Department of Chemical Engineering

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    Experimental and modeling of fluoride removal using aluminum fumarate (AlFu) metal organic framework incorporated cellulose acetate phthalate mixed matrix membrane
    (Elsevier, 2017-12) Bhattacharjee, Saikat
    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.
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    Aluminium fumarate metal organic framework incorporated polyacrylonitrile hollow fiber membranes: spinning, characterization and application in fluoride removal from groundwater
    (Elsevier, 2018-02) Bhattacharjee, Saikat
    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.
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    Aluminium terephthalate (Al-BDC) based metal organic framework decorated carboxymethylated filter cloth for defluoridation application
    (Elsevier, 2023-06) Chatterjee, Somak
    Current work adopts a novel approach for deposition of aluminium terephthalate-based metal organic framework (MOF) on carboxymethylated filter paper for defluoridation purpose. Aluminium terephthalate-based MOF was prepared using an optimized technique and showed a fluoride uptake capacity of 665 mg/g. However, due to its low yield, synthesized MOF was immobilized on carboxymethylated filter paper, using hydrothermal method. MOF immobilized filter paper (MOF cloth) showed a fluoride uptake capacity of 88 mg/g. Different surface-based characterization for MOF and MOF cloth were performed. Synthesized MOF was quasi-spherical in shape, forming flower like structures, when coalesced together and it showed crystalline property, having lattice fringes of 0.2 nm. Uniform and dense distribution was observed during its deposition process on filter paper. Both functional groups and mineralogical phases present in the MOF were also imparted to the immobilized filter paper. Uptake of fluoride by MOF cloth was governed by monolayer adsorption, as evident from Langmuir isotherm analysis. Uptake capacity increased with temperature and the highest one was recorded at 318 K. Prepared MOF cloth was subjected to dynamic studies via glass-funnel based filtration, where, effects of pH, coexisting ions including an organic pollutant and real-life feed were carried out. Regeneration of the MOF cloth was also studied for four cycles. Leaching study was performed at different time intervals. Finally, comparison was made with different conventional MOF based adsorbents and it was observed that this cloth can be an adaptable and pollution free medium for defluoridation applications.
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    Polyacrylonitrile and polyethersulfone based co-axial electrospun nanofibers for fluoride removal from contaminated stream
    (Elsevier, 2024-02) Chatterjee, Somak
    Coaxial electrospun polyacrylonitrile (PAN) and polyethersulfone (PES) based nanofibers were prepared and was used for filtration of fluoride from drinking water for the first time. Well defined fiber geometry was obtained at 1 ml/h of core polymer, i.e., PES flow rate, 1.4 ml/h of shell polymer, i.e., PAN flow rate, voltage of 22 kV, while the distance between the needle tip and the collector was 15–17 cm. Increase in bead like structure in fiber strands was observed with higher PAN concentration, while it decreased for lower PES concentration, thereby giving an optimum composition (6 wt% PAN and 10 wt% PES) for uniform fiber morphology. This nanofiber, abbreviated as N2 acted as an ultrafiltration membrane having permeability in the lower range, i.e., 0.5 × 10−11 m/s Pa and its fluoride removal efficacy was 46%. Fibers were also hydrophilic with considerable porous nature. Uptake of fluoride by this N2 nanofibers were evident from binding energy of 685.2 eV during XPS analysis. It is probable that nitrile and sulfone groups present in the core and shell of the nanofibers played an active in fluoride uptake, which was estimated as 110 mg/g at 298 K. Isoelectric point was in alkaline range which promoted negative fluoride ion uptake on positive nanofiber surface. Lead played higher masking effect in the uptake of fluoride in comparison to arsenic as coexisting ion. Dynamic cross flow filtration was also studied with this nanofiber in both synthetic and real life feed solution.