Isolation and Characterization of Gramineae and Fabaceae Soda Lignins

Abstract

Some agricultural residues such as wheat or barley straw, as well as certain fast-growing plants like Leucaena leucocephala and Chamaecytisus proliferus, could be used as raw materials for the paper industry as an alternative to traditional plants (eucalyptus, pine, etc.). In the present study, four types of lignin obtained from the spent liquors produced by the pulping processes using the abovementioned feedstocks were isolated and characterized. Lignin samples were acquired through an acid precipitation from these spent liquors. The characterization of the precipitated lignin samples were performed using a Fourier transform infrared spectroscopy (FT-IR) and both liquid- and solid-state nuclear magnetic resonance spectroscopy (NMR) to analyse the chemical structure, and thermogravimetric analysis (TGA) for determining the thermal properties. Additionally, chemical composition of lignin fractions was also measured. Even though they were of different botanical origin, all the studied samples except for wheat straw lignin had a similar chemical composition and thermal behaviour, and identical chemical structure. Wheat straw lignin showed a greater amount of Klason lignin and lower carbohydrate content. Furthermore, this lignin sample showed a higher thermal stability and significantly different cross-peak patterns in the 2D-NMR experiments. The molecular structures corresponding to p-coumarate (PCA), ferulate (FA) and cinnamyl aldehyde end-groups (J) were only detected in wheat isolated lignin.

Biorefining of Pinus pinaster Stump Wood for Ethanol Production and Lignin Recovery

“…The band at 629 cm −1 was attributed to C–S stretching, in spite of the fact that no S was detected by EA (detection limit < 0.01 wt %) of the same materials. Such C–S stretching bands have been reported in the literature, as a consequence of acidic precipitation of lignins with sulfuric acid 22.…”

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

“…So, a detailed knowledge of lignin structure, composition and purity is required in order to determine its behaviour in different potential applications. In this sense, characterization of residual lignins from Kraft and soda-anthraquinone pulping of agriculture residues such as olive tree pruning [97] and wheat or barley straw [98], as well as vegetables like L. leucocephala, C. proliferus, and H. funifera [99,100], has been carried out.…”

Libidibia ferreaFruit Crude Extract and Fractions Show Anti-Inflammatory, Antioxidant, and Antinociceptive EffectIn Vivoand Increase Cell ViabilityIn Vitro

“…There are many useful species and numerous amounts of them have been cultivated since ancient times, mainly due to their food and medicinal potential, although there are several other utilities. Libidibia ferrea (L. ferrea) , popularly known as jucá or pau-ferro, is a species of the Leguminosae family with multiple medicinal uses [1]. Studies performed with species of the Leguminosae family have demonstrated antihelmintic, antimalaria, anti-inflammatory, and analgesic activity [2–5].…”