ساخت و مشخصه يابي غشا سراميكي مسطح نانو حفره با استفاده از روش قالب ريزي ژلي اصلاح شده

چكيده انگليسي :

124 Fabrication and Characterization of Nano Pore Size Plate Ceramic Membrane by Modified Gel casting Method Hamideh Eskandari H Eskandari@ce iut ac ir Date of Submission 2011 4 18 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors A Moheb ahmad@cc iut ac ir S Gh Etemad etemad@cc iut ac irAbstract In recent years issuing severe environmental laws by the governments and economic considerations have causeda great deal of attention toward developing and improving efficient separation methods Membrane processeshave been widely used in this field during the last few decades due to their relative advantages in comparisonwith the conventional methods Besides the polymeric membranes today the ceramic ones are increasingly usedbecause of their unique characteristics among which mention can be made of their mechanical strength highthermal and chemical resistance long life higher pore volume and simultaneous diffusion and chemical reaction These membranes however have drawbacks such as being damaged in thermal cycles fragility lack offlexibility and the difficulty in sealing at high temperatures In addition they have a relatively high cost ofsynthesizing and installation Nonetheless despite the high cost of such membranes using them is economicaldue to their long life In this study nano pore size plate ceramic membranes were manufactured by a modifiedgel casting method using 8 alumina Natural gelatin traditionally intended to food industry was used as thegelling agent chosen on the basis of its low cost and environmental impact The effects of important parameterssuch as sintering temperature solid loading powder size and gelling agent content on the porosity and mean poresize of membrane were investigated when ceramic support was fabricated New method of using liquid desiccantwas used for drying of the casted supports At this step of the work the effects of concentration and molecularweight of PEG on the time of drying was evaluated To improve the separation properties of the synthesizedsupports they were coated by additional fine alumina layers by dip coating method The experiments weredesigned by Taguchi method and the quantitative effects of the important parameters such as number of layers solid loading dipping time and withdrawal speed of the substrate on the separation performance of membraneswere studied by separation of PEG 10000 from its aqueous solutions The results showed that the porosity of thesupports increased by lowering the sintering temperature and increasing diameter of the alumina powder Also the drying time of the ceramic supports decreased increase in the concentration and molecular weight of PEGused in the desiccant liquid The most proper supports were obtained when they were sintered at 1400 C by using40 wt solid and 5 wt gelling agent in the casting suspension By conducting the separation tests the Taguchimethod predicted the maximum reachable rejection and permeation flux to be 0 98 and 4 02 m3 m2 s 106 respectively According to the predictions the maximum rejection can be obtained for a membrane coated threetimes by dipping for 30 sec in a 25 wt suspension with withdrawal speed of 72 mm min On the other hand theoptimized flux can be reached when the support is coated only once by using again a 25 wt suspension butwith different dipping time and withdrawal speed of 20 sec and 36 mm min respectively However anoperationally acceptable membrane with rejection of higher than 0 9 was obtained when the support was coatedonly with one layer by using a 25 wt suspension In this case the dipping time was 30 sec and the withdrawalspeed was adjusted at 36 mm min This membrane had the highest flux among all the synthesized membraneaccording to the Taguchi experimental design Finally the molecular weight cut off of the membranes was foundto be 10 KDa which its correspondence average pore size was approximated to be 6 nano meter Keywords Plate cer

اسكندري، حميده

ساخت و مشخصه يابي غشا سراميكي مسطح نانو حفره با استفاده از روش قالب ريزي ژلي اصلاح شده

ژلاتين , محلول مايع خشك كننده , پوشش دهي غوطه وري , تاگوچي