Now showing 1 - 9 of 9
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    Studies of simultaneous electrochemical sensing of Hg2+and Cd2+ions and catalytic reduction properties of 4-nitrophenol by CuO, Au, and CuO@Au composite nanoparticles synthesised using a graft copolymer as a bio-template
    (28-12-2021)
    Saren, Rakesh Kumar
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    Banerjee, Shankha
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    Mondal, Barun
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    Tripathy, Tridib
    An efficient and selective electrochemical sensor for the simultaneous detection of Hg2+ and Cd2+ ions in an aqueous medium is developed using bimetallic CuO@Au composite nanoparticles prepared using a novel graft copolymer, sodium alginate-g-poly(allylamine-co-acrylic acid), as a bio-template. The graft copolymer is synthesized via a solution-phase graft copolymerization technique. The same graft copolymer is also used for the preparation of monometallic Au and CuO composite nanoparticles. The developed polymer and composite nanoparticles are characterized using several characterization techniques. All three composite nanoparticles are globular in shape with an average particle size of 5.5 nm for the CuO NPs, 7.5 nm for the Au NPs and 13 nm for the CuO@Au NPs, and are well polydispersed. Metal ion sensing is carried out electrochemically using the linear sweep voltammetry (LSV) technique. The sensing ability of the bimetallic composite nanoparticles towards Hg2+ and Cd2+ ions is sufficient, with limit of detection values (LODs) of 0.99 nM and 0.78 nM for [Hg2+] and [Cd2+], respectively. The catalytic activities of the three metal NPs are evaluated by the reduction of 4-nitrophenol to 4-aminophenol. Here, the developed bimetallic composite nanoparticles also show excellent results superior to those of the other two monometallic composite nanoparticles, as well as those of some other reported materials, with a Kapp value of 0.556 min-1. This journal is
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    “Novel Dextrin-Cysteine Schiff Base: A Highly Efficient Sensor for Mercury Ions in Aqueous Environmentâ€
    (14-02-2020)
    Mondal, Barun
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    Banerjee, Shankha
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    Ray, Jagabandhu
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    Jana, Subinoy
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    Tripathy, Tridib
    We report a highly sensitive electrochemical and fluorescence sensor for the detection of toxic environmental pollutant Hg2+ ions by using a novel dextrin-cysteine-Schiff base (DCS). The sensor is developed by the periodate oxidation of dextrin followed by Schiff base formation with an amino acid, cysteine. The new characterized DCS is used as an efficient and selective sensor for the detection of Hg2+ ions in aqueous solution both by electrochemical and fluorescence quenching process. The detection limit (LOD) by the electrochemical method is 0.74 nM which is much lower than that by the fluorometric detection, where LOD value is found to be 40.93 μM. The Schiff base/glassy carbon electrode (DCS/GCE) shows an excellent selectivity towards Hg2+ ions compare to other environmentally relevant ions where almost nil current response is observed. The DCS/GCE also exhibits remarkable sensing of Hg2+ in real water samples such as river and tap water. The electrochemical sensing of Hg2+ by DCS is found to be superior to that of fluorescence sensing.
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    Highly selective and sensitive electrochemical sensing of trace Zn2+ ions, by grafted Tricholoma mushroom polysaccharide/Ag composite nanoparticles in aqueous medium
    (01-04-2021)
    Mondal, Barun
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    Banerjee, Shankha
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    Samanta, Santu Kumar
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    Tripathy, Tridib
    Herein, we report a highly sensitive, selective and simple electrochemical sensor for the detection of Zn2+ ions in less than 1 nM concentration range in aqueous environment. A naturally occurring and frequently cultivated Tricholoma mushroom polysaccharide is used for the preparation of novel sensor. In the present investigation we demonstrate an electrochemical sensor, grafted Tricholoma mushroom polysaccharide-based silver composite nanoparticles (TMPSGP-Ag NPs) which show remarkable electrochemical sensing performance of Zn2+ ions without interfering with the other relevant metal ions. The sensing performance is carried out by cyclic voltammetry (CV) and chronoamperometry (CA) analysis under optimised condition. The limit of detection (LOD) is found to be 0.53 nM, which is much lower than some other reported works as well as lower than the limit of World Health Organization (WHO). The stability, reproducibility and repeatability properties of the sensor are examined where a satisfactory result is obtained. The practical application of the proposed sensor is tested by the detection of Zn2+ ions using river water sample with an excellent performance. Therefore, the developed sensor can be used as a highly efficient and effective Zn2+ ions detector in aqueous medium.
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    Effective removal of Th4+, Pb2+, Cd2+, malachite green, methyl violet and methylene blue from their aqueous solution by amylopectin dialdehyde-Schiff base
    (01-06-2020)
    Sasmal, Dinabandhu
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    Banerjee, Shankha
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    Tripathy, Tridib
    In the present study, amylopectin was oxidized to amylopectin dialdehyde by selective cleavage of C2-C3 bond of anhydroglucose units in the amylopectin chain by sodium metaperiodate to generate two aldehyde groups and modified to Schiff bases by the reactions with ethanolamine, hydrazine and semicarbazide. The well characterized Schiff bases were used as adsorbents for Th4+, Pb2+, Cd2+ ions and three cationic dyes namely malachite green, methyl violet and methylene blue. Among the three Schiff bases, amylopectin dialdehyde-ethanolamine (APDA-EA) showed stronger and selective adsorbent towards Th4+ ions and malachite green dye. The adsorption data was found to follow pseudo second order kinetics and Langmuir adsorption isotherm. The maximum adsorption capacity of APDA-EA towards Th4+ ions was 94.68 mg/g and towards malachite green dye it was 89.84 mg/g. The greater selectivity of APDA-EA towards Th4+ ion was explained theoretically by Density Functional Theory calculations.
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    Copper oxide nanocomposite particles supported on sodium alginate-g-polyallylamine based reduced graphene oxide: An efficient electrochemical sensor for sensitive detection of cadmium ions in water
    (01-09-2023)
    Tripathy, Tridib
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    Saren, Rakesh Kumar
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    Banerjee, Shankha
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    A highly sensitive and selective electrochemical sensor, sodium alginate-g-polyallylamine/reducedgrapheneoxide/CuO nanocomposite particles (SAGPMRGO@CuO NPs) has been synthesized for the detection of Cd2+ ions in the aqueous environment. The graft copolymer/reduced graphene oxide supported CuO nanocomposite particles are prepared through bioreduction of graphene oxide by a novel synthesized graft copolymer sodium alginate-g-PAAM (SAG-g-PAAM) to reduced graphene oxide (SAGPMRGO) followed by using it as both a reductant and a stabilizing agent to obtain SAGPMRGO@CuO hybrid nanocomposite particles. The graft copolymer is prepared via free radical solution phase graft copolymerization technique. The graphene oxide (GO) is prepared by the oxidation of graphite using modified Hummer's method. The prepared nanocomposite particles are characterized by UV-VIS, FTIR and Raman spectroscopy, powder X-ray diffraction (PXRD), HRTEM-EDS, FESEM, XPS and DLS analysis with zeta potential measurement in colloidal suspension. The prepared graft copolymer is characterized by 1H and 13C NMR spectroscopy, PXRD and FESEM analysis and the SAMPGRGO is characterized by UV-VIS and Raman spectroscopy, PXRD and FESEM analysis. The CuO nanocomposite particles are spindle shaped with an average particle size ranges from 15.6 nm to 32.1 nm and are well polydispersed. Metal ion (Cd2+) sensing is carried out by cyclic voltammetry (CV) and chronoamperometry (CA) analysis under optimum conditions. The limit of detection (LOD) and limit of quantitation (LOQ) is found to be 1.27 nM and 4.24 nM respectively which is lower than some other reported works. The reproducibility and stability properties of the developed sensor are examined where the results are found to be satisfactory. The selective detection of Cd2+ ions in a river water sample is also evaluated with an excellent performance.
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    An electrochemical sensor-adsorbent for lead (Pb2+) ions in an aqueous environment based on Katiragum-Arginine Schiff base
    (07-10-2022)
    Saren, Rakesh Kumar
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    Banerjee, Shankha
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    Mondal, Barun
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    Tripathy, Tridib
    Herein we report a highly sensitive and selective electrochemical sensor-adsorbent for the simultaneous detection and removal of highly toxic lead (Pb2+) ions from an aqueous solution by a Katiragum-Arginine Schiff base. The sensor is developed by the periodate oxidation of Katiragum and modified to a Schiff base by reaction with an amino acid, l-arginine (KGDR). The KGDR is characterized by NMR, FTIR, FESEM analysis and HRMS spectra. The Katiragum-Arginine Schiff base material is used as a sensor-adsorbent for Pb2+ from aqueous solution. Sensing of Pb2+ is analyzed by the electrochemical method with a detection limit of 0.146 μM with respect to the concentration of Pb2+. The Schiff base/glassy carbon electrode (KGDR/GCE) is highly selective towards Pb2+ ions in comparison to other environmentally relevant ions as well as in water samples. KGDR shows a remarkably high adsorption capacity towards Pb2+ ions with maximum specific removal (qm) of 5482.46 mg g−1. Various isotherm and kinetic models are used to analyze the data and the Langmuir and pseudo-second order kinetic model are followed for Pb2+ adsorption.
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    Extended H-Bonding through Protic Ionic Liquids Facilitates the Growth and Stability of Water Domains in Hydrophobic Environment
    (22-12-2020)
    Bardhan, Soumik
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    Rahman, Mohammad Homaidur
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    Banerjee, Shankha
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    Singh, Akhil Pratap
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    Discrete water domains in hydrophobic environment find relevance in aerosols, oil refinery, the human body, etc. The interfacial microstructure plays a crucial role in the stability of such water domains. Over the decades, the amphiphile-induced electrostatic interaction is considered to be the major stabilizing factor operating at these interfaces. Here we take the representative water/AOT/oil microemulsion to show that creating a strong H-bonding network through suitable additive, such as protic ionic liquid (IL) at the interface, helps both the growth and stability of water domains in the hydrophobic phase. On the other hand, common electrolytes and aprotic ILs fail to replicate such behavior as seen by Raman, Fourier transform infrared spectroscopy, dynamic light scattering (DLS), and electron microscopy measurements. Experimental results are further supported by the all-atomic molecular dynamics (MD) simulations that showed extended H-bonding mediated by the protic IL cations that were localized at the interface. High temperature DLS and rheology studies have shown greater thermal stability and mechanical strengths of our biocompatible microemulsions, which have potential to become suitable templates for in situ synthesis of nanoparticle and various organic compounds.
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    Structural Transitions at the Water/Oil Interface by Ionic-Liquid-like Surfactant, 1-Butyl-3-methylimidazolium Dioctyl Sulfosuccinate: Measurements and Mechanism
    (10-03-2022)
    Banerjee, Shankha
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    Bardhan, Soumik
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    Reverse micelle (RM) aggregates have a wide range of applications in various areas of science and technology. A continuous demand exists to replace interfacial surfactant molecules with various nonconventional amphiphiles. Ionic liquid (IL)-like surfactants (IL-surf’s) constitute a class of such molecules that are being researched extensively. Here, we have formulated several water/IL-surf/oil microemulsions by optimizing the core droplet size with varying oil phases. The best composition of water/[BMIM][AOT]/IPM ([BMIM][AOT]: 1-butyl-3-methylimidazolium dioctyl sulfosuccinate; IPM: isopropyl myristate) was then analyzed in detail through experimental and computer simulations. Our results from DLS measurements suggest a structural transition from spherical aggregates in the parent water/[Na][AOT]/IPM solution to cylindrical droplets in the IL-surf-based system. The Raman and ATR-FTIR spectral analysis suggest a variation in the microstructure of the water/oil interface due to the differential interaction of the counterions with AOT headgroups and water. Molecular dynamics simulation results provided the direct image of the interface showing a structured versus uneven water/oil interface in [Na][AOT] versus [BMIM][AOT] RMs, where the larger [BMIM] cations weakly bind with the AOT headgroups due to their low charge density. Finally, an application of this IL-surf-based formulation was tested by carrying out a Heck cross-coupling reaction that showed significantly higher yield under milder reaction conditions.
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    Chemical Profiling of Crush, Tear, Curl (CTC) Tea Waste of Eastern Sub-Himalayan Regions: An Elemental and Spectroscopic Analysis
    (01-12-2022)
    Sarkar, Satyajit
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    Bardhan, Soumik
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    Gangopadhyay, Arindam
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    Banerjee, Shankha
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    Chakraborti, Saurabh
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    Saha, Sumit
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    Singh, Mahipal
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    Chowdhury, Monoranjan
    Tea is not only the most popular beverage in the world but also producing a large quantity untreated wastes product every year. In particular, the tea gardens of eastern Sub-Himalayan region cumulatively produce 15 million kg of crush, tear, curl (CTC)-factory tea waste (FTW) every year, which primarily includes discarded tea leaves, leaf fibers, buds and tender stems of tea plants. Beside that ~ 80% population of Indian subcontinent consume CTC tea regularly at their homes, tea stalls, market, cafe etc. and the waste produced from it, is called CTC domestic tea waste (DTW). Thus, not only factory tea waste but also a large quantity of domestic CTC tea waste (DTW) is exposed into the environment regularly. In present study, an attempt has been made for primary screening of the compounds in both the CTC-tea wastes. It has been shown that FTW sample contains greater amount of non-metal elements such as sulfur, calcium, phosphorus and metal elements like potassium and iron compared to DTW sample. Abundance of aromatic compounds has been seen to be higher in FTWs whereas, DTW primarily contains aliphatic compounds. Using Orbitrap-HRLCMS analysis allowed to make accurate predictions about the molecular structures of the likely organic chemicals found in tea trash. Thus, various bioactive organic compounds, micronutrients and trace elements from tea waste were found.