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wypward(金币+2):鼓励下，辛苦啦！ 2010-05-27 18:39:31
alibabashiqun(金币+100, 翻译EPI+1):辛苦了，我也给楼下哥们几个哈。。别嫌少。。非常感激 2010-05-28 08:35:03
Composite ceramic membranes for microfiltration are wildly used in liquid separation, biological chemicals, environmental protection and other fields with a broad application prospects. However, it is still an important topic of membranes research that the composite ceramic membranes are of high price but of low separation efficiency. The modification of them by metal oxide can not only improve their physical and chemical properties, but also significantly enhance the separation efficiency of inorganic membrane. Therefore, the research on the modification of composite ceramic membranes for microfiltration will establish a solid technology platform for their applications.
In this thesis, the sol-gel method to prepare modified ZnO sol was first used with Zn (OAc) 2 as precursor, ethylene glycol monomethyl ether as solvent, and ethanolamine as the stabilizer. Its inner wall modification was done with Al2O3 microfiltration membrane (pore size φ = 0.89 μm) as substrate. The craft factors such as reaction temperature, reaction concentration and sol aging time influencing the ZnO modified sol were fully discussed in detail. Also the changes of pore size and water flux before and after the modification of Al2O3 micro-membrane were detected and analyzed using TEM, SEM, Zeta potential, etc. The results show that: in the water bath of 65 ℃, the concentration of Zn2 +modified sol was 0.2mol / I, pH was 3, sol aging time was 72 hours. The samples calcined at 600 ℃ can form a modified nano-ZnO layer of grain 5 ~ 15nm, with the thickness of about 15nm. In the case of the reduction of membrane pore size, the water flux of modified micro-membrane increased significantly, reaching the largest value of 159.6%.
For the regulation on the performance of modified ZnO layer, the Ag ions doping research was done in this paper on the basis of the studies on the optimal conditions for sol-gel method to prepare ZnO modified sol. Through doping with Ag ions of different molar mass, the changes of pore size, water flux and Zeta potential caused by Ag ions were tested. This paper mainly focuses on the relationship between the flux microfiltration and Zeta potential. At the PH of distilled water as filter medium of 7, the highest Zeta potential and the largest water flux of ZnO particles were achieved at 0.2mol (wt%) Ag-doped. It was found that the modified layer constituted of Ag doped ZnO nanocrystals also has the functions of improving membrane water flux, 187.96%more than the unmodified one at most, better than modified with ZnO alone. |
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