Ning Jia

Isolation and characterization of hemicelluloses extracted by hydrothermal pretreatment

The dewaxed sample from Triploid of Populus tomentosa Carr. was extracted by using organic alkaline solvent (Dimethylformamide, DMF) via hydrothermal pretreatment. Neutral sugar compositions and molecular weight analysis demonstrated that the hemicellulosic fractions with a higher Uro/Xyl ratio, namely the more branched hemicelluloses, had higher molecular weights. Interestingly, these results were different from the previous report, in which the ratio of Uro/Xyl in the water-soluble hemicellulosic fraction was more than that of the alkali-soluble hemicellulosic fraction. Spectroscopy (FTIR, (1)H NMR, (13)C NMR, and HSQC) analysis indicated that the hemicellulosic fractions were mainly composed of (1→4)-linked α-D-glucan from starch and (1→4)-linked β-D-xylan attached with minor amounts of branched sugars from hemicelluloses. In addition, thermal analysis implied that linear hemicelluloses showed more thermal stability than the branched ones during pyrolysis.

Rapid microwave-assisted synthesis and characterization of cellulose-hydroxyapatite nanocomposites in N,N-dimethylacetamide solvent

Preparation of nanocomposites was carried out using microcrystalline cellulose, CaCl(2), and NaH(2)PO(4) in N,N-dimethylacetamide (DMAc) solvent by a microwave-assisted method at 150 degrees C. XRD results showed that the nanocomposites consisted of cellulose and hydroxyapatite (HA). The cellulose existed as a matrix in the nanocomposites. SEM and TEM analysis showed that HA nanorods were homogeneously dispersed in the cellulose matrix. The effects of the microwave heating time on the products were investigated. This method has advantages of being simple, rapid, low-cost, and environmentally friendly.

Green microwave-assisted synthesis of cellulose/calcium silicate nanocomposites in ionic liquids and recycled ionic liquids

Fabrication of biomass materials by a microwave-assisted method in ionic liquids allows the high value-added applications of biomass by combining three major green chemistry principles: using environmentally preferable solvents, using an environmentally friendly method, and making use of renewable biomass materials. Herein, we report a rapid and green microwave-assisted method for the synthesis of the cellulose/calcium silicate nanocomposites in ionic liquids and recycled ionic liquids. These calcium silicate nanoparticles or nanosheets as prepared were homogeneously dispersed in the cellulose matrix. The experimental results confirm that the ionic liquids can be used repeatedly. Of course, the slight differences were also observed using ionic liquids and recycled ionic liquids. Compared with other conventional methods, the rapid, green, and environmentally friendly microwave-assisted method in ionic liquids opens a new window to the high value-added applications of biomass.

Compared study on the cellulose/CaCO3 composites via microwave-assisted method using different cellulose types

The purposes of this study were to explore the influences of different cellulose types on the cellulose/CaCO3 composites, which were synthesized via the microwave-assisted method by using alkali extraction cellulose and microcrystalline cellulose, respectively. Experimental results demonstrated that the types of cellulose played an important role in the microstructure and morphologies of the cellulose/CaCO3 composites. The composites consisted of cellulose and pure phase CaCO3 (calcite). The sample synthesized using microcrystalline cellulose had better crystallinity than that of the sample using alkali extraction cellulose. The cellulose fibers and CaCO3 particles were observed using alkali extraction cellulose. However, using microcrystalline cellulose instead of alkali extraction cellulose, the cellulose with irregular shape and CaCO3 microspheres were obtained. Therefore, choosing appropriate cellulose types is very important for the formation of cellulose/CaCO3 composites. Furthermore, the Raman spectra of the cellulose/CaCO3 composites were also researched.

Nanocomposites of cellulose/iron oxide: influence of synthesis conditions on their morphological behavior and thermal stability.

Nanocomposites of cellulose/iron oxide have been successfully prepared by hydrothermal method using cellulose solution and Fe(NO3)3·9H2O at 180 °C. The cellulose solution was obtained by the dissolution of microcrystalline cellulose in NaOH/urea aqueous solution, which is a good system to dissolve cellulose and favors the synthesis of iron oxide without needing any template or other reagents. The phases, microstructure, and morphologies of nanocomposites were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectra (EDS). The effects of the heating time, heating temperature, cellulose concentration, and ferric nitrate concentration on the morphological behavior of products were investigated. The experimental results indicated that the cellulose concentration played an important role in both the phase and shape of iron oxide in nanocomposites. Moreover, the nanocomposites synthesized by using different cellulose concentrations displayed different thermal stabilities.