Search

Cellulose Nanofibrils (CNFs) were exposed to a certain amount of sodium chloride (NaCl) before being subjected to two types of drying methods (freeze drying and vacuum drying). The effect of two drying methods on water redispersibility of CNFs was investigated by characterizing product morphology, particle size distribution, water stability, and surface chemistry. The results showed that vacuum drying was favorable for the redispersion of CNFs with NaCl resulted in more homogenous fibril structure with lower mean particle sizes and higher water stability. Fourier transform-infrared spectroscopy (FT-IR) and Energy-dispersive X-ray Spectroscopy (EDX) experiments indicated that vacuum drying at pH 8 was more conducive to complexation between Na+ and carboxyl, hydroxyl groups favorable for CNF redispersion. Furthermore, NaCl is cheap, and the process is very straightforward which does not require any organic solvents or hazardous chemicals. Therefore, vacuum drying with NaCl may be considered as a green and economically feasible method for preparation of water redispersible dried CNFs.

Pretreatment to enhance the enzymatic digestibility of cellulose usually alters the structure of lignin, resulting in subsequent inferior depolymerization and utilization. Herein, a physicochemical pretreatment strategy, specifically, using a recyclable acid hydrotrope (p-toluenesulfonic acid, p-TsOH) followed by 10 s of ultrasonic treatment, was developed to facilitate high-value lignin extraction from lignocellulosic biomass and improve enzymatic hydrolysis for high-titer ethanol production. The wood material (poplar) was first treated with the recyclable p-TsOH aqueous solution under mild conditions (C80T80t15) to extract the lignin. The obtained lignin exhibited excellent properties, including a high hydroxyl (OH) content (4.19 and 4.07 mmol/g of aliphatic and phenolic OH, respectively), abundant β-O-4 aryl ether linkages (60%), a low Mw (3357 ± 121 g/mol), and a narrow polydispersity (2.28, Mw/Mn), according to the results from FTIR spectroscopy, TGA, 31P NMR spectroscopy, 2D-HSQC NMR spectroscopy, and GPC. The pretreated substrates were then subjected to 10 s of ultrasonication to improve the enzymatic saccharification and finally afford ethanol by quasi-simultaneous enzymatic saccharification and fermentation (Q-SSF). The highest ethanol concentration (40.08 ± 3 g/L) was obtained after 60 h of fermentation, and the residual glucose concentration was only 4.22 ± 1 g/L; this experimental ethanol yield was equivalent to the theoretical ethanol yield of 81.87 ± 4% based on the glucan content. In short, this pretreatment method simultaneously enhanced the accessibility of cellulose to enzymatic hydrolysis and provided high-value lignin.

Prehydrolysis is an essential step for utilizing biomass, particularly in the Kraft-based dissolving pulp process. Once the hemicellulose was effectively extracted, it can not only upgrade the dissolving pulp, but also arise additional revenue by converting value-added products. Herein, sodium dodecyl benzene sulfonate (SDBS) was used to enhance the hemicellulose removal from poplar wood chips during mild acid hydrolysis. SDBS addition could reduce the surface tension, thus increasing the diffusion of hydrogen ion and promoting the hemicellulose and lignin dissolution. The hemicellulose removal was increased from 42.5 to 54.7% by adding SDBS in comparison with the control under condition of 170 °C and 2 h. Additionally, the lignin removal was increased from 9.6 to 19.1%. Gel permeate chronograph, scanning electron microscope, and heteronuclear single quantum coherence spectroscopy support the positive effect of SDBS addition. The properties of dissolving pulp prepared from surfactant assisted pretreatment are comparable/better than that derived from acid pretreatment. It opened a sustainable and economical way to extract hemicellulose from lignocellulose. A new surfactant assisted acid prehydrolysis process for enhancing biomass pretreatment.

Levulinic acid (LA) production from corncob acid hydrolysis residues (CAHR) using FeCl3 as Lewis acid catalyst in green solutions of salt was investigated. The reaction kinetic relationships were determined in the temperature range of 160–180 °C, with FeCl3 concentrations of 0.12–0.36 M, and a reaction time of 0–60 min. The maximum LA concentration of 59.0 mol% (24.5 g/L) was achieved at 170 °C in a 30% NaCl solution containing 0.24 M FeCl3. A pseudo first-order kinetic model was proposed to describe the cellulose deconstruction to LA. The model agreed perfectly with the evolution in the concentrations of the major compounds such as glucose, 5-hydroxymethylfurfural and LA during the CAHR hydrolysis. The kinetic model developed for CAHR was in good agreement with that previously developed for other lignocellulosic systems. Based on our kinetic model and reaction system, the LA yield is increased at the lower end of the temperature range with the higher acid concentrations. The results indicated that the concentrated seawater after desalination could be a green solvent in the biorefinery.

In the present examination, the thermochemical behavior of the lignin extracted from willow (Salix matsudana cv. Zhuliu) by deep eutectic solvents (DES) treatment (DES-lignin) with varied times were investigated with the techniques of thermogravimetric analyzer, in situ diffuse reflectance infrared pyrolysis (in situ-FTIR), and pyrolysis–gas chromatography/mass spectrometry. The results showed that thermal degradation of DES-lignin mainly occurred at 185–470 °C with two maximum weight loss peaks at 265 °C and 380 °C respectively, and the solid residue was 40% when terminated at 800 °C. The identified cluster of aromatics from in situ-FTIR was detected earlier and stronger than those of small molecular gases, suggesting cleavage of lignin intermolecular linkages dominated the initial pyrolysis process. The DES-lignin was sensitive to pyrolysis to produce aromatics. The total phenols yield from DES-lignin pyrolysis reached a maxima of 95.1% at 450 °C, among which phenol and guaiacol accounted for the largest proportion, i.e. 20.8% and 24.2% respectively. In addition, product distribution was remarkably affected by pyrolysis temperature and the DES treatment time used for lignin isolation.

The objectives of this work were to investigate the effect of the degree of fibrillation and addition method of cellulose nanofibrils (CNFs) into the wet end of the papermaking process on the drainage, filler retention, strength and optical properties of handsheets. CNFs were produced with the grinding method, and the degree of fibrillation was manipulated by varying the passing number through the grinder from 15 to 50 passes. The CNFs were added to the wet end of the papermaking process in two different ways: a precipitated calcium carbonate (PCC)-CNF composite filler and a wet-end additive. The results showed that the water retention capacity of CNFs increased as the fibrillation was performed, and this resulted in an increase in drainage time. The solid content of handsheets filled with composite filler was about 1–2% higher than in the CNF-added sheets after wet pressing. Furthermore, the composite filler-filled sheets with higher ash content had similar tensile strength, compared with the CNF-added sheets. It was also found that water retention capacity of CNFs increased as the fibrillation was performed, and this resulted in an increment in drainage time and a reduction in solid content of sheets after wet pressing. The more fibrillated CNFs significantly (p

Enhancing the swelling of chemithermomechanical pulp is essential for improving its physical properties and thus broadening its end-use applications. In this work, ionic liquid (IL) using 1-allyl-3-metheylimidazolium chloride ([Amim]Cl) was used for reducing hydrogen bonding within the fiber wall, and ultrasonic treatment was used for improving the performance of IL treatment. Mixing IL with pulp fibers at 5 ml/g concentration decreased the Canadian standard freeness (CSF) of pulp from 760 to 570 ml at room temperature, and the pretreatment with ultrasonic treatment for 20 min reduced its CSF to 545 ml. The ultrasonic-assisted IL treatment improved the tensile, tear and burst indices as well as the folding endurance of the cellulosic network by 41, 36, 12 and 150%, respectively. The surface charge density and area of fibers were improved, but the lignin and hemicellulose contents of the fibers were reduced via ultrasonic-assisted IL treatment.