Preparation and characterization of Low cost ceramic Composite Membranes for Microfiltration and Ultrafiltration Applications
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2009
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Abstract
In the past two decades, significant advances in membrane technology research have been reported. Amongst various membrane applications proposed so far, microfiltration (MF) and ultrafiltration (UF) are the most significant in chemical and biochemical processes. Polymeric and ceramic membrane materials are the most relevant materials used for MF and UF membrane processes. While polymeric membranes are inexpensive and are prone to a greater degree of fouling, ceramic membranes are expensive and possess higher corrosion and mechanical resistance. Therefore, the preparation and characterization of low cost ceramic membranes is always encouraging to further the industrial cost effectiveness of membrane technology. This work presents the preparation, characterization and applications of low cost ceramic and polymer - ceramic membranes suitable for MF and UF applications. Among various industrial applications of membranes, treatment of oily wastewater and MF of mosambi juice were chosen as the most important areas of research where low cost ceramic membranes can be used as an alternative to conventional fouling prone polymeric membranes. The entire work carried out in this research work is divided into four major parts: DD Preparation and characterization of comparatively low cost ceramic membranes. DD Application of prepared ceramic membranes for the MF of oil-in-water emulsions. DD Application of prepared ceramic membranes for the MF of mosambi juice. DD Preparation and characterization of polymer-ceramic composite membranes. In this work we have identified two distinct compositions of inorganic precursors (namely composition A and composition B) using kaolin, quartz, feldspar, sodium carbonate, calcium carbonate, boric acid and sodium metasilicate for the preparation of upper (0.547 - 0.810 Dm) and lower (0.185 - 0.332 Dm) submicron pore range ceramic membranes. The identified composition contains 70 - 85 wt % of cheaper precursors and only 15 - 30 wt % of costly precursors. The sintering temperature during membrane fabrication was varied from 800 - 1000 oC, which was lower than usual sintering temperature of 1100 oC as mentioned in various literatures. The prepared ceramic membranes were characterized by TGA/DTA, XRD, SEM analysis, pore size distribution, porosity, average pore size, gas permeation, liquid permeation and chemical stability to evaluate the membrane structural, permeation and chemical characteristics. Based on materials cost, the membrane cost is estimated to be 130 and 220 $/m2 for upper and lower submicron range membranes, respectively. The performance characteristics of the prepared ceramic membranes were studied for the treatment of oil-in-water (o/w) emulsions and MF of mosambi juice in dead end mode of operations. Synthetic o/w emulsions constituting 50 - 250 mg/L oil concentrations were subjected to MF at different trans-membrane pressure differentials (DP ). Membrane prepared with composition A and sintering temperature of 850 oC provided a permeate flux decline from 48.16D 10-6 - 12.24 D 10-6 m3/m2.s where as oil rejection efficiency of the membrane increased from 97.9 - 98.5 % within 30 minutes of experimental run at a of 41.37 kPa for a feed oil concentration of 100 mg/L. The initial permeate flux increased from 48.16 DP D 10-6 - 100.34 D10-6 m....
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Supervisors: Ramgopal V.S. Uppaluri and Mihir Kr. Purkait
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CHEMICAL ENGINEERING