http://dspace.bits-pilani.ac.in:8080/jspui/handle/123456789/1923 2026-04-01T13:44:11Z http://dspace.bits-pilani.ac.in:8080/jspui/handle/123456789/20578 Title: Effects of overlapping electric double layer on mass transport of a macro-solute across porous wall of a micro/nanochannel for power law fluid Authors: Bhattacharjee, Saikat Abstract: Effects of overlapping electric double layer and high wall potential on transport of a macrosolute for flow of a power law fluid through a microchannel with porous walls are studied in this work. The electric potential distribution is obtained by coupling the Poisson's equation without considering the Debye–Huckel approximation. The numerical solution shows that the center line potential can be 16% of wall potential at pH 8.5, at wall potential −73 mV and scaled Debye length 0.5. Transport phenomena involving mass transport of a neutral macrosolute is formulated by species advective equation. An analytical solution of Sherwood number is obtained for power law fluid. Effects of fluid rheology are studied in detail. Average Sherwood number is more for a pseudoplastic fluid compared to dilatant upto the ratio of Poiseuille to electroosmotic velocity of 5. Beyond that, the Sherwood number is independent of fluid rheology. Effects of fluid rheology and solute size on permeation flux and concentration of neutral solute are also quantified. More solute permeation occurs as the fluid changes from pseudoplastic to dilatant. 2017-03-01T00:00:00Z http://dspace.bits-pilani.ac.in:8080/jspui/handle/123456789/20577 Title: Experimental and modeling of fluoride removal using aluminum fumarate (AlFu) metal organic framework incorporated cellulose acetate phthalate mixed matrix membrane Authors: Bhattacharjee, Saikat Abstract: Selective adsorption of small sized contaminant by inorganic component incorporated in a polymeric membrane in addition to separation of total solids, iron, alkalinity and hardness makes mixed matrix membrane (MMM) a unique filtration medium. Significant separation of tiny pollutants along with high throughput at low operating pressure is the remarkable feature of MMM. Aluminum fumarate metal oxide framework (MOF), a super adsorbent for fluoride was included in cellulose acetate phthalate as base polymer to prepare a novel MMM for removal of fluoride from contaminated groundwater. The membranes were characterized by porosity, permeability, molecular weight cut off and contact angle. The morphology and the surface roughness were studied by scanning electron and atomic force microscope. The adsorption capacity of the membranes for fluoride varied from 107 to 179 mg g−1 for MOF concentration of 2 to 10 wt%. The fluoride rejection was more than 99% for 10% AlFu concentration. The life of the membrane was determined using a continuous cross flow setup with membrane area of 0.01 m2 and it was found to be 17 h for a feed concentration of 10 mg L−1 of fluoride in synthetic solution. Regeneration study and performance of the MMM in real life ground water samples were also investigated. The study provides a promising, scalable technology using MMM for fluoride mitigation by combining high throughput, selective separation of fluoride and general filtration including removal of total dissolved solids, hardness, alkalinity and iron. 2017-12-01T00:00:00Z http://dspace.bits-pilani.ac.in:8080/jspui/handle/123456789/20576 Title: Aluminium fumarate metal organic framework incorporated polyacrylonitrile hollow fiber membranes: spinning, characterization and application in fluoride removal from groundwater Authors: Bhattacharjee, Saikat Abstract: Novel mixed matrix hollow fiber membranes (MMM) were prepared by phase inversion technique using polyacrylonitrile (PAN) as base polymer and aluminium fumarate (AlFu) metal organic framework (MOF) as additive. The membranes were characterized in terms of surface morphology, surface charge, permeability, molecular weight cut off, porosity, pore size and contact angle. Permeability of the membrane increased from 3.5 × 10−10 to 4.5 × 10−10 m/Pa.s with increment of MOF concentration from 0 to 10 wt%. The contact angle of the corresponding membranes decreased from 80° to 51° indicating an increase in hydrophilicity. The MH10 (10 wt% concentration) membrane sustained up to 20, 19 and 17.5 h of operation with fluoride concentration of 4, 8 and 12 mg/l, respectively, at 35 kPa transmembrane pressure and 30 l/h cross flow rate with a membrane area of 0.026 m2. Regeneration study and performance of the MMM in real life ground water samples were also investigated. Filter performance was successfully predicted by a modified model available in literature. 2018-02-01T00:00:00Z http://dspace.bits-pilani.ac.in:8080/jspui/handle/123456789/20575 Title: Mass transport across porous wall of a microtube: a facile way to diagnosis of diseased state Authors: Bhattacharjee, Saikat Abstract: Mass transport characteristics of a neutral solute in a Casson fluid through a microtube with porous wall under the influence of both pressure and electric field are attempted in this work. The velocity and concentration fields were derived from first principles analytically. The expression of Sherwood number was obtained and impact of rheological parameters on Sherwood number was quantified. Influence of system parameters on solute transport characteristics in terms of permeation flux and concentration was established in detail. Finally, a theoretical method was developed to identify the diseased state by detecting the stagnation point in the microfluidic platform without any chemical reagents. 2018-03-01T00:00:00Z