Shu-Jen Chen

Abstracts

2 Preparation of Magnetic Hydroxyapatite Composite by Wet Chemical Process for Phycobiliproteins Adsorption

Authors: Ruey-Chi Wang, Shu-Jen Chen, Yi-Chien Wan

Abstract:

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) can be applied to the fabrication of bone replacement materials, the composite of dental filling, and the adsorption of biomolecules and dyes. The integration of HAp and magnetic materials would offer several advantages for bio-separation process because the magnetic adsorbents is capable of recovered by applied magnetic field. C-phycocyanin (C-PC) and Allophycocyanin (APC), isolated from Spirulina platensis, can be used in fluorescent labeling probes, health care foods and clinical diagnostic reagents. Although the purification of C-PC and APC are reported by HAp adsorption, the adsorption of C-PC and APC by magnetic HAp composites was not reported yet. Therefore, the fabrication of HAp with magnetic silica nanoparticles for proteins adsorption was investigated in this work. First, the magnetic silica particles were prepared by covering silica layer on Fe3O4 nanoparticles with a reverse micelle method. Then, the [email protected] nanoparticles were mixed with calcium carbonate to obtain magnetic silica/calcium carbonate composites ([email protected]/CaCO3). The [email protected]/CaCO3 was further reacted with K2HPO4 for preparing the magnetic silica/hydroxyapatite composites ([email protected]/HAp). The adsorption experiments indicated that the adsorption capacity of [email protected]/HAp toward C-PC and APC were highest at pH 6. The adsorption of C-PC and APC by [email protected]/HAp could be correlated by the pseudo-second-order model, indicating chemical adsorption dominating the adsorption process. Furthermore, the adsorption data showed that the adsorption of [email protected]/HAp toward C-PC and APC followed the Langmuir isotherm. The isoelectric points of C-PC and APC were around 5.0. Additionally, the zeta potential data showed the [email protected]/HAp composite was negative charged at pH 6. Accordingly, the adsorption mechanism of [email protected]/HAp toward C-PC and APC should be governed by hydrogen bonding rather than electrostatic interaction. On the other hand, as compared to C-PC, the [email protected]/HAp shows higher adsorption affinity toward APC. Although the [email protected]/HAp cannot recover C-PC and APC from Spirulina platensis homogenate, the [email protected]/HAp can be applied to separate C-PC and APC.

Keywords: Magnetic, hydroxyapatite, c-phycocyanin, allophycocyanin

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1 High-Performance Li Doped CuO/Reduced Graphene Oxide Flexible Supercapacitor Electrode

Authors: Ruey-Chi Wang, Po-Hsiang Huang, Ping-Chang Chuang, Shu-Jen Chen

Abstract:

High-performance Li: CuO/reduced graphene oxide (RGO) flexible electrodes for supercapacitors were fabricated via a low-temperature and low-cost route. To increase energy density while maintaining high power density and long-term cyclability, Li was doped to increase the electrical conductivity of CuO particles between RGO flakes. Electrochemical measurements show that the electrical conductivity, specific capacitance, energy density, and rate capability were all enhanced by Li incorporation. The optimized Li:CuO/RGO electrodes show a high energy density of 179.9 Wh/kg and a power density of 900.0 W/kg at a current density of 1 A/g. Cyclic life tests show excellent stability over 10,000 cycles with a capacitance retention of 93.2%. Li doping improves the electrochemical performance of CuO, making CuO a promising pseudocapacitive material for fabricating low-cost excellent supercapacitors.

Keywords: Lithium, supercapacitor, CuO, RGO

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