Yan Zhi Xia

Electrospinning of Sodium Alginate with Poly(ethylene oxide), Gelatin and Nanometer Silver Colloid

In this study, biocompatible polymer poly(ethylene oxide) (PEO), gelation (denatured collagen) and nanometer silver colloid was added to the electrospinnning solution of alginate sodium to get anti-bacterial nanofiber mats. The morphology and mechanical properties of the electrospun mats have been investigated. Smooth fibers with diameters around 300 nm were obtained from 4.0 % solutions of varied alginate/PEO/gelation proportion. The anti-water property of the electrospun mats has been improved by crosslink with glutaraldehyde acetone solution and aqueous calcium chloride and ethanol.

Preparation and Properties of Alginate Salt Fibers: An Inherent Flame-Retardant, Biodegradable Fiber

Alginate calcium fibers were prepared through wet spinning with good tensile strength which can be used for cloth materials. The morphology, mechanical property and combustion property of alginate calcium fibers were investigated. Blending yarns and textile of alginate calcium fibers and combed cotton was fabricated with good hand feeling and strength. Alginate salt fiber was prepared with wet spinning machine designed according to viscose fiber spinning machine. The diameter of alginate calcium fibers was about 10-15µm in diameter with smooth surface. The tensile strength of alginate salt fiber was larger than 4.8 cN in the dry state. The value of Limited Oxygen Index (LOI) of alginate calcium fibers was 34%. The average heat release rates (HRR) of the alginate fiber is about 21 kW/m2 which was much lower than that of most synthetic and natural fibers analysized with Cone. Alginate calcium fibers is an inherent flame-retardant fiber.

Rheological Behaviors of Carbonaceous Materials Suspended in Sodium Alginate Solutions

Three kinds of carbonaceous materials with different structural and chemical properties, Carbon Black (CB), Multi-walled Carbon Nanotubes (MWNTs), and Graphene Oxide (GO), were well suspended in sodium alginate (SA) solutions, and the suspension rheological behaviors were investigated in details. Steady rheological results showed that the suspensions exhibited same shear-thinning behaviors as SA solution. Dynamic rheological results showed that the complex viscosity (η*) was similar to that of steady rheological measurement, and both SA solution and SA/carbonaceous materials suspensions exhibited liquid-like behaviors, confirmed by the loss modulus larger than the storage modulus. The loss factor tanδ remarkably decreased for SA/GO solution compared with SA/CB and SA/MWNTs suspension at the same concentration, indicating the increase of elasticity via interactions between the GO and SA.

Graphene Modified Molecular Imprinted Electrochemical Sensor for Specific Recognition of Bovine Serum Albumin

A simple and efficient molecularly imprinted sensor (MIPs/GR/GCE) was firstly prepared by electropolymerization of pyrrole in the presence of bovine serum albumin (BSA) in an aqueous solution based on a graphene modified glassy carbon electrode for the selective recognition of bovine serum albumin. The prepared sensor was characterized by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS), in which [Fe(CN)6]3−/4− was used as an electrochemical active probe. The results showed a wide linear range from 1.0 × 10-3 to 1.0 × 10-9 g/mL. And the imprinted biosensor indicated excellent selectivity and high sensitivity.

Synthesis and Characterization of ZrO2/Graphene Nanocomposite Materials

Zirconia/graphene (ZrO2/graphene) nanocomposite has been successfully synthesized by a simple method. The as-prepared nanocomposite was characterized using transmission electron microscopy (TEM), FT-IR spectroscopy, power X-ray diffraction (XRD) and nitrogen adsorption-desorption. It was found that tetragonal ZrO2 was uniformly deposited on graphene, which resulted in the formation of two-dimensional nanocomposite, it showed a high surface area of 165 m2/g.

Controlled Hydrothermal Growth of CuO-Based Nanostructures from Copper Alginate

Schistose and aciculate CuO nanostructures have been synthesized by a novel ammonia assisted hydrothermal method of copper alginate. The conversion processes of copper alginate are investigated by thermogravimetrics (TG) analyses under N2 and air atmosphere. The morphology, structure, and composition of the obtained CuO are investigated using SEM,TEM and XRD. It is found that different temperature and pH value resulted in the morphology and structure evolution of CuO. Ammonia was used as structure-directing agent in the hydrothermal system. The aggregation state of the nanostructures was controlled by the temperature. Dispersive schistose structures about 1μm in diameter were synthesized with 0.5mL ammonia at different temperatures. Dispersive microspheres of about 4 μm in diameter were also synthesized with 1 mL ammonia. Microspheres composed of nanoneedles and nanoplates were synthesized at 120°C and 160°C, respectively. Moreover, a possible growth mechanism governing the formation of such a nanomicrostructure was primarily discussed.

A Facile Preparation of Carbon-Supported Nanoscale Zero-Valent Iron Fibers

In this paper, ferric alginate fibers was prepared by wet spinning of sodium alginate into a coagulating bath containing ferric chloride. The carbon-supported nanoscale zero-valent iron fibers (CSNZVIF) were obtained through thermal degradation of ferric alginate fiber at 900°Cunder N2 atmosphere. The product was characterized by field emission scanning electron microscopy (FESEM), X-ray power diffractometer (XRD), and Brunauer-Emmett-Teller (BET) surface area. It was found that zerovalent iron particles were well dispersed in the amorphous carbon fibers. CSNZVIF has high surface areas of 352 m2/g. The existence of carboxylic group and hydroxyl group in ferric alginate structure unit plays key role in the formation of carbon-supported nanoscale zero-valent iron fibers. Fe3+ was reduced to Fe0 by hydroxyl group and as-formed amorphous carbon during heating under N2. This thermal degradation and self-reduction reaction of ferric alginate fiber is potentially scalable to large production and continuous processing for preparing CSNZVIF.

Influence of Zirconium Oxide on Thermal Degradation and Flame Retardancy of Viscose Fibers

We have investigated the effect of zirconium oxide on the thermal degradation and flame retardancy of viscose fibers. ZrO2/cellulose fiber was prepared by wet spinning. Combustion behaviour and flammability were assessed using the limiting oxygen index (LOI) and thermogravimetric analysis from ambient temperature to 800°C and cone calorimetry. LOI results showed that the ZrO2 increased the LOI of viscose fiber from 20% to 26%, which showed that ZrO2 particles had a positive effect on cellulose flame-retardancy. Results from thermogravimetric analysis (TG) indicated that the ZrO2/cellulose fibers produced greater quantities of residues than viscose fibers. The combustion residues were examined using the scanning electron microscopy, indicating that ZrO2/cellulose fiber produced consistent, thick residues. Cone calorimetry indicated that heat release rate and total heat release values of ZrO2/cellulose fiber were less than those of viscose fibers.

Flame Retardant Properties of Viscose Fibers Containing Talcum Powder

Cellulose-insoluble silicate (talcum powder) hybrid fibers with 10%, 20%, 30% silica contents were prepared by wet spinning. The flammabilities and combustion processes were evaluated by the limiting oxygen index (LOI) and cone calorimetry. The LOI results suggested that the hybrid fibers were flame retandant with the LOI value of 22, 25 and 27, as compared to 20 of pure cellulose fibers. Cone calorimetry showed that the rate of heat release value and total heat release value of hybrid fibers decreased. Hybrid fibers with 20% SiO2 loading is the best flame retardant sample. SEM studies of residues after cone calorimetry indicated that the hybrid fibers produced tight and hard residue crusts.

Ultrasensitive Determination of Rutin on Ag Nanoparticles- Poly(p-aminobenzene sulfonic acid)/Graphene Modified Glassy Carbon Electrode

The Ag nanoparticles-Poly(p-aminobenzene sulfonic acid)/graphene modified glassy carbon electrode (AgNPs-PABSA/GR/GCE) was fabricated by electrodepositon of AgNPs-PABSA onto graphene modified glassy carbon electrode (GR/GCE). The reported method was simple and fast. Combining the advantages of GR (high surface area and good conductivity), AgNPs (excellent electronic conductivities) and PABSA (the ability to interact with many components through hydrophobic or π–π electronic interaction), the AgNPs-PABSA/GR modified electrode effectively improved the sensitivity for the determination of rutin.