Papers by Omkar Kushwaha, Ph.D.
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Hydrogen production from water has been considered as one of the potential clean and futuristic a... more Hydrogen production from water has been considered as one of the potential clean and futuristic alternates to fossil fuel. However, the development of a complete efficient system for hydrogen fuel coming from water lacks not only efficient, stable, and cost-effective generation but also off-line efficient storage. Herein, first, we present a newly designed monolithically integrated photoelectrochemical (PEC) device for hydrogen generation with a semitransparent MoOx/MoS2/FTO heterostructure as a photoanode and black 2D-MoS2/Si as a photocathode. This integrated cell eliminates the use of expensive metal (like Pt) as a counter electrode and enhances the overall stable H2 and O2 evolution, with a stable measured rate of 61 μmol/h and 28 μmol/h, respectively. The applied bias photon-to-current efficiency (ABPE) was measured to be ∼3.5% at −0.3 V vs reversible hydrogen electrode (RHE). Second, we demonstrate the storage of molecular H2 as solid hydrates, where the release of hydrogen from the hydrate requires no additional energy as it is not chemically bound to water. Operating at a moderate pressure of 10 MPa, we achieved hydrates of hydrogen with a maximum storage capacity of 1.3 wt %, which could be enhanced to 3 wt % with further fine-tuning of the process. The theoretical capacity of hydrogen storage in clathrate hydrates are ∼5 wt %. This concept of monolithic generation and molecular storage of hydrogen provides a complete long-demanding efficient and stable solution for large-scale commercial applications.
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Industrial & Engineering Chemistry Research, 2013
ABSTRACT For the first time, bulk and surface properties of hexanoic acid was simulated by classi... more ABSTRACT For the first time, bulk and surface properties of hexanoic acid was simulated by classical molecular dynamics and compared with corresponding values we measured in the range of T = 298.15–373.15 K at ambient pressure. AMBER and optimized potential for liquid substance all atom (OPLS-AA) force fields plus our calculations for atoms charges enable simulating density, surface tension, and viscosity, as well as the bulk structural and orientational profile of molecules at the hexanoic acid/vapor interface. The simulated densities are in good agreement within 2.9%, and the simulated surface tension within 2% over the whole range of experimental measurement. On the basis of structural studies, the carboxylic headgroups form tight hydrogen bonding, whereas the alkyl chains loosely interact indication of a high electrostatic to van der Waals interaction ratio prevailing the liquid system. The simulated viscosities agree well at high temperatures with experiment, though the agreement is reduced at low temperatures. This can be attributed to describing hexanoic acid system with strong Coulombic interaction, H-bonding, and weak van der Waals interaction all by the same force field. Quite interestingly, the simulated density profile shows an enhancement at the interface characteristic of liquids of high anisotropic molecules and the ionic liquids.
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Environmental Science and Pollution Research, 2022
The main objective of the present study is to develop artificial neural networks (ANN) to predict... more The main objective of the present study is to develop artificial neural networks (ANN) to predict the adsorption efficiency of multi-walled carbon nanotubes (MWCNTs) on Cr(VI) removal. Polydisperse MWCNTs were synthesized at 750 °C on alumina supported Fe-Co-Mo catalyst using CVD (chemical vapor deposition)-assisted spray pyrolysis of Azadirachta indica (Neem) oil under inert Argon (Ar) atmosphere. Growth of MCWNTs with inner diameters between 9 and 14 nm was corroborated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction analysis (XRD), and Raman spectral evidence assessments. The metal-ion adsorbent capacity (Cr-VI) of the as such prepared MWCNTs was examined for industrial purposes. Different parameters such as adsorption isotherms, kinetics, and thermodynamic parameters were analyzed for the removal of metal ions with MWCNTs. The results of isotherm, kinetic, and thermodynamic study indicated that the process suited well with Langmuir isotherm, pseudo second-order kinetics, and followed endothermic reaction, respectively. The effects of parameters such as adsorbent dosage, concentration of chromium ion (Cr-VI), pH, and contact time were studied to optimize the maximum removal of Cr(VI). In order to optimize the process conditions using Artificial Neural Networks, Box-Behnken design (BBD) was used to design the batch adsorption experiments, and the resulting datasets were used as the input for ANN. To predict the adsorption efficiency, various ANN architectures were examined using different training algorithms, number of neurons in the hidden layer, and the transfer function for the hidden and output layers. A neural network structure with Levenberg–Marquardt (LM) training algorithm, 14 hidden neurons, and tangent sigmoid transfer function at the hidden layer and logarithmic sigmoid transfer function at the output layer furnished the best level of prediction results. Comparing with experimental data, the optimal model capitulated mean square error (MSE),and correlation coefficient (R2) of 0.0324 and 0.99512, respectively. The results showed that ANN is well-organized in predicting the adsorption efficiency of MWCNTs for Cr(VI) metal ion removal process.
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The effect of few monovalent salts (NaCl, NH4Cl, and GdmCl) as additives, according to the Hofmei... more The effect of few monovalent salts (NaCl, NH4Cl, and GdmCl) as additives, according to the Hofmeister series on the growth of methane gas hydrates, has been studied using experiments as well as mol...
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Journal of Cleaner Production, 2021
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Journal of Molecular Liquids, 2021
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Springer Proceedings in Physics, 2019
At present, gas hydrates are the most abundant source of methane on the earth and could be a prom... more At present, gas hydrates are the most abundant source of methane on the earth and could be a promising option in the context of climate change and energy challenges in the upcoming years. It is estimated that nearly 20,000 trillion cubic meters of methane gas is trapped in the naturally existing gas hydrate reserves. This amount will be sufficient to fulfill the energy requirements for centuries, even if 20–30% of methane is recovered by using recently developed technologies. Although gas hydrates have immense energy potential on the one hand, gas hydrate plugging, on the other hand, is one of the major industrial challenges that can cause huge economic losses. The increasing energy demand has led to drilling of deeper oil wells and has increased the length of transmission lines. The problems associated with hydrate formation have gained more attention from both researchers and industries. The current methods of combating gas hydrate plugging involve the use of methanol and ethylene glycol in a large concentration, which usually shifts the three-phase boundary region from hydrate stability region and prevents hydrate plugging. However, a large portion of these chemicals ends up in the gas stream. In such scenarios, the use of kinetic hydrate inhibitors (KHIs) becomes attractive, since these additives are required in low concentrations. The KHIs delay the nucleation of hydrate or decrease the kinetics of gas hydrate formation or both can occur simultaneously. In this work, we have reported the effect of three low molecular weight di-acids, namely oxalic acid, malonic acid and succinic acid on synthetic natural gas hydrate formation kinetics. The di-acids were tested at two molar concentrations of 0.01 and 0.05 M at 3.0 MPa and 273.15 K. The hydrate former gas consumption and induction time data are reported, and discussion on the nature of results is also presented in this work.
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A fundamental study on hydrate formation from an equimolar CO2–CH4 gas mixture has been carried o... more A fundamental study on hydrate formation from an equimolar CO2–CH4 gas mixture has been carried out with two focal points: accelerating the kinetics of hydrate formation and enhancing the gas separ...
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Applied Energy, 2019
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Current Environmental Engineering, 2018
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Chinese Journal of Chemical Engineering, 2019
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The Journal of Chemical Thermodynamics, 2018
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Energy Procedia, 2017
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Industrial & Engineering Chemistry Research, 2017
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Applied Materials Today, 2016
Abstract Carbon quantum dots (CQDs or C-dots, ≤10 nm in size) are tiny carbon nanoparticles being... more Abstract Carbon quantum dots (CQDs or C-dots, ≤10 nm in size) are tiny carbon nanoparticles being envisaged in biosensing, bio-imaging and biomolecular/drug delivery. In the present investigation, green fluorescent carbon quantum/nano dots (GCQDs, ∼3 nm in size) were synthesized through facile chemical slicing method. Further, folic acid (FA) functionalized GCQDs (GCQDs-FA) were obtained to enhance their targeting ability. FA is known to positively influence the binding potential and penetration into the cancer cells because of high abundance of folate receptors (FR) on various cancer cell membranes. We report high biocompatibility, photoluminescence stability and excellent in vitro cancer cell cytoplasm and nucleus targeting performance of GCQDs-FA on MCF-7 breast cancer cells.
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The Canadian Journal of Chemical Engineering, 2016
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Advanced Materials Letters, 2014
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Advanced Materials Letters, 2013
ABSTRACT High temperature polymer electrolyte membrane fuel cells (HTPEMFCs) are energy efficient... more ABSTRACT High temperature polymer electrolyte membrane fuel cells (HTPEMFCs) are energy efficient systems with the potential to address all energy issues of present and future generations. Polybenzimidazole (PBI) based high temperature fuel cells are subject of high importance because PBI membranes are proved to be one of the best candidates for high temperature fuel cell applications. The stability of PBI membranes has been identified as crucial issue for the long-term durability under oxidative conditions of fuel cells. The present investigation highlights the photo-oxidative degradation studies accomplished on polybenzimidazole based poly(2,2'-butylene-5,5'-bibenzimidazole) (PBIB) membranes. The PBIB polymer membranes are found suitable for both in high temperature fuel cells as well as other high temperature applications. In this research article, PBIB membranes were photoirradiated under polychromatic UV rays (λ > 290 nm). The photo-oxidative degradation of membranes was characterized by Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscopy (SEM). FT-IR results showed significant amount of photo-oxidation and chemical degradation in fuel cell membranes which is proposed to be initiated by free radical mechanism. SEM images revealed development of nano-dimensional cracks and holes on surface of membranes which indicate structural and morphological degradation. The present study showed better results of accelerated photo-degradation as compared to the oxidative degradation results already reported in literature obtained chemically and thermally. Hence, the proposed photo-oxidative degradation method may be useful in determining stability, life time expectancy and degradation mechanism of fuel cell and other high performance membranes.
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Papers by Omkar Kushwaha, Ph.D.
At present, the solid wastes generated by hospitals, research centers, community centers, public places, etc. need immediate disposal/degradation policy. The recent work done by us in the solid waste management and technology especially by the use of Gamma radiations will be discussed in this presentation.
Key words: disposal policy; Gamma radiations; management; municipal solid waste; management and technology.
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UV resistant nanocomposites of biopolymer and transition metal oxide nanoparticles was prepared and characterized. Metal oxide nanoparticles were successfully dispersed in the solution of bio-polymer. The photo-screening efficiency of metal oxide nanoparticles as a photostabilizer was studied. The nanocomposite films were photoirradiated by UV with λ > 300 nm.
The resulting nanocomposite material exhibited excellent UV-resistibility in very low percentages of metal oxide nanoparticles. The irradiated and neat nanocomposites were characterized by using FT-IR spectroscopy, DSC, and contact angle measurements.
Key words: Bionanocomposite membrane; Biopolymer; Contact angle measurement; Fourier transform infrared spectroscopy; Photostabilization; Metal oxide nanoparticles.
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As you may be aware, Department of Science and Technology (DST), Govt. of India has initiated various schemes under INSPIRE (Innovation in Science Pursuit for Inspired Research) program of DST (http://www.inspire-dst.gov.in/ ) to attract and retain large number of students in basic science and to promote research and innovation in Engineering and medicine. One of the schemes is to organize workshops for 11th std students (http://www.inspire-dst.gov.in/internship.html). The workshops are intended to expose students to the excitement and methods of science, research and innovation, just prior to the time when they make their career decisions (normally after 12th std).
I am happy to inform you that Indian Institute of Science Education and Research (IISER) Pune, is organizing one such INSPIRE Science Internship Camp from 10th to 14th December, 2012 to be held at IISER campus in Pune. (http://www.iiserpune.ac.in)
The students participating in this five day residential camp, will have an excellent opportunity to interact with the best scientific leaders of this country. They would provide thought provoking lectures, open discussions and demonstrations, encourage group activities, facilitated self-learning, close interactions, and motivation towards independent thoughts and inquiry-based questions. In addition, students would be taken for visits to local research labs and would also be shown inspiring scientific documentaries. All the participating students will be provided free boarding and lodging on campus, local transport, and study materials for all five days of the camp. Besides, a transport allowance of Rs. 500/- (Rupees five hundred only) or actual, whichever is less, would be provided on arrival at the accommodation venue. Students should arrive at the accommodation venue on 9th of December, 2012. There is no registration fee.
We request you to kindly recommend five of your best students (top five scorers based on their class Xth examination marks), who are presently studying science subjects in class XI. The recommended students should not have attended any previously organized science camp by DST elsewhere. The camp requires that students stay in our accommodation for the entire duration of the camp. You are also requested to approve leave of absence for all five days to the nominated students.
Completed application form (attached), duly attested and recommended by the Principal / Head of the Institution, should reach Dr.Sheela Donde, Coordinator, INSPIRE Science Camp, IISER, First Floor, Sai Trinity Building, Near Garware Circle, Sutarwadi Road, Pashan, Pune – 411021. on or before 15th November, 2012. Shortlisted students would be informed by 26th of November, 2012, with details of the camp, time of arrival, accommodation etc.