Study On The Preparation And Properties Of γ-Al₂O₃ Nanofiltration Membrane

The γ-Al2O3 NF membranes were produced by sol-gel technique using aluminium iso-propoxide as precursor. The effect of quantity of water and peptizing acids, temperature and time of reaction on the stability of boehmite sol (AlOOH) was analyzed. The influence of filming, gel drying and calcinating processes and template agent on the preparation of γ-Al2O3 NF membrane with excellent quality was discussed in detail.The structure ofγ-Al2O3 NF membranes were studied by N2 absorption and desorption test. The BJH desorption average pore diameter, BJH desorption cumulative volume of pores and BET surface area of these obtained membranes under the optimized experimental conditions were about 3.9nm, 0.33cm3/g and 245m2/g respectively, and the pore size distribution was very narrow. So, the membranes areγ-Al2O3 NF membranes with high quality. It is shown that the membrane sheets were corroded in hydrochloric acid solution with pH=1 and sodium hydroxide solution with pH=13. In this work, membrane thickness and pore size and its distribution were controlled effectively by using certain template agent, temperature programming and retention VS thickness gradient curve method.The retention property ofγ-Al2O3 NF membrane for Ca2+ was studied firstly. The quite special curve was obtained by studying the relationship between Ca2+ retention and the pH of solution treated: when the pH of solution treated is 7.5, there is minimal Ca2+ retention. The experimental results show that Ca2+ retention decreased with the increasing of feed concentration, and with the increasing of trans-membrane differential pressure, the Ca2+ retention increased, water volume flux increased linearly and the retention of Ca2+ is more than that of Mg2+ at same pressure. In this study, penicillin pharmaceutical wastewater was treated by ceramic NF membrane firstly. When pressure is 0.5MPa, with obtained γ-Al2O3 NF membrane, the retentions of hardness, sulfate and chroma were 55.5%, 52.1% and 83.0% respectively, and the retention of foreign taste is very high. The flux of membrane is 21.76L/m2·h。...