Papers by Author: Yun Fa Chen

Abstract: In present work, ceria microspheres were synthesized by template hydrothermal method. Crystalline form of the as-synthesized ceria microspheres was defined by X-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Dispersibility of ceria microspheres was comprehensively characterized using scanning electron microscope (SEM) observation and laser particle size analyzer. Furthermore, the ultraviolet light absorption performances of ceria microspheres with several different sizes were compared by ultraviolet visible spectrophotometer. The results showed that ceria microspheres presented excellent UV absorbent property and the size influence was remarkable.

Abstract: Hydroxyapatite (HA) has attracted many attentions because it has a similar structure to that of human bones and favorable biocompatibility. However, the antibacterial effect of HA must be improved. In this paper, HA nanoparticles were prepared by a simple method. Then, Ag-carrying HA powder (Ag-HA) was prepared by an ion-solution reaction and its antibacterial property was investigated. The results showed that Ag-HA powder had excellent ability in inhibiting the growth of two species of bacteria, namely E. coli and S. aureus. Ag ion was believed to play a key role in killing bacteria.

Abstract: Low agglomerating spherical α-Fe2O3 nanopowders were synthesized by catalytic phase transformation in hydrothermal reaction and then dried through freeze-drying. It was found that the as-synthesized particles were spherical and the particle size results obtained from the different measurement methods, including BET, XRD, TEM, SEM and laser particle size analyzer, were almost the same, implying that the α-Fe2O3 nanopowders were low agglomerating.

Abstract: A series of sorbents for SO2 in flue gas were prepared from hydrated lime and blast furnace slag using a factorial experiment design. It is found that the reaction between hydrated lime and blast furnace slag is fast. The reactivities of the as-prepared sorbents are higher than those of hydrated lime alone due to the formation of calcium silicate hydrates, and hence the utilization of hydrated lime as well as the Ca in the blast furnace slag is improved. Furthermore, the effects of preparation variables on the reactivity of the sorbents are also discussed.

Abstract: Activated carbon was employed as the adsorption carrier for the metal ions in HCl solution of red mud, a solid waste produced in alumina industry. To improve the adsorption capacity to valuable metal ions, the activated carbon was modified by chemicals including HNO3, H2O2, H2SO4, H3PO4, NH3, Na2CO3, and tri-butyl phosphate (TBP). It was found that the modifications contributed the high adsorption capacity to almost all metal ions we focused on. In the case of TBP, remarkably higher adsorption capacity and selectivity of Sc3+ was observed. The correlation between the surface areas, IR spectra of those chemically modified activated carbons and adsorption was schemed.

Abstract: In this study, α-ZrP-CPC layered compound was gained by inserting cetyl pyridinium chloride (CPC) into α-ZrP with amines as pillaring agent. The amount of CPC intercalated reached the highest with the molar ratio of the amine/α-ZrP being 2. The lower concentration of CPC resulted in more CPC molecules intercalated into the interlayer of α-ZrP. The intercalation products were characterized by XRD, IR, TG-DSC and SEM. The result of TG-DSC showed that the amount of xylene adsorbed reached the peak value of 5.56%, when the content of CPC in α-ZrP-CPC was 41%.

Abstract: The open-cell macroporous ceramic foams can be used to air and water decontamination after loading catalyst. A new kind of ceramic foam was prepared using pumice, porcelain stone, quartz as main raw materials and polyurethane sponge as template. During the process, the polyurethane sponges were immersed in the powder slurry while submerged to fill all the pores, which makes it uniformly coating the sponge. Then the samples were dried at 80°C, and then sintered at 1050°C -1200°C for 2h in air. The ceramic foams present high porosity from 75% to 90%, higher compassion strength from 10 MPa to 50MPa and lower volume density from 0.15g/cm3 to 0.32g/cm3. The SEM images revealed the open-cell structure in the product.

Abstract: In this paper, mass production of quasi-aligned CNTs was achieved with a new tri-metallic catalyst (Fe-Ni-Mo/MgO) by thermal CVD method, using methane as carbon precursor. The growth process was in-situ monitored by thermal gravimetry/differential scanning calorimetry (TG-DSC) technique, and the yield of CNTs over 2200% was attained under the mixture atmosphere of CH4 and H2 with flow rate about 25 ml/min and 5 ml/min respectively at 900°C for 30 min. The as-prepared products were characterized. Raman spectrums showed that the CNTs are multi-wall structure. The diameter of the CNTs was estimated to be 20-30 nm. We think the synergism of FeNi3 alloy and Mo is the main reason for the high catalytic activity of tri-metallic catalyst.

Abstract: The nanocomposite coatings were prepared on the surface of PVC substrate using spinning technique with attempts of introducing nanosized iron oxide particles with different morphology into the organic-inorganic hybrid matrices. The hybrid matrices were derived from 3-glycidoxypropyltrimethoxysilane (GLYMO) and tetraethoxysilane (TEOS) with a process of hydrolyzing and condensation. Nanosized iron oxide particles were synthesized by hydrolysis of FeCl3 solution at different pH value and different temperature. The effects of different additions on nanomechanical properties of the nanocomposite coatings were investigated using X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and MTS Nano Indenter XP system. It was found that the acicular α-FeOOH and spherical α-Fe2O3 particles were synthesized, both of them dispersed homogeneously. Nanoindentation and nanoscratch behaviors of the nanoindenter system showed that both of the nanocomposite coatings reinforced the nanomechanical properties of the PVC obviously. Especially, the contribution of acicular α-FeOOH was more remarkable than the spherical α-Fe2O3.

Abstract: Hydroxyapatite nanoparticles were synthesized in the presence of two kinds of acidic amino acids in order to investigate the effects of acidic amino acids on the morphology of hydroxyapatite obtained by homogeneous precipitation and hydrothermal treating. The results of X-ray diffraction analysis and microphotographs of transmission electron microscope showed that the morphology of hydroxyapatite nanoparticles changed significantly only with aspartic acid. Hydroxyapatite synthesized with aspartic acid showed smooth flake-like morphology at pH= 11 and flake-like morphology with stripes at pH= 8. However, hydroxyapatite synthesized in the present of glutamic acid showed rod-like morphology at both pH values. Variation in the morphology of nanoparticles could be consistent with the difference in the affinity of amino acids binding at the hydroxyapatite crystal surface. The adsorption process was revealed by computer simulation of molecular mechanics using energy minimizing method.