Faculty Publications
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Item Methanol selective oxidation to formaldehyde over a modified Fe-Mo catalyst with two different stoichiometric (Mo/Fe atomic ratio = 1.5 and 3.0) was studied experimentally in a fixed bed reactor over a wide range of reaction conditions. The physicochemical characterization of the prepared catalysts provides evidence that Fe2(MoO4)3 is in fact the active phase of the catalyst. The experimental results of conversion of methanol and selectivity towards formaldehyde for various residence times were studied. The results showed that as the residence time increases the yield of formaldehyde decreases. Selectivity of formaldehyde decreases with increase in residence time. This result is attributable to subsequent oxidation of formaldehyde to carbon monoxide due to longer residence time.(Selective oxidation of methanol to formaldehyde using modified iron-molybdate catalysts) Kim, T.-H.; Badekai Ramachandra, B.; Choi, J.-S.; Saidutta, M.B.; Choo, K.-Y.; Song, S.-D.; Rhee, Y.-W.2004Item Phase transformation, structural evolution and mechanical property of nanostructured FeAl as a result of mechanical alloying(2009) Rajath Hegde, M.M.R.; Surendranathan, A.O.Objective of the work was to synthesize nanostructured FeAl alloy powder by mechanical alloying (MEA). The work concentrated on synthesis, characterization, structural and mechanical properties of the alloy. Nanostructured FeAl intermetallics were prepared directly by MEA in a high energy rate ball mill. Milling was performed under toluene solution to avoid contamination from the milling media and atmosphere. Mixtures of elemental Fe and Al were progressively transformed into a partially disordered solid solution with an average composition of Fe-50 at % Al. Phase transformation, structural changes, morphology, particle size measurement and chemical composition during MEA were investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS) respectively. Vickers micro hardness (VMH) indentation tests were performed on the powders. XRD and SEM studies revealed the alloying of elemental powders as well as transition to nanostructured alloy, crystallite size of 18 nm was obtained after 28 hours of milling. Expansion/contraction in lattice parameter accompanied by reduction in crystallite size occurs during transition to nanostructured alloy. Longer milling duration introduces ordering in the alloyed powders as proved by the presence of superlattice reflection. Elemental and alloyed phase coexist while hardness increased during MEA. © 2009 Allerton Press, Inc.Item Synthesis, characterization of N, N?-bis(2-hydroxynaphthalidene) phenylene- 1,2-diamine with M(II)(M = Ni, Zn and Fe) Schiff-base complexes and their non-linear optical studies by z-scan technique(Elsevier B.V., 2010) Kumar, H.C.S.; Badekai Ramachandra, B.; Rudresha, B.J.; Ravindra, R.; Philip, R.Schiff-base complexes of N,N?-bis(2-hydroxynaphthalidene)phenylene-1, 2-diamine ligand with metal M (M = Ni(II), Zn(II) and Fe(II)) have been synthesized and characterized by their UV, FT-IR, NMR, elemental analysis and magnetic susceptibility measurements. Non-linear optical measurements carried out using nanosecond laser pulses at 532 nm show that these complexes can be used for optical limiting applications. © 2010 Elsevier B.V. All rights reserved.Item Diluted magnetism in Mn-doped SrZnO2 single crystals(American Institute of Physics Inc., 2013) Rahman, M.R.; Koteswararao, B.; Huang, S.H.; Kim, K.; Chou, F.C.We have investigated the magnetic properties of Mn- and Cu-substituted SrZnO2 single crystals (SrZn1-xMnxO2 and SrZn1-xCuxO2). We observed signatures of weak ferromagnetism as a sharp increase of magnetic susceptibility below 5 K even in the low-percentage (x = 0.01) of Mn-substituted single crystals. Magnetic susceptibility data measured parallel or perpendicular to the ab-plane yield anisotropic behavior with Curie-Weiss temperature of about -320 K and -410 K, respectively, suggesting the presence of strong antiferromagnetic couplings among Mn at high temperatures, similar to the Mn-doped ZnO and Fe-doped BaTiO3. In contrast, the SrZn0.99Cu0.01O 2 crystal shows paramagnetic behavior down to 2 K. © 2013 AIP Publishing LLC.Item Inhibitory and stimulating effect of single and multi-metal ions on hexavalent chromium reduction by Acinetobacter sp. Cr-B2(Kluwer Academic Publishers, 2014) Hora, A.; Shetty K, V.Potential application of chromium reducing bacteria for industrial scale wastewater treatment demands that effect of presence of other metal ions on rate of Cr(VI) reduction be investigated, as industrial wastewaters contain many toxic metal ions. In the current study, the effect of different heavy metal ions (nickel, zinc, cadmium, copper, lead, iron) on chromium reduction by a novel strain of Acinetobacter sp. Cr-B2 that shows high tolerance up to 1,100 mg/L and high Cr(VI) reducing capacity was investigated. The alteration in Cr(VI) reduction capacity of Cr-B2 was studied both in presence of individual metal ions and in the presence of multi-metal ions at different concentrations. The study showed that the Cr(VI) reduction rates decreased in presence of Ni2+, Zn2+ and Cd2+ when present individually. Pb2+ at lower concentration did not show significant effect while Cu2+ and Fe3+ stimulated the rate of Cr(VI) reduction. In the studies on multi-metal ions, it was observed that in presence of Cu2+ and Fe3+, the inhibiting effect of Ni2+, Zn2+, Cd2+ and Pb2+ on Cr(VI) reduction was reduced. Each of these metals affect the overall rate of Cr(VI) reduction by Cr-B2. This work highlights the need to consider the presence of other heavy metal ions in wastewater when assessing the bioreduction of Cr(VI) and while designing the bioreactors for the purpose, as rate of reduction is altered by their presence. © 2014, Springer Science+Business Media Dordrecht.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 Novel RGO-ZnWO4-Fe3O4 nanocomposite as an efficient catalyst for rapid reduction of 4-nitrophenol to 4-aminophenol(American Chemical Society service@acs.org, 2016) Mohamed, M.J.; Bhat Denthaje, K.We report herein a simple, economic, and facile approach for the synthesis of a novel reduced graphene oxide-zinc tungstate-iron oxide (RGO-ZnWO4-Fe3O4) nanocomposite by a one-pot microwave method and its efficiency as a catalyst in reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride (NaBH4). The as-prepared RGO-ZnWO4-Fe3O4 nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) techniques. The prepared nanocomposites showed excellent catalytic performance in the reduction of 4-NP to 4-AP. The reaction was completed in just 40 s at room temperature. The RGO in RGO-ZnWO4-Fe3O4 nanocomposite plays an essential role to improve the catalytic performance through facilitation of easy electron transfer and high adsorption of the substrate on graphene sheets. The synergistic effects of RGO, ZnWO4, and Fe3O4 in the RGO-ZnWO4-Fe3O4 nanocomposite toward reduction, apart from its excellent stability and reusability, make it an efficient candidate as catalyst for hydrogenation reactions of aromatic compounds in research and industrial applications. © 2016 American Chemical Society.Item Low cost Fenton's oxidative degradation of 4-nitroaniline using iron from laterite(IWA Publishing 12 Caxton Street London SW1H 0QS, 2016) Amritha, A.S.; Manu, B.The present study aims to establish the use of iron (Fe) from larerite in the case of Fenton's oxidation process which is a simple and cost-effective method for degradation of nitro compounds in effluents and in surface or ground water. 4-nitroaniline (4-NA) degradation by Fenton's oxidation method is the subject of the present study so as to optimize pH, hydrogen peroxide/iron (H/F) ratio at different initial concentrations of 4-NA. The optimum pH obtained was 3. The present study has also established optimum H/F ratio for the different initial concentrations of 4-NA for both conventional and use of Fe from laterite. The maximum removal efficiency of 99.84% was obtained for an H/F ratio of 100 for 0.5 mM initial concentration of 4-NA. The study establishes the use of Fe extracted from locally available laterite soil (LS) as a replacement of Fe salts so as to reduce the cost of the process. © 2016 IWA Publishing.Item Fenton's treatment of actual agriculture runoff water containing herbicides(IWA Publishing 12 Caxton Street London SW1H 0QS, 2017) Sangami, S.; Manu, B.This research was to study the efficiency of the Fenton's treatment process for the removal of three herbicides, namely 2,4-dichlorophenoxy acetic acid (2,4-D), ametryn and dicamba from the sugarcane field runoff water. The treatment process was designed with the Taguchi approach by varying the four factors such as H 2 O 2 /COD (1-3.5), H 2 O 2 /Fe 2+ (5-50), pH (2-5) and reaction time (30-240 min) as independent variables. Influence of these parameters on chemical oxygen demand (COD), ametryn, dicamba and 2,4-D removal efficiencies (dependent variables) were investigated by performing signal to noise ratio and other statistical analysis. The optimum conditions were found to be H 2 O 2 /COD: 2.125, H 2 O 2 /Fe 2+ : 27.5, pH: 3.5 and reaction time of 135 min for removal efficiencies of 100% for ametryn, 95.42% for dicamba, 88.2% for 2,4-D and with 75% of overall COD removal efficiencies. However, the percentage contribution of H 2 O 2 /COD ratio was observed to be significant among all four independent variables and were 44.16%, 67.57%, 51.85% and 50.66% for %COD, ametryn, dicamba and 2,4-D removal efficiencies, respectively. The maximum removal of herbicides was observed with the H 2 O 2 dosage of 5.44 mM and Fe 2+ dosage of 0.12 mM at pH 3.5. © IWA Publishing 2017 W.