真空限氧法制备纳米氧化锌及其动力学

Growth of Zinc Oxide Nano-Particles by Vacuum Oxidation

以热镀锌渣为原料、以空气为氧源,采用真空限氧法制备了纳米氧化锌。用热重法测定了不同系统压力条件下锌蒸气的氧化动力学曲线,用扫描电镜研究了氧化产物ZnO的形貌。结果表明:采用真空限氧法制备的纳米氧化锌晶体为六方纤锌矿结构,纯度≥99.98%;当氧化反应遵守抛物线规律时,纳米氧化锌的形貌主要为颗粒状、无定形、四针状或单针状;当氧化反应遵守直线规律时,产物主要为短小的四针状或单针状;在锌氧化反应前期和后期分别受收缩球状模型R3和三维扩散模型D4控制,表观活化能分别为101.3～122.1 kJ/mol和111.2～143.4 kJ/mol。

The zinc oxide nano-particles were formed by vacuum oxidation with the waste galvanized zinc as the raw material.The impacts of oxidation conditions,including ratio of the oxygen/nitrogen flow rates,oxidation temperature and pressure,were evaluated.The microstructures of the zinc oxide nano-particles were characterized with X-ray diffraction and scanning electron microscopy.The results show that the low oxygen partial pressure strongly affects the microstructures of the zinc oxide nano-particles with a wurtzite phase and purity up to 99.98%.In the parabolic oxidation mode,the main morphologies of the zinc oxide were found to be granular,amorphous,tetrapod and/or needle-like;whereas in the linear oxidation mode,the needle-like particles and clusters made of 4 short needles were observed.Possible nano-particle formation mechanisms were tentatively discussed.