纳米ZnO涂层对不同孔径α-Al_2O_3微滤膜的修饰作用

Modifying Effect of Zinc Oxide Nano-coating on the Different Pore Size of α-Alumina Microfiltration Membrane

采用不同粒径的α-Al_2O_3微粒,利用浸渍涂覆的工艺方法,在粒径为10μm的α-Al_2O_3载体上制备了厚度约为25μm的不同孔径的微滤膜.并以Zn(NO_3)_2和尿素为原料,采用共沉淀法,对上述不同孔径的微滤膜进行纳米ZnO涂层修饰改性.结果表明:采用ZnO改性后的微滤膜的水通量都得到了提高,且以粒径为0.5μm的α-Al_2O_3微粒构成孔径为0.15μm的微滤膜其水通量增幅最大;当Zn(NO_3)_2的浓度为0.3mol/L,经二次涂覆后,改性作用最佳,微滤膜的水通量增幅最高达到46.4%.同时,文中还对纳米ZnO涂层改性作用机理进行了初步探讨.

Different α-A12O3 micro-powders with grain size of 0.5-3μm were coated on α-A12O3 substrate by the dipping process, and microfiltration membranes with different pore sizes were prepared. The thickness of all the membranes was controlled to be about 25μm. Then the membranes were modified by nano zinc oxide coating deposited by coprecipitation process with zinc nitrate and urea as starting materials. The influences of the size of α-alumina micro-powders for preparing the membranes and the concentration of zinc nitrate in the precursor of the zinc oxide coating on the water flux of the modified filtration membranes were studied. The results show that the flux of the modified membranes is increased and the amplitude of the flux increasing reaches maximum for the membrane which is made of a-alumina micro-powers with size of 0.5μm. When the concentration of zinc nitrate is 0.3mol/L, the twice coated membrane possessed the best modification effect and the amplitude of the flux increase reaches 46.4%. Furthermore, the mechanism of zinc oxide modification is discussed initially.