Chemical functional groups of extractives, cellulose and lignin extracted from native Leucaena leucocephala bark

Abstract

Bark from trees is considered a worthless raw material. However, this resource could be economically beneficial if utilized efficiently due to its rich chemical compounds. In this study, an ethanol toluene-soluble extractive, alpha-cellulose and lignin obtained from Leucaena leucocephala bark were characterized to determine their chemical functional groups. Based on FTIR spectral analysis, the results indicated that the bands of the functional groups of the extractive from the original bark remain unchanged; however, the absorbance intensity was found to be weaker in the group frequency and fingerprint regions. Removal of extractive, pectin, hemicellulose and lignin from the bark indirectly increased the strong absorbance intensity of cellulose. Broad peaks of OH stretching found in all spectra were assigned to the presence of phenolic OH and aliphatic structures for extractive and aromatic structures of lignin. It was revealed that aromatic functional groups were mainly found in the extractive, while water, carbonyl and ether were the dominant groups in cellulose, and methyl, methylene, carbonyl and carboxyl groups were enriched in lignin. Graphic abstract

A comparative study on the structural and functional properties of water‐soluble and alkali‐soluble dietary fibres from rice bran after hot‐water, ultrasound, hydrolysis by cellulase, and combined pre‐treatments

“…A strong absorption peak in the 3500–3000 cm −1 region, for example stretching vibration at 3281 cm −1 (Fig. 1) corresponds to the hydroxyl groups of the hemicellulose and cellulose and water involved in hydrogen bonding (Md Salim et al ., 2021). The extension (Fig.…”

“…1b) of this peak indicates that temperature, cellulase action and US promoted the disintegration of hydrogen bonding between hydroxyl groups in the cellulose crystalline structure and formation of additional free hydroxyl groups (Huang et al ., 2018). The two sharp absorption peaks that appeared at 2924 cm −1 (symmetric) and asymmetrically at 2855 cm −1 for WS‐DF, and at 2916 and at 2851 cm −1 for AS‐DF are attributed to the C–H stretching vibrations, indicating the presence of the typical structure of polysaccharide compounds (Fan et al ., 2020; Md Salim et al ., 2021). The weakening of the peak intensity in both DF fractions can be attributed to the modification of the hemicelluloses and cellulose structure and lignin degradation with a strongest effect when HWT and HC were applied.…”

Simultaneous Enzymatic Cellulose Hydrolysis and Product Separation in a Radial-Flow Membrane Bioreactor

“…The peak at 1654 cm −1 reflects the C=C or C=N vibration in the aromatic region, which is influenced by the lignin [ 28 ]. The band at 993 cm −1 represents the C–O–C glycosidic bond vibration, and C–C stretching is assigned to the peak at 791 cm −1 , which are related to the cellulose component [ 30 ]. After partial pretreatment, where lignin is removed, a similar spectrum to that of the fresh DSs was observed but with the appearance of two peaks at 1743 and 864 cm −1 .…”

Cleaner Approach for Atrazine Removal Using Recycling Biowaste/Waste in Permeable Barriers

“…The 860, 820 and 773 cm −1 bands indicate the -CH bending vibrations from aromatic rings, related to phenolic compounds [60]. In this spectrum, the distinct signal at 1036 cm −1 is identified, produced by the aliphatic C-O stretching [58]. When comparing raw pine spectra with the ones obtained after two desorption steps, no substantial differences occur, in contrast to the other materials.…”

“…The bands at 1610 cm −1 and 1510 cm −1 are attributed to the aromatic C-C skeletal vibrations, and the band around 1733 cm −1 results from the stretching vibrations in C-O carbonyl structure. At 1160 cm −1 and 1210 cm −1 , the stretching of C-O-C in the cellulose and hemicellulose is detected [58,59]. The phenolic -OH and aliphatic -CH stretch vibrations can be identified at 1364 cm −1 .…”