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Sesa Sterlite Ltd and CSIR - Institute of Minerals And Materials Technology | Date: 2015-08-12

The present disclosure provides a method of preparing a composition of a cold setting geo-polymer based building material. The cold-setting geo-polymer concrete is a green concrete that requires curing at ambient conditions. The method includes mixing one or more aggregates and a plurality of chemical ingredients in a mixing apparatus, and chemically activating an obtained geo-polymer concrete mix by adding an alkaline activator. The one or more aggregates include a plurality of stone chips and a plurality of sand particles. The plurality of chemical ingredients includes a fly ash and a calcium hydroxide solution. The fly ash includes one or more alumino-silicate aggregates. The fly ash, the plurality of sand particles and the calcium hydroxide solution, and the plurality of stone chips are mixed in a first pre-determined ratio. The alkaline activator prevents temperature curing of the cold-setting geo-polymer concrete.

Parida K.,CSIR - Institute of Minerals And Materials Technology | Mohapatra L.,CSIR - Institute of Minerals And Materials Technology
Dalton Transactions | Year: 2012

A series of novel photocatalysts Zn/Cr LDH with different Zn/Cr molar ratios (2:1, 3:1, 4:1 and 2:1-CO 3) were fabricated by a co-precipitation method and evaluated for photodecomposition of water using visible light irradiation. Various characterization methods were employed to investigate the structures, morphologies and photocatalytic properties. In comparison to Zn/Cr (2:1) LDH, Zn/Cr-CO 3 (2:1) LDH extends the absorption edges to the visible region and exhibits good photocatalytic activity, even without the assistance of co-catalysts. The visible light photocatalytic activity is ascribed to the charge transfer spectra of octahedral Cr ions in LDH. Zn/Cr-CO 3 LDH shows enhanced photocatalytic activities compared to Zn/Cr LDH as carbonate ions oxidise by holes to form carbonate radicals, inhibit the rapid recombination of e - and h + charge carriers and thereby suppress the backward reaction to some extent. This work provides a detailed understanding of the semiconductor properties of LDHs for photocatalytical hydrogen evolution. © 2012 The Royal Society of Chemistry.

Samanta S.,CSIR - Institute of Minerals And Materials Technology | Martha S.,CSIR - Institute of Minerals And Materials Technology | Parida K.,CSIR - Institute of Minerals And Materials Technology
ChemCatChem | Year: 2014

Noble-metal Au nanoparticles deposited on graphitic carbon nitride polymer (g-C3N4) photocatalyst by a facile deposition- precipitation method exhibited high photocatalytic activity for hydrogen gas production under visible-light irradiation. The Au/g-C3N4 nanocomposite plasmonic photocatalysts were characterized by X-ray diffraction spectroscopy, diffuse reflectance UV/Vis spectroscopy, FTIR spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, selected-area electron diffraction, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and photoelectrochemical measurements. We studied the effect of Au deposition on the photocatalytic activity of g-C3N4 by investigation of optical, electronic, and electrical properties. Enhanced photocatalytic activity of Au/g-C3N4 naocomposite for hydrogen production was attributed to the synergic mechanism operating between the conduction band minimum of g-C3N4 and the plasmonic band of Au nanoparticles including high optical absorption, uniform distribution, and nanoscale particle size of gold. The mechanism of te photocatalytic activity of the nanocomposite photocatalyst is discussed in detail. Deposition of Au nanoparticles on g-C3N4 was optimized and it was found that 1 wt % Au-loaded g-C3N4 composite plasmonic photocatalyst generated a photocurrent density of 49 mA cm-2 and produced a hydrogen gas amount of 532 μmol under visible light, which were more than 3000 times higher and 23 times higher, respectively, than the values of neat g-C3N4. Golden excitement: Au nanoparticles deposited on g-C3N4 photocatalyst by a facile deposition-precipitation method exhibit high photocatalytic activity for hydrogen gas production under visible light irradiation. The accumulated electron density on the surface of the Au nanoparticles easily reduce water molecules to produce hydrogen gas. (VB=valence band, CB=conduction band, TEA=triethanolamine). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Padhi D.K.,CSIR - Institute of Minerals And Materials Technology | Parida K.,CSIR - Institute of Minerals And Materials Technology
Journal of Materials Chemistry A | Year: 2014

A facile one step hydrothermal route has been adopted for in situ deposition of α-FeOOH nanorods over reduced graphene oxide sheets (RGO) where sodium hydroxide plays a dual role in the growth of α-FeOOH nanorods and reduction of graphene oxide (GO) to RGO. The crystallographic, microscopic, and spectroscopic properties of the as-synthesized α-FeOOH nanorod/RGO composites were explored by XRD, Raman, DRUV-vis, PL, TRPL, XPS, FESEM, TEM, and photoelectrochemical measurement. The α-FeOOH nanorod/RGO composite displays superior photocatalytic activity towards the reduction of hexavalent chromium [Cr(vi)] compared with neat α-FeOOH nanorod under visible light irradiation. The extended π-conjugated flat 2D layer of graphene plays a crucial role in enhancing the photocatalytic activity of α-FeOOH nanorod by channelizing the photoexcited electrons on its surface. This leads to minimization of the electron-hole recombination which is successfully derived from photoluminescence study, time-resolved photoluminescence spectra, and photoelectrochemical measurement of α-FeOOH nanorod/RGO composites. The time resolved decay measurements showed longer average decay time (〈τ〉) for 3 wt% RGO loaded α-FeOOH of the order of 4.13 ns, than that of the neat α-FeOOH (2.536 ns). The improved photocurrent generation (nearly three times higher than that of the neat α-FeOOH nanorod) and low photoluminescence (PL) intensity of α-FeOOH nanorod/RGO composite is a result of the well decoration and strong attachment of α-FeOOH nanorods over RGO sheets, which significantly enhance its photocatalytic activity. 2014 This journal is © the Partner Organisations.

Pradhan G.K.,CSIR - Institute of Minerals And Materials Technology | Parida K.M.,CSIR - Institute of Minerals And Materials Technology
ACS Applied Materials and Interfaces | Year: 2011

This work reports the facile synthesis of α-Fe 2O 3 nanorods and nanohexagons and its application as sunlight-driven photocatalysis. The obtained products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), diffused reflectance spectroscopy (DRUV-vis), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The phase and crystallinity were confirmed from the XRD study. Electron microscopy study clearly indicates the formation of different morphologies of nanocrystals. These hematite nanostructures were used as a model system for studying the shape-dependent photocatalytic degradation of phenol, methylene blue, and congo red. Amongst all the nanostructured semiconductors, Pt-doped hematite nanorod showed 55% efficiency towards the decolonization of methylene blue and 63% toward congo red under sun light illumination. The difference in photocatalytic activity is discussed in terms of their crystallize size and morphological ordering. © 2011 American Chemical Society.

Bag B.,CSIR - Institute of Minerals And Materials Technology | Pal A.,CSIR - Institute of Minerals And Materials Technology
Organic and Biomolecular Chemistry | Year: 2011

The new signaling probes 2-6, rhodamine-B derivatives of various receptors which contain different donor atoms for effective metal ion coordination, were synthesized and their absorption as well as fluorescence spectral responses were evaluated in the presence of various metal ions. All these probes along with the reference probe 1 have exhibited optimal metal ion-induced absorption and fluorescence enhancement with Hg(ii) ion in the longer wavelength region (>500 nm) in MeCN, exploiting the spectral characteristics of metal ion-induced structural transformation of rhodamine. The selectivity and sensitivity towards Hg(ii) ion were better pronounced in MeCN-H 2O (1:1 v/v) medium, implying the role of the solvent molecules, water in particular, in the preferential Hg(ii) coordination environment. Complexation of Hg(ii) to 1-6 not only enhanced the absorption at ∼560 nm, which turned the colourless solution into pink to facilitate a naked eye detection, but also amplified the fluorescence intensity simultaneously to offer high sensitivity of detection at lower concentration. The Hg(ii)-induced photo-physical spectral responses of 1-6 in presence of other competitive metal ions rendered their high selectivity towards Hg(ii). Further, their reversible dual channel signaling pattern under the action of counter anions, exploiting coordination tendency of anions towards Hg(ii), which compete with probe-metal interaction, implied the reversibility in their Hg(ii) coordination. The selectivity, sensitivity and reversibility, in principle, establishes the potential of these probes as chemosensors for Hg(ii) ion detection. © 2011 The Royal Society of Chemistry.

Reddy K.H.,CSIR - Institute of Minerals And Materials Technology | Martha S.,CSIR - Institute of Minerals And Materials Technology | Parida K.M.,CSIR - Institute of Minerals And Materials Technology
Inorganic Chemistry | Year: 2013

With the purpose of efficient electron-hole separation and enhancement of photocatalytic performance in the visible region, we have fabricated a novel p-BiOI/n-ZnTiO3 heterojunction by a precipitation-deposition method and studied its activity toward dye degradation. The physicochemical characteristics of the fabricated BiOI/ZnTiO3 heterojunctions were surveyed by powder X-ray diffraction pattern (PXRD), BET-surface area, diffuse reflectance UV-vis (DRUV-vis), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence spectroscopy (PL spectra), X-ray photoelectron spectroscopy (XPS), and photoelectrochemical measurement. The photosensitization effect of BiOI enhanced the spectral response of ZnTiO3 from UV to visible region, making all the BiOI/ZnTiO3 heterojunctions active under visible light. The PEC measurement confirmed the p-type character of BiOI and n-type character of ZnTiO3. The optimal amount of BiOI in BiOI/ZnTiO3 heterojunctions was found to be 50% which degraded 82% of 50 ppm Rh 6G under visible light irradiation. The degradation rate of 50% BiOI/ZnTiO3 heterojunction was found to be 9.8 and 11.1 times higher than that of bare BiOI and ZnTiO3, respectively. The photosensitization effect of BiOI and the formed heterojunction between p-type BiOI and n-type ZnTiO3 contribute to improved electron-hole separation and enhancement in photocatalytic activity. © 2013 American Chemical Society.

Behera G.C.,CSIR - Institute of Minerals And Materials Technology | Parida K.M.,CSIR - Institute of Minerals And Materials Technology
Applied Catalysis A: General | Year: 2012

Vanadium phosphate (VPO) is well known as a heterogeneous catalyst in gas phase oxidation reactions. Till date, this material has not drawn much attention for its application in liquid phase reactions. This paper briefly highlights our recent research on vanadyl metaphosphate concerning its fabrication, characterization and application towards liquid phase oxidation of benzyl alcohol to benzaldehyde using tert-butyl hydroperoxide (TBHP) as the oxidant. In our preliminary catalytic studies, we find that the VO(PO 3) 2 exhibits extraordinarily high activity and selectivity in oxidation of benzyl alcohol under mild conditions. The benzyl alcohol conversion is largely increased but the selectivity for benzaldehyde is slightly decreased with the increase in reaction period or temperature. The present catalyst VO(PO 3) 2 showed remarkable catalytic activity with respect to other catalytic system; conversion and selectivity with respect to aldehyde is 97 and 99%, respectively. © 2011 Elsevier B.V.

Pradhan A.C.,CSIR - Institute of Minerals And Materials Technology | Parida K.M.,CSIR - Institute of Minerals And Materials Technology
Journal of Materials Chemistry | Year: 2012

In situ incorporation of mesoporous Al 2O 3 (meso-Al 2O 3) into the MCM-41 extraframework without blocking the pores generates an ordered, long range and high surface area mesoporous support Al 2O 3-MCM-41 (AM). The mesoporous support surprisingly shows high surface area as compared to pristine MCM-41. The incorporation of meso-Al 2O 3 into the extraframework of MCM-41 through the silanol group is evidenced by FTIR, 27Al MAS NMR and 29Si MAS NMR spectroscopy. The result shows that Si/Al ratio 10 (AM 10) possesses improved textural properties as compared to AM 50 and AM 90. Iron is incorporated onto the surface of AM 10 in order to modify the surface property of AM 10, forming composite Fe/Al 2O 3-MCM-41 (Fe/AM 10). Characterization by small angle X-ray diffraction (SXRD), transmission electron microscopy (TEM), and N 2 adsorption-desorption measurements reveals that the mesoporous support and iron incorporated support possess large BET surface area (207-1244 m 2 g -1), narrow pore size (2.4-2.7 nm) and high pore volume (0.370-2.37 cm 3 g -1). Among them, AM 10 shows highest surface area (1244 m 2 g -1), narrow pore size (2.7 nm) and pore volume (2.37 cm 3 g -1). The incorporation effect of both meso-Al 2O 3 and iron in the formation of Fe/AM 10 has been well established by 27Al MAS NMR spectroscopy. X-Ray photoelectron spectroscopy study confirms the 2+ state of iron in Fe/AM 10 and also establishes the incorporation of meso-Al 2O 3 and iron. Among the prepared mesoporous supports and different wt% of iron incorporated supports, it is seen that 5 Fe/AM 10 ('5' denotes the wt% of iron) has high adsorption as well as photo-Fenton degradation activity for MB. Moreover, 5 Fe/AM 10 is not merely a good adsorbent but also an efficient catalyst in the adsorption and photo-Fenton degradation (100%) of MB in 15 and 5 minutes, respectively. Furthermore, in the case of mixed cationic and anionic dyes (uniform mixture of methylene blue and methyl orange), MO adsorption and degradation (by photo-Fenton process) occur appreciably on the surface of MB through cationic-anionic interaction of MB and MO. © 2012 The Royal Society of Chemistry.

Nayak B.B.,CSIR - Institute of Minerals And Materials Technology
Applied Physics A: Materials Science and Processing | Year: 2012

Defect-free and long SiC/C nanocables have been produced by heating SiC powder at 3000°C by employing dc arc plasma (Ar) in a specially designed configuration of graphite arc. Microstructural characterizations of the heat-treated powder carried out by TEM, HRTEM, SAED, EDS, and micro Raman spectroscopy showed the nanocables to consist of a SiC shell/sheath stuffed with wire type solid C core. A possible mechanism is discussed to explain the cable-type growth. © 2011 Springer-Verlag.

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