• Amitava Mukherjee

      Articles written in Bulletin of Materials Science

    • Studies on interfacial interactions of TiO2 nanoparticles with bacterial cells under light and dark conditions

      Swayamprava Dalai Sunandan Pakrashi Sujay Chakravarty Shamima Hussain N Chandrasekaran Amitava Mukherjee

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      The probable underlying mechanism(s) of bacterial cell–TiO2 nanoparticles (TiO2 NPs) interaction in the absence of photo-irradiation has been less studied since most of the prior cytotoxicity studies focused on irradiated TiO2. The present study draws attention to the possible role of cell surface–TiO2 NP interactions under dark conditions, through an array of spectroscopic and microscopic investigations. A dominant freshwater bacterial isolate, Bacillus licheniformis, which interacted with environmentally relevant concentrations of TiO2 NPs (1 𝜇g/mL), was analysed and compared under both light and dark conditions. Aggregation of cells upon NP interaction and adsorption of NPs onto the cell membrane was evident from the scanning electron micrographs under both light and dark conditions. The FT–IR and FT–Raman spectra suggested stress response of bacterial cells by elevated protein and polysaccharide content in the cell–NP interaction. The X-ray photoelectron spectroscopic data substantiated the reduction of titanium from Ti(IV) to Ti(III) species which might have contributed to the redox interactions on the cell surface under light as well as dark conditions. The internalization of NPs in the cytoplasm were obvious from the transmission electron micrographs. The consequent cell death/damage was confirmed through fluorescence spectroscopy and microscopy. To conclude, the current study established the substantial role of interfacial interactions in cytotoxicity of the TiO2 NPs irrespective of the irradiation conditions.

    • Studies on Cr(VI) removal from aqueous solutions by nanotitania under visible light and dark conditions

      Madona Lien Paul Jastin Samuel Rajdeep Roy Natarajan Chandrasekaran Amitava Mukherjee

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      The current study deals with Cr(VI) removal by nanotitania under fluorescent light and dark conditions. The equilibrium removal capacities, 85.85 and 59.4 mg of Cr(VI)g−1 of nanoparticle were noted for nanotitania interacted under light and dark conditions, respectively, at optimized conditions (pH: 7.0, contact time: 30 min, initial Cr(VI) concentration: 20 mg l−1, nanoparticle dosage: 0.1 g l−1). Under both the conditions, the equilibrium removal data fitted well with the Langmuir isotherm model. The nanotitania followed a second-order kinetics under light condition whereas a pseudo-second-order kinetics was observed under dark condition. The surface characterization of nanotitania was carried out by zeta potential measurement and transmission electron microscope (TEM). Fourier transform infrared (FT-IR) studies carried out under light and dark conditions indicate the interaction of surface functional groups to Cr(VI). Cr(VI) removal study carried out in the Cr(VI)–Cr(III) mixture showed a decrease in Cr(VI) removal capacity with increase in Cr(III) concentration. A 92% regeneration of nanoparticle was observed indicating efficient reusability of the system. The applicability of the nanotitania in Cr(VI) contaminated water was studied by spiking Cr(VI) in natural water matrices like ground water and lake water.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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      Posted on July 25, 2019

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