF) organosolv process in acetic acid (AA) and phosphinic acid (H3PO2) at 150°C. The delignification rate and structure of the dissolved lignin was followed as a function of time. The degree of delignification increased steadily up to 88% during the 120 min treatment time. The dissolved lignins were precipitated from the spent liquor (SL) by water addition, washed, and purified for the analyses. Elemental analysis, 31P nuclear magnetic resonance (NMR), heteronuclear single-quantum coherence (HSQC) NMR, pyrolysis-gas chromatography/mass spectrometry (GC/MS), and gel permeation chromatography (GPC) were applied for the structural elucidation. It was found that the cleavage of the ß-aryl ether linkages is the main reaction leading to delignification, accompanied by the formation of free phenolic hydroxyl groups and reduction in the content of aliphatic hydroxyl groups. The structure of the dissolved lignin remained the same after the drastic changes at the early stages of cooking (up to 30 min cooking time), indicating that secondary reactions (e.g., condensation) do not take place to a significant extent. H3PO2 probably enhances the acidolysis reaction via an ester derivative that both boosts the cleavage reaction and prevents the formation of the carbocation intermediate that induces condensation. Homolytic cleavage reactions may take place parallel to the acidolytic reactions.
Original languageEnglish
JournalHolzforschung
Volume69
Issue number3
DOIs
Publication statusPublished - 2015
MoE publication typeA1 Journal article-refereed

Fingerprint

Delignification
Lignin
Acetic acid
Acetic Acid
Cooking
Hydroxyl Radical
Phosphinic Acids
Nuclear magnetic resonance
Condensation reactions
Gel permeation chromatography
Gas chromatography
Ether
Mass spectrometry
Condensation
Ethers
Esters
Pyrolysis
Derivatives
Acids
Water

Keywords

  • acetic acid
  • degradation mechanism
  • delignification
  • lignin
  • Lignofibre (LGF) process
  • organosolv pulping
  • phosphinic acid

Cite this

@article{8ce493d902cb4291bb5fd51fe69f198b,
title = "Characterization of dissolved lignins from acetic acid Lignofibre (LGF) organosolv pulping and discussion of its delignification mechanisms",
abstract = "Birch chips were cooked by means of the Lignofibre (LGF) organosolv process in acetic acid (AA) and phosphinic acid (H3PO2) at 150°C. The delignification rate and structure of the dissolved lignin was followed as a function of time. The degree of delignification increased steadily up to 88{\%} during the 120 min treatment time. The dissolved lignins were precipitated from the spent liquor (SL) by water addition, washed, and purified for the analyses. Elemental analysis, 31P nuclear magnetic resonance (NMR), heteronuclear single-quantum coherence (HSQC) NMR, pyrolysis-gas chromatography/mass spectrometry (GC/MS), and gel permeation chromatography (GPC) were applied for the structural elucidation. It was found that the cleavage of the {\ss}-aryl ether linkages is the main reaction leading to delignification, accompanied by the formation of free phenolic hydroxyl groups and reduction in the content of aliphatic hydroxyl groups. The structure of the dissolved lignin remained the same after the drastic changes at the early stages of cooking (up to 30 min cooking time), indicating that secondary reactions (e.g., condensation) do not take place to a significant extent. H3PO2 probably enhances the acidolysis reaction via an ester derivative that both boosts the cleavage reaction and prevents the formation of the carbocation intermediate that induces condensation. Homolytic cleavage reactions may take place parallel to the acidolytic reactions.",
keywords = "acetic acid, degradation mechanism, delignification, lignin, Lignofibre (LGF) process, organosolv pulping, phosphinic acid",
author = "Heli Kangas and Tiina Liiti{\"a} and Stella Rovio and Taina Ohra-aho and Harri Heikkinen and Tarja Tamminen and Kristiina Poppius-Levlin",
note = "Project code: 100332 Project code: 73553",
year = "2015",
doi = "10.1515/hf-2014-0070",
language = "English",
volume = "69",
journal = "Holzforschung",
issn = "0018-3830",
publisher = "De Gruyter",
number = "3",

}

Characterization of dissolved lignins from acetic acid Lignofibre (LGF) organosolv pulping and discussion of its delignification mechanisms. / Kangas, Heli (Corresponding Author); Liitiä, Tiina; Rovio, Stella; Ohra-aho, Taina; Heikkinen, Harri; Tamminen, Tarja; Poppius-Levlin, Kristiina.

In: Holzforschung, Vol. 69, No. 3, 2015.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Characterization of dissolved lignins from acetic acid Lignofibre (LGF) organosolv pulping and discussion of its delignification mechanisms

AU - Kangas, Heli

AU - Liitiä, Tiina

AU - Rovio, Stella

AU - Ohra-aho, Taina

AU - Heikkinen, Harri

AU - Tamminen, Tarja

AU - Poppius-Levlin, Kristiina

N1 - Project code: 100332 Project code: 73553

PY - 2015

Y1 - 2015

N2 - Birch chips were cooked by means of the Lignofibre (LGF) organosolv process in acetic acid (AA) and phosphinic acid (H3PO2) at 150°C. The delignification rate and structure of the dissolved lignin was followed as a function of time. The degree of delignification increased steadily up to 88% during the 120 min treatment time. The dissolved lignins were precipitated from the spent liquor (SL) by water addition, washed, and purified for the analyses. Elemental analysis, 31P nuclear magnetic resonance (NMR), heteronuclear single-quantum coherence (HSQC) NMR, pyrolysis-gas chromatography/mass spectrometry (GC/MS), and gel permeation chromatography (GPC) were applied for the structural elucidation. It was found that the cleavage of the ß-aryl ether linkages is the main reaction leading to delignification, accompanied by the formation of free phenolic hydroxyl groups and reduction in the content of aliphatic hydroxyl groups. The structure of the dissolved lignin remained the same after the drastic changes at the early stages of cooking (up to 30 min cooking time), indicating that secondary reactions (e.g., condensation) do not take place to a significant extent. H3PO2 probably enhances the acidolysis reaction via an ester derivative that both boosts the cleavage reaction and prevents the formation of the carbocation intermediate that induces condensation. Homolytic cleavage reactions may take place parallel to the acidolytic reactions.

AB - Birch chips were cooked by means of the Lignofibre (LGF) organosolv process in acetic acid (AA) and phosphinic acid (H3PO2) at 150°C. The delignification rate and structure of the dissolved lignin was followed as a function of time. The degree of delignification increased steadily up to 88% during the 120 min treatment time. The dissolved lignins were precipitated from the spent liquor (SL) by water addition, washed, and purified for the analyses. Elemental analysis, 31P nuclear magnetic resonance (NMR), heteronuclear single-quantum coherence (HSQC) NMR, pyrolysis-gas chromatography/mass spectrometry (GC/MS), and gel permeation chromatography (GPC) were applied for the structural elucidation. It was found that the cleavage of the ß-aryl ether linkages is the main reaction leading to delignification, accompanied by the formation of free phenolic hydroxyl groups and reduction in the content of aliphatic hydroxyl groups. The structure of the dissolved lignin remained the same after the drastic changes at the early stages of cooking (up to 30 min cooking time), indicating that secondary reactions (e.g., condensation) do not take place to a significant extent. H3PO2 probably enhances the acidolysis reaction via an ester derivative that both boosts the cleavage reaction and prevents the formation of the carbocation intermediate that induces condensation. Homolytic cleavage reactions may take place parallel to the acidolytic reactions.

KW - acetic acid

KW - degradation mechanism

KW - delignification

KW - lignin

KW - Lignofibre (LGF) process

KW - organosolv pulping

KW - phosphinic acid

U2 - 10.1515/hf-2014-0070

DO - 10.1515/hf-2014-0070

M3 - Article

VL - 69

JO - Holzforschung

JF - Holzforschung

SN - 0018-3830

IS - 3

ER -