Faculty Publications
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Item Polymer Nanocomposites for Food Packaging Applications(CRC Press, 2016) George, G.; Kumar, B.; Srinivasan, A.Polymers are widely used in packaging of food, chemicals, medicines, industrial components, agriculture, and household items as listed in Table 26.1. Polymer consumption has an average growth rate of 5% and it will touch a gure of 227 million metric tons in 2015. Criteria for selection of a particular polymer for packaging is its biodegradability, migration of hazardous compounds, barrier properties, processability, strength, and inertness. Polymers are made to order in a variety of fashions using additives, functionalization, crosslinking, and so on for a particular application. A successful packaging material should be able to maintain the quality of the packed commodities to meet the customers’ expectation as it moves from manufacturer to customer. © 2017 by Taylor and Francis Group, LLC.Item An optimization study of microwave assisted extraction of oil from oily sludge using response surface methodology(CAFET INNOVA Technical Society cafetinnova@gmail.com 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2014) Kumar, B.; Raj Mohan, B.Petroleum oily sludge, a hazardous waste, generated by the refineries and at the production sites in huge quantities comprises of a mixture of petroleum hydrocarbons, asphaltenes, long chain paraffinic wax, waste water, sediments and metals. The present study is aimed to recover oil from the petroleum oily sludge using n-heptane as the solvent in microwave assisted solvent extraction process and to optimize the process variables for the recovery of oil from the oily sludge. The simultaneous effects of process variables such as irradiation time (2 - 10 minutes), solvent to sludge ratio (40 – 80 wt %), reactant volume (100 – 300 ml) and microwave power (80 – 400 W) on the recovery of oil were evaluated. A central composite design (CCD) and response surface methodology (RSM) were used for the optimization of the extraction process. Based on the CCD, quadratic model was developed to correlate the extraction process variables with the responses and the model was analysed using appropriate statistical method (ANOVA). Optimization of process variables shows that the maximum recovery of oil was about 88.6% at 100 ml of reactant volume with microwave power output of 351 W at 6.5 minutes of irradiation time with 58.99% of nheptane to sludge ratio. © 2014 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Microwave-Assisted Extraction of Wax from Oily Sludge: An Experimental Study and its Process Variables Optimization Using Response Surface Methodology(Bellwether Publishing, Ltd., 2015) Kumar, B.; Raj Mohan, B.The wax present in petroleum sludge, generated by refineries and at crude production sites, consists of paraffin hydrocarbons (C18–C36) known as paraffin wax and naphthenic hydrocarbons (C30–C60). The present study is aimed at the recovery of wax from petroleum oily sludge by microwave-assisted solvent extraction using a Toluene/MEK mixture and subsequently de-crystallizing the wax. The process variables affecting the microwave-assisted solvent extraction are optimized for recovery of wax. The simultaneous effects of process variables such as irradiation time (2–10 minutes), solvent to sludge ratio (40–80 wt%), reactant volume (100–300 ml), and microwave power (80–400 W) on the recovery of wax were evaluated. A central composite design and response surface methodology were used for the optimization of the extraction process. Based on the central composite design, quadratic models were developed to correlate the extraction process variables with the responses and the models were analyzed using appropriate statistical methods for analysis of variance. Optimization of process variables shows the maximum recovery of wax was about 79.57% at 300 ml of reactant volume with microwave power output of 400 W at 7.6 minutes of retention time with 56.56% of Toluene/MEK to sludge ratio. © 2015, Taylor & Francis Group, LLC.Item Seismic base isolation for structures using river sand(Techno Press technop2@chollian.net, 2016) Patil, S.J.; Reddy, G.R.; Shivshankar, R.; Ramesh Babu, R.; Jayalekshmi, B.R.; Kumar, B.Generally seismic isolation is achieved by supporting the structure on laminated rubber bearings, friction pendulum bearings, roller bearings etc. Very little work has been performed using soil as a base isolation media. Experiments and analytical work has been performed on a structural model with isolated footing and found encouraging results. Details of this work are presented in this paper. © 2016 Techno-Press, Ltd.Item Sol–gel electrospun mesoporous ZnMn2O4 nanofibers with superior specific surface area(Springer New York LLC barbara.b.bertram@gsk.com, 2017) Shamitha, C.; Senthil, T.; Wu, L.; Kumar, B.; Anandhan, S.ZnMn2O4 has application potential in lithium ion batteries, supercapacitors, sensors, and thermistors. In this study, mesoporous spinel ZnMn2O4 nanofibers were synthesized by sol–gel assisted electrospinning combined with calcination, using poly(styrene-co-acrylonitrile) as sacrificial polymeric binder. Structural, morphological and optical properties of these ceramic nanofibers were characterized. X-ray diffraction and X-ray photoelectron spectroscopy results revealed the presence of hexagonal ZnMnO3 and MnO phases in the ZnMn2O4 nanofibers produced. Based on these observations we propose a plausible mechanism of formation of ZnMn2O4 nanofibers. The nanofibers calcined at 773 K exhibit a specific surface area of 79.5 m2 g?1, which is higher than that of the zinc manganite nanofibers synthesized hitherto by sol–gel electrospinning. Moreover, this material exhibits four bandgaps, which is believed to be the first observation in ZnMn2O4 nanofibers. © 2017, Springer Science+Business Media, LLC.Item Synergism of fictitious forces on nickel cobaltite nanofibers: Electrospinning forces revisited(Royal Society of Chemistry, 2018) Kumar, B.; Kalpathy, S.K.; Anandhan, S.Randomly oriented nanofibers of nickel cobaltite (NCO) were fabricated using sol-gel electrospinning followed by calcination. The precursor fibers were collected on rotating disc (RDI) and rotating drum (RDR) collectors. Variable fictitious forces produce continuous deflection at each fiber landing position on the RDI collector, which subjects the nanofibers to non-bundling. On the other hand, in the case of the RDR collector, the fictitious forces act just at the surface, and these forces merely cause slip of the fibers along the rotational axis of the RDR. This slip along with the retained Columbic charges on the surface of the fibers produces fiber bundling, which affects the morphological and structural properties of the NCO nanofibers obtained by calcining the precursor fibers. The use of the RDI collector in sol-gel electrospinning is a simple and optimal method of fabricating precursor nanofibers, which yields non-agglomerated and impurity-free inorganic nanofibers. © the Owner Societies 2018.Item Organoclay enabled nanofiber formation from a polyolefin elastomer(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2018) Kumar, B.; Prakrthi, A.N.; Senthil, T.; Bhat, K.; Anandhan, S.The solution electrospinning of polyolefins has not been deeply studied mainly due to the difficulty in dissolving these polymers in appropriate solvents. In this study, composite nanofibers of organically modified montmorillonite/ethylene-octene random copolymer were produced for the first time with a mixture of cyclohexane and xylene as a solvent by solution electrospinning. Montmorillonite was used as an additive to increase the electrical charge density of the polymer solution. The influence of solution and process parameters on the electrospun ethylene-octene copolymer fibers' morphology and diameter was investigated using the design of experiment. Multiple regression analysis was used for the optimization of the electrospinning parameters. Ultrafine fibers, with diameters in the range of 150–350 nm were obtained; these nanofibers exhibited an excellent hydrophobicity over a period of 10 min as revealed by contact angle measurements. © 2016 Wiley Periodicals, Inc.Item A Mechanistic Study on the Structure Formation of NiCo2O4 Nanofibers Decorated with In Situ Formed Graphene-Like Structures(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Kumar, B.; Gudla, V.C.; Ambat, R.; Kalpathy, S.K.; Anandhan, S.Nickel cobaltite (NCO) nanofibers were synthesized using poly(styrene-co-acrylonitrile) (SAN) as the polymeric binder through sol–gel assisted electrospinning. Defect-free precursor nanofiber mats were pyrolyzed at 773 K at three different pyrolysis soaking times t = 2, 4, and 6 h. The SAN present in the precursor nanofibers caused morphological changes in the NCO nanofibers during their thermochemical degradation. Consequently, fractal aggregates of NCO nanoparticles were formed along the length of the nanofibers. X-ray photoelectron spectroscopy (XPS) revealed both + 2 and + 3 oxidation states for Ni and Co, with spinel crystal defects due to oxygen rich atmosphere. XPS, high-resolution transmission microscopy, and optical analysis showed graphene-like structures embedded within the NCO nanofibers. With increase in pyrolysis soaking time, the morphology of the NCO particles markedly changed from spherical to rod-like. We propose a mechanism for the morphological change of NCO nanoparticles on the basis of crystallite splitting accompanied by particle splitting and reordering. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.Item Polymorph nickel titanate nanofibers as bifunctional electrocatalysts towards hydrogen and oxygen evolution reactions(Royal Society of Chemistry, 2019) Kumar, B.; Tarafder, K.; Shetty, A.R.; Hegde, A.C.; Gudla, V.C.; Ambat, R.; Kalpathy, S.K.; Anandhan, S.Producing pure H2 and O2 to sustain the renewable energy sources with minimal environmental damage is a key objective of photo/electrochemical water-splitting research. Metallic Ni-based electrocatalysts are expensive and eco-hazardous. This has rendered the replacement or reduction of Ni content in Ni-based electrocatalysts a decisive criterion in the development of bifunctional electrocatalytic materials. In the current study, spinel/ilmenite composite nickel titanate (NTO) nanofibers were synthesised using sol-gel assisted electrospinning followed by pyrolysis at different soaking temperatures (viz., 773, 973, and 1173 K). The presence of a defective spinel NTO phase (SNTO) distributed uniformly along the nanofibers was confirmed by X-ray photoelectron and Raman spectroscopy. The electron micrographs revealed the morphological change of NTO nanofibers from a mosaic to bamboo structure with an increase in pyrolysis soaking temperature. The electrocatalytic activity of NTO nanofibers obtained at different pyrolysis soaking temperatures for alkaline water-splitting was studied. The highly defective SNTO manifests properties similar to metallic Ni and favours H2 evolution through the hydrogen evolution reaction (HER) by adsorbing more H+ ions on active sites. In contrast, the ilmenite NTO favours O2 discharge. These results are explained based on the morphology of the NTO nanofibers. The mosaic structure which has higher porosity and greater SNTO content shows excellent HER performance. In contrast, the large bamboo structured NTO nanofibers which have lesser porosity and SNTO content cage the bigger (OH)ads ions at their catalytic sites to facilitate OER performance. 2019 © The Royal Society of Chemistry.Item Performance evaluation of cement mortar compositions at elevated temperatures(Associated Cement Companies Ltd., 2019) Yaragal, S.C.; Vivek, S.; Kumar, B.Natural river sand is becoming scarce day by day due to rapid growth in construction sector. There is need for alternatives to be used in place of river sand. The performance of alternatives to river sand at elevated temperatures is also important in the likely event of fire accidents. In this study, the effect of elevated temperatures on the compressive strength of mortars containing Crushed Rock Fines (CRF) and Lateritic Sand (LS) is investigated. Cement mortar cubes were cast for varied proportion of lateritic soil and quarry dust as fine aggregate. Lateritic content was varied from 25%-100%, and 50% quarry dust was adopted. After 28 days of water curing, specimens were exposed to temperatures of 200, 400, 600, and 800°C. At room temperature, the compressive strength decreases with increase in level of lateritic fine aggregate. The lateritic mortar mixes (50, 75, and 100%) have exhibited superior elevated temperature endurance characteristics at 400, 600, and 800°C when compared to control mix. Even the 25% laterized mortar has performed equally well as that of control mix. At elevated temperatures, CRF blended mix has performed very poorly. Mortar containing lateritic sand has potential for utilization in buildings and other structures, for better fire endurance in the likely event of fire accidents. © 2019 Associated Cement Companies Ltd.. All rights reserved.