Department of Chemical Engineering
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Item Adsorptive removal of fluoride by activated alumina doped cellulose acetate phthalate (CAP) mixed matrix membrane(Elsiever, 2014-04) Chatterjee, SomakFlat sheet mixed matrix membranes were prepared using cellulose acetate phthalate (CAP) and activated granular alumina using phase inversion technique. The membranes were characterized using porosity, permeability, molecular weight cut off (MWCO) and contact angle. Compositional analysis of the membrane was carried out by X-ray diffraction and the morphology and surface roughness were investigated by scanning electron microscope and atomic force microscope, respectively. The permeability of the membrane was reduced from 3.0 × 10−11 to 1.4 × 10−11 m/Pa s as alumina concentration increased from 0 to 35 wt% for constant CAP concentration at 20 wt%. Decrease in porosity from 75% to 45% supported the above fact. Membrane hydrophilicity was improved and most importantly, fluoride rejection from contaminated water increased to 91% using 35 wt% of alumina. Maximum adsorption capacity for fluoride was 2.3 mg/g for the mixed matrix membrane at room temperature. Continuous cross flow experiments revealed that the virgin membrane (24 kDa), having a surface area of 0.01 m2, could produce water well within the safety limit for a time of 11 h. Regeneration study was conducted for five cycles. Effect of other co-existing anions on fluoride removal efficiency of the membrane was also studied.Item Theoretical investigation of cross flow ultrafiltration by mixed matrix membrane: A case study on fluoride removal(Elsiever, 2015-06-01) Chatterjee, SomakSelective membrane filtration with high throughput can be achieved using mixed matrix membrane (MMM). The application of MMM in integrated membrane processing requires a continuous mode of operation. Therefore, understanding the mechanism of cross flow ultrafiltration of MMM is important from the design and operational point of view. Theoretical analysis based on first principles presented in this study takes into account the simultaneous occurrence of adsorption in the matrix and spatially developing concentration polarization layer over the membrane surface. The change in the filtration regime from adsorption dominated to diffusion governed can be identified. The developed model is validated with cross flow ultrafiltration experiments of fluoride contaminated solution using activated alumina MMM, for different operating conditions. The impact of the adsorption isotherm constants on the system performance is also evaluated.Item Adsorptive removal of arsenic from groundwater using chemically treated iron ore slime incorporated mixed matrix hollow fiber membrane(Elsiever, 2017-05-31) Chatterjee, SomakIron ore slime was chemically treated and impregnated in polysulfone hollow fibers for treatment of arsenic contaminated water. Improvement of arsenic removal capacity of the treated slime was observed due to deposition of metallic hydroxide/oxyhydroxide on its surface. Successful incorporation of iron ore slime within the membrane matrix was confirmed by X-ray diffractograms. Scanning electron micrographs confirmed the blockage of pores within polysulfone membranes by the additive, resulting in decrease of porosity, permeability and molecular weight cut off. However, improved hydrophilicity, higher surface roughness and arsenic uptake capacity of prepared membranes were observed. Mechanism of arsenic removal by the mixed matrix membrane was governed by electrostatic attraction mediated adsorption. Membrane with the highest additive percentage (10 wt%) produced arsenic free water for 14 h for real life feed solution at 11.5 L/m2 h, when operated in dynamic mode. Exhausted membrane was regenerated for three cycles using synthetic solution. Breakthrough time for arsenic removal was reduced from 28 h to 22 h and 14 h after second and third cycle, respectively. Maximum interference effect on removal process is shown by dissolved sulfate ions. The membrane was also able to remove microorganisms and iron simultaneously from real life feed solution below their WHO approved permissible level.Item Groundwater defluoridation and disinfection using carbonized bone meal impregnated polysulfone mixed matrix hollow-fiber membranes(Elsiever, 2020-02) Chatterjee, SomakDefluoridation and disinfection of groundwater have been attempted in this study, using carbonized bone meal (CBM) impregnated polysulfone based mixed matrix hollow fiber membrane. The membranes were characterized in terms of permeability, hydrophilicity, molecular weight cut off for different CBM concentrations. The membrane permeability was decreased from 5 × 10−10 m/Pa.s (without CBM) to 2.8 × 10-11 m/Pa.s with addition of 15 wt% CBM. Corresponding reduction in molecular weight cut off was from 85 kDa to 23 kDa. Variation of such properties were corroborated by the scanning electron micrographs of the prepared membranes that showed the membrane morphology became dense due to CBM addition in the polymer matrix. However, membrane hydrophilicity became more pronounced. In addition, the surface roughness of the prepared membranes was increased facilitating the adsorptive properties. The maximum fluoride adsorption capacity of the hollow fibers with 15 wt% CBM was observed to be 5 mg/g. Breakthrough studies were conducted for the membranes in cross flow filtration mode that showed a fresh membrane (area: 0.029 m2) can filter fluoride contaminated feed solution successfully for 24 h and 19 h, for the first and second regeneration cycles. For a real-life groundwater feed solution, the breakthrough time was observed to be 18 h. The bacterial concentration in the filtrate samples was found to be 0 CFU/ml, highlighting the antibacterial property of the prepared membranes.