Faculty Publications
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Item Optimization and analysis of nickel adsorption on microwave irradiated rice husk using response surface methodology (RSM)(2009) Ganesapillai, M.G.; Iyyaswami, I.; Helen Kalavathy, M.H.; Murugesan, T.; Miranda, L.R.Background: The removal of heavy metals using adsorption techniques with low cost biosorbents is being extensively investigated. The improved adsorption is essentially due to the pores present in the adsorbent. One way of improving the porosity of the material is by irradiation of the precursor using microwaves. In the present study, the adsorption characteristics of nickel onto microwave-irradiated rice husks were studied and the process variables were optimized through response surface methodology (RSM). Result: The adsorption of nickel onto microwave-irradiated rice husk (MIRH) was found to be better than that of the raw rice husk (RRH). The kinetics of the adsorption of Ni(II) from aqueous solution onto MIRH was found to follow a pseudo-second-order model. Thermodynamic parameters such as standard Gibbs free energy (?G°), standard enthalpy (?H°), and standard entropy (?S°)were also evaluated. The thermodynamics of Ni(II) adsorption onto MIRH indicates that it is spontaneous and endothermic in nature. The response surface methodology (RSM) was employed to optimize the design parameters for the present process. Conclusion: Microwave-irradiated rice husk was found to be a suitable adsorbent for the removal of nickel(II) ions from aqueous solutions. The adsorption capacity of the rice husk was found to be 1.17 mg g-1. The optimized parameters for the current process were found as follows: adsorbent loading 2.8 g (100 mL)-1; Initial adsorbate concentration 6 mg L-1; adsorption time 210 min.; and adsorption temperature 35°C. © 2008 Society of Chemical Industry.Item Catalytic oxidation of alcohols by nickel(II) Schiff base complexes containing triphenylphosphine in ionic liquid: An attempt towards green oxidation process(2010) Ramakrishna, D.; Badekai Ramachandra, B.; Karvembu, R.A series of square planar nickel(II) complexes containing N,O donor Schiff base ligand, i.e. N-(2-pyridyl)-N?-(5-substituted-salicylidene)hydrazine and triphenylphosphine, have been synthesized and characterized by analytical and spectral methods. Catalytic activities of all the complexes have been studied for the oxidation of alcohols in ionic liquid media using NaOCl as oxidant. © 2009 Elsevier B.V. All rights reserved.Item High yield synthesis of carbon nanofibers in an environmental friendly route(Springer Nature, 2011) Ravindra, R.; Badekai Ramachandra, B.An environmental friendly route for the high yield synthesis of carbon nanofibers (CNFs) has been developed. CNFs have been synthesized using nickel formate as catalyst precursor at 680°C using chemical vapor deposition method. Upon pyrolysis this catalyst precursor yields metal catalyst nanoparticles directly. The sodium chloride and potassium chloride was used as catalyst support, it was chosen because of its non-toxic and water soluble nature. The problems such as detrimental effect, environment and even cost has been avoided by using water soluble supports. The structure of the products was characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and X-ray diffraction method. The purity of as grown products and purified products was determined by thermal analysis. Here, we report the 7,800 and 7,200 wt% yield of CNFs synthesized over NaCl and KCl support. This synthetic route can be used for the large scale synthesis in industries. © 2011, The Author(s).Item Comparison of spreading behaviour and interfacial microstructure in Sn-0·7Cu, Sn-0·3Ag-0·7Cu and Sn-2·5Ag-0·5Cu lead free solder alloys on Fe-42Ni substrate(Maney Publishing michael.wagreich@univie.ac.at, 2013) Satyanarayan, S.; Prabhu, K.In the present work, spreading behaviour and development of interfacial microstructure in Sn- 0·7Cu, Sn-0·3Ag-0·7Cu and Sn-2·5Ag-0·5Cu lead free solder alloys on Fe-42Ni substrates having two different surface textures were investigated. Smooth textured surfaces yielded better wettability than rough surfaces particularly for Sn-0·7Cu solder alloy. Wettability of Sn-0·7Cu solder on rough textured surfaces was found to be poor compared to other solder alloys. Spreading of Sn-0·7Cu solder on substrate surface showed longer viscous regime, Sn-2·5Ag- 0·5Cu solder exhibited shortest viscous regime. Sn-0·3Ag-0·7 solder showed intermediate behaviour. Sn-Cu solder alloy exhibited needle and coarse shaped (Cu,Ni)6Sn5 intermetallics at the interface and in the matrix of the solder alloy on smooth substrate, whereas on rough substrate, formation of only coarse shaped (Cu,Ni)6Sn5 intermetallic compounds (IMCs) was observed. For Sn-0·3Ag-0·7Cu solder alloy, Fe-Ni-Sn and FeSn2 IMCs identified at the interface. (Cu,Ni)6/Sn5 IMCs were found to be less coarser than as observed at Sn-0·7Cu/substrate interface. Sn-2·5Ag-0·5Cu alloy exhibited (Cu,Ni) 3Sn4 and (Cu,Ni)6 Sn5 IMCs at the interface and in the bulk of solder alloy. © 2013 Institute of Materials, Minerals and Mining.Item Nickel(II) complex of p-[N,N-bis(2-chloroethyl)amino]benzaldehyde-4-methyl thiosemicarbazone: Synthesis, structural characterization and biological application(Elsevier Ltd, 2013) Sankaraperumal, A.; Karthikeyan, J.; Nityananda Shetty, A.N.; Lakshmisundaram, R.New complex of Ni(II) with p-[N,N-bis(2-chloroethyl)amino]benzaldehyde-4- methyl thiosemicarbazone (CEAB-4-MTSC) have been synthesized and characterized by elemental analysis, IR, electronic, 1H NMR spectroscopy. The crystal structure of the free ligand and complex has been determined by single crystal X-ray diffraction technique. In the complex, thiosemicarbazone ligand is coordinated to nickel through (1:2 complex) SNNS mode. The complex crystallizes in the triclinic with space group P1?. The complex has been tested for their antibacterial activity against various pathogenic bacteria. From this study, it was found out that the activity of complex reaches the effectiveness of the conventional bacteriocide Streptomycin compared to simple ligand. © 2012 Elsevier Ltd. All rights reserved.Item Magnetically retrievable nickel hydroxide functionalised AFe2O4 (A = Mn, Ni) spinel nanocatalyst for alcohol oxidation(Springer Nature, 2016) Bhat, P.B.; Badekai Ramachandra, B.R.Ultrasmall nickel hydroxide functionalised AFe2O4 (A = Mn, Ni) nanocatalyst was synthesized by traditional co-precipitation method and was examined for oxidation of aromatic alcohols to carbonyls using hydrogen peroxide as terminal oxidant. A very high surface area of 104.55 m2 g?1 was achieved for ferromagnetic MnFe2O4 and 100.50 m2 g?1 for superparamagnetic NiFe2O4, respectively. Efficient oxidation was observed due to the synergized effect of nickel hydroxide (bronsted base) on Lewis center (Fe) of the nanocatalyst. Catalyst recycling experiments revealed that the ultrasmall nanocatalyst can be easily recovered by external magnet and applied for nearly complete oxidation of alcohols for at least five successive cycles. Furthermore, the nickel hydroxide functionalised ultrasmall nanocatalyst exhibited higher efficiency for benzyl alcohol oxidation compared to Ni(OH)2, bare MnFe2O4 and NiFe2O4. Higher conversion rate was observed for nickel hydroxide functionalised NiFe2O4 compared to MnFe2O4. Ultrasmall magnetic nickel hydroxide functionalised nanocatalyst showed environmental friendly, greener route for the oxidation of alcohols without significant loss in activity and selectivity within successive runs. © 2015, The Author(s).Item Air-Stable Cobalt(II) and Nickel(II) Complexes with Schiff Base Ligand for Catalyzing Suzuki–Miyaura Cross-Coupling Reaction(Pleiades journals, 2018) Ansari, R.M.; Kumar, L.M.; Badekai Ramachandra, B.R.The Co(II) complex [Co{C6H4–1,2-(N=CH–C6H4O)2}] (I) and Ni(II) complex [Ni{C6H4–1,2-(N=CH–C6H4O)2}] (II) with Schiff base of o-phenylenediamine and salicylaldehyde have been synthesized. The structure of the ligand and its complexes were derived on the basis of various techniques such as elemental analysis, mass, FT-IR, electronic spectra and magnetic susceptibility. From the Singal crystal X-ray diffraction (SCXRD) analysis techniques (CIF file CCDC no. 1498772 (II)), it has been confirmed that the Schiff base ligand (L), coordinates to the metal ion in a tetradentate fashion through the nitrogen and oxygen atom. In addition, the square planar geometry of Ni(II) complex also has been confirmed from SCXRD. Electronic spectra, mass spectra, and magnetic susceptibility measurements reveal square planar geometry for the Co(II) complex. Synthesized complexes were used in cross-coupling of arylhalides with phenylboronic acid. The transformation offers products in good yields using 0.02 mmol catalysts loading, thereby proving the efficiency of the complexes as catalysts for Suzuki–Miyaura reaction. © 2018, Pleiades Publishing, Ltd.Item HVOF sprayed Ni3Ti and Ni3Ti+(Cr3C2+20NiCr) coatings: Microstructure, microhardness and oxidation behaviour(Elsevier Ltd, 2018) Reddy, N.C.; Kumar, B.S.A.; Reddappa, H.N.; Ramesh, M.R.; Koppad, P.G.; Kord, S.This paper reports the development of Ni3Ti and Ni3Ti+(Cr3C2+20NiCr) coatings on AISI 420 stainless steel (MDN-420) and titanium alloy ASTM B265 (Ti-15) by HVOF technique. Microstructure, microhardness and high temperature oxidation behaviour of coatings were investigated. Microstructure of coatings was dense and displayed layers depicting lamellar structure. The microhardness of coatings was significantly higher than that of substrate owing to higher density and cohesive strength between individual splats of coating materials. Cyclic oxidation studies conducted on Ni3Ti and Ni3Ti+(Cr3C2+20NiCr) coatings showed oxide scale was composed of various oxides like NiO, NiCr2O4 and Cr2O3 phases. The formation of compact and protective NiO phase in case of Ni3Ti coatings; NiO and Cr2O3 phases in Ni3Ti+(Cr3C2+20NiCr) coatings stabilised the weight gain exhibited slow oxidation rate at higher temperatures. © 2017 Elsevier B.V.Item Characterization of Thermal Stability and High-Temperature Tribological Behavior of Electroless Ni-B Coating(Springer Boston, 2018) Pal, S.; Sarkar, R.; Jayaram, V.A preliminary study has been conducted using sequences of isothermal heat treatments and unidirectional high-temperature wear test following ball-on-flat geometry against an alumina counterface, to assess thermal stability and high-temperature tribological properties of the crystalline electroless Ni-B coating, a potential candidate for high-temperature solid lubricant coating. Isothermal heat treatment of 450 °C/15 h causes a significant amount of B diffusion into the Fe substrate without altering the coating’s through-thickness hardness and nanostructure. At room temperature, a very low wear rate is observed, which increases up to two orders of magnitude above a testing temperature of 100 °C. Room-temperature wear behavior is mostly governed by oxidative wear, where friction-induced heating produces a thick oxide scale on the wear track, which subsequently decreases the wear rate by preventing direct contact between the coating and counterface. In the case of wear tests above 100 °C, removal of the same oxide layer occurs through local plastic deformation, essentially plastic ratcheting at the contacting region by flow softening of the contacting surface layer due to a local rise in temperature. Worn track morphology shows similarity with the severe wear seen in steel–steel contacts. Experimental observations have been explained and validated using the concept of contact point flash temperature. A quantitative assessment of contact point flash temperature has been carried out adopting the methodology, proposed by Ashby et al. The effects of applied normal load, test geometry, choice of counterface material, and testing temperatures on the transition of wear mechanism are critically discussed. © 2018, The Minerals, Metals & Materials Society and ASM International.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.