Studies On The Evaporation Rate Of Water From The Nanopores Of Porous Alumina Template

Nano-materials, due to its unusual mechanical, optical, electrical, and magnetic properties, have attracted more and more attentions in the recent years. In the further research, nano-materials show great future of potential applications in many fields, including catalyst, filtrating light, light absorption, medicine, magnetism storage media and so on. Now the attention has changed from the property exploration of single nano-structure material to the fabrication of nano-structure with special property. And then, a great number of methods and technologies to synthesize nano-materials have appeared. Meanwhile, a great many of materials with new nanostructures have been fabricated.Anodic aluminum oxide film have attracted great attention in the areas of nanoscience and engineering due to their highly ordered pore arrangement, controllable pore diameter and well-characterized morphology. Porous anodic alumina template has many features, its preparation process is simple and inexpensive preparation of nano-materials has broad application prospects.Porous anodic aluminum oxide film was prepared on highly pure aluminum foil in an oxalic acid electrolyte of0.3mol/L concentration at10℃by applying a stable voltage of40V and two-step anodization. The morphology of the porous anodic alumina templates was characterized by environmental scanning electron microscope (ESEM). Comparing the morphology of the porous anodic aluminum oxide prepared by single and double anodizations, we can find that the porous anodic alumina template prepared by double anodization method offers more regular and ordered structure. After eliminating the aluminum oxide film prepared by the first anodization, the ordered array of pits was left at the aluminum surface, which is important for formation of highly ordered anodic alumina template. Using H3PO4solution to remove the barrier, we can get the through-pore porous anodic alumina template. We can adjust the etching time to control the proper diameter of the pores. The proper diameter of the pores of the porous anodic alumina template is50～80nm.We have studied the wettability of porous anodic alumina template and found that the surface of porous anodic alumina template is hydrophilic. An organic layer of low surface energy was deposited on the surface of the porous anodic alumina template and the contact angle of surface became larger. The organic layer of low surface energy is very thin so that it has no effect on the morphology of the porous anodic alumina template. The capillary experiment of porous anodic alumina template has been studied, we found that water molecules and ions can travel through the nanotube of the porous anodic alumina template.Special experiments have been carried out to measure the water evaporation from the porous anodic alumina template. We found that the evaporation of water from the porous anodic alumina template is faster than usual evaporation of water and the reason need more research.