Study Of New Preparation And Characterization On AAO Film

In this paper, we used the roughness instrument to quantify the surface of aluminum after polishing, in order to quantitatively describe the surface of the anodic film. At first we reduced the aluminum in the reducing acid solution, and then prepared anodic alumina membrane on the other surface. The feed concentration, operating pressure and soaking time were studied on the process of filtration. Through the relationship of flux and rejection with time, the analysis of filtration resistance data and the establishment of occlusion, we proposed to control membrane fouling.Using three-acid-chemical polishing method, we discussed the influence of chemical polishing time, temperature of polishing, volume of solution and times been used on the aluminum surface roughness. To some extent of surface roughness within (0.1785～0.236), the surface of anodic alumina membrane could be predicted. The result showed that suitable chemical polishing conditions were:In the chemical polishing solution of H3PO4:H2SO4: HNO3 which the volume ratio was 76:18:6 the best time of polishing is 2 minutes, the ratio of the work pieces'size and the slurry volume is 2cm2:80mL, the effect of using polishing solution for 5 times is nearly same, the property operating temperature is 100-105℃.In this dissertation, we measured the thinning rate of every pretreated reaction:thinning rate of alkaline etching process was 0.257μm/s, the chemical polishing process was 1.014μm/ s and the electrolysis process was 0.167μm/s. The limit thickness of anodic oxide film could be calculated under certain condition. At first we put the sample into the acid Electrolysis to obtain the macroporous supported body, then anodic oxidatized the sample on the other surface. We succeed preparing the anodic alumina membrane with support structure which had good toughness and strength. The average pore size was 116.9nm, the porosity was 0.2527, and the pore density was 3.22×109 cm-2.In this study, we made some filtration experiments on self-made film to analyze the influence of PEG20000 concentration, operating pressure and soaking time on the filtration flux and rejection. The results showed that with the PEG concentration increased, the stability of flux increased, but the rejection decreased; with the operating pressure increased, the stable flux increased first and decreased, the rejection vice versa. The longer soaking time, the larger steady flux, the lower rejection. The pure water flux could be recovered to 73.6% and the flux of slurry returned to 68.4% after water rinsing and lightly.brushing by hairbrush. This experiment also discussed the resistance of membrane separation process and separation model. The results were as follows:with the PEG concentration increased, the total resistance value decreased, blocking resistance increased, the gel layer and cake layer resistance decreased. As the operation pressure increased, the total resistance value increased, the proportion of blocking resistance first increased and then decreased, the resistance proportion of gel layer and cake layer first increased and then decreased. The longer immersion time, the lower total resistance value, the larger resistance of blocking, the smaller resistance of gel layer and cake layer. At the same time, we found that intermediate blocking model can match the filtration process of home-made membrane.