ساخت غشاء سراميكي لوله اي با اندازه منافذ سطحي در ابعاد نانوبه روش قالب ريزي ژلي اصلاح شده همراه با پوشش دهي سطحي

چكيده انگليسي :

108 Manufacture of Nano pore Size Tubular Ceramic Membranes using Modified Gel casting Followed by Dip coating Seyyed Faridoddin Rezazadeh sf rezazadeh@ec iut ac ir Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Ahmad Moheb Associate Professor ahmad@cc iut ac ir Abstract During the last 35 years membranes have evolved from a laboratory tool to an industrial product with a wide variety of applications such as desalination of sea and brackish water and treatment of industrial effluents Nowadays a large number of research works are being done on making and development of ceramic membranes due to their better inherent stability at hard operating conditions in comparison with the polymeric membranes The aim of the present work was making tubular ceramic membranes by using a modified gel casting method in which harmless natural polymers were used instead of conventional synthetic polymers with their potential risks To this aim at the first step some primary experiments were done to find the optimum amount of stabilizing agent Darvan that must be added to alumina suspension in order to make a stable suspension These experiments showed that the optimum value of the stabilizing agent is dependent on the concentration of alumina suspension and this value increases with the concentration of suspension In the next step tubular ceramic supports were manufactured by modified gel casting method using micron size Alumina powders Gelatin and carboxymethyl cellulose were used as gelling agents A number of experiments were conducted in order to verify the optimum value of gelling agents These optimum values were found to be 5wt and 7wt for gelatin and CMC respectively Effects of sintering temperature solid loading and median particle size of the alumina powder on the porosity of final casted part were investigated It was seen that the porosity decreased as the sintering temperature and the solid loading increased On the other hand at similar sintering temperature and solid loading conditions powders with larger particle diameter resulted in higher porosity Dip coating method was used to modify the surface of manufactured supports In this part of the work a number of alumina supports with the same characteristics were produced and used for dip coating step Taguchi method was used to design the experiments and the quantitative effects of important parameters namely suspension concentration dipping time withdrawal speed and the number of coated layers on separation properties of the membranes were investigated Three levels were selected for the first three parameters and the last parameter was adjusted at two levels Two objective functions of the permeated flux and rejection were defined to evaluate the performance of the membranes These membranes were tested in separation of 5 gr Lit PEG10000 water solutions Analysis of variance ANOVA showed that the number of coated layers is the main effective parameter on the membrane flux and rejection Using Taguchi analysis optimum conditions for synthesis of the optimized membranes for each objective function were determined These membranes were different in dip coating conditions The membrane coated twice by 20wt suspension with dipping time of 20 second and withdrawal speed of 72 mm min had the optimum rejection of 0 962 Also the membrane with one coated layer coated by 20wt suspension dipped for 30 second with a withdrawal speed of 36 mm min showed the maximum flux of 6 53 10 6 m3 m2 s The rejection obtained by the most of the synthesized membranes were higher than 90 for filtration of low concentration PEG10000 water solution which means these membranes had MWCO of 10000 Keyword Gel Casting Dip Coating Taguchi Design of Experiments MWCO

رضا زاده، فريدالدين

ساخت غشاء سراميكي لوله اي با اندازه منافذ سطحي در ابعاد نانوبه روش قالب ريزي ژلي اصلاح شده همراه با پوشش دهي سطحي

پوشش دهي به روش غوطه وري , طراحي آزمايشات تاگوچي , MWCO