Browsing by Author "Venkateshaiah, Abhilash"

Now showing 1 - 5 of 5
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    Gum Kondagogu/Reduced Graphene Oxide Framed Platinum Nanoparticles and Their Catalytic Role
    (MDPI, 2019-10-01) Venkateshaiah, Abhilash; Silvestri, Daniele; Ramakrishnan, Rohith K; Wacławek, Stanislaw; Padil, Vinod V. T; Černík, Miroslav; Varma, Rajender S.
    This study investigates an environmentally benign approach to generate platinum nanoparticles (Pt NP) supported on the reduced graphene oxide (RGO) by non-edible gum waste of gum kondagogu (GK). The reaction adheres to the green chemistry approach by using an aqueous medium and a nontoxic natural reductant-GK-whose abundant hydroxyl groups facilitate in the reduction process of platinum salt and helps as well in the homogenous distribution of ensued Pt NP on RGO sheets. Scanning Electron Microscopy (SEM) confirmed the formation of kondagogu gum/reduced graphene oxide framed spherical platinum nanoparticles (RGO-Pt) with an average particle size of 3.3 ± 0.6 nm, as affirmed by Transmission Electron Microscopy (TEM). X-ray Diffraction (XRD) results indicated that the Pt NPs formed are crystalline with a face-centered cubic structure, while morphological analysis by XRD and Raman spectroscopy revealed a simultaneous reduction of GO and Pt. The hydrogenation of 4-nitrophenol could be accomplished in the superior catalytic performance of RGO-Pt. The current strategy emphasizes a simple, fast and environmentally benign technique to generate low-cost gum waste supported nanoparticles with a commendable catalytic activity that can be exploited in environmental applications.
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    Microscopic Techniques for the Analysis of Micro and Nanostructures of Biopolymers and Their Derivatives
    (MDPI, 2020-03-01) Venkateshaiah, Abhilash; Padil, Vinod V. T.; Nagalakshmaiah, Malladi; Waclawek, Stanislaw; Černík, Miroslav; Varma, Rajender S.
    Natural biopolymers, a class of materials extracted from renewable sources, is garnering interest due to growing concerns over environmental safety; biopolymers have the advantage of biocompatibility and biodegradability, an imperative requirement. The synthesis of nanoparticles and nanofibers from biopolymers provides a green platform relative to the conventional methods that use hazardous chemicals. However, it is challenging to characterize these nanoparticles and fibers due to the variation in size, shape, and morphology. In order to evaluate these properties, microscopic techniques such as optical microscopy, atomic force microscopy (AFM), and transmission electron microscopy (TEM) are essential. With the advent of new biopolymer systems, it is necessary to obtain insights into the fundamental structures of these systems to determine their structural, physical, and morphological properties, which play a vital role in defining their performance and applications. Microscopic techniques perform a decisive role in revealing intricate details, which assists in the appraisal of microstructure, surface morphology, chemical composition, and interfacial properties. This review highlights the significance of various microscopic techniques incorporating the literature details that help characterize biopolymers and their derivatives.
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    Recycling non-food-grade tree gum wastes into nanoporous carbon for sustainable energy harvesting
    (ROYAL SOC CHEMISTRY, THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND, 2020-02-21) Venkateshaiah, Abhilash; Cheong, Jun Young; Shin, Sung-Ho; Akshaykumar, K. P.; Yun, Tae Gwang; Bae, Jaehyeong; Waclawek, Stanislaw; Černík, Miroslav; Agarwal, Seema; Greiner, Andreas; Padil, Vinod V. T.; Kim, Il-Doo; Varma, Rajender S.
    The disposal of natural wastes has become a global problem and the use of lower-grade gums is very limited owing to their impurities as well as sticky nature. Rather than disposing these wastes, nanoporous carbon (nC) has instead been synthesized by carbonization and exfoliation. The synthesized nC exhibits a substantially high surface area along with abundant micro/mesopores. This desirable and useful nature of nC is well-suited for water-driven effective electrical energy conversion, which enables the fast evaporation of water via a capillary action through nanopores. Under asymmetric wetting in a water container and ambient conditions, the nC-based energy harvesters showed high capability of electricity production and reliable output generation, easily turning on a blue light-emitting diode (2.5 V and 20 mA) using a stored power source. In summary, many energy harvesters can be manufactured for the scale-up of electricity, and the suitability of regenerated carbon nanomaterials for green energy harvesting can contribute toward alleviating chronic environmental issues.
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    Synthesis of Ag nanoparticles by a chitosan-poly(3-hydroxybutyrate) polymer conjugate and their superb catalytic activity
    (Elsevier Ltd, 2020-01-01) Silvestri, Daniele; Wacławek, Stanisław; Venkateshaiah, Abhilash; Krawczyk, Kamil; Sobel, Bartłomiej; Padil, Vinod V.T.; Černík, Miroslav; Varma, Rajender S.
    This work describes an eco-friendly and sustainable technique for the synthesis of silver nanoparticles (nAg), where chitosan-poly(3-hydroxybutyrate) polymer conjugate (Chit-PHB) acts as a reducing and stabilizing material. The ensuing nanoparticles show an exceptional catalytic activity in the reduction of 4-nitrophenol to 4-aminophenol. nAg were characterized by several techniques, i.e. SEM and TEM-EDX, to confirm their production, size and morphology. Furthermore, infrared spectroscopy analysis proved the presence of a Chit-PHB coating on the nAg. The excellent catalytic properties of the nAg-Chit-PHB was discernible when the activity parameter (κc) normalized by the specific surface area (SSA) of the nanoparticles was taken into consideration; normalization of κc by the SSA is a vital parameter for the assessment of the accessibility to the surface area of particles. Herein synthesized Ag nanoparticles, as far as we know, exhibited the fastest reaction kinetics of 4-nitrophenol reduction compared to the silver nanoparticles reported in the literature
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    Tree Gum-Graphene Oxide Nanocomposite Films as Gas Barriers
    (AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2020-01-01) Venkateshaiah, Abhilash; Cheong, Jun Young; Habel, Christoph; Waclawek, Stanislaw; Lederer, Tomáš; Černík, Miroslav; Kim, Il-Doo; Padil, Vinod V. T.; Agarwal, Seema
    To reduce the dependency on petro-based conventional plastics, research focusing on bioplastics derived from biological origin has gained precedence. Herein, we report an ecofriendly and a facile synthetic route to develop a freestanding nanocomposite film prepared from the combination of nonedible biodegradable tree gum waste and graphene oxide (GO). Three variants of bionanocomposite films such as GO-gum arabic (GA-GO), GO-gum karaya (GK-GO), and GO- kondagogu gum (KG-GO) were fabricated via solution casting of respective gums with GO (0.5% and 1.0%) in an aqueous environment. GO was thoroughly blended within different types of gum matrices via the hydrogen bond interaction and electrostatic attraction, thus forming interconnected homogeneous GO-gum layered structure. Morphological analysis revealed a natural nacre-like structure comprised of gum-intercalated graphene sheets, which was further confirmed by X-ray diffraction studies. The addition of GO further transformed the brittle gum film into a freestanding film with substantial mechanical strength. Furthermore, the layered nanocomposite films demonstrated enhanced oxygen gas barrier property as well as reduced water vapor transmittance. The barrier properties are comparable to the plastics traditionally used in packaging, emphasizing the potential of tree gums nanocomposite films in packaging applications. Such frugally viable gums can be a cost-effective alternative in the development of nanocomposite films that could be readily used for applications in food packaging, pharmaceutical, and various biomedical industries.