Properties, Applications and Perspectives of Lignin II

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Biomacromolecules, Biobased and Biodegradable Polymers".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 5198

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BBG-DiSB, Department of Biomedical Sciences, Cagliari State University, 09042 Monserrato, Italy
Interests: biomimetic catalysis; applied enzymology; fungal phenol oxidases
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Special Issue Information

Dear Colleagues,

After the success of the Polymers Special Issue “Properties, Applications and Perspectives of Lignin”, we are delighted to open a new Special Issue entitled “Properties, Applications and Perspectives of Lignin II.”

Lignin is one of the most abundant organic substances and is produced by vascular plants. It is an irregular aliphatic–aromatic heteropolymer based on C6C3 monomeric units. Arising from radical chain reactions, its hydrolysis to afford such monomeric units is quite a difficult task, whereas its highly cross-linked nature makes it almost insoluble in common solvents, unless it is more or less deeply altered in its native structure.

This Special Issue welcomes experimental studies and reviews describing new insights or presenting the state of the art in the fields of lignin biosynthesis and its regulation and in  delignification treatments (both chemical and biological/biomimetic), as well as new frontiers in lignin utilization—possibly after suitable modification—as a biomaterial and/or as a promising source of derived chemicals.

Dr. Enrico Sanjust
Guest Editor

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Published Papers (3 papers)

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Research

24 pages, 4449 KiB  
Article
Vacuum Low-Temperature Microwave-Assisted Pyrolysis of Technical Lignins
by Johannes Karthäuser, Vladimirs Biziks, Holm Frauendorf, Carsten Mai and Holger Militz
Polymers 2022, 14(16), 3383; https://doi.org/10.3390/polym14163383 - 18 Aug 2022
Cited by 7 | Viewed by 1525
Abstract
Cleavage by microwave-assisted pyrolysis is a way to obtain higher-value organic chemicals from technical lignins. In this report, pine kraft lignin (PKL), spruce and beech organosolv lignin (SOSL and BOSL), and calcium lignosulfonates from spruce wood (LS) were pyrolyzed at temperatures between 30 [...] Read more.
Cleavage by microwave-assisted pyrolysis is a way to obtain higher-value organic chemicals from technical lignins. In this report, pine kraft lignin (PKL), spruce and beech organosolv lignin (SOSL and BOSL), and calcium lignosulfonates from spruce wood (LS) were pyrolyzed at temperatures between 30 and 280 °C using vacuum low-temperature, microwave-assisted pyrolysis. The mass balance, energy consumption, condensation rate, and pressure changes of the products during the pyrolysis process were recorded. Phenolic condensates obtained at different temperatures during pyrolysis were collected, and their chemical composition was determined by GC-MS and GC-FID. The origin of the technical lignin had a significant influence on the pyrolysis products. Phenolic condensates were obtained in yields of approximately 15% (PKL and SOSL) as well as in lower yields of 4.5% (BOSL) or even 1.7% (LS). The main production of the phenolic condensates for the PKL and SOSL occurred at temperatures of approximately 140 and 180 °C, respectively. The main components of the phenolic fraction of the three softwood lignins were guaiacol, 4-methylguaiacol, 4-ethylguaiacol, and other guaiacol derivatives; however, the quantity varied significantly depending on the lignin source. Due to the low cleavage temperature vacuum, low-temperature, microwave-assisted pyrolysis could be an interesting approach to lignin conversion. Full article
(This article belongs to the Special Issue Properties, Applications and Perspectives of Lignin II)
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16 pages, 4510 KiB  
Article
Dual-Modified Lignin-Assembled Multilayer Microsphere with Excellent Pb2+ Capture
by Zhaohui Zhang, Yehong Chen and Chaojun Wu
Polymers 2022, 14(14), 2824; https://doi.org/10.3390/polym14142824 - 11 Jul 2022
Cited by 3 | Viewed by 1399
Abstract
With the continuous research on lignin-based sorbents, there are still limitations in the research of spherical sorbents with a high adsorption capacity for Pb2+. In order to solve the problem of low adsorption effect, alkali lignin (AL) was modified and assembled [...] Read more.
With the continuous research on lignin-based sorbents, there are still limitations in the research of spherical sorbents with a high adsorption capacity for Pb2+. In order to solve the problem of low adsorption effect, alkali lignin (AL) was modified and assembled to increase the adsorption active sites. In this work, we used dual-modified lignin (DML) as a raw material to assemble a singular lignin-based multilayer microsphere (LMM) with sodium alginate (SA) and dopamine. The prepared adsorbent had various active functional groups and spherical structures; the specific surface area was 2.14 m2/g and the average pore size was 8.32 nm. The adsorption process followed the Freundlich isotherm and the second-order kinetic model. Therefore, the LMM adsorbed Pb2+ ascribed by the electrostatic attraction and surface complexation; the adsorption capacity was 250 mg/g. The LMM showed a selective adsorption performance for Pb2+ and the adsorption capacity followed the order Pb2+ (187.4 mg/g) > Cu2+(168.0 mg/g) > Mn2+(166.5 mg/g). After three cycles, the removal efficiency of Pb2+ by the LMM was 69.34%, indicating the reproducibility of LMM. Full article
(This article belongs to the Special Issue Properties, Applications and Perspectives of Lignin II)
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15 pages, 3450 KiB  
Article
Features of the Chemical Composition and Structure of Birch Phloem Dioxane Lignin: A Comprehensive Study
by Anna V. Faleva, Ilya I. Pikovskoi, Sergey A. Pokryshkin, Dmitry G. Chukhchin and Dmitry S. Kosyakov
Polymers 2022, 14(5), 964; https://doi.org/10.3390/polym14050964 - 28 Feb 2022
Cited by 5 | Viewed by 1572
Abstract
Understanding the chemical structure of lignin in the plant phloem contributes to the systematics of lignins of various biological origins, as well as the development of plant biomass valorization. In this study, the structure of the lignin from birch phloem has been characterized [...] Read more.
Understanding the chemical structure of lignin in the plant phloem contributes to the systematics of lignins of various biological origins, as well as the development of plant biomass valorization. In this study, the structure of the lignin from birch phloem has been characterized using the combination of three analytical techniques, including 2D NMR, Py-GC/MS, and APPI-Orbitrap-HRMS. Due to the specifics of the phloem chemical composition, two lignin preparations were analyzed: a sample obtained as dioxane lignin (DL) by the Pepper’s method and DL obtained after preliminary alkaline hydrolysis of the phloem. The obtained results demonstrated that birch phloem lignin possesses a guaiacyl–syringyl (G-S) nature with a unit ratio of (S/G) 0.7–0.9 and a higher degree of condensation compared to xylem lignin. It was indicated that its macromolecules are constructed from β-aryl ethers followed by phenylcoumaran and resinol structures as well as terminal groups in the form of cinnamic aldehyde and dihydroconiferyl alcohol. The presence of fatty acids and flavonoids removed during alkaline treatment was established. Tandem mass spectrometry made it possible to demonstrate that the polyphenolic components are impurities and are not incorporated into the structure of lignin macromolecules. An important component of phloem lignin is lignin–carbohydrate complexes incorporating xylopyranose moieties. Full article
(This article belongs to the Special Issue Properties, Applications and Perspectives of Lignin II)
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