Shu-Ming Li

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.

Cellulose/CaCO3 nanocomposites: microwave ionic liquid synthesis, characterization, and biological activity.

The purposes of this article are to synthesize the biomass-based hybrid nanocomposites using green method in green solvent and evaluate its biological activity. In this paper, microwave-assisted ionic liquid method is applied to the preparation of cellulose/CaCO(3) hybrid nanocomposites in the alkali extraction cellulose using CaCl(2) and Na(2)CO(3) as starting reactants. The ionic liquid acts as the excellent solvent for absorbing microwave and the dissolution of cellulose, and the synthesis of cellulose/CaCO(3) nanocomposites. The influences of reaction parameters such as the cellulose concentration and the types of solvent on the products were investigated. The increasing cellulose concentration favored the growth of CaCO(3). The morphologies of CaCO(3) changed from polyhedral to cube to particle with increasing cellulose concentration. Moreover, the solvents had an effect on the shape and dispersion of CaCO(3). Cytotoxicity experiments demonstrated that the cellulose/CaCO(3) nanocomposites had good biocompatibility and could be a candidate for the biomedical applications.

Compare study CaCO3 crystals on the cellulose substrate by microwave-assisted method and ultrasound agitation method

The purposes of this article were to investigate the influences of synthesis strategy on the CaCO(3) crystals on the cellulose substrate. In this study, CaCO(3) crystals were synthesized using cellulose as matrix by the microwave-assisted method and ultrasound agitation method, respectively. The CaCO(3) crystals on the cellulose substrate were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Experimental results demonstrated that the synthesis strategy had a dramatically influences on the phase, microstructure, morphology, thermal stability, and biological activity of the CaCO(3) crystals. The pure phase of vaterite spheres with the diameter of about 320-600nm were obtained by ultrasound agitation method, meanwhile, the mixed phases of calcite and vaterite with the diameter of about 0.82-1.24μm were observed by microwave-assisted method. In view of experimental results, one can conclude that the ultrasound agitation method do more favors to the synthesis of CaCO(3) crystals with uniform morphology and size, compared with microwave-assisted method. Furthermore, cytotoxicity experiments indicated that the CaCO(3) crystals on the cellulose substrate had good biocompatibility and could be a candidate for the biomedical applications.

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.

Microwave synthesis of cellulose/CuO nanocomposites in ionic liquid and its thermal transformation to CuO.

The purpose of this study is to develop a green strategy to synthesize the cellulose-based nanocomposites and open a new avenue to the high value-added applications of biomass. Herein, we reported a microwave-assisted ionic liquid route to the preparation of cellulose/CuO nanocomposites, which combined three major green chemistry principles: using environmentally friendly method, greener solvents, and sustainable resources. The influences of the reaction parameters including the heating time and the ratio of cellulose solution to ionic liquid on the products were discussed by X-ray powder diffraction, Fourier transform infrared spectrometry, and scanning electron microscopy. The crystallinity of CuO increased and the CuO shape changed from nanosheets to bundles and to particles with increasing heating time. The ratio of cellulose solution to ionic liquid also affected the shapes of CuO in nanocomposites. Moreover, CuO crystals were obtained by thermal treatment of the cellulose/CuO nanocomposites at 800 °C for 3 h in air.

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.

Hydrothermal synthesis, characterization, and bactericidal activities of hybrid from cellulose and TiO2

The purpose of this study was to explore a new strategy to improve the high value-added applications of biomass. Hybrid from cellulose and titanium dioxide (TiO2) was successfully prepared by using tetra-n-butyl titanate and cellulose solution via a hydrothermal method at 180°C for 24h. The phase, microstructure, morphology, and thermal stability of the hybrid were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and scanning electron microscopy (SEM). The influences of the tetra-n-butyl titanate concentration and the types of solvent on the products were investigated. The TiO2 nanoparticles were dispersed on the surface of cellulose and/or in the cellulose matrix. The hybrid possessed an antimicrobial activity against the model microbes Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), and were a promising antimicrobial material for the applications in the biomedical field.

Compare study cellulose/Ag hybrids using fructose and glucose as reducing reagents by hydrothermal method.

The primary objective of this work was to evaluate the effect of reducing reagents on the hybrids from cellulose and Ag, which have been successfully synthesized by using fructose and glucose as reducing reagents via a hydrothermal method, respectively. The hybrids were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The influences of the various reaction parameters including the heating time, heating temperature, and types of reducing reagents on the hybrids were investigated. Silver particles can be better dispersed in the cellulose matrix by adjusting reaction parameters. Experimental results demonstrated that the types of reducing reagents played an important role in the shape and dispersion of silver particles in hybrids.

Environmentally-friendly sonochemistry synthesis of hybrids from lignocelluloses and silver

The purpose of this study was to explore a green strategy about the high value-added applications of biomass. Hybrids from lignocelluloses and silver have been successfully prepared using NaBH4 as reducing reagent by an environmentally-friendly sonochemistry method. The phase, microstructure, and morphology of the hybrids were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The influences of the various reaction parameters including reaction time, lignocelluloses concentration, and types of reducing reagents on the products were investigated in detail. Silver particles can be better dispersed on the lignocelluloses matrix by adjusting reaction parameters. These hybrids may be a promising antimicrobial material for their applications in the biomedical field. This environmentally-friendly synthetic strategy reported here opens a new window to the high value-added applications of lignocelluloses.