Fractionation of Aspen Wood to Produce Microcrystalline, Microfibrillated and Nanofibrillated Celluloses, Xylan and Ethanollignin

Abstract

A new method for extractive-catalytic fractionation of aspen wood to produce microcrystalline (MCC), microfibrillated (MFC), nanofibrilllated (NFC) celluloses, xylan, and ethanollignin is suggested in order to utilize all of the main components of wood biomass. Xylan is obtained with a yield of 10.2 wt.% via aqueous alkali extraction at room temperature. Ethanollignin was obtained with a yield of 11.2 wt.% via extraction with 60% ethanol from the xylan-free wood at 190 °C. The lignocellulose residue formed after the extraction of xylan and ethanollignin was subjected to catalytic peroxide delignification in the acetic acid-water medium at 100 °C in order to obtain microcrystalline cellulose. MCC is hydrolyzed with 56% sulfuric acid and treated with ultrasound to produce microfibrillated cellulose and nanofibrillated cellulose. The yields of MFC and NFC were 14.4 and 19.0 wt.%, respectively. The average hydrodynamic diameter of NFC particles was 36.6 nm, the crystallinity index was 0.86, and the average zeta-potential was 41.5 mV. The composition and structure of xylan, ethanollignin, cellulose product, MCC, MFC, and NFC obtained from aspen wood were characterized using elemental and chemical analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses, Gas chromatography (GC), Gel permeation-chromatography (GPC), Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Dynamic light scattering (DLS), Thermal gravimetric analysis (TGA).

Extraction and Modification of Cellulose Microfibers Derived from Biomass of the Amazon Ochroma pyramidale Fruit

“…The O. pyramidale fruit fiber presented a surface constituted of extractives (E% = 3.7 ± 0.3) [16] based on secondary metabolites. Despite presenting a low concentration of extractives, their association to lignin allows for a hydrophobic-lipophilic fiber's property [15,17] preventing their interaction to water [50]. Similar behavior was observed in kapok fibers [15].…”

“…Different methods of cellulose extraction have been proposed, showing their influence on the material surface [60] and physicochemical properties, as is also observed in the present work. The bands at 1597 cm −1 and 1503 cm −1 (C=C of lignin) [46,50,55,60] presented in the IN sample completely disappeared in the PU sample. On the other hand, the bands at 1739 cm −1 (C=O stretching of lignin and hemicellulose fractions) [55,59,61], 1463 cm −1 (CH 3 of lignin) [19,62] and 1246 cm −1 (C-O of lignin) [55,59,63] were still observed.…”