ZHOU Tao, AI Jianping, CHEN Zhiqin, WANG Xiping, ZHOU Zehua, ZHANG Kui, JIANG Jiali, LI Wenkui
(Jiangxi Key Laboratory of Surface Engineering, Jiangxi Science and Technology Normal University, Nanchang 330038, Jiangxi , China)

Abstract: Zinc oxide nano-powder was prepared by hydrothermal method using zinc nitrate hexahydrate, sodium hydroxide and citric acid by altering the pH of the suspension. The phase, morphology, band gap, specific surface area and stability of ZnO nanorods were studied by X ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Vis diffuse reflectance spectroscopy (DRS), low-temperature nitrogen absorption and fourier transform infrared spectrometer(FT-IR).The photocatalytic properties of different ZnO samples were studied using an ultraviolet lamp as illumination device and 15 mg/L methyl-orange as stimulant pollutant. The results indicate that, the photocatalytic degradation reaction of methyl orange is first order reaction, when the pH=12(No citric acid), excellent photocatalytic activity of the ZnO powders (2 h, degradation rate reach 99%) under 300 W high pressure mercury lamp. In addition, the pH value has a great influence on the phase, morphology and photocatalytic properties of ZnO powders. Although the specific surface area of the as-prepared powders was largest in pH about 8, the poor degree of crystallinity worsen its photocatalytic properties. ZnO powder was synthesized at pH=12.0 (No citric acid)with a high degree of crystallinity and larger specific surface area (about 8.99 m²·g-¹).

Key words: ZnO; pH; hydrothermal synthesis; photocatalytic