Lignin as feedstock for nanoparticles production

Lignin is an interesting natural polymer with characteristics that contribute for the development and growth of plants. Lignin presents high variability associated with the diversity of plants, which presents great challenges for its recovery after delignification (technical lignin), because lignin is prone to irreversible degradation, producing recalcitrant condensed structures that are difficult to disassemble afterward. Although researchers have made efforts to obtain lignin in high yields and with good characteristics for specific uses, this is not an easy task. The mind-set has changed and new biorefinery concepts are emerging, where lignin is the primary goal to achieve, and the so-called lignin-first approach has arisen. Lignin can be obtained firstly to prevent structural degradations, enabling an efficient and highly selectivity of the lignin monomers. Therefore, this concept places lignin and its valorization at the head of the biorefinery. However, lignin valorization is still a challenge, and to overcome this, lignin nanoparticles (LNPs) production presents a good way to achieve this goal. This chapter presents a resume of the several techniques to attain lignin, how to produce LNPs, and their possible applications (from pharmaceutical to the automobile and polymer industries).info:eu-repo/semantics/publishedVersio

Variability of Heartwood Content in Plantation-Grown Eucalyptus Globulus Labill.

The heartwood content in Eucalyptus globulus Labill. was studied in 9-year-old trees from commercial pulpwood plantations in three sites in Portugal. Heartwood was present in all the trees and attained 60-75% of total tree height and approximately one-third of the total volume. Within the tree, heartwood decreased from the base upwards, on average representing 40%, 31%, 22%, and 10% of the cross-sectional area at, respectively, 5%, 25%, 35%, and 55% of total tree height. The heartwood: sapwood ratio at each position within the tree depended highly significantly on site and on the tree. The axial development of heartwood also showed an interaction with site and tree. A positive correlation was found between heartwood content and growth. Considering its negative impact in pulping, the heartwood of E. globulus should be considered in management and breeding programs

Heartwood, sapwood and bark variation in coppiced Eucalyptus globulus trees in 2nd rotation and comparison with the single stem 1st rotation

Research ArticleCoppiced Eucalyptus globulus trees with 18 years in a 2nd rotation were analysed in relation to heartwood, sapwood and bark content taking into account the effect of the initial planting density by using a spacing trial. A total of 25 stumps, with a variable number of stems per stump from 1 to 3, were analysed. Comparison was made to the previous 1st rotation single stem trees, also harvested at 18 years. In the 2nd rotation, the stump density did not significantly affect stem height and diameter, in opposition to the 1st rotation where spacing significantly impacted on tree dimensions. The effect of the initial planting density is somewhat lost in the coppiced stand in relation with i.e. the number of stems per stump. Heartwood was present in all the coppiced trees up to 49.9% of the total tree height and heartwood volume amounted to 38.9–51.7% of the total tree volume. Within the tree, heartwood content decreased from the base upwards, representing, on average, 54.1% at the base and decreasing to 5.1% at 15.3 m. The sapwood width remained relatively constant with an average radial width of approximately 2 cm. The average stem bark content of coppiced trees was 17.4% of the total stem volume. The comparison of heartwood and sapwood development in the coppiced trees did not show significant differences to the 1st rotation trees, nor did the initial spacing. Heartwood diameter could be modelled using the tree diameter both for 1st and 2nd rotation treesinfo:eu-repo/semantics/publishedVersio

Chemical Characterization of Lignocellulosic Materials by Analytical Pyrolysis

Analytical pyrolysis is used to chemically study complex molecular materials and is applied in a wide range of fields. Pyrolysis is a thermochemical process associated to the breaking of chemical bonds using thermal energy, transforming a nonvolatile compound into a volatile degradation mixture. This chapter refers to analytical pyrolysis of lignocellulosic materials, i.e., when pyrolysis is used for chemical characterization, applied to samples with small particle sizes, at 500–650°C, and with short residence times. The reactions that occur during pyrolysis of the structural components are discussed regarding the mechanisms and the pyrolysis products obtained from cellulose, hemicelluloses, and lignin. A compilation of data is made on the characterization of lignocellulosic materials using Py-GC/FID(MS) or Py-GC/MS as analytical tools including woods and barks of several species. The pyrogram profiles and important parameters on lignin chemical composition such as the H:G:S relation and the S/G ratio are summarized. Analytical pyrolysis is a versatile methodology that may be applied to characterize the lignin directly on the lignocellulosic material or after isolation from the cell wall matrix (e.g., as MWL or dioxane lignin) or from pulps or spent liquors. It is therefore an excellent tool to study lignin compositional variability in different materials and along various processing pathways

The identification of new triterpenoids in Eucalyptus globulus wood

Eight polyhydroxy triterpenoid acids, hederagenin, (4 )-23-hydroxybetulinic acid, maslinic acid, corosolic acid, arjunolic acid, asiatic acid, caulophyllogenin, and madecassic acid, with 2, 3, and 4 hydroxyl substituents, were identified and quantified in the dichloromethane extract of Eucalyptus globulus wood by comparing their GC-retention time and mass spectra with standards. Two other triterpenoid acids were tentatively identified by analyzing their mass spectra, as (2 )-2- hydroxybetulinic acid and (2 ,4 )-2,23-dihydroxybetulinic acid, with 2 and 3 hydroxyl substituents. Two MS detectors were used, a quadrupole ion trap (QIT) and a quadrupole mass filter (QMF). The EI fragmentation pattern of the trimethylsilylated polyhydroxy structures of these triterpenoid acids is characterized by the sequential loss of the trimethylsilylated hydroxyl groups, most of them by the retro-Diels-Alder (rDA) opening of the C ring with a -bond at C12-C13. The rDA C-ring opening produces ions at m/z 320 (or 318) and m/z 278 (or 277, 276, 366). Sequential losses of the hydroxyl groups produce ions with m/z from [M - 90] to [M - 90*y], where y is the number of hydroxyl substituents present (from 2 to 4). Moreover, specific cleavage in ring E was observed, passing from m/z 203 to m/z 133 and conducting other major fragments such as m/z 189info:eu-repo/semantics/publishedVersio

The influence of heartwood on the pulping properties of Acacia melanoxylon wood

The pulping wood quality of Acacia melanoxylon was evaluated in relation to the presence of heartwood. The sapwood and heartwood from 20 trees from four sites in Portugal were evaluated separately at 5% stem height level in terms of chemical composition and kraft pulping aptitude. Heartwood had more extractives than sapwood ranging from 7.4% to 9.5% and from 4.0% to 4.2%, respectively, and with a heartwood-to-sapwood ratio for extractives ranging from 1.9 to 2.3. The major component of heartwood extractives was made up of ethanol-soluble compounds (70% of total extractives). Lignin content was similar in sapwood and heartwood (21.5% and 20.7%, respectively) as well as the sugar composition. Site did not infl uence the chemical composition. Pulping heartwood differed from sapwood in chemical and optical terms: lower values of pulp yield (53% vs 56% respectively), higher kappa number (11 vs. 7), and lower brightness (28% vs 49%). Acacia melanoxylon wood showed an overall good pulping aptitude, but the presence of heartwood should be taken into account because it decreases the raw-material quality for pulping. Heartwood content should therefore be considered as a quality variable when using A. melanoxylon wood in pulp industrie

Fractioning of bark of Pinus pinea by milling and chemical characterization of different fractions

The bark of stone pine (Pinus pinea) from 50 year old trees grown in Portugal was submitted to grinding and fractioning into different particles sizes. The trees had a thick bark with an average 3,7 cm constituted mainly by the periderm and rhytidome (3,2 cm).The bark fractured easily into particles: yield of fines was low, and 74,0% of the particles were over 2 mm. The chemical composition, as a mass weighed average of all granulometric fractions showed a content of 1,1% ash 20,6% extractives (91% of which polar extractives) 2,2% suberin, 43,0% lignin and 37,6% holocellulose. The percentage of material dissolved by extraction with 1% NaOH was 42,3%. The chemical characterization of the different granulometric fractions showed that extractives were present preferentially in the finest fractions (<80 mesh and 60-80 mesh), representing 34-35%, particularly with enrichment in ethanol soluble extractives, that also showed lower content of lignin. The coarser fractions contained higher proportions of lignin and holocellulose. P. pinea bark grinding and fractionation by particle size may be used to selectively enrich the finest fractions in soluble materials, while the coarser fractions tend to have higher holocellulose content and will be therefore more suitable for carbohydrate related usesinfo:eu-repo/semantics/publishedVersio

Comparison of Py-GC/FID and Wet Chemistry Analysis for Lignin Determination in Wood and Pulps from Eucalyptus globulus

The kraft pulps produced from heartwood and sapwood of Eucalyptus globulus at 130 degrees C, 150 degrees C, and 170 degrees C were characterized by wet chemistry (total lignin as sum of Klason and soluble lignin fractions) and pyrolysis (total lignin denoted as py-lignin). The total lignin content obtained with both methods was similar. In the course of delignification, the py-lignin values were higher (by 2 to 5%) compared to Klason values, which is in line with the importance of soluble lignin for total lignin determination. Pyrolysis analysis presents advantages over wet chemical procedures, and it can be applied to wood and pulps to determine lignin contents at different stages of the delignification process. The py-lignin values were used for kinetic modelling of delignification, with very high predictive value and results similar to those of modelling using wet chemical determinations

Py-GC/MS(FID) assessed behavior of polysaccharides during kraft delignification of Eucalyptus globulus heartwood and sapwood

Eucalyptus globulus heartwood, sapwood and their delignified samples by kraft pulping at 130, 150 and 170 degrees C along time were characterized in respect to total carbohydrates by Py-GC/MS(FID). No significant differences between heartwood and sapwood were found in relation to pyrolysis products and composition. The main wood carbohydrate derived pyrolysis compounds were levoglucosan (25.1%), hydroxyacetaldehyde (12.5%), 2-oxo-propanal (10.3%) and acetic acid (8.7%). Levoglucosan decreased during the early stages of delignification and increased during the bulk and residual phases. Acetic acid decreased hydroxyacetaldehyde and 2-oxo-propanal increased, and 2-furaldehyde and hydroxypropanone remained almost constant during delignification. The C/L ratio was 3.2 in wood and remained rather constant in the first pulping periods until a loss of 15-25% in carbohydrate and 60% in lignin. Afterwards it increased sharply until 44 that correspond to the removal of 25-35% of carbohydrates and 95% of lignin. The pulping reactive selectivity to lignin vs. polysaccharides was the same for sapwood and heartwood. (C) 2013 Elsevier B.V. All rights reserved

Lignin as Feedstock for Nanoparticles Production

Lignin is an interesting natural polymer with characteristics that contribute for the development and growth of plants. Lignin presents high variability associated with the diversity of plants, which presents great challenges for its recovery after delignification (technical lignin), because lignin is prone to irreversible degradation, producing recalcitrant condensed structures that are difficult to disassemble afterward. Although researchers have made efforts to obtain lignin in high yields and with good characteristics for specific uses, this is not an easy task. The mind-set has changed and new biorefinery concepts are emerging, where lignin is the primary goal to achieve, and the so-called lignin-first approach has arisen. Lignin can be obtained firstly to prevent structural degradations, enabling an efficient and highly selectivity of the lignin monomers. Therefore, this concept places lignin and its valorization at the head of the biorefinery. However, lignin valorization is still a challenge, and to overcome this, lignin nanoparticles (LNPs) production presents a good way to achieve this goal. This chapter presents a resume of the several techniques to attain lignin, how to produce LNPs, and their possible applications (from pharmaceutical to the automobile and polymer industries)