Search

Cellulose nanowhiskers (CNWs) from plant biomass are of considerable interest, primarily due to their low density, biodegradability, mechanical strength, economic output, and renewability. Here, a new pretreatment method has been developed to produce CNWs based on supercritical CO2 and ethanol. The raw material was micro-fibrillated cellulose (MFC) and experimental factors were controlled to enhance the properties of CNWs produced using a ball-milling technique following supercritical CO2 pretreatment. Cellulose nanofibers (CNFs) were also prepared using a high-pressure Microfluidizer©. A comparative study was conducted of the properties of the raw materials, the CNWs and the CNFs. The solid yields of P-MFC after supercritical CO2 pretreatment gradually decreased, along with the temperature and the reaction time. Scanning electron microscopy (SEM) images of the CNWs and CNFs show that the morphology of the CNWs was basically acicular, while that of the CNFs was mainly soft fibrous. Thermogravimetric analysis results suggest that the thermal stability of the CNWs was substantially higher than those of the CNFs and the raw material. XRD results indicate that the crystallinity showed an initial increasing trend and then declined with increasing temperature and reaction time, and the crystallinity value of CNWs was higher than that of CNFs. The smaller CNWs became rougher and had a larger surface area.

Superhydrophobic surfaces have high potential in self-cleaning and oil-water separation applications. We developed a three-step method for the preparation of superhydrophobic filter paper. It involved citric acid (CA) pretreatment to activate cellulose fibers, coating with cellulose nanofibrils/functionalized silica (CNFs/m-SiO2) slurry to increase surface roughness, and grafting of hexadecyltrimethoxysilane (HDTMS) to enhance water resistance. The water contact angle (WCA) and siding angle (SA) of the prepared filter paper reached 151.5° and 7.5°, respectively. The results showed that, compared to the coated filter paper without the added CNFs, the coated paper with CNFs had higher retention of m-SiO2, thus roughness required for superhydrophobic surface was achieved. Further test under frequent abrasion and acid or alkali conditions showed that CA pretreatment improved the durability of superhydrophobic filter paper due to chemical crosslinking between the modified substrate and m-SiO2. Besides, the prepared superhydrophobic filter paper had outstanding self-cleaning property and high oil-water separation efficiency for various oil-water mixtures. Therefore, it is expected to be used for the treatment of oily wastewater.

To investigate the high phenolic lignin extraction process, deep eutectic solvents based on oxalic acid and glycerol as a hydrogen bond donor were first prepared and analyzed. Two different types o...

The antioxidant activity of lignin for producing biochemicals has attracted attention. In this paper, a separation method for lignin is proposed, with high-yield and high-antioxidant activity by using a formic acid-catalyzed subcritical ethanol process. The formic acid-catalyzed ethanol lignin (EOL/FA) and ethanol organosolv lignin (EOL) were first prepared using a high-pressure autoclave at different formic acid dosages. Then, the antioxidant activity and the structural and thermal properties of EOL/FA, EOL, alkali lignin, and sodium lignosulfonate were analyzed using antioxidant analysis, Fourier transform infrared (FTIR) spectroscopy analysis, and thermogravimetric analysis (TGA). The phenolic hydroxyl content of the four lignins was also determined by the Folin–Ciocalteau colorimetric method. Results showed EOL/FA had a higher radical scavenging ability and higher total phenolic hydroxyl content than industrial lignin. It indicated that the formic acid-catalyzed subcritical ethanol process was effective for enhancing the antioxidant activity of lignin.

The possibility and feasibility of nanocrystalline cellulose (NCC) for dispersing hydrophobic graphene in aqueous solutions were studied in the present work. The dispersion properties of graphene particles in aqueous media as a function of various amounts of NCC were investigated. The rheological behavior of NCC-dispersed graphene suspensions was studied, and a polynomial model was proposed and employed to simulate the obtained shear flow of graphene suspensions. The results of UV–Vis analysis and sedimentation test suggested that the increased NCC addition significantly led to the improved dispersion properties of graphene suspensions. Rheological behavior measurements demonstrated that graphene suspensions exhibited a reduction trend in the shear viscosity, shear stress, and viscoelasticity with the increased amount of NCC addition. Meanwhile, the shear viscosity and shear stress of graphene suspensions were found to show a dependency on the process temperature. The above results supported the conclusion that NCC is a promising candidate for improving the dispersion and flowability of graphene in aqueous media.

To raise H-2/CO and remove tar for biomass product gas, sodium titanates 4Na(2)O center dot 5TiO(2) and Na2O center dot 3TiO(2) were evaluated at 850 degrees C using wood powder pyrolysis gas produced from a 0.3 kg/h screw pyrolyzer with no extra steam, silica sand was selected as an inert material for comparison. The GHSV of the runs were around 2000 h(-1) with tar content of about 200 g/Nm(3). The results suggest that 4Na(2)O center dot 5TiO(2) presents the highest activity, Na2O center dot 3TiO(2) ranks slightly lower, and silica sand shows no activity of enhancing hydrogen yield. The hydrogen formation is promoted through tar cracking, water gas shift and/or methane reforming. The H-2/CO increases to 1.8-2.0, which is higher than that of silica sand (about 0.35) and raw gas (about 0.25). Tar conversion in the 4Na(2)O center dot 5TiO(2) reforming was about 99% and nearly no coke was formed within the test duration of about 8 h, whereas the silica sand was coked obviously in 1 h. Most tar components can be effectively reformed, except for parts of xylene, naphthalene, biphenylene, and anthracene. The activity of 4Na(2)O center dot 5TiO(2) decreases gradually in the long-term test because of the release of sodium and has a tendency to transform to Na2O center dot 3TiO(2), the latter exhibits satisfactory stability and activity. (C) 2017 Elsevier Ltd. All rights reserved.

The effects of molecular weight on the pyrolysis products properties of alkali lignin were investigated by using thermogravimetric analyzer coupled with Fourier transform infrared spectrometry (TG-FTIR) and tube furnace. Four lignin samples, including pure alkali lignin (AL), more than 10 kDa lignin fraction (AL-10kDa), 5–10 kDa lignin fraction (AL-5kDa) and 1–5 kDa lignin fraction (AL-1kDa) were firstly prepared by ultrafiltration membrane technology. Then the thermal behavior and volatile evolution patterns of the four lignin samples were investigated by TG-FTIR, and the component properties of condensable and incondensable products obtained from tube furnace were characterized by the gas chromatography/mass spectroscopy (GC/MS) and gas chromatography (GC). TG-FTIR results indicated that the molecular weight of lignin was not significantly affected on the evolution temperature ranges and volatile product species, while has an obviously effect on the total yields of CH 4 , CO 2 , phenols and aromatics products. GC/MS and GC results indicated that low molecular weight helps to crack the methoxy groups of lignin leading to the yields of CH 4 , CO, CO 2 , phenol and alkyl phenol increased, while high molecular weight favored the generation of guaiacol and alkyl guaiacol. Meanwhile, the effect of molecular weight on the yields of aromatics was also affected by the pyrolysis temperature.

We presented a three-step method for the preparation of superhydrophobic cellulose filter paper. It involved ZnCl2 pre-treatment to activate the cellulose fibers, a SiO2 sol-gel process to increase surface roughness and grafting of hexadecyl trimethoxysilane groups to chemically enhance the water repellency. The water contact angle of the modified paper reached 154.8°. XRD analysis confirmed silica as the product from the sol-gel process. EDS and SEM analysis showed that pre-treatment results in greater silica adhesion and retention on the paper surface. The modified paper proved to be self-cleaning and resistant to staining. Further tests under various conditions showed that ZnCl2 pre-treatment improved the durability of the superhydrophobic paper. It was concluded that pre-treatment of the filter paper prior to superhydrophobic coating results in a disruption in the cellulose crystalline structure that favours greater silica adhesion and retention.

Nanocrystalline cellulose (NCC) has shown great potential for reinforcing nanocomposite systems, particularly in biopolymer-based nanocomposites. In the present work, transparent and biodegradable chitosan (CH)/guar gum (GG)/NCC nanocomposite films were designed and prepared. The effect of NCC loadings on the rheological behavior of the as-prepared nanocomposite suspensions was investigated, the overall properties of the resultant nanocomposite films as a function of various amounts of NCC were determined, and the surface morphology of various nanocomposite films was characterized by scanning electron microscopy (SEM). Results indicated that the increased NCC loadings increased the shear viscosity of the nanocomposite suspensions. Moreover, as expected, the obtained CH/GG/NCC nanocomposite films were found to exhibit improved tensile strength and reduced air permeability in comparison to pure CH/GG films. This work supported the conclusion that NCC was effective in reinforcing the CH/GG composite films, which may be a promising material for food packaging applications.

Polyaniline (PANI)/graphene oxide (GO) composites were synthesized via in situ polymerization of aniline in the presence of GO. The effect of microwave treatment of graphite on the electrical conductivity and electrochemical properties of PANI/GO composites was highlighted, and the morphology and microstructure were subsequently characterized using transmission electron microscopy, scanning electron microscopy, Fourier-transformed infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. The results demonstrated that microwave treatment of graphite imparted a well-dispersed, highly ordered layered structure to the as-prepared GO, and in turn facilitated strong bonding between the GO and PANI nanosheets, which may be responsible for the improved electrical conductivity and electrochemical properties of the resulting PANI/GO composites. The desired PANI/GO composites possessed an electrical conductivity of 508 S/m, an areal capacitance of 172.8 mF/cm2, and a retained capacitance of 87.4% after cycling, representing percentage increases of 102, 232, and 112, respectively, as a result of the microwave treatment of graphite. The resulting composites are promising electrode materials for high-performance and ecofriendly electrical energy storage devices.

Incorporation of nanofillers into a polymeric matrix has received much attention as a route to reinforced polymer nanocomposites. In the present work, an environmentally friendly chitosan (CTS)/titanium dioxide (TiO2) nanocomposite coating was designed/prepared and subsequently employed for imparting antibacterium and improved mechanical properties to cellulosic paper via surface coating. Effect of TiO2 nanoparticle loadings on the rheological behavior of nanocomposite coatings was investigated. Surface application of CTS/TiO2 nanocomposite coatings to cellulosic paper was performed, and the antibacterial activity and mechanical properties of surface-coated cellulosic paper were examined. Results showed that the increased TiO2 nanoparticle loadings decreased the viscosity and dynamic viscoelasticity of the as-prepared coatings, and improved the antibacterial activity and mechanical properties of surface-coated cellulosic paper. The optimum loading of TiO2 nanoparticles was identified at 10%. This work suggested that CTS/TiO2 nanocomposite coatings may have the potential to be used as a promising antibacterial protective coating for paper packaging.