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Structural Characterization of the Milled-Wood Lignin Isolated from Sweet Orange Tree (Citrus sinensis) Pruning Residue
- Source :
- Polymers, Vol 15, Iss 8, p 1840 (2023)
- Publication Year :
- 2023
- Publisher :
- MDPI AG, 2023.
-
Abstract
- The pruning of sweet orange trees (Citrus sinensis) generates large amounts of lignocellulosic residue. Orange tree pruning (OTP) residue presents a significant lignin content (21.2%). However, there are no previous studies describing the structure of the native lignin in OTPs. In the present work, the “milled-wood lignin” (MWL) was extracted from OTPs and examined in detail via gel permeation chromatography (GPC), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and two-dimensional nuclear magnetic resonance (2D-NMR). The results indicated that the OTP-MWL was mainly composed of guaiacyl (G) units, followed by syringyl (S) units and minor amounts of p-hydroxyphenyl (H) units (H:G:S composition of 1:62:37). The predominance of G-units had a strong influence on the abundance of the different linkages; therefore, although the most abundant linkages were β–O–4′ alkyl–aryl ethers (70% of total lignin linkages), the lignin also contained significant amounts of phenylcoumarans (15%) and resinols (9%), as well as other condensed linkages such as dibenzodioxocins (3%) and spirodienones (3%). The significant content of condensed linkages will make this lignocellulosic residue more recalcitrant to delignification than other hardwoods with lower content of these linkages.
Details
- Language :
- English
- ISSN :
- 20734360
- Volume :
- 15
- Issue :
- 8
- Database :
- Directory of Open Access Journals
- Journal :
- Polymers
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.0f197b93d04f4deb8c7f651b7b2614d6
- Document Type :
- article
- Full Text :
- https://doi.org/10.3390/polym15081840