Faculty Publications
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Item Principles of crystallization process(Elsevier, 2024) Bhoi, S.; Lenka, M.; Sarkar, D.Crystallization is an important mass transfer operation, having applications in pharmaceutical, chemical, food industries, etc. It is defined as the process of producing crystals from solution, melt, or vapor phase. The crystallization process is mainly used to purify and separate compounds. Further, it can also be used to perform particle engineering, which in turn has a great effect on the efficiency of downstream operations such as filtration, drying, etc. The driving force of any crystallization process can be commonly termed supersaturation. The supersaturation can be generated by several methods such as evaporation, chemical reaction, cooling, addition of antisolvent, etc. The key events in crystallization processes are nucleation, growth, agglomeration, and breakage. These processes can be mathematically modeled using the population balance equation for the discrete solid phase, and mass and heat balance equation for the continuous liquid phase. The mathematical model is helpful in performing control and optimization-related studies. © 2025 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.Item Crystallinity, conductivity, and magnetic properties of PVDF-Fe 3O4 composite films(2011) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.The formation of Fe3O4 nanoparticles by hydrothermal process has been studied. X-ray Diffraction measurements were carried out to distinguish between the phases formed during the synthesis. Using the synthesized Fe3O4 nanoparticles, poly(vinyledene fluoride)-Fe3O4 composite films were prepared by spin coating method. Scanning electron microscopy of the composite films showed the presence of Fe3O4 nanoparticles in the form of aggregates on the surface and inside of the porous polymer matrix. Differential Scanning calorimetry revealed that the crystallinity of PVDF decreased with the addition of Fe3O4. The conductitivity of the composite films was strongly influenced by the Fe3O4 content; conductivity increased with increase in Fe3O4 content. Vibration sample magnetometry results revealed the ferromagnetic behavior of the synthesized iron oxide nanoparticles with a Ms value of 74.50 emu/g. Also the presence of Fe3O4 nanoparticles rendered the composite films magnetic. © 2010 Wiley Periodicals, Inc.Item Effect of Drying on the Index Properties of Lateritic Soils(2012) Sunil, B.M.; Krishnappa, H.Due to significant variation in geological and climatic conditions the characteristics of lateritic soils vary from place to place. Because of the prevailing climatic conditions, the laterites and lateritic soils of a particular region may be different from those found in other parts of the world. Some investigators report that the pretest drying has significant effect on the properties of soils. In such studies the authors associate the effect of drying on the properties of soils due to the mineralogy of soil. From this context there is a need to investigate the effect of sample preparation on lateritic soils prior to testing. In the present study lateritic soils from different sources in west coast region of India were studied to investigate the effect of drying on their index properties. Due to pretest drying it is observed from the results that there is a significant change in Atterberg limits and other properties of soils tested. These changes are attributed due to aggregation of particles. The observed changes are found to be permanent. © 2012 Springer Science+Business Media B.V.Item Influence of Drying Temperature on Three Soils Physical Properties(Springer International Publishing, 2016) Sunil, B.M.; Deepa, A.V.Changes in plasticity characteristics of three soils upon drying are examined in this paper. These changes are attributed to aggregation of particles. The key characteristic evaluated was the impact of drying temperature on the index properties, compaction characteristics and California bearing ratio. The study found the effect of drying strongly depended on soil type, mineralogy or presence of cementing agents. The observed changes are found to be permanent and the implications are that these changes may affect the field performance of test soils. © 2016, Springer International Publishing Switzerland.Item Ceria-samarium binary metal oxides: A comparative approach towards structural properties and soot oxidation activity(Elsevier B.V., 2018) Anjana, A.P.; Geethu, J.; P, M.R.; Prasad Dasari, H.P.; Lee, J.-H.; Harshini, H.; Bhaskar Babu, G.U.Binary metal oxides of CeO2-Sm2O3 (CSx, x varies from 10 to 90 mol%) along with pure CeO2 and Sm2O3 were synthesised successfully by the EDTA-Citrate method. From XRD, Raman spectroscopy and UV–vis DRS results, the whole composition of metal oxides exist in three phases: (fluorite phase (F) (CS10-CS30), bi-phase (fluorite (F) + cubic (C)) (CS30-CS90) and cubic phase (C) (Sm2O3)). For CSx samples, the calculated band gap energy values obtained from the UV–vis DRS results were in between 3.0–5.1 eV and fluorite phase samples (CS10–CS30) displayed lower band gap energy values (3.04–3.07 eV) than compared to the samples in other phases. Similarly, from XPS analysis, fluorite phase samples (CS10–CS30) showed higher surface oxygen vacancy concentration than compared to samples in other phases. Catalytic activity for soot oxidation is carried out on CSx samples, and the T50 temperature is in between 480–540 °C. Fluorite phase samples (CS10 CS30) showed higher surface area, lower degree of agglomeration, lower band gap energy, higher oxygen vacancy concentration and better catalytic activity for soot oxidation. Among all the CSx samples, CS10 sample displayed highest surface area (38 m2/g), lowest degree of agglomeration (0.36), lowest band gap energy (3.04 eV), highest oxygen vacancy concentration (64%) and highest soot oxidation activity (T50 = 480 °C). The order of the soot oxidation activity of CSx samples followed the same trend of band gap energy values. © 2018 Elsevier B.V.Item Highly fluorescent materials derived from ortho-vanillin: Structural, photophysical electrochemical and theoretical studies(Elsevier B.V., 2019) Poojary, S.; Acharya, M.; Abdul Salam, A.A.; Kekuda, D.; Nayek, U.; Madan Kumar, S.; Vasudeva Adhikari, A.V.; Dhanya, D.Small-molecule organic fluorophores are highly in demand attributed to their extensive prospective in material and biomedical applications. Particularly, luminescent ?-conjugated organic molecules that possess an efficient solid-state emission are excellent candidates for optoelectronic devices. Focusing on high demand of organic fluorophores, we herein report the synthesis of three organic fluorescent materials derived from o?vanillin, viz. an ester (F1), an azine (F2) and an azo dye (F3). Interestingly, F2 exhibited very intense luminescence in its aggregate phase due to the restriction in intra-molecular rotation (RIR), as demonstrated by solution thickening studies. Further, its Single Crystal X-ray Crystallography (SCXRD) study suggested the existence of various intra and inter molecular interactions and gave evidences for locked intra-molecular rotations of the benzene rings in the rigid conformation of the molecule. The bathochromic shift in fluorescence from solution to solid phase was confirmed by its thin-film emission spectrum, which evidences the formation of J-aggregates. The observed RIR, development of J-aggregates and high conjugation in F2 impart an excellent fluorescence in its aggregated state. Thin films of both F2 and F3 on ITO plates exhibited a bathochromic shift with a deep orange to red photoluminescence on UV excitation. Furthermore, the morphological characterization revealed the presence of clear dense grains in case of F2 and F3, while the DSC analysis indicated phase transitions of all the derivatives. As seen from dielectric measurement studies, the azo dye F3 exhibited the highest dielectric constant among the three derivatives. The electronic and photophysical data based on Density Functional Theory (DFT) and Time Dependent-DFT (TD-DFT) calculations are in agreement with the experimental results. All the above data clearly advocate that, the synthesized fluorophoric o?vanillin derivatives are excellent candidates for electro-optical devices. © 2018 Elsevier B.V.Item Effect of carbon black and titanium dioxide dispersants on solidification of multiwall carbon nanotube-added salt-based phase change material(ASTM International, 2021) Rajagopalan, S.; Prabhu, K.N.The effect of carbon black and titanium dioxide (TiO2) dispersants on solidification of potassium nitrate phase change material (PCM) with multiwall carbon nanotube (MWCNT) addition was investigated using the Fourier method of thermal analysis. On addition of 0.1 % of MWCNT, the solidification time of PCM decreased by 26 %, enhancing the heat release rates. A decrease in thermal diffusivity of the PCM was observed on addition of MWCNT particles. These benefits were observed to diminish over successive thermal cycles because of the agglomeration of MWCNT particles. To prevent the agglomeration of additives, dispersants such as carbon black and TiO2 were used. In the presence of carbon black, the nanosalt PCM retained all the cooling curve parameters over 10 thermal cycles, preventing the agglomeration of nanoadditives. On the other hand, the dispersant TiO2 significantly enhanced the thermal diffusivity property of PCM by virtue of its superior thermal conductivity. These are critical outcomes in development of nanosalt PCMs for thermal energy storage applications. © © 2021 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 ASTM International is not responsible, as a body, for the statements and opinions expressed in this paper. ASTM International does not endorse any products represented in this paper.Item A semi-analytical nonlocal elasticity model for static stability and vibration behaviour of agglomerated CNTs reinforced nano cylindrical panel under non-uniform edge loads(Elsevier Inc., 2022) Twinkle, C.M.; Jeyaraj, J.A semi analytical nonlocal elasticity model to analyze the effect of non-uniform edge loads on static stability and free vibration characteristics of agglomerated carbon nanotubes (CNTs) reinforced nano cylindrical panels are presented. Effective material properties of the agglomerated CNT reinforced composite are obtained using a two-parameter micro-mechanics model while Eringen's non-local theory is used to account the size effect. Sinusoidal shear deformation theory is adopted to analyze the buckling and vibration parameters using Galerkin's approach. The accuracy of the proposed model is presented first by comparing the results in the literature. Then a comprehensive study is carried out to analyze the influence of various degrees of agglomeration (complete, partial), nature of edge load, and non-local effects on the buckling and free vibration response of CNT reinforced nano cylindrical panel. The results revealed that non-local size effect leads to a reduction in stiffness and thus reduces buckling and dynamic characteristics. Moreover, it is observed that critical buckling load varies with type of in plane load and reduction in natural frequency is different for different in plane loading conditions. © 2021 Elsevier Inc.Item Waste dry cell derived photo-reduced graphene oxide and polyoxometalate composite for solid-state supercapacitor applications(Royal Society of Chemistry, 2023) Maity, S.; Biradar, B.R.; Srivastava, S.; Chandewar, P.R.; Shee, D.; Das, P.; Mal, S.S.In the modern era, realizing highly efficient supercapacitors (SCs) derived through green routes is paramount to reducing environmental impact. This study demonstrates ways to recycle and reuse used waste dry cell anodes to synthesize nanohybrid electrodes for SCs. Instead of contributing to landfill and the emission of toxic gas to the environment, dry cells are collected and converted into a resource for improved SC cells. The high performance of the electrode was achieved by exploiting battery-type polyoxometalate (POM) clusters infused on a reduced graphene oxide (rGO) surface. Polyoxometalate (K5[α-SiMo2VW9O40]) assisted in the precise bottom-up reduction of graphene oxide (GO) under UV irradiation at room temperature to produce vanadosilicate embedded photo-reduced graphene oxide (prGO-Mo2VW9O40). Additionally, a chemical reduction route for GO (crGO) was trialed to relate to the prGO, followed by the integration of a faradaic monolayer (crGO-Mo2VW9O40). Both composite frameworks exhibit unique hierarchical heterostructures that offer synergic effects between the dual components. As a result, the hybrid material's ion transport kinetics and electrical conductivity enhance the critical electrochemical process at the electrode's interface. The simple co-participation method delivers a remarkable specific capacity (capacitance) of 405 mA h g−1 (1622 F g−1) and 117 mA h g−1 (470 F g−1) for prGO-Mo2VW9O40 and crGO-Mo2VW9O40 nanocomposites alongside high capacitance retentions of 94.5% and 82%, respectively, at a current density of 0.3 A g−1. Furthermore, the asymmetric electrochromic supercapacitor crGO//crGO-Mo2VW9O40 was designed, manifesting a broad operating potential (1.2 V). Finally, the asymmetric electrode material resulted in an enhanced specific capacity, energy, and power of 276.8 C g−1, 46.16 W h kg−1, and 1195 W kg−1, respectively, at a current density of 0.5 A g−1. The electrode materials were tested in the operating of a DC motor. © 2023 The Royal Society of Chemistry.Item Enhancing the Photoelectrochemical Performance of Ru(II)-Sensitized Dye-Sensitized Solar Cells Using Cyanopyridine-Based Cosensitizers(John Wiley and Sons Inc, 2025) Naik, P.; Abdellah, I.M.; Abdel-Shakour, M.; Keremane, K.S.; Vasudeva Adhikari, A.V.The cosensitization approach is one of the widely adopted strategies for systematically enhancing photovoltaic performance of dye-sensitized solar cells (DSSCs) by utilizing two or more dyes with distinct absorption spectra. This method achieves panchromatic absorption, improves intramolecular charge transfer performance, prevents dye aggregation, and increases dye loading capability. In this study, we investigated four previously reported push–pull-type dianchored chromophores (CP1–4) featuring a cyanopyridine scaffold as cosensitizer to enhance the performance of Ru(II)-based N3-sensitized DSSCs. Both the co-sensitized devices (N3 + CP1–4) and the N3-only devices were fabricated using a fixed dye concentration of 0.2 mM for each sensitizer/cosensitizers, while the coadsorbent chenodeoxycholic acid (CDCA) was systematically varied between 0 and 20 mM. This systematic variation of CDCA concentration was designed to examine its role in suppressing dye aggregation and modulating interfacial charge dynamics. Among the Series, CP4, carrying a thiobarbituric acid anchoring/acceptor group, demonstrated superior performance at all CDCA concentrations, achieving power conversion efficiency of 6.67%, 6.79%, and 5.74%, compared to 6.02%, 6.10%, and 5.44% for devices sensitized with N3 alone. Further, electrochemical impedance spectroscopy measurements confirmed the improved charge transport and reduced recombination in these devices. These findings highlight the potential of rationally engineered cosensitizers and optimized coadsorbent concentrations for enhancing the performance of metal-based sensitizers in DSSCs. © 2025 Wiley-VCH GmbH.