Structural Modifications of Residual Lignins from Sisal and Flax Pulps during Soda-AQ Pulping and TCF/ECF Bleaching

Rencoret, Jorge; Marques, Gisela; Gutiérrez, Ana; Jiménez‐Barbero, Jesús; Martínez, Ángel T.; Río, José C. del

doi:10.1021/ie302810c

Cited by 14 publications

(16 citation statements)

References 33 publications

(83 reference statements)

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“…The same12 % value was also obtained for γ-acylated cinnamyl alcohol endgroups (I') by integration of their signals. This is a rather low value when compared to those obtained in other plants such as sisal, elephant grass, or Miscanthus that presented, respectively, 68, 39-55, and 46 % of acylation [22,33,34]. Lignin acylation in cardoon stalks occurred exclusively at the Cγ position, as also reported for other plants [35].…”

Section: Lignin Structural Units and Interunit Linkages As Seen By 2dsupporting

confidence: 41%

Isolation and Structural Characterization of Lignin from Cardoon (Cynara cardunculus L.) Stalks

et al. 2015

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The lignin from Cynara cardunculus stalks was isolated by the classical Björkman method and characterized by pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS), two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR), and derivatization followed by reductive cleavage (DFRC). The milled Cynara lignin (MCyL) was constituted mainly by guaiacyl (G) and syringyl-units(S) (S/G molar ratio of 0.7), with the complete absence of p-hydroxyphenyl (H) units. The 2D-NMR analysis indicated a predominance of alkyl-aryl ether linkages (70 % of all inter unit linkages are β-O-4′) and significant amounts of condensed structures such as phenylcoumarans (β-5′, 14 %), resinols (β-β′, 7 %), spirodienones (β-1′, 5 %), and dibenzodioxocins (5-5′, 4 %). Furthermore, the analyses indicated that the lignin is partially acylated at the γ-OH (12 % acylation) by acetate groups and that acetylation occurs preferentially on syringyl-units. As in other plants, acetylation occurs at the monomer stage, and sinapyl acetate behaves as a real lignin monomer participating in lignification in cardoon stalks. The detailed structural characterization of cardoon lignin reported here will foster the industrial use of this biomass for the production of biofuels and other bio-based chemicals under the lignocellulosic biorefinery.

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Section: Lignin Structural Units and Interunit Linkages As Seen By 2dsupporting

confidence: 41%

Isolation and Structural Characterization of Lignin from Cardoon (Cynara cardunculus L.) Stalks

et al. 2015

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“…[19] Undoubtedly,a complete scientific explanation of the structural transformation of lignin during bleaching process will promote the sequential work in the subsequent delignification and decoloration of pulps. [19,23,37] In general, the bleached lignin is isolated by enzymatic hydrolysis of the bleached pulp, which is al aborious and costly process. Additionally,t he representativeness of the isolated residual lignin is not ideal for tracing the structural changes of lignin during the bleaching process.…”

Section: Bleaching Of "Native Lignin"mentioning

confidence: 99%

“…[19] Ab etter elucidation of the structuralt ransformation of lignin during the bleaching process will be beneficial to understand the delignificationm echanismsi nt he currentp ulpingi ndustry and biorefinery. [20][21][22][23] Although the structures of bleached ligninsh ave been characterized by NMR spectroscopy, [22,23] more information about the reactionp athways and structural transformations of lignins during different bleaching process should be acquired. In addition, few detailed investigations were performed to properly evaluatet he structuralc haracteristics of lignin from eucalyptus and poplar during the integrated pulping and subsequentbleaching process.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the Fate of Lignin from Eucalyptus and Poplar during Integrated Delignification and Bleaching

Wang

Sun

et al. 2019

ChemSusChem

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Efficient deconstruction of lignocellulose is vitally important for the biorefinery industry because lignin structures play a crucial role in the high value‐added conversion of lignin. In this study, an integrated process based on hydrothermal pretreatment (HTP) and Kraft delignification was proposed to deconstruct lignocellulosic biomass. It was found that the HTP not only facilitated the production of xylo‐oligosaccharides but also reduced the chemicals dosage of the following delignification. The structural characteristics of lignin obtained from the integrated process were investigated by NMR spectroscopy and gel‐permeation chromatography. Additionally, double enzymatic lignins (DELs) isolated from different feedstocks were used as “model lignin” to delineate the structural transformations of lignin during H2O2, ClO2, and O3 bleaching. Significant changes of the lignin structure were observed during the ClO2 bleaching process, including degradation of aromatic rings, enrichment in p‐hydroxyphenyl units, and increase of carboxylic groups. A comparison of the structural characteristics of the bleached lignins indicated that HTP benefited the subsequent bleaching process. Enhanced knowledge of lignin chemistry during deconstruction and delignification could provide valuable insight into the current lignocellulose biorefinery.

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“…In the case of rice straw, the influence of temperature (150-190°C), time (0 to 20 min after reaching the working temperature) and liquid/solid ratio (6:10) on the hydrothermal treatment, on the lignin content, on the yield of the resulting solid fraction and on the composition of the corresponding liquid phase (glucose, xylose, arabinose and acetic acid) was studied [71]. It follows that in order to obtain high values of glucose (1.92 g/L), xylose (3.97 g/L), arabinose (0.99 g/L) and acetic acid (1.96 g/L) concentrations, it is necessary to operate at high temperature (190°C) and low-medium conditions for time (15 min) and hydromodule (9), which allows capital savings by not operating with the maximum time and using the maximum hydromodule value. The yield obtained for the solid fraction is 88.1%, and the lignin content is 24.43%.…”

Section: Hemicellulose Isolation By Hydrothermal Treatmentsmentioning

confidence: 99%

“…With the same purpose, government bodies devote economic and human resources to research into alternative raw materials to conventional ones. For these reasons, a large number of studies on the use of non-woody materials, including agriculture residues and vegetables as alternative source for cellulosic pulp production, have emerged in recent years [1,[7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Alternative Raw Materials for Pulp and Paper Production in the Concept of a Lignocellulosic Biorefinery

Eugenio¹,

Ibarra²,

Martín‐Sampedro³

et al. 2019

Cellulose

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The main source of cellulosic fibre used for pulp and paper production comes from wood, while non-wood fibres are used to a lesser extent. However, a renewed interest exists in the use of non-woody raw materials due to their abundance as source of low-cost fibres and because they are sometimes the only exploitable source of fibres in certain geographical areas, mainly in developing countries. Moreover, the great variety of characteristics, fibre dimensions and chemical composition of these alternative raw materials give them a great potential to produce different types of papers. On the other hand, the pulp and paper industry is an excellent starting point for the development of lignocellulosic biorefineries, possessing the necessary technology and infrastructure as well as extensive experience in lignocellulosic biomass transformation. Since its beginnings, the pulp and paper industry has been practicing certain aspects of the biorefinery concept, generating the energy necessary for the production of cellulosic pulp from the combustion of lignocellulosic waste and black liquors, recovering the chemical reagents used and generating high value-added products (e.g. tall oil) together with cellulosic pulp. However, the evolution of the pulp and paper industry to a lignocellulosic biorefinery requires technological innovations to make bioenergy and new bioproducts available alongside traditional products.

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Structural Modifications of Residual Lignins from Sisal and Flax Pulps during Soda-AQ Pulping and TCF/ECF Bleaching

Cited by 14 publications

References 33 publications

Isolation and Structural Characterization of Lignin from Cardoon (Cynara cardunculus L.) Stalks

Isolation and Structural Characterization of Lignin from Cardoon (Cynara cardunculus L.) Stalks

Unraveling the Fate of Lignin from Eucalyptus and Poplar during Integrated Delignification and Bleaching

Alternative Raw Materials for Pulp and Paper Production in the Concept of a Lignocellulosic Biorefinery

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