Chemical, Thermal and Antioxidant Properties of Lignins Solubilized during Soda/AQ Pulping of Orange and Olive Tree Pruning Residues

Some agroforestry residues such as orange and olive tree pruning have been extensively evaluated for their valorization due to its high carbohydrates content. However, lignin-enriched residues generated during carbohydrates valorization are normally incinerated to produce energy. In order to find alternative high added-value applications for these lignins, a depth characterization of them is required. In this study, lignins isolated from the black liquors produced during soda/anthraquinone (soda/AQ) pulping of orange and olive tree pruning residues were analyzed by analytical standard methods and Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (solid state 13C NMR and 2D NMR) and size exclusion chromatography (SEC). Thermal analysis (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)) and antioxidant capacity (Trolox equivalent antioxidant capacity) were also evaluated. Both lignins showed a high OH phenolic content as consequence of a wide breakdown of β-aryl ether linkages. This extensive degradation yielded lignins with low molecular weights and polydispersity values. Moreover, both lignins exhibited an enrichment of syringyl units together with different native as well as soda/AQ lignin derived units. Based on these chemical properties, orange and olive lignins showed relatively high thermal stability and good antioxidant activities. These results make them potential additives to enhance the thermo-oxidation stability of synthetic polymers.

Bibliographic Details

Main Authors:	Eugenio Martín, María Eugenia, Martín-Sampedro, R., Santos, José I., Wicklein, Bernd, Ibarra, David
Other Authors:	Universidad de Jaén
Format:	artículo biblioteca
Language:	English
Published:	Multidisciplinary Digital Publishing Institute 2021-06-23
Subjects:	Lignin antioxidant properties, Lignin purity and composition, Lignin structural characterization, Lignin thermal properties, Olive tree pruning, Orange tree pruning, Soda/AQ pulping,
Online Access:	http://hdl.handle.net/10261/266516 http://dx.doi.org/10.13039/501100007064 http://dx.doi.org/10.13039/501100000921 https://api.elsevier.com/content/abstract/scopus_id/85109132550
Tags:	Add Tag No Tags, Be the first to tag this record!