Papers by Author: Zuo Wan Zhou

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Authors: Shuchun Hu, Zuo Wan Zhou
Abstract: As FeOx particles were prepared by oxidation-reduction reaction, the surfactant of polyethylene glycol (ab. PEG) was used to cover the FeOx particles, thus the PEG/FeOx ferrofluids were obtained. The morphology, structure and composition of the ferrofluids were investigated. The results show that the product is spheric in the shape, and the diameter of the product is obviously influenced by PEG content and slightly influenced by the stirring rate. When the content of PEG increases in the range of 50~350g/L, the diameter of the product decreases. However, when the content of PEG is in the range of 350~750g/L, the diameter increases with the increasing of PEG content. When the stirring rate is between 50 and 150r/min, the diameter of the product slightly decreases as the stirring rate increases. Moreover, the results demonstrate that the products are mainly constituted of PEG and FeOx, and the value of x in the formula of FeOx can be adjusted by controlling the molar ratio of H2O2 to Fe2+. Further analysis indicates that the organic and inorganic components of the PEG/FeOx ferrofluids are combined by both physical adsorption and coordinate combination.
Authors: Guo Mei Liu, Kai Wang, Zuo Wan Zhou
Abstract: TiO2 nanoparticles doped with V, Mn or Zn, respectively, were synthesized from pure TiO2 and dopants calcinating at definite temperature. The physical properties of prepared TiO2 nanoparticles were characterized by TEM, XRD and UV-vis spectrum. The TEM images showed that the diameters of the particles were 20~50 nm. There was no peak of doping elements in the XRD spectrum of nano-sized TiO2 doped, but the peak of a little amount of rutile was observed, which demonstrated that V, Mn and Zn might locate in the TiO2 octahedral lattice, or might be highly dispersed within crystalline of TiO2. In the meanwhile, doping of the TiO2 decreased the temperature for TiO2 transforming from anatase into rutile, and promoted the transforming. It was found that a little amount of V5+ may take the place of Ti4+ in the lattice of TiO2. The red-shift was clearly observed in the UV-vis spectrum of TiO2 nanopowders doped with V. As a result, the band gap was changed and the TiO2 nanopowders doped with V enable to absorb visible light. The red-shift could be assigned to the charge transfer transition between the 3d orbital of V5+ and the TiO2 conduction or valance band. The red-shift was not observed in the UV-vis spectrum of TiO2 nanopowders doped with Mn and with Zn, the shape of which was similar to that of pure TiO2. The results of the minimum inhibition concentration (MIC) for Escherichia coli and Staphylococcus aureus showed that vanadium ions doping intensely improved the antibacterial efficiency of nanocrystallites. This was attributed to the change of surface properties of metal ions doped semiconductor, such as O vacancies, Ti interstitial ions and vanadium ions which took the place of titanium.
Authors: Zuo Wan Zhou, Jing Jing Liu, Long Sheng Chu
Abstract: Tetra-needle like zinc oxide whiskers (T-ZnOw) were doped with Al3+, Fe3+ or Ag+. The morphological structures and the doped ions were characterized, and the results indicated that mostof the Aluminum existed in a second phase of ZnAl2O4, most of the Fe3+ solid-solutioned into the crystal lattice and the silver generated as nano-particles on the surface of the needles of the ZnO whiskers. Anti-bacterial experiments gave the result that Fe3+ doped T-ZnOw and the nano-silver adnascent ZnOw had obvious effect of killing and inhibiting the bacteria such as Staphylococcus Aureus (ATCC 6538), Escherichia Coli (ATCC 25922) and Candida Albicans (ATCC 10231). The minimum inhibitory concentrations (MIC) of the related doping T-ZnOw were 55~440 PPM. Further experiments indicated that there appeared high margin of safety and no stimulation on skins or eyes for the tested animals. Products such as plastics, coatings, fibbers and papers containing 2wt% of the doped T-ZnOw had more than 99% efficiency for anti the mentioned bacteria. Effect of degradation of organic compound for the doped T-ZnOw was also evaluated by degradation of formaldehyde. The mechanism was tentatively put forward to explain the phenomena and the effect of antibiosis.
Authors: Jing Jing Liu, Zuo Wan Zhou, Kai Wang, Yanxia Li
Abstract: Tin doped tetra-pod shaped ZnO (T-ZnO) were fabricated by equilibrant airflow reaction method. The microstructure of tin doped T-ZnO was characterized by X-ray Diffraction analysis and Scanning Electron Microscope. The results demonstrated that most of tin acted as a catalyst during the ZnO crystal growth process and the others reacted with ZnO to generate Zn2SnO4. Tin had catalytic influences on the morphology of T-ZnO, which promoted predominant growth on the c axis of ZnO crystal at the addition of 15% in weight and advanced the growth on the a axis at higher weight proportion.
Authors: Zuo Wan Zhou, Shuchun Hu, Long Sheng Chu
Abstract: Tetra-needle like ZnO whisker modified NR-SBR-BR and PPS composites were prepared. The outcome of the investigation indicated that T-ZnO had an instinct effect on reinforcing polymer material isotropically. Further analysis showed that experiment results of T-ZnO/PPS composite gave much higher strength than that of the theoretical calculation from classical rule of mixing, and the explanations were put forward. The experimental tests on wear behavior of the composites of T-ZnO/NR-SBR-BR were carried out and got the conclusion that T-ZnO had a good effect of improving the wear resistance. The worn surfaces of the composites of T-ZnO/NR-SBR-BR appeared an instinct character of fractal, and the values of both the fractal dimension and the abrasion loss decreased synchronously as the increasing of T-ZnO loading in the composites.
Authors: Xiao Ling Xu, Zuo Wan Zhou, Wen Jun Zhu
Abstract: Active oxygen species generated from semiconductor under irradiation play an important role in decomposing and mineralizing pollutants and undesirable compounds in the air and waste water. The production of superoxide anion (O2-) and hydroxyl radical (•OH) generated in the suspension of zinc oxides with different morphologies and particle sizes were studied in the present paper. Three kinds of zinc oxides, which named tetra-needle like ZnO (T-ZnO) whisker with length of 10~20 μm and basal diameter of 1~3 μm, nanosized ZnO (n-ZnO) with particle size of 20~30 nm and commercial ZnO powder (p-ZnO) with particle size of ~1 μm, respectively, were used in this work. Nitroblue tetrazolium (abbr. NBT) was used to determine the amount of super oxide anion generated from the related zinc oxides, in which NBT can be reduced to insoluble purple formazan by super oxide anion. The amount of hydroxyl radicals was determined by detecting the decreased absorption intensity of Fe(phen)32+ (complex of iron (II) with 1,10-phenanthroline) at 510 nm with UV-Vis spectrophotometer. The results indicated that the most amounts of superoxide anion and hydroxyl radical were detected in T-ZnO whiskers and n-ZnO respectively. The difference between the production amount of superoxide anion and hydroxyl radical can be attributed to the different mechanisms for both of the production and transportation of these two kinds of active oxygens.
Authors: Long Sheng Chu, Zuo Wan Zhou, Yong Zhao
Abstract: In this paper, the microwave absorption behaviors of zinc oxide whisker were studied. The morphological structure of zinc oxide whisker was observed through scanning electron microscope. The effect of the structure of zinc oxide whisker on the microwave absorption, such as length-diameter ratio, cross-section appearance, and doping was analyzed. The result shows that the more irregular the cross section of the needle of zinc oxide whisker is, the more prominent the microwave absorption appears. The less the length-diameter ratio of the needle of zinc oxide whisker is, the more obvious the microwave absorption of zinc oxide whisker becomes. The zinc oxide whisker, which had inlet ion, such as Al3+, Fe3+ , etc., in its crystal lattice has a better microwave absorption efficiency than the pure zinc oxide whisker. The further analysis found that electric conductive network can be formed easily because of the zinc oxide whisker, and the coating had the porous structure. When microwave reaches the coating of zinc oxide whisker, the polarization of zinc oxide whisker was resulted and the electromagnetic energy lost. Firstly, electric current was transmitted through the electric conductive network and the energy transformed to heat. Secondly, tips’ phenomenon has been observed, which lead to the energy lost. Finally, the microwave energy was lost because of the tunnel effect, which will bring about leakage current. Based on the three reasons above, microwave energy was absorbed by the coating containing the zinc oxide whisker.
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