Department of Chemical Engineering

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Start date: 2000Subject: search.filters.subject.Adsorption

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Now showing 1 - 10 of 23
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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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    Polyaniline-doped sawdust as a promising adsorbent for defluoridation
    (Elsevier, 2023-11) Chatterjee, Somak
    Fluoride’s presence in groundwater is a growing concern, especially where access to safe drinking water is limited. Traditional water treatment methods have limitations in effectively removing fluoride. Thus, there is a need for an alternative, sustainable and cost-effective solution. This study develops an adsorbent where a conducting polymer (PAni) will be coated on agricultural byproduct (sawdust) for defluoridation application. Introduction of amino-tris-methylene-phosphonic acid (ATMPA) as a dopant into PAni enhances its exchange mechanism, thereby increasing its uptake capacity (58 mg/g). Potential application of this adsorbent lies in water treatment plants, which will cater needs of industry, mankind and agriculture
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    Undoped polyaniline-modified sawdust as an adsorbent for lead removal
    (Elsevier, 2023-12) Chatterjee, Somak
    Heavy metal ion adsorption employing abundant natural and agricultural wastes appears to be promising. Biodegradable sawdust is promoted as a green and sustainable alternative. In this work, potential application of sawdust has been explored for uptake of lead ions from contaminated water. Specifically, undoped polyaniline, a highly conductive polymer, was added to sawdust to improve its uptake capacity. Highest lead uptake capacity of 218 mg/g was observed at 318 K. Different surface-based characterizations for this material were performed. Morphology of prepared sawdust revealed a one-dimensional flake-like structure having a porous nature. FTIR and XRD analysis inferred successful incorporation of polyaniline into sawdust. In addition, XPS analysis revealed the importance of polyaniline chains during electrostatic adsorption of lead ions. At an adsorbent dosage of 1 g/l, optimal equilibrium conditions were reached. In accordance with Langmuir isotherm analysis, lead ion uptake was mainly driven by monolayer adsorption. As-prepared adsorbent was subjected to batch studies, where, effects of pH and interfering ions were carried out. Regeneration was also studied for four cycles.
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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.
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    Hydrogen adsorption in pyridine bridged porphyrin-covalent organic framework
    (Elsevier, 2019) Ghosh, Sarbani
    Covalent organic frameworks (COFs), a class of carbon-based polymeric materials have the potential to be used as hydrogen adsorbent. Three dimensional (3D) COFs, due to their low density and high surface area, although have higher hydrogen adsorption, they have less stability than two dimensional (2D) COFs. Here we studied porphyrin group containing 2D COF, namely H2,P-COF for hydrogen storage using density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulations and the results were compared with the most common 2D COFs, COF-1 and COF-5. Cylindrical shaped 2D COFs where isolated unit blocks are stacked in multiple layers due to van der Waals interactions between individual layers, increase the effective surface area for hydrogen storage. A further modification has been done by bridging the inter-layer gap by pyridine molecules. Insertion of pyridine increases the separation distance of layers of 2D COFs as well as the free volume. Feasibility of the structure formation and stability of all the structures were checked using DFT study. To ensure the structural stability of bridged COFs after hydrogen loading, alternating layers of COF were bridged. Single, bi, tri and tetra -pyridine molecules were chemically bonded with the existing carbon ring present in between two C2O2B rings to form pyridine bridged H2,P-COFs. Our GCMC results show a significant increase in storage capacity which is mainly due to an increase in the free volume of the material. The highest capacity of 5.1 wt% and 20 g H2/L at 298 K and 100 bar, above the gravimetric DOE goal, has been found at room temperature for tetra-pyridine doped porphyrin COF structure.
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    Hydrogen storage using novel graphene-carbon nanotube hybrid
    (Elsevier, 2023) Ghosh, Sarbani
    Hydrogen storage is an active area of research particularly due to urgent requirements for green energy technologies. In this paper, we study the storage of hydrogen gas molecules in terms of physical adsorption on a carbon-based nanomaterial, i.e., a novel graphene-carbon nanotube hybrid. The novel carbon nanostructures were prepared from pristine nanotubes and graphene sheets using molecular dynamics simulations and hydrogen storage quantified in terms of gravimetric capacity was simulated using grand canonical Monte Carlo Simulations. We found the highest storage capacity of 5.90 wt% at room temperature and 100 bar with high reversibility of operation
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    Efficient copper removal using low-cost H3PO4 impregnated red-gram biochar-MnO2 nanocomposites
    (Elsevier, 2023-02) Sopanrao, Khandgave Santosh
    Copper metal removal from wastewater is an essential step to detoxify wastewater before release into human contact. To serve the same purpose, H3PO4 impregnated and KMnO4 functionalised, red-gram seed coat biochar is synthesized, for efficient and economic biosorption of aqueous copper ions. Response Surface Methodology (RSM) is employed to achieve a high optimal adsorption capacity of 493.34 mg/g, using a low adsorbent dosage of 0.6 g/L in only 90 min. Pre- and post-adsorption characterization of the adsorbent was done using XRD & XPS spectroscopy, FE-SEM, TGA and BET analysis to study its microstructure and mechanism of adsorption. A high mesoporous surface area of 207 m2/g and the negatively charged moieties on the surface help in complexation of the ions by reduced monolayer chemisorption. Cyclic regeneration of the adsorbent was studied to assess the adsorption efficiency, which retained a value as high as 70 % after 3 adsorption-desorption cycles.
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    Theoretical investigation of cross flow ultrafiltration by mixed matrix membrane: A case study on fluoride removal
    (Elsiever, 2015-06-01) Chatterjee, Somak
    Selective 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.
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    Adsorptive removal of potentially toxic metals (cadmium, copper, nickel and zinc) by chemically treated laterite: Single and multicomponent batch and column study
    (Elsiever, 2017-08) Chatterjee, Somak
    Efficiency of chemically treated laterite was tested to remove, copper, cadmium, zinc and nickel (potentially toxic metals) from drinking water. Infrared spectroscopy confirms the uptake of these contaminants by treated laterite. Optimum treatment parameters are observed at 10 mg/L adsorbent concentration, 0.26 mm particle size and pH range of 6–9. Maximum uptake capacities are observed to be 3.7 mg/g (0.03 mmol/g), 2.8 mg/g (0.04 mmol/g), 2.8 mg/g (0.04 mmol/g) and 2 mg/g (0.03 mmol/g), for cadmium, copper, zinc and nickel, respectively. Adsorption was endothermic and physical in nature. Fixed bed column study was carried out using a multicomponent feed having concentration 5 mg/L of each potentially toxic metal, and the effect of bed depth and flow rate were observed. Corresponding to a specific process condition, saturation was faster for nickel followed by zinc, cadmium and copper. The column was also tested for a real-life toxic metal contaminated river sample, collected from Yamuna River, New Delhi (GPS location 30° 54/N and 76° 59/E).
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    A socio-economic study along with impact assessment for laterite based technology demonstration for arsenic mitigation
    (Elsiever, 2017-04-01) Chatterjee, Somak; Bhattacharjee, Saikat
    Arsenic contamination mitigation technologies have been adsorption-based, but the most widely-used and traditionally available adsorbents suffered inherent limitations, including cost infeasibility and problems associated with regeneration and disposal of the spent adsorbent. The present technology is based on indigenously developed activated laterite prepared from the naturally and abundantly available material, and can hence easily be scaled up for community usage and large scale implementation. The total arsenic removal capacity is 32.5 mg/g, which is the highest among all naturally occurring arsenic adsorbents. A major issue in earlier adsorbents was that during regeneration, the adsorbed arsenic would be released back into the environment (leaching), and would eventually contaminate the groundwater again. But the adsorbent in this filter does not require regeneration during its five-year lifespan and does not leach upon disposal.