Preparation and Characterization of Impregnated Commercial Rice Husks Activated Carbon with Piperazine for Carbon Dioxide (CO2) Capture

NASA Astrophysics Data System (ADS)

Masoum Raman, S. N.; Ismail, N. A.; Jamari, S. S.

2017-06-01

Development of effective materials for carbon dioxide (CO2) capture technology is a fundamental importance to reduce CO2 emissions. This work establishes the addition of amine functional group on the surface of activated carbon to further improve the adsorption capacity of CO2. Rice husks activated carbon were modified using wet impregnation method by introducing piperazine onto the activated carbon surfaces at different concentrations and mixture ratios. These modified activated carbons were characterized by using X-Ray Diffraction (XRD), Brunauer, Emmett and Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy (FESEM). The results from XRD analysis show the presence of polyethylene butane at diffraction angles of 21.8° and 36.2° for modified activated carbon with increasing intensity corresponding to increase in piperazine concentration. BET results found the surface area and pore volume of non-impregnated activated carbon to be 126.69 m2/g and 0.081 cm3/g respectively, while the modified activated carbons with 4M of piperazine have lower surface area and pore volume which is 6.77 m2/g and 0.015 cm3/g respectively. At 10M concentration, the surface area and pore volume are the lowest which is 4.48 m2/g and 0.0065 cm3/g respectively. These results indicate the piperazine being filled inside the activated carbon pores thus, lowering the surface area and pore volume of the activated carbon. From the FTIR analysis, the presence of peaks at 3312 cm-1 and 1636 cm-1 proved the existence of reaction between carboxyl groups on the activated carbon surfaces with piperazine. The surface morphology of activated carbon can be clearly seen through FESEM analysis. The modified activated carbon contains fewer pores than non-modified activated carbon as the pores have been covered with piperazine.

Methanol Oxidation Using Ozone on Titania-Supported Vanadium Catalyst

EPA Science Inventory

Ozone-enhanced catalytic oxidation of methanol has been conducted at mild temperatures of 100 to 250NC using V2O5/TiO2 catalyst prepared by the sol-gel method. The catalyst was characterized using XRD, surface area measurements, and temperature-programmed desorption of methanol. ...

An Integrated XRF/XRD Instrument for Mars Exobiology and Geology Experiments

NASA Technical Reports Server (NTRS)

Koppel, L. N.; Franco, E. D.; Kerner, J. A.; Fonda, M. L.; Schwartz, D. E.; Marshall, J. R.

1993-01-01

By employing an integrated x-ray instrument on a future Mars mission, data obtained will greatly augment those returned by Viking; details characterizing the past and present environment on Mars and those relevant to the possibility of the origin and evolution of life will be acquired. A combined x-ray fluorescence/x-ray diffraction (XRF/XRD) instrument was breadboarded and demonstrated to accommodate important exobiology and geology experiment objectives outlined for MESUR and future Mars missions. Among others, primary objectives for the exploration of Mars include the intense study of local areas on Mars to establish the chemical, mineralogical, and petrological character of different components of the surface material; to determine the distribution, abundance, and sources and sinks of volatile materials, including an assessment of the biologic potential, now and during past epoches; and to establish the global chemical and physical characteristics of the Martian surface. The XRF/XRD breadboard instrument identifies and quantifies soil surface elemental, mineralogical, and petrological characteristics and acquires data necessary to address questions on volatile abundance and distribution. Additionally, the breadboard is able to characterize the biogenic element constituents of soil samples providing information on the biologic potential of the Mars environment. Preliminary breadboard experiments confirmed the fundamental instrument design approach and measurement performance.

Synthesis of nanoporous carbohydrate metal-organic framework and encapsulation of acetaldehyde

NASA Astrophysics Data System (ADS)

Al-Ghamdi, Saleh; Kathuria, Ajay; Abiad, Mohamad; Auras, Rafael

2016-10-01

Gamma cyclodextrin (γ-CD) metal organic frameworks (CDMOFs) were synthesized by coordinating γ-CDs with potassium hydroxide (KOH), referred hereafter as CDMOF-a, and potassium benzoate (C7H5KO2), denoted as CDMOF-b. The obtained CDMOF structures were characterized using nitrogen sorption isotherm, thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). High surface areas were achieved by the γ-CD based MOF structures where the Langmuir specific surface areas (SSA) of CDMOF-a and CDMOF-b were determined as 1376 m2 g-1 and 607 m2 g-1; respectively. The dehydrated CDMOF structures demonstrated good thermal stability up to 250 °C as observed by the TGA studies. XRD results for CDMOF-a and CDMOF-b reveal a body centered-cubic (BCC) and trigonal crystal system; respectively. Due to its accessible porous structure and high surface area, acetaldehyde was successfully encapsulated in CDMOF-b. During the release kinetic studies, we observed peak release of 53 μg of acetaldehyde per g of CDMOF-b, which was 100 times greater than previously reported encapsulation in β-CD. However, aldol condensation reaction occurred during encapsulation of acetaldehyde into CDMOF-a. This research work demonstrates the potential to encapsulate volatile organic compounds in CDMOF-b, and their associated release for applications including food, pharmaceuticals and packaging.

Surface segregation of additives on SnO 2 based powders and their relationship with macroscopic properties

NASA Astrophysics Data System (ADS)

Pereira, Gilberto J.; Castro, Ricardo H. R.; Hidalgo, Pilar; Gouvêa, Douglas

2002-07-01

Surface properties of ceramic powders frequently play an important role in producing high-quality, high-performance, and reliable ceramic products. These properties are related to the surface bond types and interactions with the surroundings. Oxide surfaces generally contain adsorbed hydroxyl groups and modifications in the chemical composition of the surface may be studied by infrared spectroscopy. In this work, we prepared SnO 2 containing Fe or Mg ions by organic chemical route derived from Pechini's method. The prepared powders were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), dynamic electrophoretic mobility and surface area determination. Results demonstrated that the studied additives segregate onto the oxide surface and modify the hydroxyl IR bands of the adsorbed hydroxyl groups. These surface modifications change some macroscopic properties of the powder such as the isoelectric point (IEP) in aqueous suspensions and the final specific surface area. The increase of the surface area with additive concentration is supposedly due to the reduction of surface energy of the powders when additives segregate on the powder surface.

OXIDATION OF METHANOL USING OZONE ON TITANIA-SUPPORTED VANADIUM CATALYST

EPA Science Inventory

Catalytic ozone decomposition of methanol has been conducted at mild temperatures of 100 to 250°C using V2O5/TiO2 catalyst prepared by either sol-gel or wet impregnation methods. The catalysts were characterized using XRD, surface area measurements, and desorption of CH3OH. Gas p...

In-situ Polymerization of Polyaniline/Polypyrrole Copolymer using Different Techniques

NASA Astrophysics Data System (ADS)

Hammad, A. S.; Noby, H.; Elkady, M. F.; El-Shazly, A. H.

2018-01-01

The morphology and surface area of the poly(aniline-co-pyrrole) copolymer (PANPY) are important properties which improve the efficiency of the copolymer in various applications. In this investigation, different techniques were employed to produce PANPY in different morphologies. Aniline and pyrrole were used as monomers, and ammonium peroxydisulfate (APS) was used as an oxidizer with uniform molar ratio. Rapid mixing, drop-wise mixing, and supercritical carbon dioxide (ScCO2) polymerization techniques were appointed. The chemical structure, crystallinity, porosity, and morphology of the composite were distinguished by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) analysis, and transmission electron microscopy (TEM) respectively. The characterization tests indicated that the polyaniline/polypyrrole copolymer was successfully prepared with different morphologies. Based on the obtained TEM, hollow nanospheres were formed using rapid mixing technique with acetic acid that have a diameter of 75 nm and thickness 26 nm approximately. Also, according to the XRD, the produced structures have a semi- crystalline structure. The synthesized copolymer with ScCO2-assisted polymerization technique showed improved surface area (38.1 m2/g) with HCl as dopant.

Acid activation of upper Eocene Ca-bentonite for soybean oil clarification.

PubMed

Chakroun, Salima; Herchi, Mongi; Mechti, Wafa; Gaied, Mohamed Essghaier

2017-10-01

In central Tunisia, many upper Eocene outcrops supply smectitic claystone which are characterized by several analytical techniques (calcimetry, XRD, SediGraph, chemical analysis, surface area, etc.). Beidellite is the main mineral detected by the XRD method. Representative raw samples M1, taken from Henchir Souar (Zaghouan, Tunisia), were acid activated in order to improve their physicochemical properties. This study consists in optimizing the activation conditions with HCl 3 N by varying the following parameters: time (2, 4, and 6 h) and temperature (25, 50, 75, and 90 °C). The characterization by XRD and chemical analysis was carried out on the samples (M1, activated for 2 and 6 h at 75 °C), showing a structural modification of the clay by reduction of intensity reflection 001 order of smectite and dissolution of metal ions (Al 3+ , Fe 3+ , and Mg 2+ ) from clay structure. Optimum condition for soybean oil clarification is obtained using a variety of amount raw clays (0.5, 0.75, and 1%). Thus, the best clarification yield is given at 0.75% of clay, showing a capacity of about 55%. Various forms of activated materials were used with a 75% proportion to leach soybean oil. Results were compared with commercial bentonite (Tonsil) having surface area (378 m 2 /g). The activated sample M1 during 4 h at 75 °C possesses a decolorizing capacity of about 85% greater than the oil treated by Tonsil in laboratory (58%).

Proxy-based accelerated discovery of Fischer–Tropsch catalysts† †Electronic supplementary information (ESI) available: Details of synthesis, analysis and testing, validation experiments for high-throughput XRD and gas treatment, details of statistical analysis and calculations, tabulation of synthesis parameters and XRD results, alternatives to Fig. 3 highlighting different data points, FTS testing results displayed graphically. See DOI: 10.1039/c4sc02116a Click here for additional data file.

PubMed Central

Boldrin, Paul; Gallagher, James R.; Combes, Gary B.; Enache, Dan I.; James, David; Ellis, Peter R.; Kelly, Gordon; Claridge, John B.

2015-01-01

Development of heterogeneous catalysts for complex reactions such as Fischer–Tropsch synthesis of fuels is hampered by difficult reaction conditions, slow characterisation techniques such as chemisorption and temperature-programmed reduction and the need for long term stability. High-throughput (HT) methods may help, but their use has until now focused on bespoke micro-reactors for direct measurements of activity and selectivity. These are specific to individual reactions and do not provide more fundamental information on the materials. Here we report using simpler HT characterisation techniques (XRD and TGA) along with ageing under Fischer–Tropsch reaction conditions to provide information analogous to metal surface area, degree of reduction and thousands of hours of stability testing time for hundreds of samples per month. The use of this method allowed the identification of a series of highly stable, high surface area catalysts promoted by Mg and Ru. In an advance over traditional multichannel HT reactors, the chemical and structural information we obtain on the materials allows us to identify the structural effects of the promoters and their effects on the modes of deactivation observed. PMID:29560180

Electrospinning Fabrication of SrTiO3 Nanofibers and Their Photocatalytic Activity

NASA Astrophysics Data System (ADS)

Xu, Lei; Zhao, Yiping; Wang, Wei; Liu, Hao; Wang, Rui

2018-06-01

SrTiO3 nanofibers were fabricated by an electrospinning process. The phase, microstructure and photocatalytic activity of the obtained SrTiO3 nanofibers were investigated. The XRD patterns and the SEM images suggest that SrTiO3 nanofibers with perovskite phase and rough surface have been fabricated in the current work. The SrTiO3 nanofibers show a high efficiency decomposition of RhB under ultraviolet light irradiation. The high photocatalytic activity of SrTiO3 nanofibers results from the large specific surface area. The large specific surface area provides more surface active sits and makes an easier charge carrier transport. On the basis of the photocatalytic performance of SrTiO3 nanofibers, the possible photocatalysis mechanism was proposed.

Characterization of organo-modified bentonite sorbents: The effect of modification conditions on adsorption performance

NASA Astrophysics Data System (ADS)

Parolo, María E.; Pettinari, Gisela R.; Musso, Telma B.; Sánchez-Izquierdo, María P.; Fernández, Laura G.

2014-11-01

The organic modification of a natural bentonite was evaluated using two methods: exchanging the interlayer cations by hexadecyltrimethylammonium (HDTMA) and grafting with vinyltrimethoxysilane (VTMS) and γ-methacryloyloxy propyl trimethoxysilane (TMSPMA) on montmorillonite surface. The physicochemical characterization of all materials was made by X-ray diffraction (XRD), IR spectroscopy, thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) surface area techniques. HDTMA cations and organosilanes were intercalated into the interlayer space of montmorillonite, as deduced from the increase of the basal spacing. IR spectroscopy, TGA and BET area give evidence of successful organic modification. The studies show a decrease in the IR absorption band intensity at 3465 cm-1 with surfactant modification, and also a decrease of mass loss due to adsorbed water observed in two samples: the organoclay and functionalized bentonites, which are evidences of a lower interlayer hydrophilicity. The efficiency of aniline removal onto natural bentonite, organobentonite and functionalized bentonites from aqueous solutions was evaluated. Aniline sorption on natural bentonite was studied using batch experiments, XRD and IR spectroscopy. The hydrophobic surface of organobentonite and functionalized bentonites increased the retention capacity for nonionic organic substances such as aniline on bentonites. The sorption properties of modified bentonite, through different modification methods, enhanced the potential industrial applications of bentonites in water decontamination.

The effects of fuel type in synthesis of NiFe2O4 nanoparticles by microwave assisted combustion method

NASA Astrophysics Data System (ADS)

Karcıoğlu Karakaş, Zeynep; Boncukçuoğlu, Recep; Karakaş, İbrahim H.

2016-04-01

In this study, it was investigated the effects of the used fuels on structural, morphological and magnetic properties of nanoparticles in nanoparticle synthesis with microwave assisted combustion method with an important method in quick, simple and low cost at synthesis of the nanoparticles. In this aim, glycine, urea and citric acid were used as fuel, respectively. The synthesised nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmet-Teller surface area (BET), and vibrating sample magnetometry (VSM) techniques. We observed that fuel type is quite effective on magnetic properties and surface properties of the nanoparticles. X-ray difractograms of the obtained nanoparticles were compared with standard powder diffraction cards of NiFe2O4 (JCPDS Card Number 54-0964). The results demonstrated that difractograms are fully compatible with standard reflection peaks. According to the results of the XRD analysis, the highest crystallinity was observed at nanoparticles synthesized with glycine. The results demonstrated that the nanoparticles prepared with urea has the highest surface area. The micrographs of SEM showed that all of the nanoparticles have nano-crystalline behaviour and particles indication cubic shape. VSM analysis demonstrated that the type of fuel used for synthesis is highly effective a parameter on magnetic properties of nanoparticles.

Graphene/semicrystalline-carbon derived from amylose films for supercapacitor application

NASA Astrophysics Data System (ADS)

Deraman, M.; Sazali, N. E. S.; Hanappi, M. F. Y. M.; Tajuddin, N. S. M.; Hamdan, E.; Suleman, M.; Othman, M. A. R.; Omar, R.; Hashim, M. A.; Basri, N. H.; Nor, N. S. M.; Dolah, B. N. M.; Noor, A. M.; Jasni, M. R. M.

2016-08-01

Graphene/semicrystalline-carbon in the form of carbon flakes is produced by carbonization up to 600, 700, 800, 900 and 1000°C, respectively, of the amylose films prepared by a casting method on copper foil substrate. The carbon flakes are characterized by X-ray diffraction (XRD) method to determine their microcrystallite interlayer spacing, width and stack-height; and Raman spectroscopy (RS) method to obtain structural information from the D-, D2- and G-bands peak-intensities. The XRD results show that increase in carbonization temperature lead to ~(1-3%), ~85% and ~30%increase in the microcrystallites interlayer spacing, width and stack-height, respectively, indicating that a larger growth of microcrytallite of carbon flakes occurs in the direction parallel to (001) plane or film planar surface. The specific surface area of carbon flakes estimated from the XRD results in decreases from ~4400 to ~3400 m2/g, corresponding to the specific capacitance between ~500 to ~400 F/g, which are well within the range of specific capacitance for typical electrodes carbon for supercapacitor application. The RS results show that the multilayer graphene co-exist with semicrystalline- carbon within the carbon flakes, with the multilayer graphene relative quantities increase with increasing carbonization temperature.

Remote X-Ray Diffraction and X-Ray Fluorescence Analysis on Planetary Surfaces

NASA Technical Reports Server (NTRS)

Blake, David F.; DeVincenzi, D. (Technical Monitor)

1999-01-01

The legacy of planetary X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) began in 1960 when W. Parish proposed an XRD instrument for deployment on the moon. The instrument was built and flight qualified, but the Lunar XRD program was cancelled shortly before the first human landing in 1969. XRF chemical data have been collected in situ by surface landers on Mars (Viking 1 & 2, Pathfinder) and Venus (Venera 13 & 14). These highly successful experiments provide critical constraints on our current understanding of surface processes and planetary evolution. However, the mineralogy, which is more critical to planetary surface science than simple chemical analysis, will remain unknown or will at best be imprecisely constrained until X-ray diffraction (XRD) data are collected. Recent progress in X-ray detector technology allows the consideration of simultaneous XRD (mineralogic analysis) and high-precision XRF (elemental analysis) in systems miniaturized to the point where they can be mounted on fixed landers or small robotic rovers. There is a variety of potential targets for XRD/XRF equipped landers within the solar system, the most compelling of which are the poles of the moon, the southern highlands of Mars and Europa.

Tracking Hydrothermal Fluid Pathways from Surface Alteration Mineralogy: The Case of Licancura Geothermal Field, Northern Chile

NASA Astrophysics Data System (ADS)

Camus, E.; Elizalde, J. D.; Morata, D.; Wechsler, C.

2017-12-01

In geothermal systems alteration minerals are evidence of hot fluid flow, being present even in absence of other surface manifestations. Because these minerals result from the interaction between geothermal fluids and surrounding host rocks, they will provide information about features of thermal fluids as temperature, composition and pH, allowing tracking their changes and evolution. In this work, we study the Licancura Geothermal field located in the Andean Cordillera in Northern Chile. The combination of Principal Components Analysis on ASTER-L1T imagery and X Ray Diffraction (XRD) allow us to interpret fluid conditions and the areas where fluid flow took place. Results from red, green, blue color composite imagery show the presence of three types of secondary paragenesis. The first one corresponds to hematite and goethite, mainly at the east of the area, in the zone of eroded Pliocene volcanic edifices. The second one, mainly at the center of the area, highlighting propylitic alteration, includes minerals such as chlorite, illite, calcite, zeolites, and epidote. The third paragenesis, spatially related to the intersection between faults, represents advanced argillic alteration, includes minerals as alunite, kaolinite, and jarosite. XRD analysis support results from remote sensing techniques. These results suggest an acid pH hydrothermal fluid reaching temperatures at surface up to 80-100°C, which used faults as a conduit, originating advanced argillic minerals. The same fluid was, probably, responsible for propylitic paragenesis. However, iron oxides paragenesis identified in the area of eroded volcanoes probably corresponds to other processes associated with weathering rather than geothermal activity. In this work, we propose the applicability of remote sensing techniques as a first level exploration tool useful for high-altitude geothermal fields. Detailed clay mineral studies (XRD and SEM) would allow us to a better characterization of the geothermal fluid flow and the defining fluid pathways in the Licancura geothermal field. This work is a contribution to the FONDAP-CONICYT 15090013 Project. E.C. thanks CONICYT for her Ph.D. grant.

Adsorption and photocatalytic degradation of methylene blue using high surface area titanate nanotubes (TNT) synthesized via hydrothermal method

NASA Astrophysics Data System (ADS)

Subramaniam, M. N.; Goh, P. S.; Abdullah, N.; Lau, W. J.; Ng, B. C.; Ismail, A. F.

2017-06-01

Removal of methylene blue (MB) via adsorption and photocatalysis using titanate nanotubes (TNTs) with different surface areas were investigated and compared to commercial titanium dioxide (TiO2) P25 Degussa nanoparticles. The TNTs with surface area ranging from 20 m2/g to 200 m2/g were synthesized via hydrothermal method with different reaction times. TEM imaging confirmed the tubular structure of TNT while XRD spectra indicated all TNTs exhibited anatase crystallinity. Batch adsorption rate showed linearity with surface properties of TNTs, where materials with higher surface area showed higher adsorption rate. The highest MB adsorption (70%) was achieved by TNT24 in 60 min whereas commercial TiO2 exhibited the lowest adsorption of only 10% after 240 min. Adsorption isotherm studies indicated that adsorption using TNT is better fitted into Langmuir adsorption isotherm than Freundlich isotherm model. Furthermore, TNT24 was able to perform up to 90% removal of MB within 120 min, demonstrating performance that is 2-fold better compared to commercial TiO2. The high surface area and surface Bronsted acidity are the main reasons for the improvement in MB removal performance exhibited by TNT24. The improvement in surface acidity enhanced the adsorption properties of all the nanotubes prepared in this study.

Paramagnetic iron-doped hydroxyapatite nanoparticles with improved metal sorption properties. A bioorganic substrates-mediated synthesis.

PubMed

Mercado, D Fabio; Magnacca, Giuliana; Malandrino, Mery; Rubert, Aldo; Montoneri, Enzo; Celi, Luisella; Bianco Prevot, Alessandra; Gonzalez, Mónica C

2014-03-26

This paper describes the synthesis of paramegnetic iron-containing hydroxyapatite nanoparticles and their increased Cu(2+) sorbent capacity when using Ca(2+) complexes of soluble bioorganic substrates from urban wastes as synthesis precursors. A thorough characterization of the particles by TEM, XRD, FTIR spectroscopy, specific surface area, TGA, XPS, and DLS indicates that loss of crystallinity, a higher specific area, an increased surface oxygen content, and formation of surface iron phases strongly enhance Cu(2+) adsorption capacity of hydroxyapatite-based materials. However, the major effect of the surface and morphologycal modifications is the size diminution of the aggregates formed in aqueous solutions leading to an increased effective surface available for Cu(2+) adsorption. Maximum sorption values of 550-850 mg Cu(2+) per gram of particles suspended in an aqueous solution at pH 7 were determined, almost 10 times the maximum values observed for hydroxyapatite nanoparticles suspensions under the same conditions.

Effect of cetyl trimethyl ammonium bromide concentration on structure, morphology and carbon dioxide adsorption capacity of calcium hydroxide based sorbents

NASA Astrophysics Data System (ADS)

Hlaing, Nwe Ni; Vignesh, K.; Sreekantan, Srimala; Pung, Swee-Yong; Hinode, Hirofumi; Kurniawan, Winarto; Othman, Radzali; Thant, Aye Aye; Mohamed, Abdul Rahman; Salim, Chris

2016-02-01

Calcium hydroxide (Ca(OH)2) has been proposed as an important material for industrial, architectural, and environmental applications. In this study, calcium acetate was used as a precursor and cetyl trimethyl ammonium bromide (CTAB) was used as a surfactant to synthesize Ca(OH)2 based adsorbents for carbon dioxide (CO2) capture. The effect of CTAB concentration (0.2-0.8 M) on the structure, morphology and CO2 adsorption performance of Ca(OH)2 was studied in detail. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), BET surfaced area and thermogravimetry-differential thermal analysis (TG-DTA) techniques. The phase purity, crystallite size, Brunauer-Emmett-Teller (BET) surface area and CO2 adsorption performance of Ca(OH)2 precursor adsorbents were significantly increased when the concentration of CTAB was increased. XRD results showed that pure Ca(OH)2 phase was obtained at the CTAB concentration of 0.8 M. TGA results exhibited that 0.8 M of CTAB-assisted Ca(OH)2 precursor adsorbent possessed a residual carbonation conversion of ∼56% after 10 cycles.

Effect of SrO content on Zeolite Structure

NASA Astrophysics Data System (ADS)

Widiarti, N.; Sari, U. S.; Mahatmanti, F. W.; Harjito; Kurniawan, C.; Prasetyoko, D.; Suprapto

2018-04-01

The aims of current studies is to investigate the effect of strontium oxide content (SrO) on synthesized zeolite. Zeolite was synthesized from Tetraethyl orthosilicate (TEOS) as precursors of SiO2 and aluminum isopropoxide (AIP) precursors. The mixture was aged for 3 days and hydrothermally treated for 6 days. The SrO content was added by impregnation method. The products were then characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Surface Area Analyzer (SAA). The diffractogram confirmed the formation of Faujasite-like zeolite. However, after the addition of SrO, the crystallinity of zeolite was deformed. The diffractograms shows the amorphous phase of zeolite were decrease as the SrO content is increase. The structural changes was also observed from FTIR spectra which shows the shifting and peak formation. The surface area analysis showed that the increasing loading of SrO/Zeolites reduced the catalyst surface area.

Sodium Hydroxide Activated Nanoporous Carbons Based on Lapsi Seed Stone.

PubMed

Joshi, Sahira; Shrestha, Lok Kumar; Kamachi, Yuichiro; Yamauchi, Yusuke; Pradhananga, Mandira Adhikari; Pokhrel, Bhadra Prasad; Ariga, Katsuhiko; Pradhananga, Raja Ram

2015-02-01

Nanoporous activated carbons (ACs) were prepared from Lapsi (Choerospondias axillaris) seed powder by chemical activation with sodium hydroxide (NaOH) at different NaOH impregnation ratios. The prepared ACs were characterized by Fourier transform-infrared (FTIR) spectroscopy, Raman scattering, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Semi-quantitative information on the surface properties was obtained by estimating iodine number. FTIR spectra showed the presence of oxygenated functional groups such as hydroxyl, carbonyl, and carboxyl in the prepared ACs. Raman scattering showed clear D and G bands in the spectra. The intensity ratio of G and D band peak intensity was ca. 1.39 at lowest NaOH and Lapsi seed powder ratio 0.25:1 showing high graphitic degree. This ratio decreased with increase in the NaOH impregnation ratio and reached minimum ca. 0.94 (comparable with commercial AC) at NaOH and Lapsi seed powder ratio 1:1 demonstrating that higher NaOH impregnation reduces the graphitic structure of the carbon. XRD patterns showed two broad peaks at diffraction angles of approximately 25 and 43 degrees indicating the amorphous structure. Surface properties of the ACs (BET surface area, pore volume, and pore size distributions) were evaluated by nitrogen adsorption-desorption isotherm. Our ACs showed strong methylene blue adsorption property (maximum methylene blue is ca. 200 mg/g). Judging from the iodine number and methylene blue values, structure, and surface areas, it can be concluded that NaOH impregnation ratio is one of the key parameters to tune the surface properties of Lapsi seed stone-based activated carbons.

Oxidation behavior and area specific resistance of La, Cu and B alloyed Fe-22Cr ferritic steels for solid oxide fuel cell interconnects

NASA Astrophysics Data System (ADS)

Swaminathan, Srinivasan; Ko, Yoon Seok; Lee, Young-Su; Kim, Dong-Ik

2017-11-01

Two Fe-22 wt% Cr ferritic stainless steels containing varying concentrations of La (0.14 or 0.52 wt%), Cu (0.17 or 1.74 wt%) and B (48 or 109 ppm) are investigated with respect to oxidation behavior and high temperature area specific resistance (ASR) of the surface oxide scales. To determine the oxidation resistance of developed steels, continuous isothermal oxidation is carried out at 800 °C in air, for 2000 h, and their thermally grown oxide scale is characterized using dynamic SIMS, SEM/EDX, XRD and GI-XRD techniques. To assess their electrical performance, the ASR measurement by four-point probe method is conducted at 800 °C in air, for 400 h. In higher La content steel, the La-oxides at the scale/alloy interface promotes the oxygen transport which resulted in sub-surface oxidation of Mn, Cr, Ti and Al. Moreover, the inward growth of oxides contributes to increase of Fe-Cr alloy protrusions within the scale, which reduced the ASR. In contrast, sub-surface oxidation is reduced in high Cu-alloyed steel by segregated Cu at the scale/alloy interface. Thus, addition of Cu is effective to oxidation resistance and also to better electrical performance. However, no obvious impact of B on the scale sequence and/or ASR is observed.

The equation of state of 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one determined via in-situ optical microscopy and interferometry measurements

DOE PAGES

Stavrou, Elissaios; Zaug, Joseph M.; Bastea, Sorin; ...

2016-04-07

Quasi-hydrostatic high-pressure equations of state (EOS) are typically determined, for crystalline solids, by measuring unit-cell volumes using x-ray diffraction (XRD) techniques. However, when characterizing low-symmetry materials with large unit cells, conventional XRD approaches may become problematic. To overcome this issue, we examined the utility of a "direct" approach toward determining high pressure material volume by measuring surface area and sample thickness using optical microscopy and interferometry (OMI) respectively. We have validated this experimental approach by comparing results obtained for TATB (2,4,6-triamino-1,3,5-trinitrobenzene) with an EOS determined from synchrotron XRD measurements; and, a good match is observed. We have measured the highmore » pressure EOS of 5-nitro-2,4-dihydro-1,2,4-triazol-3-one (α-NTO) up to 33 GPa. No high-pressure XRD EOS data have been published on α-NTO, probably due to its complex crystal structure. Furthermore, the results of this study suggest that OMI is a reliable and versatile alternative for determining EOSs, especially when conventional methodologies are impractical.« less

Inhibitive effect of Pt on Pd-hydride formation of Pd@Pt core-shell electrocatalysts: An in situ EXAFS and XRD study

DOE PAGES

Wise, Anna M.; Richardson, Peter W.; Price, Stephen W. T.; ...

2017-12-27

In situ EXAFS and XRD have been used to study the electrochemical formation of hydride phases, H abs, in 0.5 M H 2SO 4 for a Pd/C catalyst and a series of Pd@Pt core-shell catalysts with varying Pt shell thickness, from 0.5 to 4 monolayers. Based on the XRD data a 3% lattice expansion is observed for the Pd/C core catalyst upon hydride formation at 0.0 V. In contrast, the expansion was ≤0.6% for all of the core-shell catalysts. The limited extent of the lattice expansion observed suggests that hydride formation, which may occur during periodic active surface area measurementsmore » conducting during accelerated aging tests or driven by H 2 crossover in PEM fuel cells, is unlikely to contribute significantly to the degradation of Pd@Pt core-shell electrocatalysts in contrast to the effects of oxide formation.« less

Inhibitive effect of Pt on Pd-hydride formation of Pd@Pt core-shell electrocatalysts: An in situ EXAFS and XRD study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wise, Anna M.; Richardson, Peter W.; Price, Stephen W. T.

In situ EXAFS and XRD have been used to study the electrochemical formation of hydride phases, H abs, in 0.5 M H 2SO 4 for a Pd/C catalyst and a series of Pd@Pt core-shell catalysts with varying Pt shell thickness, from 0.5 to 4 monolayers. Based on the XRD data a 3% lattice expansion is observed for the Pd/C core catalyst upon hydride formation at 0.0 V. In contrast, the expansion was ≤0.6% for all of the core-shell catalysts. The limited extent of the lattice expansion observed suggests that hydride formation, which may occur during periodic active surface area measurementsmore » conducting during accelerated aging tests or driven by H 2 crossover in PEM fuel cells, is unlikely to contribute significantly to the degradation of Pd@Pt core-shell electrocatalysts in contrast to the effects of oxide formation.« less

Key factor affecting the structural and textural properties of ZSM-5/MCM-41 composite

NASA Astrophysics Data System (ADS)

Boukoussa, Bouhadjar; Aouad, Nafissa; Hamacha, Rachida; Bengueddach, Abdelkader

2015-03-01

ZSM-5/MCM-41 micro/mesoporous composite materials were synthesized by the hydrothermal technique with alkali-treated ZSM-5 zeolite as source of silica and aluminum and characterized by various physico-chemical techniques such as X-ray diffraction (XRD), nitrogen sorption at 77 K, transmission electronic microscopy (TEM), FTIR spectroscopy and NH3 temperature programmed desorption (TPD) techniques. The effect of concentration of CTAB in the synthesis of these solids has been investigated, the mesopore volume, surface area and surface acidity decrease with increasing the concentration of CTAB. Increasing the CTAB concentration causes the recrystallization of zeolite ZSM-5 and it disadvantage the formation of mesoporous materials MCM-41. The catalytic activity of ZSM-5/MCM-41 materials has been evaluated in the Friedel-Crafts acylation of anisole with benzoyl chloride as alkylating agent. The results revealed the reaction to be influenced by surface area, pore volume and surface acidity.

Synthesis, optical properties and efficient photocatalytic activity of CdO/ZnO hybrid nanocomposite

NASA Astrophysics Data System (ADS)

Reddy, Ch Venkata; Babu, B.; Shim, Jaesool

2018-01-01

Pure CdO, ZnO and CdO/ZnO hybrid nanocomposite photocatalyst were synthesized using simple co-precipitation technique and studied in detail. The synthesized photocatalysts were characterized using several measurements such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), surface analysis (BET), diffuse reflectance UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, FT-IR, TG-DTA and photoluminescence (PL). The XRD results revealed that the hexagonal and cubic crystal structure of CdO and ZnO nanoparticles. The optical response for the composite showed the presence of separate absorption signature for CdO and ZnO in the visible region at about 510 nm and 360 nm respectively. The CdO/ZnO hybrid nanocomposite photocatalyst exhibited enhanced photocatalytic degradation activity compared to pristine CdO and ZnO. The enhanced photocatalytic activity may be due to the higher specific surface area and significantly reduced the electron-hole recombination rate.

Conversion of glycerol to polyglycerol over waste duck-bones as a catalyst in solvent free etherification process

NASA Astrophysics Data System (ADS)

Ayoub, Muhammad; Sufian, Suriati; Mekuria Hailegiorgis, Sintayehu; Ullah, Sami; Uemura, Yoshimitsu

2017-08-01

The alkaline catalyst derived from the duck-bones was used for conversion of glycerol to polyglycerol via solvent free etherification process. The physicochemical properties of prepared materials were duck-bones were systematically investigated as a catalyst by latest techniques of Thermo gravimetric analysis (TGA), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface properties. TGA showed different trends of duck-bones decomposition from room temperature to 1000C. XRD pattern showed a clear and sharp peaks of a crystalline phase of CaO. The activity of the catalysts was in line with the basic amount of the strong base sites, surface area, and crystalline phase in the catalysts. The prepared catalyst derived from duck-bones provided high activity (99 %) for glycerol conversion and around 68 % yield for polyglycerol production. These ample wastes of duck-bones have good potential to be used as polyglycerol production catalysts due to have high quantity of Ca compare to other types of bones like cow, chicken and fish bones.

An investigation of phase transformation and crystallinity in laser surface modified H13 steel

NASA Astrophysics Data System (ADS)

Aqida, S. N.; Brabazon, D.; Naher, S.

2013-03-01

This paper presents a laser surface modification process of AISI H13 tool steel using 0.09, 0.2 and 0.4 mm size of laser spot with an aim to increase hardness properties. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). X-ray diffraction analysis (XRD) was conducted to measure crystallinity of the laser-modified surface. X-ray diffraction patterns of the samples were recorded using a Bruker D8 XRD system with Cu K α ( λ=1.5405 Å) radiation. The diffraction patterns were recorded in the 2 θ range of 20 to 80°. The hardness properties were tested at 981 mN force. The laser-modified surface exhibited reduced crystallinity compared to the un-processed samples. The presence of martensitic phase was detected in the samples processed using 0.4 mm spot size. Though there was reduced crystallinity, a high hardness was measured in the laser-modified surface. Hardness was increased more than 2.5 times compared to the as-received samples. These findings reveal the phase source of the hardening mechanism and grain composition in the laser-modified surface.

Morphological driven photocatalytic activity of ZnO nanostructures

NASA Astrophysics Data System (ADS)

Abbas, Khaldoon N.; Bidin, Noriah

2017-02-01

Using a simple combination of pulse laser ablation in liquid and hydrothermal (PLAL-H) approaches, we control the morphology of ZnO nanostructures (ZNSs) to determine the feasibility of their photocatalytic efficacy. These ZNSs are deposited on Si (100) substrates and two different morphologies are achieved. In this synergistic approach, PLAL synthesized NSs are used as a nutrient solution with different pH for further hydrothermal treatment at 110 °C under varying growth time (5, 30 and 60 min). Surface morphology, structure, composition, and optical characteristics of the prepared ZNSs are determined using FESEM, XRD, FTIR and Photoluminescence (PL) and UV-vis absorption measurements. The morphology revealed remarkable transformation from nanorods (NRs)/nanoflowers (NFs) (at pH 7.6) to nanoparticles (NPs)-like (at pH 10.5) structure. XRD patterns showed better polycrystallinity for NPs with enlarged band gap than NR/NF-like structures. Both PL and UV-vis spectral analysis of ZNPs exhibited higher surface area and deep level defects density dependent morphology, where the nutrient pH and growth time variation are found to play a significant role towards structural evolution. Furthermore, the photocatalytic activities of, such ZNSs are evaluated via sunlight driven photo-degradation of methylene blue (MB) dye. The photocatalytic efficiency of ZNPs is demonstrated to be much superior (97.4%) than ZNRs/ZNFs-like morphology (86%). Such enhanced photocatalytic activities of as-synthesized ZNPs is attributed to the synergism of the improved surface area and defects density, which is useful for promoting the adsorption of the MB dye and suppressed surface recombination of photo-generated charge carriers.

Self-assembled spongy-like MnO2 electrode materials for supercapacitors

NASA Astrophysics Data System (ADS)

Dong, Meng; Zhang, Yu Xin; Song, Hong Fang; Qiu, Xin; Hao, Xiao Dong; Liu, Chuan Pu; Yuan, Yuan; Li, Xin Lu; Huang, Jia Mu

2012-08-01

Mesoporous spongy-like MnO2 has been synthesized via a facile and biphasic wet method, accompanied with tetraoctylammonium bromide (TOAB) as a soft template under ambient condition. A well-defined spongy morphology of MnO2 with uniform filament diameters 10-20 nm have been observed by FESEM, TEM, HRTEM, XRD, FT-IR,TGA-DSC studies. Further physical characterizations revealed that MnO2 sponges owned a large surface area of 155 m2 g-1 with typical mesoporous appearance. A specific capacitance value as high as 336 F g-1 was obtained. This improved capacitive behavior was attributed to the large surface area, morphology nature of nano-MnO2, and its broad pore size distribution.

Structured mesoporous Mn, Fe, and Co oxides: Synthesis, physicochemical, and catalytic properties

NASA Astrophysics Data System (ADS)

Maerle, A. A.; Karakulina, A. A.; Rodionova, L. I.; Moskovskaya, I. F.; Dobryakova, I. V.; Egorov, A. V.; Romanovskii, B. V.

2014-02-01

Structured mesoporous Mn, Fe, and Co oxides are synthesized using "soft" and "hard" templates; the resulting materials are characterized by XRD, SEM, TEM, BET, and TG. It is shown that in the first case, the oxides have high surface areas of up to 450 m2/g that are preserved after calcination of the material up to 300°C. Even though, the surface area of the oxides prepared by the "hard-template" method does not exceed 100 m2/g; it is, however, thermally stable up to 500°C. Catalytic activity of mesoporous oxides in methanol conversion was found to depend on both the nature of the transition metal and the type of template used in synthesis.

Evaluation of Advanced Reactive Surface Area Estimates for Improved Prediction of Mineral Reaction Rates in Porous Media

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Mitnick, E. H.; Zhang, S.; Voltolini, M.; Yang, L.; Steefel, C. I.; Swift, A.; Cole, D. R.; Sheets, J.; Kneafsey, T. J.; Landrot, G.; Anovitz, L. M.; Mito, S.; Xue, Z.; Ajo Franklin, J. B.; DePaolo, D.

2015-12-01

CO2 sequestration in deep sedimentary formations is a promising means of reducing atmospheric CO2 emissions but the rate and extent of mineral trapping remains difficult to predict. Reactive transport models provide predictions of mineral trapping based on laboratory mineral reaction rates, which have been shown to have large discrepancies with field rates. This, in part, may be due to poor quantification of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area are ad hoc and typically based on grain size, adjusted several orders of magnitude to account for surface roughness and reactivity. This results in orders of magnitude discrepancies in estimated surface areas that directly translate into orders of magnitude discrepancies in model predictions. Additionally, natural systems can be highly heterogeneous and contain abundant nano- and micro-porosity, which can limit connected porosity and access to mineral surfaces. In this study, mineral-specific accessible surface areas are computed for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan). Accessible mineral surface areas are determined from a multi-scale image analysis including X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB. Powder and flow-through column laboratory experiments are performed and the evolution of solutes in the aqueous phase is tracked. Continuum-scale reactive transport models are used to evaluate the impact of reactive surface area on predictions of experimental reaction rates. Evaluated reactive surface areas include geometric and specific surface areas (eg. BET) in addition to their reactive-site weighted counterparts. The most accurate predictions of observed powder mineral dissolution rates were obtained through use of grain-size specific surface areas computed from a BET-based correlation. Effectively, this surface area reflects the grain-fluid contact area, or accessible surface area, in the powder dissolution experiment. In the model of the flow-through column experiment, the accessible mineral surface area, computed from the multi-scale image analysis, is evaluated in addition to the traditional surface area estimates.

Simultaneous formation and micronization of pharmaceutical cocrystals by rapid expansion of supercritical solutions (RESS).

PubMed

Müllers, Katrin C; Paisana, Maria; Wahl, Martin A

2015-02-01

We investigated the RESS process as a means of simultaneous micronization and cocrystallization of a model drug with poor aqueous solubility. 1:1 cocrystals of ibuprofen (IBU) and nicotinamide (NA) were produced with a pilot scale unit for RESS processing.IBU and NA were dissolved in scCO2 at 30 MPa and 50°C. After 24 h, the supercritical solution was expanded at a medium CO2 flow rate of 3.8 kg/h during 60 min into an expansion vessel kept at ambient conditions. Cocrystals were identified with DSC, XRD and confocal Raman microscopy (CRM) and further characterized by SEM, specific surface area, wetting ability, solubility and dissolution testing. Judging by DSC, XRD and CRM, cocrystals with high purity could be produced with the RESS technique. Micronization via RESS was successful, since the specific surface area of RESS cocrystals was increased almost tenfold in comparison to cocrystals produced by slow solvent evaporation. Due to the additional micronization, the mean dissolution time of IBU from RESS cocrystals was decreased. RESS cocrystallization offers the advantage of combining micronization and cocrystallization in a single production step. For drugs with dissolution-limited bioavailability, RESS cocrystallization may therefore be a superior approach in comparison to established cocrystallization techniques.

TiO2/bone composite materials for the separation of heavy metal impurities from waste water solutions

NASA Astrophysics Data System (ADS)

Dakroury, G.; Labib, Sh.; Abou El-Nour, F. H.

2012-09-01

Pure bone material obtained from cow meat, as apatite-rich material, and TiO2-bone composite materials are prepared and studied to be used for heavy metal ions separation from waste water solutions. Meat wastes are chemically and thermally treated to control their microstructure in order to prepare the composite materials that fulfill all the requirements to be used as selective membranes with high performance, stability and mechanical strength. The prepared materials are analyzed using Hg-porosimetry for surface characterization, energy dispersive X-ray spectroscopy (EDAX) for elemental analysis and Fourier transform infrared spectroscopy (FTIR) for chemical composition investigation. Structural studies are performed using X-ray diffraction (XRD). Microstructural properties are studied using scanning electron microscopy (SEM) and specific surface area studies are performed using Brunauer-Emmet-Teller (BET) method. XRD studies show that multiphase structures are obtained as a result of 1h sintering at 700-1200 °C for both pure bone and TiO2-bone composite materials. The factors affecting the transport of different heavy metal ions through the selected membranes are determined from permeation flux measurements. It is found that membrane pore size, membrane surface roughness and membrane surface charge are the key parameters that control the transport or rejection of heavy metal ions through the selected membranes.

Ultrasound-assisted facile synthesis of a new tantalum(V) metal-organic framework nanostructure: Design, characterization, systematic study, and CO2 adsorption performance

NASA Astrophysics Data System (ADS)

Sargazi, Ghasem; Afzali, Daryoush; Mostafavi, Ali; Ebrahimipour, S. Yousef

2017-06-01

This work presents a fast route for the preparation of a new Ta(V) metal-organic framework nanostructure with high surface area, significant porosity, and small size distribution. X-ray diffraction (XRD), scanning electron microscopy (SEM), Transition electron microscopy (TEM), energy dispersive spectrometer (EDS), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), CHNS/O elemental analyser, and Brunauer-Emmett-Teller (BET) surface area analysis were applied to characterize the synthesized product. Moreover, the influences of ultrasonic irradiation including temperature, time, and power on different features of the final products were systematically studied using 2k-1 factorial design experiments, and the response surface optimization was used for determining the best welding parameter combination. The results obtained from analyses of variances showed that ultrasonic parameters affected the size distribution, thermal behaviour, and surface area of Ta-MOF samples. Based on response surface methodology, Ta-MOF could be obtained with mean diameter of 55 nm, thermal stability of 228 °C, and high surface area of 2100 m2/g. The results revealed that the synthesized products could be utilized in various applications such as a novel candidate for CO2 adsorption.

Enhanced reactivity of nanoscale iron particles through a vacuum annealing process

NASA Astrophysics Data System (ADS)

Riba, Olga; Barnes, Robert J.; Scott, Thomas B.; Gardner, Murray N.; Jackman, Simon A.; Thompson, Ian P.

2011-10-01

A reactivity study was undertaken to compare and assess the rate of dechlorination of chlorinated aliphatic hydrocarbons (CAHs) by annealed and non-annealed nanoscale iron particles. The current study aims to resolve the uncertainties in recently published work studying the effect of the annealing process on the reduction capability of nanoscale Fe particles. Comparison of the normalized rate constants (m2/h/L) obtained for dechlorination reactions of trichloroethene (TCE) and cis-1,2-dichloroethene (cis-1,2-DCE) indicated that annealing nanoscale Fe particles increases their reactivity 30-fold. An electron transfer reaction mechanism for both types of nanoscale particles was found to be responsible for CAH dechlorination, rather than a reduction reaction by activated H2 on the particle surface (i.e., hydrogenation, hydrogenolysis). Surface analysis of the particulate material using X-ray diffraction (XRD) and transmission electron microscopy (TEM) together with surface area measurement by Brunauer, Emmett, Teller (BET) indicate that the vacuum annealing process decreases the surface area and increases crystallinity. BET surface area analysis recorded a decrease in nanoscale Fe particle surface area from 19.0 to 4.8 m2/g and crystallite dimensions inside the particle increased from 8.7 to 18.2 nm as a result of annealing.

Cooked Food Waste-An Efficient and Less Expensive Precursor for the Generation of Activated Carbon.

PubMed

Krithiga, Thangavelu; Sabina, Xavier Janet; Rajesh, Baskaran; Ilbeygi, Hamid; Shetty, Adka Nityananda; Reddy, Ramanjaneya; Karthikeyan, Jayabalan

2018-06-01

Activated carbon was synthesized from cooked food waste, especially dehydrated rice kernels, by chemical activation method using NaOH and KOH as activating agents. It was then characterized by ultimate and proximate analysis, BET surface analysis, XRD, FTIR, Raman and SEM. The XRD patterns and Raman spectra confirmed the amorphous nature of the prepared activated carbons. Ultimate analysis showed an increase in the carbon content after activation of the raw carbon samples. Upon activation with NaOH and KOH, the surface area of the carbon sample was found to have increased from 0.3424 to 539.78 and 306.83 m2g-1 respectively. The SEM images revealed the formation of heterogeneous pores on the surface of the activated samples. The samples were then tested for their adsorption activity using acetic acid and methylene blue. Based on the regression coefficients, the adsorption kinetics of methylene blue dye were fitted with pseudo-second order model for both samples. Similarly, the Freundlich isotherm was found to be a better fit than Langmuir isotherm for both samples. The activity of thus prepared activated carbons was found to be comparable with the commercial carbon.

Feasibility of an integrated X-ray instrument for Mars exobiology and geology. [Abstract only

NASA Technical Reports Server (NTRS)

Fonda, M. L.; Schwartz, D. E.; Koppel, L. N.; Franco, E. D.; Kerner, J. A.

1994-01-01

By employing an integrated X-ray instrument on a future Mars mission, data obtained will greatly augment those returned by Viking; details relevant to the possibility of the origin and evolution of life on Mars will be acquired. An integrated combined X Ray Fluorescence/X Ray Detection (XRF/XRD) instrument has been breadboarded and demonstrated to accommodate important exobiology and geology experiment objectives outlined for Mars Environmental Survey (MESUR) and future Mars missions. Among others, primary objectives for the exploration of Mars include: the intense study of local areas on Mars to 'establish the chemical, mineralogical, and petrological character of different components of the surface material; to determine the distribution, abundance and sources and sinks of volatile materials, including an assessment of the biologic potential, now and during past epochs; and to establish the global chemical and physical characteristics of the Martian surface'. The XRF/XRD breadboard instrument identifies and quantifies soil surface elemental, mineralogical, and petrological characteristics and acquires data necessary to address questions on volatile abundance and distribution. Additionally, the breadboard is able to characterize the biogenic element constituents of soil samples providing information on the biologic potential of the Mars environment.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors.

PubMed

Prasad, Kumaresa P S; Dhawale, Dattatray S; Sivakumar, Thiripuranthagan; Aldeyab, Salem S; Zaidi, Javaid S M; Ariga, Katsuhiko; Vinu, Ajayan

2011-08-01

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g -1 at a 20 mV s -1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

NASA Astrophysics Data System (ADS)

Prasad, Kumaresa P. S.; Dhawale, Dattatray S.; Sivakumar, Thiripuranthagan; Aldeyab, Salem S.; Zaidi, Javaid S. M.; Ariga, Katsuhiko; Vinu, Ajayan

2011-08-01

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g-1 at a 20 mV s-1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

PubMed Central

Prasad, Kumaresa P S; Dhawale, Dattatray S; Sivakumar, Thiripuranthagan; Aldeyab, Salem S; Zaidi, Javaid S M; Ariga, Katsuhiko; Vinu, Ajayan

2011-01-01

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g-1 at a 20 mV s-1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles. PMID:27877410

Influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for the synthesis of dimethyl carbonate

NASA Astrophysics Data System (ADS)

Zhang, Guoqiang; Li, Zhong; Zheng, Huayan; Hao, Zhiqiang; Wang, Xia; Wang, Jiajun

2016-12-01

Activated carbon (AC) supported Cu catalysts are employed to study the influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for oxidative carbonylation of methanol to dimethyl carbonate (DMC). The AC supports are thermal treated under different temperatures in order to adjust the levels of surface oxygenated groups. The AC supports are characterized by BET, TPD-MS and XRD, and the Cu/AC catalysts are characterized by BET, XRD, TEM, XPS, AAS, CH3OH-TPD and N2O chemisorption. The results show that as the treatment temperature is below 800 °C, the BET surface area of the corresponding AC supports are nearly unchanged and close to that of the original AC (1529.6 m2/g). But as the thermal treatment temperature is elevated from 1000 to 1600 °C, the BET surface area of AC supports gradually decreases from 1407.6 to 972.2 m2/g. After loading of Cu, the BET surface area of copper catalysts is in the range of 834.4 to 1545.3 m2/g, which is slightly less than that of the respective supports. When AC is thermal treated at 400 and 600 °C, the unstable carboxylic acid and anhydrides groups are selectively removed, which has weakened the mobility and agglomeration of Cu species during the calcination process, and thus improve the Cu species dispersion over AC support. But as the treatment temperature is elevated from 600 °C to 1200 °C, the Cu species dispersion begins to decline suggesting further removal of stable surface oxygenated groups is unfavorable for Cu species dispersion. Moreover, higher thermal treatment temperature (above 1200 °C) promotes the graphitization degree of AC and leds to the decrease of Cu loading on AC support. Meanwhile, the removal of surface oxygenated groups by thermal treatment is conducive to the formation of more π-sites, and thus promote the reduction of Cu2+ to Cu+ and Cu0 as active centers. The specific surface area of (Cu+ + Cu0) is improved by thermal treatment of AC, however, the space time yield of DMC on unit specific surface area of (Cu+ + Cu0) is in the range of 23.1-49.1 mg h-1 m-2, which is much less than that (77.6 mg h-1 m-2) of the original catalyst. The possible reason is that the removal of surface oxygenated groups results in AC support transforms from hydrophilicity to hydrophobicity, which is detrimental for the adsorption of CH3OH resulting in the decreased local concentration of CH3OH on active Cu species.

Biotemplated synthesis of high specific surface area copper-doped hollow spherical titania and its photocatalytic research for degradating chlorotetracycline

NASA Astrophysics Data System (ADS)

Bu, Dan; Zhuang, Huisheng

2013-01-01

Copper-doped titania (Cu/TiO2) hollow microspheres were fabricated using the rape pollen as biotemplates via an improved sol-gel method and a followed calcinations process. In the fabricated process, a titanium(IV)-isopropoxide-based sol directly coated onto the surface of rape pollen. Subsequently, after calcinations, rape pollen was removed by high temperature and the hollow microsphere structure was retained. The average diameter of as-obtained hollow microspheres is 15-20 μm and the thickness of shell is approximately 0.6 μm. Knowing from XRD results, the main crystal phase of microspheres is anatase, coupled with rutile. The specific surface area varied between 141.80 m2/g and 172.51 m2/g. This hollow sphere photocatalysts with high specific surface area exhibited stronger absorption ability and higher photoactivity, stimulated by visible light. The degradation process of chlortetracycline (CTC) solution had been studied. The degradated results indicate that CTC could be effective degradated by fabricated hollow spherical materials. And the intermediate products formed in the photocatalytic process had been identified.

In situ synchrotron X-ray diffraction study on epitaxial-growth dynamics of III–V semiconductors

NASA Astrophysics Data System (ADS)

Takahasi, Masamitu

2018-05-01

The application of in situ synchrotron X-ray diffraction (XRD) to the molecular-beam epitaxial (MBE) growth of III–V semiconductors is overviewed along with backgrounds of the diffraction theory and instrumentation. X-rays are sensitive not only to the surface of growing films but also to buried interfacial structures because of their large penetration depth. Moreover, a spatial coherence length up to µm order makes X-rays widely applicable to the characterization of low-dimensional structures, such as quantum dots and wires. In situ XRD studies during growth were performed using an X-ray diffractometer, which was combined with an MBE chamber. X-ray reciprocal space mapping at a speed matching a typical growth rate was achieved using intense X-rays available from a synchrotron light source and an area detector. The importance of measuring the three-dimensional distribution of XRD intensity in a reciprocal space map is demonstrated for the MBE growth of two-, one-, and zero-dimensional structures. A large amount of information about the growth process of two-dimensional InGaAs/GaAs(001) epitaxial films has been provided by three-dimensional X-ray reciprocal mappings, including the anisotropic strain relaxation, the compositional inhomogeneity, and the evolution of surface and interfacial roughness. For one-dimensional GaAs nanowires grown in a Au-catalyzed vapor-liquid–solid mode, the relationship between the diameter of the nanowires and the formation of polytypes has been suggested on the basis of in situ XRD measurements. In situ three-dimensional X-ray reciprocal space mapping is also shown to be useful for determining the lateral and vertical sizes of self-assembled InAs/GaAs(001) quantum dots as well as their internal strain distributions during growth.

Microwave Synthesis, Characterization, and Photoluminescence Properties of Nanocrystalline Zirconia

PubMed Central

Singh, A. K.; Nakate, Umesh T.

2014-01-01

We report synthesis of ZrO2 nanoparticles (NPs) using microwave assisted chemical method at 80°C temperature. Synthesized ZrO2 NPs were calcinated at 400°C under air atmosphere and characterized using FTIR, XRD, SEM, TEM, BET, and EDS for their formation, structure, morphology, size, and elemental composition. XRD results revealed the formation of mixed phase monoclinic and tetragonal ZrO2 phases having crystallite size of the order 8.8 nm from most intense XRD peak as obtained using Scherrer formula. Electron microscope analysis shows that the NPs were less than 10 nm and highly uniform in size having spherical morphology. BET surface area of ZrO2 NPs was found to be 65.85 m2/g with corresponding particle size of 16 nm. The band gap of synthesized NPs was found to be 2.49 eV and PL spectra of ZrO2 synthesized NPs showed strong peak at 414 nm, which corresponds to near band edge emission (UV emission) and a relatively weak peak at 475 and 562 nm. PMID:24578628

Preparation of TiO2-SiO2 via sol-gel method: Effect of Silica precursor on Catalytic and Photocatalytic properties

NASA Astrophysics Data System (ADS)

Fatimah, I.

2017-02-01

TiO2-SiO2have been synthesized by the sol-gel method from titanium isopropoxide and varied silica precursors: tetraethyl orthosilicate and tetra methyl ortho silicate. To study the effect of the precursor, prepared materials were characterized by X-ray diffraction, scanning electron microscopy, Diffuse Reflectance UV-vis optical absorption, and also gas sorption analysis. XRD patterns showed the formation of TiO2 anatase in the TiO2-SiO2 composite with different crystallite size from different silica precursor as well as the different surface morphology. The DRUV-vis absorption spectra exhibit similar band gap energy correspond to 3.21eV value while the surface area, pore volume and pore radius of the materials seems to be affected by the precursor. The higher specific surface area contributes to give the enhanced activity in phenol hydroxylation and methylene blue photodegradation.

Note: application of a pixel-array area detector to simultaneous single crystal X-ray diffraction and X-ray absorption spectroscopy measurements.

PubMed

Sun, Cheng-Jun; Zhang, Bangmin; Brewe, Dale L; Chen, Jing-Sheng; Chow, G M; Venkatesan, T; Heald, Steve M

2014-04-01

X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are two main x-ray techniques in synchrotron radiation facilities. In this Note, we present an experimental setup capable of performing simultaneous XRD and XAS measurements by the application of a pixel-array area detector. For XRD, the momentum transfer in specular diffraction was measured by scanning the X-ray energy with fixed incoming and outgoing x-ray angles. By selecting a small fixed region of the detector to collect the XRD signal, the rest of the area was available for collecting the x-ray fluorescence for XAS measurements. The simultaneous measurement of XRD and X-ray absorption near edge structure for Pr0.67Sr0.33MnO3 film was demonstrated as a proof of principle for future time-resolved pump-probe measurements. A static sample makes it easy to maintain an accurate overlap of the X-ray spot and laser pump beam.

Surface acid-base properties and hydration/dehydration mechanisms of aluminum (hydr)oxides.

PubMed

Yang, Xiaofang; Sun, Zhongxi; Wang, Dongsheng; Forsling, Willis

2007-04-15

In this paper, surface physiochemical properties of three typical aluminas, gamma-Al(OH)3, gamma-Al2O3, and alpha-Al2O3, were investigated by means of XRD, SEM, TEM, BET surface area, TG/DTA, and potentiometric titration techniques. Based on the titration data, surface protonation and deprotonation constants were determined using the constant capacitance model (CCM). The emphasis of this research was laid on the comparison of the crystal structure, surface hydration/dehydration and acid-base properties of these three typical alumina minerals. The calculation results revealed that the surface acidity of the aluminas is in the order of alpha-Al2O3>gamma-Al(OH)3>gamma-Al2O3 after being hydrated for 1 h. The correlation between the hydration/dehydration mechanisms of alumina and its acid/base properties is discussed.

A novel ultrasound assisted method in synthesis of NZVI particles.

PubMed

Jamei, Mir Roozbeh; Khosravi, Mohamad Reza; Anvaripour, Bagher

2014-01-01

This research is about a novel ultrasound assisted method for synthesis of nano zero valent iron particles (NZVI). The materials were characterized using TEM, FESEM, XRD, BET and acoustic PSA. The effect of ultrasonic power, precursor/reductant concentration (NaBH4, FeSO4·7H2O) and delivery rate of NaBH4 on NZVI characteristics were investigated. Under high ultrasonic power the morphology of nano particles changed from spherical type to plate and needle type. Also, when high precursor/reductant and high ultrasonic power was used the particle size of NZVI decreased. The surface area of NZVI particles synthesized by ultrasonic method was increased when compared by the other method. From the XRD patterns it was found also the crystallinity of particles was poor. Copyright © 2013 Elsevier B.V. All rights reserved.

Copper Oxide Nanograss for Efficient and Stable Photoelectrochemical Hydrogen Production by Water Splitting

NASA Astrophysics Data System (ADS)

Borkar, Rajnikant; Dahake, Rashmi; Rayalu, Sadhana; Bansiwal, Amit

2018-03-01

A biphasic copper oxide thin film of grass-like appendage morphology is synthesized by two-step electro-deposition method and later investigated for photoelectrochemical (PEC) water splitting for hydrogen production. Further, the thin film was characterized by UV-Visible spectroscopy, x-ray diffraction (XRD), Scanning electron microscopy (SEM) and PEC techniques. The XRD analysis confirms formation of biphasic copper oxide phases, and SEM reveals high surface area grass appendage-like morphology. These grass appendage structures exhibit a high cathodic photocurrent of - 1.44 mAcm-2 at an applied bias of - 0.7 (versus Ag/AgCl) resulting in incident to photon current efficiency (IPCE) of ˜ 10% at 400 nm. The improved light harvesting and charge transport properties of grass appendage structured biphasic copper oxides makes it a potential candidate for PEC water splitting for hydrogen production.

Sintering Effects on Morphology, Thermal Stability and Surface Area of Sol-Gel Derived Nano-Hydroxyapatite Powder

NASA Astrophysics Data System (ADS)

Kapoor, Seema; Batra, Uma; Kohli, Suchita

2011-12-01

Hydroxyapatite (HAP) ceramics have been recognized as substitute materials for bone and teeth in orthopedic and dentistry field due to their chemical and biological similarity to human hard tissue. The nanosized and nanocrystalline forms of HAP have great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This paper reports the synthesis of biomimetic nano-hydroxyapatite (HAP) by sol-gel method using calcium nitrate tetrahydrate (CNT) and potassium dihydrogen phosphate (KDP) as calcium and phosphorus precursors, respectively to obtain a desired Ca/P ratio of 1.67. Deionized water was used as a diluting media for HAP sol preparation and ammonia was used to adjust the pH to 11. After aging, the HAP gel was dried at 55 °C and sintered to different temperatures (200 °C, 400 °C, 600 °C, 800 °C, 1000 °C and 1200 °C). The dried and sintered powders were characterized for phase composition using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The particle size and morphology was studied using transmission electron microscopy (TEM). The thermal behavior of the dried HAP nanopowder was studied in the temperature range of 55 °C to 1000 °C using thermal gravimetric analyser (TGA). The BET surface area of absorbance was determined by Nitrogen adsorption using Brunauer-Emmett-Teller (BET) method. The presence of characteristic peaks of the phosphate and OH groups in FTIR spectrums confirmed the formation of pure HAP in dried as well as sintered powders. XRD results also confirmed the formation of stoichiometric nano-HAP. Sintering revealed that with increase in temperature, both the crystallinity and crystallite size of nano-HAP particles increased. The synthesized nano-HAP powder was found to be stable upto 1000 °C without any additional phase other than HAP, whereas peak of β-TCP (tricalcium phosphate) was observed at 1200 °C. Photomicrograph of TEM showed that the nanopowder sintered at 600 °C is composed of hydroxyapatite nanoparticles (26.0-45.6 nm), which is well in agreement with the crystallite size calculated using XRD data. TGA study showed the thermal stability of the synthesized nano-HAP powder. The BET surface area decreased with increase in sintering temperature.

Nanograin Ceramic Optical Composite Window

DTIC Science & Technology

2005-07-15

parts are sintered in air at 1100 C̊. Table 1: Carbon content of the calcined Alumina- Zirconia powders analyzed by LECO Calcination Temperature Carbon...estimated particle size of the Alumina and Zirconia powders Material name Surface area (m2/g) Estimated particle size (nm) Alumina 315.7 4.7 Zirconia...200 300 400 500 600 700 800 900 1000 2-Theta - Scale 20 30 40 50 60 70 80 Figure 3: XRD patterns of zirconia powder prepared by sonochemical method

Biopolymer protected silver nanoparticles on the support of carbon nanotube as interface for electrocatalytic applications

NASA Astrophysics Data System (ADS)

Satyanarayana, M.; Kumar, V. Sunil; Gobi, K. Vengatajalabathy

2016-04-01

In this research, silver nanoparticles (SNPs) are prepared on the surface of carbon nanotubes via chitosan, a biopolymer linkage. Here chitosan act as stabilizing agent for nanoparticles and forms a network on the surface of carbon nanotubes. Synthesized silver nanoparticles-MWCNT hybrid composite is characterized by UV-Visible spectroscopy, XRD analysis, and FESEM with EDS to evaluate the structural and chemical properties of the nanocomposite. The electrocatalytic activity of the fabricated SNP-MWCNT hybrid modified glassy carbon electrode has been evaluated by cyclic voltammetry and electrochemical impedance analysis. The silver nanoparticles are of size ˜35 nm and are well distributed on the surface of carbon nanotubes with chitosan linkage. The prepared nanocomposite shows efficient electrocatalytic properties with high active surface area and excellent electron transfer behaviour.

Escape of carbon element in surface ablation of cobalt cemented tungsten carbide with pulsed UV laser

NASA Astrophysics Data System (ADS)

Li, Tiejun; Lou, Qihong; Dong, Jingxing; Wei, Yunrong; Liu, Jingru

2001-03-01

Surface ablation of cobalt cemented tungsten carbide hardmetal has been carried out in this work using a 308 nm, 30 ns XeCl excimer laser. The surface phase transformation on different pulse number of laser shots has been investigated by means of XRD and microphotography as well as AES at laser fluence of 2.5 J/cm 2. The experimental results showed that the phase structure of irradiated area has partly transformed from original WC to β-WC 1- x, then to α-W 2C and CW 3, and finally to W crystal. It is suggested that the formation of non-stoichiometric tungsten carbide should result from the escaping of carbon element due to accumulated heating of surface by pulsed laser irradiation.

Multiple techniques for mineral identification of terrestrial evaporites relevant to Mars exploration

NASA Astrophysics Data System (ADS)

Stivaletta, N.; Dellisanti, F.; D'Elia, M.; Fonti, S.; Mancarella, F.

2013-05-01

Sulfates, commonly found in evaporite deposits, were observed on Mars surface during orbital remote sensing and surface exploration. In terrestrial environments, evaporite precipitation creates excellent microniches for microbial colonization, especially in desert areas. Deposits comprised of gypsum, calcite, quartz and silicate deposits (phyllosilicates, feldspars) from Sahara Desert in southern Tunisia contain endolithic colonies just below the rock surface. Previous optical observations verified the presence of microbial communities and, as described in this paper, spectral visible analyses have led to identification of chlorophylls belonging to photosynthetic bacteria. Spectral analyses in the infrared region have clearly detected the presence of gypsum and phyllosilicates (mainly illite and/or smectite), as well as traces of calcite, but not quartz. X-ray diffraction (XRD) analysis has identified the dominant presence of gypsum as well as that of other secondary minerals such as quartz, feldspars and Mg-Al-rich phyllosilicates, such as chlorite, illite and smectite. The occurrence of a small quantity of calcite in all the samples was also highlighted by the loss of CO2 by thermal analysis (TG-DTA). A normative calculation using XRD, thermal data and X-ray fluorescence (XRF) analysis has permitted to obtain the mineralogical concentration of the minerals occurring in the samples. The combination of multiple techniques provides information about the mineralogy of rocks and hence indication of environments suitable for supporting microbial life on Mars surface.

Fabrication of MCM-41 fibers with well-ordered hexagonal mesostructure controlled in acidic and alkaline media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jafarzadeh, A.; Sohrabnezhad, Sh., E-mail: sohrabnezhad@guilan.ac.ir; Zanjanchi, M.A.

In this paper, synthesis and characterization of two type morphologies of the MCM-41mesoporous material, nano and microfibers, were investigated by electrospinning technique. The synthesis was performed in acidic and alkaline media, separately. The MCM-41 morphologies were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray powder diffraction (XRD), and nitrogen adsorption–desorption measurement. Tetraethylorthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) were used as silica and template sources for the synthesis of MCM-41 morphologies, respectively. The SEM results showed that MCM-41 nanofibers were spun in acidic media and microfibers of MCM-41 were produced in alkaline media. The XRD study revealed amore » long range structural ordering of mesoporous materials. The TEM results indicated rough surfaces with uniform average diameter 200 nm for nanofibers and 2 µm for microfibers. The pore diameter and surface area of calcined MCM-41 nanofibers were 2.2 nm and 970 m{sup 2}/g, respectively. For the MCM-41 microfibers, pore sizes of 2.7 nm and surface areas 420 m{sup 2}/g was measured. - Graphical abstract: Electrospinning method was used for fabricating of MCM-41 microfibers from TEOS in alkaline media (top) and MCM-41 nanofibers in acidic media (bottom). - Highlights: • Synthesis of MCM-41 nanofibers and microfibers by electrospinning technique. • MCM-41 nanofibers were synthesized in acidic media. • MCM-41 manofibers spun in alkaline media. • Electrospinning was a simple method for preparing of fibers with respect to chemical method.« less

Improved solar-driven photocatalytic performance of Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} prepared in-situ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, Junbo, E-mail: junbozhong@163.com; Li, Jianzhang, E-mail: lschmanuscript@163.com; Huang, Shengtian

Highlights: • Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} photocatalysts were prepared in-situ. • The photo-induced charge separation rate has been greatly increased. • The photocatalytic activity has been greatly promoted. - Abstract: Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} composites have been fabricated in-situ via a facile parallel flaw co-precipitation method. The specific surface area, structure, morphology, and the separation rate of photo-induced charge pairs of the photocatalysts were characterized by Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy(DRS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and surface photovoltage (SPV) spectroscopy, respectively. XRD patterns and DRS demonstrated that Ag{submore » 2}CO{sub 3} has no effect on the crystal phase and bandgap of (BiO){sub 2}CO{sub 3}. The existence of Ag{sub 2}CO{sub 3} in the composites enhances the separation rate of photo-induced charge pairs of the photocatalysts. The photocatalytic performance of Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} was evaluated by the decolorization of methyl orange (MO) aqueous solution under simulated solar irradiation. It was found that the simulated solar-induced photocatalytic activity of Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} copmposites was significantly improved, which was mainly attributed to the enhanced surface area and the separation rate of photo-induced charge pairs.« less

Silica Aerogel-supported Hydrozincite and Carbonate-intercalated Hydrotalcite for High-efficiency Removal of Pb(II) Ions by Precipitation Transformation Reactions

NASA Astrophysics Data System (ADS)

Wang, Lijun; Wang, Xiaoxia; Li, Jianfa; Feng, Xiaolan; Wang, Yusen

2017-09-01

In this work, hydrozincite and Zn/Al-CO3 2- hydrotalcite supported on silica aerogel were prepared via a simple and economical process and used as adsorbents for Pb(II) removal. The supported hydrozincite and Zn/Al-CO3 2- hydrotalcite possess ultra-thin thickness, high surface area, and weak crystallinity. In the batch Pb(II) adsorption experiments, the adsorbents with higher Zn(II) contents showed higher Pb(II) adsorption capacities, and the adsorption data fitted well with the Langmuir isotherm model and pseudo-second-order kinetic model, indicating a mechanism of surface chemisorption. The adsorption capacities calculated based Langmuir isotherm model are 684.9 mg/g and 555.6 mg/g for the supported hydrozincite and Zn/Al-CO3 2- hydrotalcite, respectively, higher than the adsorption capacities of other hydrotalcite-based adsorbents and most of other inorganic adsorbents reported previously. The XRD diffraction peaks of hydrozincite and Zn/Al-CO3 2- hydrotalcite disappeared after the adsorption, and the Pb(II) species were uniformly dispersed in the adsorbents in form of Pb3(CO3)2(OH)2 proven by TEM, EDS mapping and XRD analysis, demonstrating the nature of the adsorption is the precipitation conversion of hydrozincite or Zn/Al-CO3 2- hydrotalcite into Pb3(CO3)2(OH)2. These results demonstrate the synergic Pb(II) removal effect of the CO3 2- and OH- derived from hydrozincite and Zn/Al-CO3 2- hydrotalcite together with their ultra-thin thickness and high surface area contribute the excellent properties of the adsorbents.

Surface modification and electrochemical properties of activated carbons for supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Yang, Dan; Qiu, Wenmei; Xu, Jingcai; Han, Yanbing; Jin, Hongxiao; Jin, Dingfeng; Peng, Xiaoling; Hong, Bo; Li, Ji; Ge, Hongliang; Wang, Xinqing

2015-12-01

Modifications with different acids (HNO3, H2SO4, HCl and HF, respectively) were introduced to treat the activated carbons (ACs) surface. The microstructures and surface chemical properties were discussed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), ASAP, Raman spectra and Fourier transform infrared (FTIR) spectra. The ACs electrode-based supercapacitors were assembled with 6 mol ṡ L-1 KOH electrolyte. The electrochemical properties were studied by galvanostatic charge-discharge and cyclic voltammetry. The results indicated that although the BET surface area of modified ACs decreased, the functional groups were introduced and the ash contents were reduced on the surface of ACs, receiving larger specific capacitance to initial AC. The specific capacitance of ACs modified with HCl, H2SO4, HF and HNO3 increased by 31.4%, 23%, 21% and 11.6%, respectively.

Ultrasound-assisted facile synthesis of a new tantalum(V) metal-organic framework nanostructure: Design, characterization, systematic study, and CO{sub 2} adsorption performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sargazi, Ghasem, E-mail: g.sargazi@gmail.com; Young Researchers Society, Shahid Bahonar University of Kerman, Kerman, Iran; Afzali, Daryoush, E-mail: daryoush_afzali@yahoo.com

2017-06-15

This work presents a fast route for the preparation of a new Ta(V) metal-organic framework nanostructure with high surface area, significant porosity, and small size distribution. X-ray diffraction (XRD), scanning electron microscopy (SEM), Transition electron microscopy (TEM), energy dispersive spectrometer (EDS), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), CHNS/O elemental analyser, and Brunauer-Emmett-Teller (BET) surface area analysis were applied to characterize the synthesized product. Moreover, the influences of ultrasonic irradiation including temperature, time, and power on different features of the final products were systematically studied using 2{sup k-1} factorial design experiments, and the response surfacemore » optimization was used for determining the best welding parameter combination. The results obtained from analyses of variances showed that ultrasonic parameters affected the size distribution, thermal behaviour, and surface area of Ta-MOF samples. Based on response surface methodology, Ta-MOF could be obtained with mean diameter of 55 nm, thermal stability of 228 °C, and high surface area of 2100 m{sup 2}/g. The results revealed that the synthesized products could be utilized in various applications such as a novel candidate for CO{sub 2} adsorption. - Graphical abstract: A facile route was used for fabrication of a new metal -organic framework based on tantalum nanostructures that have high surface area, considerable porosity, homogenous morphology, and small size distribution.« less

Activated carbon coated palygorskite as adsorbent by activation and its adsorption for methylene blue.

PubMed

Zhang, Xianlong; Cheng, Liping; Wu, Xueping; Tang, Yingzhao; Wu, Yucheng

2015-07-01

An activation process for developing the surface and porous structure of palygorskite/carbon (PG/C) nanocomposite using ZnCl2 as activating agent was investigated. The obtained activated PG/C was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM), and Brunauer-Emmett-Teller analysis (BET) techniques. The effects of activation conditions were examined, including activation temperature and impregnation ratio. With increased temperature and impregnation ratio, the collapse of the palygorskite crystal structure was found to accelerate and the carbon coated on the surface underwent further carbonization. XRD and SEM data confirmed that the palygorskite structure was destroyed and the carbon structure was developed during activation. The presence of the characteristic absorption peaks of CC and C-H vibrations in the FTIR spectra suggested the occurrence of aromatization. The BET surface area improved by more than 11-fold (1201 m2/g for activated PG/C vs. 106 m2/g for PG/C) after activation, and the material appeared to be mainly microporous. The maximum adsorption capacity of methylene blue onto the activated PG/C reached 351 mg/g. The activated PG/C demonstrated better compressive strength than activated carbon without palygorskite clay. Copyright © 2015. Published by Elsevier B.V.

Platinum nanocatalysts prepared with different surfactants for C1-C3 alcohol oxidations and their surface morphologies by AFM

NASA Astrophysics Data System (ADS)

Ertan, Salih; Şen, Fatih; Şen, Selda; Gökağaç, Gülsün

2012-06-01

In this study, platinum nanoparticle catalysts have been prepared using PtCl4 as a starting material and 1-octanethiol, 1-decanethiol, 1-dodecanethiol, and 1-hexadecanethiol as surfactants for methanol, ethanol, and 2-propanol oxidation reactions. The structure, particle sizes, and surface morphologies of the catalysts were characterized by X-ray diffraction (XRD), atomic force microscopy and transmission electron microscopy (TEM). XRD and TEM results indicate that all prepared catalysts have a face-centered cubic structure and are homogeneously dispersed on the carbon support with a narrow size distribution (2.0-1.3 nm). X-ray photoelectron spectra of the catalysts were examined and it is found that platinum has two different oxidation states, Pt (0) and Pt(IV), oxygen and sulfur compounds are H2Oads and OHads, bound and unbound thiols. The electrochemical and electrocatalytic properties of these catalysts were investigated with respect to C1-C3 alcohol oxidations by cyclic voltammetry and chronoamperometry. The highest electrocatalytic activity was obtained from catalyst I which was prepared with 1-octanethiol. This may be attributed to a decrease in the ratio of bound to unbound thiol species increase in Pt (0)/Pt(IV), H2Oads/OHads ratios, electrochemical surface area, CO tolerance and percent platinum utility.

Surface characterization and chemical analysis of bamboo substrates pretreated by alkali hydrogen peroxide.

PubMed

Song, Xueping; Jiang, Yan; Rong, Xianjian; Wei, Wei; Wang, Shuangfei; Nie, Shuangxi

2016-09-01

The surface characterization and chemical analysis of bamboo substrates by alkali hydrogen peroxide pretreatment (AHPP) were investigated in this study. The results tended to manifest that AHPP prior to enzymatic and chemical treatment was potential for improving accessibility and reactivity of bamboo substrates. The inorganic components, organic solvent extractives and acid-soluble lignin were effectively removed by AHPP. X-ray photoelectron spectroscopy (XPS) analysis indicated that the surface of bamboo chips had less lignin but more carbohydrate after pre-treatment. Fiber surfaces became etched and collapsed, and more pores and debris on the substrate surface were observed with Scanning Electron Microscopy (SEM). Brenauer-Emmett-Teller (BET) results showed that both of pore volume and surface area were increased after AHPP. Although XRD analysis showed that AHPP led to relatively higher crystallinity, pre-extraction could overall enhance the accessibility of enzymes and chemicals into the bamboo structure. Copyright © 2016. Published by Elsevier Ltd.

The synthesis of Fe3O4/MWCNT nanocomposites from local iron sands for electrochemical sensors

NASA Astrophysics Data System (ADS)

Rahmawati, Retno; Taufiq, Ahmad; Sunaryono, Yuliarto, Brian; Suyatman, Nugraha, Noviandri, Indra; Setyorini, Dian Ayu; Kurniadi, Deddy

2018-05-01

The aim of this research is producing the electrochemical sensor, especially for working electrodes based on the nanocomposites of multi-walled carbon nanotube (MWCNT) and magnetite (Fe3O4) nanoparticles from iron sands. The sonochemical method by ultrasonic horn was successfully used for the synthesis of the nanocomposites. The characterizations of the sample were conducted via X-Ray Diffractometer (XRD), Fourier Transform Infra-Red (FTIR) Spectrometer, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Brunauer-Emmett-Teller (BET) method for surface area, Vibrating Sample Magnetometer (VSM) and Cyclic Voltammetry (CV). The analysis of X-Ray Diffraction (XRD) pattern showed two phases of crystalline, namely MWCNT and Fe3O4, peak of MWCNT comes from (002) plan while peaks of Fe3O4 come from (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1), and (4 4 0) plans. From XRD data, MWCNT has a hexagonal structure and Fe3O4 has inverse spinel cubic structure, respectively. The FTIR spectra revealed that the functionalization process of MWCNT successfully generated carboxyl and carbonyl groups to bind Fe3O4 on MWCNT surfaces. Moreover, the functional groups of Fe-O bonding that showed the existence of Fe3O4 in the nanocomposites were also detected in those spectra. Meanwhile, the SEM and TEM images showed that the nanoparticles of Fe3O4 attached on the MWCNT surface and formed agglomeration between particles due to magnetic forces. Through Brunauer-Emmett-Teller (BET) method, it is identified that the nanocomposite has a large surface area 318 m2/g that makes this material very suitable for electrochemical sensor applications. Moreover, the characterization of magnetic properties via Vibrating Sample Magnetometer (VSM) showed that the nanocomposites have superparamagnetic behavior at room temperature and the presence of the MWCNT reduced the magnetic properties of Fe3O4. Lastly, the electrochemical characterization with Cyclic Voltammetry (CV) proved that Fe3O4/MWCNT nanocomposites with iron sands as the starting materials have high sensitivity and serve as excellent electron transfer materials. Based on the results of the research, the Fe3O4/MWCNT nanocomposites from iron sands are much recommended for electrochemical sensor.

Mineralogical and morphological constraints on the reduction of Fe(III) minerals by Geobacter sulfurreducens

NASA Astrophysics Data System (ADS)

Cutting, R. S.; Coker, V. S.; Fellowes, J. W.; Lloyd, J. R.; Vaughan, D. J.

2009-07-01

The biologically-mediated reduction of synthetic samples of the Fe(III)-bearing minerals hematite, goethite, lepidocrocite, feroxhyte, ford ferrihydrite, akaganeite and schwertmannite by Geobacter sulfurreducens has been investigated using microbiological techniques in conjunction with X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). This combination of approaches offers unique insights into the influence of subtle variations in the crystallinity of a given mineral on biogeochemical processes, and has highlighted the importance of (oxyhydr)oxide crystallite morphology in determining the changes occurring in a given mineral phase. Problems arising from normalising the biological Fe(III) reduction rates relative to the specific surface areas of the starting materials are also highlighted. These problems are caused primarily by particle aggregation, and compounded when using spectrophotometric assays to monitor reduction. For example, the initial rates of Fe(III) reduction observed for two synthetic feroxyhytes with different crystallinities (as shown by XRD and TEM studies) but almost identical surface areas, differ substantially. Both microbiological and high-resolution TEM studies show that hematite and goethite are susceptible to limited amounts of Fe(III) reduction, as evidenced by the accumulation of Fe(II) during incubation with G. sulfurreducens and the growth of nodular structures on crystalline goethite laths during incubation. Lepidocrocite and akaganeite readily transform into mixtures of magnetite and goethite, and XRD data indicate that the proportion of magnetite increases within the transformation products as the crystallinity of the starting material decreases. The presence of anthraquinone-2,6-disulfonate (AQDS) as an electron shuttle increases both the initial rate and longer term extent of biological Fe(III) reduction for all of the synthetic minerals examined. High-resolution XPS indicates subtle but measurable differences in the Fe(III):Fe(II) ratios at the mineral surfaces following extended incubation. For example, for a poorly crystalline schwertmannite, deconvolution of the Fe2p 3/2 peak suggests that the Fe(III):Fe(II) ratio of the near-surface regions varies from 1.0 in the starting material to 0.9 following 144 h of incubation with G.sulfurreducens, and to 0.75 following the same incubation period in the presence of 10 μM AQDS. These results have important implications for the biogeochemical cycling of iron.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Cheng-Jun, E-mail: cjsun@aps.anl.gov; Brewe, Dale L.; Heald, Steve M.

X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are two main x-ray techniques in synchrotron radiation facilities. In this Note, we present an experimental setup capable of performing simultaneous XRD and XAS measurements by the application of a pixel-array area detector. For XRD, the momentum transfer in specular diffraction was measured by scanning the X-ray energy with fixed incoming and outgoing x-ray angles. By selecting a small fixed region of the detector to collect the XRD signal, the rest of the area was available for collecting the x-ray fluorescence for XAS measurements. The simultaneous measurement of XRD and X-ray absorptionmore » near edge structure for Pr{sub 0.67}Sr{sub 0.33}MnO{sub 3} film was demonstrated as a proof of principle for future time-resolved pump-probe measurements. A static sample makes it easy to maintain an accurate overlap of the X-ray spot and laser pump beam.« less

Synthesis of silica aerogel monoliths with controlled specific surface areas and pore sizes

NASA Astrophysics Data System (ADS)

Gao, Bingying; Lu, Shaoxiang; Kalulu, Mulenga; Oderinde, Olayinka; Ren, Lili

2017-07-01

To replace traditional preparation methods of silica aerogels, a small-molecule 1,2-epoxypropane (PO) has been introduced into the preparation process instead of using ammonia as the cross-linking agent, thus generating a lightweight, high porosity, and large surface area silica aerogel monolithic. We put forward a simple solution route for the chemical synthesis of silica aerogels, which was characterized by scanning electron microscopy (SEM), TEM, XRD, FTIR, thermogravimetric analysis (TGA) and the Brunauer-Emmett-Teller (BET) method In this paper, the effect of the amount of PO on the microstructure of silica aerogels is discussed. The BET surface areas and pore sizes of the resulting silica aerogels can be freely adjusted by changing the amount of PO, which will be helpful in promoting the development of silica aerogels to fabricate other porous materials with similar requirements. We also adopted a new organic solvent sublimation drying (OSSD) method to replace traditional expensive and dangerous drying methods such as critical point drying and freeze drying. This simple approach is easy to operate and has good repeatability, which will further facilitate actual applications of silica aerogels.

Preparation of Hierarchical Porous Silicalite-1 Encapsulated Ag NPs and Its Catalytic Performance for 4-Nitrophenol Reduction

NASA Astrophysics Data System (ADS)

Wang, Bin; Wang, Haojiang; Zhang, Fengwei; Sun, Tijian

2018-06-01

A facile and efficient strategy is presented for the encapsulation of Ag NPs within hierarchical porous silicalite-1. The physicochemical properties of the resultant catalyst are characterized by TEM, XRD, FTIR, and N2 adsorption-desorption analytical techniques. It turns out that the Ag NPs are well distributed in MFI zeolite framework, which possesses hierarchical porous characteristics (1.75, 3.96 nm), and the specific surface area is as high as 243 m2 · g-1. More importantly, such catalyst can rapidly transform the 4-nitrophenol to 4-aminophenol in aqueous solution at room temperature, and a quantitative conversion is also obtained after being reused 10 times. The reasons can be attributed to the fast mass transfer, large surface area, and spatial confinement effect of the advanced support.

Influence of N2 annealing on TiO2 tubes structure and its photocatalytic activity

NASA Astrophysics Data System (ADS)

Chen, Xiaoxiang; Pan, Zhanchang; Yu, Ke; Xiao, Jun; Wu, Shoukun; Li, Jinghong; Chen, Chun; Lin, Yingsheng; Hu, Guanghui; Xu, Yanbin

2018-02-01

In this work, the TiO2 tubes (TBs) were prepared by solvothermal method. The morphology and phase structure of TiO2 TBs is significantly affected by N2 annealing temperature. XRD was used to characterize the phase structure of the as-prepared samples. The morphology and surface areas were characterized by SEM and N2 adsorption-desorption, which show that the tubes were assembled with about 100-nm nanosheets and small ball particles under 400 and 600 °C N2 annealing; when temperature reached 800 °C, the surface of tubes appeared a lot of collapse and many large holes. In addition, the surface areas of 400 °C TiO2, 600 °C TiO2, and 800 °C TiO2 TBs were significantly affected by N2 annealing. Most importantly, the UV-vis and electrochemical tests demonstrate 600 °C TiO2 TBs exhibit higher absorption intensity and photocurrent; thus, it possess on better photocatalytic activity. Therefore, the photocatalytic performance for TiO2 TBs is significantly co-affected by surface area and mix-phase. [Figure not available: see fulltext.

Mechanisms of biochar assisted immobilization of Pb2+ by bioapatite in aqueous solution.

PubMed

Shen, Zhengtao; Tian, Da; Zhang, Xinyu; Tang, Lingyi; Su, Mu; Zhang, Li; Li, Zhen; Hu, Shuijin; Hou, Deyi

2018-01-01

Bioapatite (BAp) is regarded as an effective material to immobilize lead (Pb 2+ ) via the formation of stable pyromorphite. However, when applied in contaminated soil, due to its low surface area and low adsorption capacity, BAp might not sufficiently contact and react with Pb 2+ . Biochar, a carbon storage material, typically has high surface area and high adsorption capacity. This study investigated the feasibility of using biochar as a reaction platform to enhance BAp immobilization of Pb 2+ . An alkaline biochar produced from wheat straw pellets (WSP) and a slightly acidic biochar produced from hardwood (SB) were selected. The results of aqueous adsorption showed the combination of biochar (WSP or SB) and BAp effectively removed Pb 2+ from the aqueous solution containing 1000 ppm Pb 2+ . XRD, ATR-IR, and SEM/EDX results revealed the formation of hydroxypyromorphite on both biochars' surfaces. This study demonstrates that biochars could act as an efficient reaction platform for BAp and Pb 2+ in aqueous solution due to their high surface area, porous structure, and high adsorption capacity. Therefore, it is mechanistically feasible to apply biochar to enhance BAp immobilization of Pb 2+ in contaminated soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation and characterization of pitch-based nanoporous carbons for improving CO{sub 2} capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Seul-Yi; Yoo, Hye-Min; Park, Sang Wook

2014-07-01

Pitch is considered a promising low-cost carbon precursor. However, when pitch is pyrolyzed, it forms polycrystalline graphite, which is non-porous, and therefore, not useful for CO{sub 2} adsorption. In this work, pitch was chemically activated to obtain a large specific surface area and micropore volume. Varying weight ratios of KOH (i.e., 0, 1, 2, and 3) were used as the activating agent. The characteristics of the samples were investigated using scanning electron microscopy (SEM), N{sub 2}/77 K adsorption isotherms, and X-ray diffraction (XRD). The CO{sub 2} adsorption performance was studied by isothermal adsorption/desorption measurements. The results showed that an increasemore » in specific surface areas and total pore volumes of pitch-based nanoporous carbons, resulted in an enhancement of CO{sub 2} adsorption capacity. - Graphical abstract: This is the surface morphologies of pitch precursor and pitch-derived activated carbon (AC-2). - Highlights: • Pitch is considered a promising low-cost carbon precursor. • Specific surface area: 1442 m{sup 2}/g and micropore volume: 0.504 cm{sup 3}/g. • CO{sub 2} adsorption capacity showed 203 mg/g (@ RT/1 bar)« less

Activity of titania and zeolite samples dosed with triethylamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Caitlin; Gole, James L.; Brauer, Jonathan

2016-01-01

Certain properties of titania and the ammonium- and proton-form of Y zeolites (silica/alumina ratio of 5.2) were explored before and after treatment by triethylamine (TEA). The effect of the triethylamine upon the physical and chemical properties of both titania and the zeolite were characterized by physical and chemical adsorption methods. BET surface area data showed enhanced surface area of the TEA-treated nanotitania over the untreated nanotitania whereas the TEA-treated zeolite showed a considerable decrease in surface area compared to the untreated zeolite. TPD of the TEA-treated Y zeolite showed that weakly adsorbed TEA left the surface between 150 and 300more » oC; strongly adsorbed TEA decomposed to ethylene and ammonia at higher temperatures. XPS, IR, and Raman spectroscopies, powder XRD, and 27Al MAS-NMR spectroscopy were used to further characterize the changes introduced by in-situ nitridation. Pre-adsorbed triethylamine decorated acid sites so as to neutralize these sites for the reaction of methanol to dimethylether. Carbon monoxide and ormaldehyde, products of the methanol probe reaction, were observed-- suggesting that basic sites are present in this treated zeolite and titania.« less

High surface area calcite

NASA Astrophysics Data System (ADS)

Schultz, L. N.; Andersson, M. P.; Dalby, K. N.; Müter, D.; Okhrimenko, D. V.; Fordsmand, H.; Stipp, S. L. S.

2013-05-01

Calcite (CaCO3) is important in many fields—in nature, because it is a component of aquifers, oil reservoirs and prospective CO2 storage sites, and in industry, where it is used in products as diverse as paper, toothpaste, paint, plastic and aspirin. It is difficult to obtain high purity calcite with a high surface area but such material is necessary for industrial applications and for fundamental calcite research. Commercial powder is nearly always contaminated with growth inhibitors such as sugars, citrate or pectin and most laboratory synthesis methods deliver large precipitates, often containing vaterite or aragonite. To address this problem, we (i) adapted the method of carbonating a Ca(OH)2 slurry with CO2 gas to develop the first simple, cheap, safe and reproducible procedure using common laboratory equipment, to obtain calcite that reproducibly had a surface area of 14-17 m2/g and (ii) conducted a thorough characterization of the product. Scanning electron microscopy (SEM) revealed nanometer scale, rhombohedral crystals. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) confirmed highly crystalline, pure calcite that more closely resembles the dimensions of the biogenic calcite produced by algae in coccoliths than other methods for synthesizing calcite. We suggest that this calcite is useful when purity and high surface area are important.

Oxidation behavior of a ferritic stainless steel Crofer22 APU with thermal cycling

NASA Astrophysics Data System (ADS)

Song, MyoungYoup; Duong, Anh T.; Mumm, Daniel R.

2013-01-01

Crofer22 APU specimens were prepared by grinding with grit 80 and 120 SiC grinding papers and were thermally cycled. The variation in oxidation behavior with thermal cycling was then investigated. Observation of microstructure, measurement of area specific resistance (ASR), analysis of the atomic percentages of the elements by EDX, and XRD analysis were performed. XRD patterns showed that the (Cr, Mn)3O4 spinel phase grew on the surface of the Crofer22 APU samples ground with grit 120. For the samples ground with grit 80, the ASR increased as the number of thermal cycles increased. Plots of ln (ASR/T) vs. 1/T for the samples ground with grit 80 after n = 4, 20 and 40 exhibited good linearity, and the apparent activation energies were between 63.7 kJ/mole and 76.3 kJ/mole.

Aluminium and titanium modified mesoporous TUD-1: A bimetal acid catalyst for Biginelli reaction

NASA Astrophysics Data System (ADS)

Pasupathi, M.; Santhi, N.; Pachamuthu, M. P.; Alamelu Mangai, G.; Ragupathi, C.

2018-05-01

Using a simple, non-surfactant template triethanolamine (TEA), bimetal (Al3+ and Ti4+ ions) incorporated mesoporous catalyst AlTiTUD-1 (Si/Al+Ti = 50) was synthesized. The catalyst was characterized by XRD (Low and High angle), N2 Sorption, FTIR, SEM, TEM, DR UV Visible, and pyridine adsorbed FT-IR techniques. The XRD and N2 sorption studies confirmed its amorphous, mesoporous nature, which possessed a BET surface area of 590 m2 g-1 and pore diameter of 4.4 nm. The Al3+ and Ti4+ co-ordination within the TUD-1 was evaluated by DR UV-Vis. Pyridine adsorbed FTIR revealed both Bronsted (B) and Lewis (L) acidity, which is responsible for the catalytic activity. The acid catalyst showed a good catalytic performance in Biginelli type multicomponent coupling reaction for the substituted aldehydes, ethyl acetoacetate and thiourea to yield about 70% in reflux condition.

Simple Preparation of Novel Metal-Containing Mesoporous Starches †

PubMed Central

Ojeda, Manuel; Budarin, Vitaliy; Shuttleworth, Peter S.; Clark, James H.; Pineda, Antonio; Balu, Alina M.; Romero, Antonio A.; Luque, Rafael

2013-01-01

Metal-containing mesoporous starches have been synthesized using a simple and efficient microwave-assisted methodology followed by metal impregnation in the porous gel network. Final materials exhibited surface areas >60 m2 g−1, being essentially mesoporous with pore sizes in the 10–15 nm range with some developed inter-particular mesoporosity. These materials characterized by several techniques including XRD, SEM, TG/DTA and DRIFTs may find promising catalytic applications due to the presence of (hydr)oxides in their composition. PMID:28809249

Regeneration of Waste Edible Oil by the Use of Virgin and Calcined Magnesium Hydroxide as Adsorbents.

PubMed

Ogata, Fumihiko; Kawasaki, Naohito

2016-01-01

In this study, we prepared virgin (S, L) and calcined (S-380, S-1000, L-380, L-1000) magnesium hydroxide for regeneration of waste edible oil. Deterioration of soybean oil, rapeseed oil, and olive oil was achieved by heat and aeration treatment. The properties of the different adsorbents were investigated using specific surface area measurements, scanning electron microscopy, X-ray diffraction analysis, thermogravimetric-differential thermal analysis, and surface pH measurement. Moreover, the relationship between the changes in acid value (AV) and carbonyl value (CV) and the adsorbent properties were evaluated. The specific surface areas of S-380 and L-380 were greater than that of other adsorbents. In addition, the XRD results show that S-380 and L-380 contain both magnesium hydroxide and magnesium oxide structures. The decreases in AV and CV using S-380 and L-380 were greater than achieved using other adsorbents. The correlation coefficients between the decrease in AV and CV and specific surface area were 0.947 for soybean oil, 0.649 for rapeseed oil, and 0.773 for olive oil, respectively. The results obtained in this study suggest that a physical property of the adsorbent, namely specific surface area, was primarily responsible for the observed decreases in AV and CV. Overall, the results suggest that S-380 and L-380 are useful for the regeneration of waste edible oil.

Tailoring surface and photocatalytic properties of ZnO and nitrogen-doped ZnO nanostructures using microwave-assisted facile hydrothermal synthesis

NASA Astrophysics Data System (ADS)

Rangel, R.; Cedeño, V.; Ramos-Corona, A.; Gutiérrez, R.; Alvarado-Gil, J. J.; Ares, O.; Bartolo-Pérez, P.; Quintana, P.

2017-08-01

Microwave hydrothermal synthesis, using an experimental 23 factorial design, was used to produce tunable ZnO nano- and microstructures, and their potential as photocatalysts was explored. Photocatalytic reactions were conducted in a microreactor batch system under UV and visible light irradiation, while monitoring methylene blue degradation, as a model system. The variables considered in the microwave reactor to produce ZnO nano- or microstructures, were time, NaOH concentration and synthesis temperature. It was found that, specific surface area and volume/surface area ratio were affected as a consequence of the synthesis conditions. In the second stage, the samples were plasma treated in a nitrogen atmosphere, with the purpose of introducing nitrogen into the ZnO crystalline structure. The central idea is to induce changes in the material structure as well as in its optical absorption, to make the plasma-treated material useful as photocatalyst in the visible region of the electromagnetic spectrum. Pristine ZnO and nitrogen-doped ZnO compounds were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (BET), XPS, and UV-Vis diffuse reflectance spectroscopy. The results show that the methodology presented in this work is effective in tailoring the specific surface area of the ZnO compounds and incorporation of nitrogen into their structure, factors which in turn, affect its photocatalytic behavior.

Adsorption and desorption of carbaryl on hexadecyl trimethyl ammonium bromide modified zeolite NaY using RGB portable photometer

NASA Astrophysics Data System (ADS)

Patdhanagul, Nopbhasinthu; Chanpaka, Saiphon; Intharaksa, Orapan; Sirival, Rujikarn; Thanomsith, Kannikar; Wongkwanklom, Sarayuth

2018-04-01

The carbaryl adsorption-desorption isotherms of zeolite NaY and hexadecyl trimethyl ammonium bromide (HTAB) modified zeolite NaY were investigated. Zeolite NaY was synthesized and modified by HTAB in the concentration range 0.1 - 10.0 mM. The adsorption isotherms indicated that zeolite modified with HTAB could significantly enhance the carbaryl adsorption capacity. Zeolite NaY modified with 5.0 mM HTAB gave great carbaryl adsorption because of hydrophilic surface. The 5.0 mM HTAB could adsorb up to 145.75 ppm g-1 of carbaryl which was equivalent to a 36.7% increase. The Surface area characterization showed the remaining of pore volume and pore size diameter and external surface area whereas the BET surface area and micropore surface area of modified zeolite slightly decreased. The XRD results indicate that modification of zeolite NaY with HTAB does not change the crystallinity of the starting zeolite. The elemental analysis indicated that the Si/Al ratio of synthesized zeolite NaY was close to 2.43. Desorption of carbaryl was tested by organic solvents such as methanol, ethanol, tetrahydrofuran, hexane and Deionized water. The results demonstrated that the percentage desorption of methanol is the highest. Carbaryl was quantitatively desorbed with percentage desorption of 82-100 %. It indicated sorption mechanism of carbaryl on the modified sorbent which was principally driven by hydrophobic forces.

The role of advanced reactive surface area characterization in improving predictions of mineral reaction rates

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Zhang, S.; Mitnick, E.; Cole, D. R.; Yang, L.; Anovitz, L. M.; Sheets, J.; Swift, A.; Kneafsey, T. J.; Landrot, G.; Mito, S.; Xue, Z.; Steefel, C. I.; DePaolo, D. J.; Ajo Franklin, J. B.

2014-12-01

Geologic sequestration of CO2 in deep sedimentary formations is a promising means of mitigating carbon emissions from coal-fired power plants but the long-term fate of injected CO2 is challenging to predict. Reactive transport models are used to gain insight over long times but rely on laboratory determined mineral reaction rates that have been difficult to extrapolate to field systems. This, in part, is due to a lack of understanding of mineral reactive surface area. Many models use an arbitrary approximation of reactive surface area, applying orders of magnitude scaling factors to measured BET or geometric surface areas. Recently, a few more sophisticated approaches have used 2D and 3D image analyses to determine mineral-specific reactive surface areas that account for the accessibility of minerals. However, the ability of these advanced surface area estimates to improve predictions of mineral reaction rates has yet to be determined. In this study, we fuse X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB analysis to determine mineral-specific accessible reactive surface areas for a core sample from the Nagaoka pilot CO2 injection site (Japan). This sample is primarily quartz, plagioclase, smectite, K-feldspar, and pyroxene. SEM imaging shows abundant smectite cement and grain coatings that decrease the fluid accessibility of other minerals. However, analysis of FIB-SEM images reveals that smectite nano-pores are well connected such that access to underlying minerals is not occluded by smectite coatings. Mineral-specific accessible surfaces are determined, accounting for the connectivity of the pore space with and without connected smectite nano-pores. The large-scale impact of variations in accessibility and dissolution rates are then determined through continuum scale modeling using grid-cell specific information on accessible surface areas. This approach will be compared with a traditional continuum scale model using mineral abundances and common surface area estimates. Ultimately, the effectiveness of advanced surface area characterization to improve mineral dissolution rates will be evaluated by comparison of model results with dissolution rates measured from a flow-through column experiment.

Ceramic Spheres From Cation Exchange Beads

NASA Technical Reports Server (NTRS)

Dynys, F. W.

2003-01-01

Porous ZrO2 and hollow TiO2 spheres were synthesized from a strong acid cation exchange resin. Spherical cation exchange beads, polystyrene based polymer, were used as a morphological-directing template. Aqueous ion exchange reaction was used to chemically bind (ZrO)(2+) ions to the polystyrene structure. The pyrolysis of the polystyrene at 600 C produces porous ZrO2 spheres with a surface area of 24 sq m/g with a mean sphere size of 42 microns. Hollow TiO2 spheres were synthesized by using the beads as a micro-reactor. A direct surface reaction - between titanium isopropoxide and the resin beads forms a hydrous TiO2 shell around the polystyrene core. The pyrolysis of the polystyrene core at 600 C produces hollow anatase spheres with a surface area of 42 sq m/g with a mean sphere size of 38 microns. The formation of ceramic spheres was studied by XRD, SEM and B.E.T. nitrogen adsorption measurements.

The double peaks and symmetric path phenomena in the catalytic activity of Pd/Al2O3-TiO2 catalysts with different TiO2 contents

NASA Astrophysics Data System (ADS)

Zhang, Shen; Guo, Yuyu; Li, Xingying; Wu, Xu; Li, Zhe

2018-06-01

Physicochemical properties of Pd/Al2O3-TiO2 catalysts with different amounts of TiO2 contents were investigated by XRD, nitrogen adsorption-desorption, FTIR, NH3-TPD, H2-TPR and XPS techniques. Catalysts of different compositions were tested in the ethanol oxidation reaction to study the effects of TiO2 contents. Double peaks and symmetric path phenomena were observed at certain temperatures with the increase in TiO2 contents. The symmetric peak phenomena and the diverse activity fluctuations have been ascribed to the controlling factors such as temperature and compositions. With the increase in TiO2 content, the surface area, adsorbed oxygen contents and surface acid quantity decreased gradually. The large surface area and adsorbed oxygen contents were conducive to the performance, while increased acid amounts were not beneficial for ethanol oxidation. At 150 and 175 °C, Pd/AT(X1

Biopolymer protected silver nanoparticles on the support of carbon nanotube as interface for electrocatalytic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Satyanarayana, M.; Kumar, V. Sunil; Gobi, K. Vengatajalabathy, E-mail: drkvgobi@gmail.com, E-mail: satyam.nitw@gmail.com

In this research, silver nanoparticles (SNPs) are prepared on the surface of carbon nanotubes via chitosan, a biopolymer linkage. Here chitosan act as stabilizing agent for nanoparticles and forms a network on the surface of carbon nanotubes. Synthesized silver nanoparticles-MWCNT hybrid composite is characterized by UV-Visible spectroscopy, XRD analysis, and FESEM with EDS to evaluate the structural and chemical properties of the nanocomposite. The electrocatalytic activity of the fabricated SNP-MWCNT hybrid modified glassy carbon electrode has been evaluated by cyclic voltammetry and electrochemical impedance analysis. The silver nanoparticles are of size ∼35 nm and are well distributed on the surface ofmore » carbon nanotubes with chitosan linkage. The prepared nanocomposite shows efficient electrocatalytic properties with high active surface area and excellent electron transfer behaviour.« less

The Mineralogy of Martian Dust: Design and Analysis Considerations for an X-Ray Diffraction/X-Ray Fluorescence (XRD/XRF) Instrument for Exobiological Studies

NASA Technical Reports Server (NTRS)

Blake, David; Vaniman, David; Bish, David; Morrison, David (Technical Monitor)

1994-01-01

A principal objective of Mars exploration is the search for evidence of past life which may have existed during an earlier clement period of Mars history. We would like to investigate the history of surface water activity (which is a requirement for all known forms of life) by identifying and documenting the distribution of minerals which require water for their formation or distribution. A knowledge of the mineralogy of the present Martian surface would help to identify areas which, due to the early activity of water, might have harbored ancient life. It would be desirable to establish the presence and characterize the distribution of hydrated minerals such as clays, and of minerals which are primarily of sedimentary origin such as carbonates, silica and evaporites. Mineralogy, which is more critical to exobiological exploration than is simple chemical analysis (absent the detection of organics), will remain unknown or will at best be imprecisely constrained unless a technique sensitive to mineral structure such as powder X-ray diffraction (XRD) is employed. Additional information is contained in the original extended abstract.

Textured Pr{sub 2}Fe{sub 14}B flakes with submicron or nanosize thickness prepared by surfactant-assisted ball milling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zuo, Wen-Liang, E-mail: wlzuo@iphy.ac.cn, E-mail: shenbg@aphy.iphy.ac.cn; Liu, Rong-Ming; Zheng, Xin-Qi

2014-05-07

The textured Pr{sub 2}Fe{sub 14}B nanoflakes were produced by surfactant-assisted ball milling (SABM). Single phase tetragonal structure was characterized for the samples before and after SABM by X-ray diffraction (XRD). The thickness and length of the as-milled flakes are mainly in the range of 50–150 nm and 0.5–2 μm, respectively. For the field-aligned Pr{sub 2}Fe{sub 14}B nanoflakes, the out-of-plane texture (the easy magnetization direction (EMD) along the c-axis) is indicated from the increasing (00l) peaks in the XRD patterns. SEM image demonstrates that the EMD is parallel to flaky surface, which is different from the RCo{sub 5} (R = rare earth) system with EMDmore » perpendicular to the surface. We propose a hypothesis that the easy glide planes are related with the area of crystal planes. In addition, a large coercivity H{sub c} = 3.9 kOe is observed in the Pr{sub 2}Fe{sub 14}B flakes with strong texture.« less

Chemical synthesis of hierarchical NiCo2S4 nanosheets like nanostructure on flexible foil for a high performance supercapacitor.

PubMed

Kim, D -Y; Ghodake, G S; Maile, N C; Kadam, A A; Sung Lee, Dae; Fulari, V J; Shinde, S K

2017-08-29

In this study, hierarchical interconnected nickel cobalt sulfide (NiCo 2 S 4 ) nanosheets were effectively deposited on a flexible stainless steel foil by the chemical bath deposition method (CBD) for high-performance supercapacitor applications. The resulting NiCo 2 S 4 sample was characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and electrochemical measurements. XRD and X-ray photoelectron spectroscopy (XPS) results confirmed the formation of the ternary NiCo 2 S 4 sample with a pure cubic phase. FE-SEM and HR-TEM revealed that the entire foil surface was fully covered with the interconnected nanosheets like surface morphology. The NiCo 2 S 4 nanosheets demonstrated impressive electrochemical characteristics with a specific capacitance of 1155 F g -1 at 10 mV s -1 and superior cycling stability (95% capacity after 2000 cycles). These electrochemical characteristics could be attributed to the higher active area and higher conductivity of the sample. The results demonstrated that the interconnected NiCo 2 S 4 nanosheets are promising as electrodes for supercapacitor and energy storage applications.

Porous carbon materials synthesized using IRMOF-3 and furfuryl alcohol as precursor

NASA Astrophysics Data System (ADS)

Deka, Pemta Tia; Ediati, Ratna

2016-03-01

IRMOF-3 crystals have been synthesized using solvothermal method by adding zinc nitrate hexahydrate with 2-amino-1,4-benzenedicarboxylic acid in N'N-dimethylformamide (DMF) at 100°C for 24 (note as IR-24) and 72 h (note as IR-72). The obtained crystals were characterized using X-ray Diffraction (XRD), SEM (Scanning Electron Microscopy) and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), FTIR and Isothermal adsorption-desorption N2. The diffractogram solids synthesized show characteristic peak at 2θ 6.8, 9.6 and 13.7°. SEM micrograph show cubic shape of IRMOF-3 crystal. Based on FTIR characterization, IRMOF-3 appear at wavelength (1691,46; 1425,3; 1238,21; 1319,22 dan 3504,42)cm-1. The Isotherm of crystal IRMOF-3 at heating time 24 h and 72 h are type IV. The surface area of IR-24 and IR-72 are respectively 24,758 m2/g and 29,139 m2/g with its dominant mesopores. Carbonaceous materials has been successfully synthesized using IR-24, IR-72 and furfuryl alcohol (FA) as second carbon precursor with variation of carbonation temperature 550, 700 and 850°C. The XRD result from both carbonaceous materials show formation of amorphous carbon and caharacteristic peak of ZnO oxide. Micrograph SEM show that carbonaceous materials have cubic shape as IRMOF-3 and SEM-EDX result indicate Zn and nitrogen content of these materials has decrease until temperature 850°C. Porous carbon using IR-24 and FA (notes as C-24) has increased surface area with higher carbonation temperature. The highest surface area is 1495,023 m2/g. Total pore volume and pore size of C-24 from low to high temperature respectively as (0,338; 0,539 and 1,598) cc/g; (0,107; 0,152 and 0,610) cc/g. Porous carbon using IR-72 and FA (notes as C-72) has smaller surface area than C-24 but its also increased during higher carbonation heating. The highest surface area is 1029,668 m2/g.The total pore volume and pore size of these carbon materials from low to high temperature respectively as (0,390; 0,727 and 1,345) cc/g and (0,065; 0,157 and 0,381) cc/g. Carbonaceous materials with high porosity and nitrogen content will be expected increase mechanical properties and hydrogen storage from these materials.

Titania nanotube powders obtained by rapid breakdown anodization in perchloric acid electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, Saima, E-mail: saima.ali@aalto.fi; Hannula, Simo-Pekka

Titania nanotube (TNT) powders are prepared by rapid break down anodization (RBA) in a 0.1 M perchloric acid (HClO{sub 4}) solution (Process 1), and ethylene glycol (EG) mixture with HClO{sub 4} and water (Process 2). A study of the as-prepared and calcined TNT powders obtained by both processes is implemented to evaluate and compare the morphology, crystal structure, specific surface area, and the composition of the nanotubes. Longer TNTs are formed in Process 1, while comparatively larger pore diameter and wall thickness are obtained for the nanotubes prepared by Process 2. The TNTs obtained by Process 1 are converted tomore » nanorods at 350 °C, while nanotubes obtained by Process 2 preserve tubular morphology till 350 °C. In addition, the TNTs prepared by an aqueous electrolyte have a crystalline structure, whereas the TNTs obtained by Process 2 are amorphous. Samples calcined till 450 °C have XRD peaks from the anatase phase, while the rutile phase appears at 550 °C for the TNTs prepared by both processes. The Raman spectra also show clear anatase peaks for all samples except the as-prepared sample obtained by Process 2, thus supporting the XRD findings. FTIR spectra reveal the presence of O-H groups in the structure for the TNTs obtained by both processes. However, the presence is less prominent for annealed samples. Additionally, TNTs obtained by Process 2 have a carbonaceous impurity present in the structure attributed to the electrolyte used in that process. While a negligible weight loss is typical for TNTs prepared from aqueous electrolytes, a weight loss of 38.6% in the temperature range of 25–600 °C is found for TNTs prepared in EG electrolyte (Process 2). A large specific surface area of 179.2 m{sup 2} g{sup −1} is obtained for TNTs prepared by Process 1, whereas Process 2 produces nanotubes with a lower specific surface area. The difference appears to correspond to the dimensions of the nanotubes obtained by the two processes. - Graphical abstract: Titania nanotube powders prepared by Process 1 and Process 2 have different crystal structure and specific surface area. - Highlights: • Titania nanotube (TNT) powder is prepared in low water organic electrolyte. • Characterization of TNT powders prepared from aqueous and organic electrolyte. • TNTs prepared by Process 1 are crystalline with higher specific surface area. • TNTs obtained by Process 2 have carbonaceous impurities in the structure.« less

Silica Aerogel-supported Hydrozincite and Carbonate-intercalated Hydrotalcite for High-efficiency Removal of Pb(II) Ions by Precipitation Transformation Reactions.

PubMed

Wang, Lijun; Wang, Xiaoxia; Li, Jianfa; Feng, Xiaolan; Wang, Yusen

2017-09-25

In this work, hydrozincite and Zn/Al-CO 3 2- hydrotalcite supported on silica aerogel were prepared via a simple and economical process and used as adsorbents for Pb(II) removal. The supported hydrozincite and Zn/Al-CO 3 2- hydrotalcite possess ultra-thin thickness, high surface area, and weak crystallinity. In the batch Pb(II) adsorption experiments, the adsorbents with higher Zn(II) contents showed higher Pb(II) adsorption capacities, and the adsorption data fitted well with the Langmuir isotherm model and pseudo-second-order kinetic model, indicating a mechanism of surface chemisorption. The adsorption capacities calculated based Langmuir isotherm model are 684.9 mg/g and 555.6 mg/g for the supported hydrozincite and Zn/Al-CO 3 2- hydrotalcite, respectively, higher than the adsorption capacities of other hydrotalcite-based adsorbents and most of other inorganic adsorbents reported previously. The XRD diffraction peaks of hydrozincite and Zn/Al-CO 3 2- hydrotalcite disappeared after the adsorption, and the Pb(II) species were uniformly dispersed in the adsorbents in form of Pb 3 (CO 3 ) 2 (OH) 2 proven by TEM, EDS mapping and XRD analysis, demonstrating the nature of the adsorption is the precipitation conversion of hydrozincite or Zn/Al-CO 3 2- hydrotalcite into Pb 3 (CO 3 ) 2 (OH) 2 . These results demonstrate the synergic Pb(II) removal effect of the CO 3 2- and OH - derived from hydrozincite and Zn/Al-CO 3 2- hydrotalcite together with their ultra-thin thickness and high surface area contribute the excellent properties of the adsorbents.

The Sulphur Poisoning Behaviour of Gadolinia Doped Ceria Model Systems in Reducing Atmospheres

PubMed Central

Gerstl, Matthias; Nenning, Andreas; Iskandar, Riza; Rojek-Wöckner, Veronika; Bram, Martin; Hutter, Herbert; Opitz, Alexander Karl

2016-01-01

An array of analytical methods including surface area determination by gas adsorption using the Brunauer, Emmett, Teller (BET) method, combustion analysis, XRD, ToF-SIMS, TEM and impedance spectroscopy has been used to investigate the interaction of gadolinia doped ceria (GDC) with hydrogen sulphide containing reducing atmospheres. It is shown that sulphur is incorporated into the GDC bulk and might lead to phase changes. Additionally, high concentrations of silicon are found on the surface of model composite microelectrodes. Based on these data, a model is proposed to explain the multi-facetted electrochemical degradation behaviour encountered during long term electrochemical measurements. While electrochemical bulk properties of GDC stay largely unaffected, the surface polarisation resistance is dramatically changed, due to silicon segregation and reaction with adsorbed sulphur. PMID:28773771

Characterization of biochar prepared from biogas digestate.

PubMed

Hung, Chao-Yi; Tsai, Wen-Tien; Chen, Jie-Wei; Lin, Yu-Quan; Chang, Yuan-Ming

2017-08-01

In the study, the biogas digestate was evaluated as a potential feedstock for preparing biochars at a broad temperature range of 300-900°C. The physico-chemical and pore properties of the resulting biochars (denoted as SDBC, solid digestate biochar), including calorific value (higher heating value), surface area/pore volume/pore size distribution, true density, scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD), were studied. It was found that the higher heating values of the SDBC products were on a decreasing trend as pyrolysis temperature increased, but they indicated an increase in true density. The results are probably associated with the active pyrolysis of the lignocellulosic fragments and the calcination (or shrinkage) processes, thus resulting in the increased contents of aromatic carbon clusters and main mineral constituents remained. Based on the pore properties, pyrolysis temperature at around 800°C seemed to be the optimal condition for producing SDBC, where its Brunauer-Emmet-Teller (BET) surface area (>100m 2 /g) largely increased as compared to that of the digestate feedstock (<1m 2 /g). Furthermore, the main compositions of mineral ash in the resulting biochar could exist as phosphates, carbonates, or oxides of calcium and other alkali/alkaline earth elements. According to the data on EDS and XRD, more pores could be significantly generated under severe pyrolysis (>700°C) due to the high aromaticity via the thermal decomposition of lignocelluloses and the volatilization of inorganic minerals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrothermal synthesis of high surface area ZIF-8 with minimal use of TEA

NASA Astrophysics Data System (ADS)

Butova, V. V.; Budnyk, A. P.; Bulanova, E. A.; Lamberti, C.; Soldatov, A. V.

2017-07-01

In this paper we present, for the first time, a simple hydrothermal recipe for the synthesis of ZIF-8 Metal-Organic Framework (MOF) with a large specific surface area (1340 m2/g by BET). An important feature of the method is that the product forms in aqueous medium under standard hydrothermal conditions without DMF and great excess of linker with the use of TEA as structure directing agent. The ZIF-8 crystal phase of the product was confirmed by XRD; this technique has been also exploited to check the crystallinity and to follow the changes in the MOF structure induced by heating. TGA and temperature dependent XRD testify the high thermal stability of the material (470 °C in N2 and at 400 °C in air). The IR spectral profile of the material provides a complete picture of vibrations assigned to the linker and the metal center. The systematic investigation of the products obtained by increasing the TEA amount in the reacting medium from 0 to 25.5 mol equivalent Zn2+, allowed us to understand its role and to find 2.6 mol equivalent Zn2+ as the minimum amount needed to obtain a single phase ZIF-8 material with the high standard reported above. The stability of the material under severe basic conditions makes it a promising candidate in heterogeneous catalysis. The material has shown high capacity in I2 uptake, making it interesting also for selective molecular adsorption.

Synthesis and characterization of MOF-aminated graphite oxide composites for CO2 capture

NASA Astrophysics Data System (ADS)

Zhao, Yunxia; Ding, Huiling; Zhong, Qin

2013-11-01

A kind of metal-organic frameworks (MOF-5) and aminated graphite oxide (AGO) composites were prepared for CO2 capture to mitigate global warming. MOF-5, MOF-5/GO (composite of MOF-5 and graphite oxide) and MOF-5/AGO samples were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscope (SEM), nitrogen adsorption as well as thermogravimetric analysis to figure out their chemistry and structure information. Three types of samples with suitable specific surface area and pore diameter were chosen to test CO2 adsorption performance and stability under humidity conditions. The results indicate that high surface area and pore volume, pore similar in size to the size of gas adsorbate, and extra reactive sites modified in the composites contributes to the high CO2 capacity. Besides, the composites involved by GO or AGO show better anti-moisture performance than the parent MOF.

Mesoporous CeO2 nanoparticles synthesized by an inverse miniemulsion technique and their catalytic properties in methane oxidation

NASA Astrophysics Data System (ADS)

Nabih, Nermeen; Schiller, Renate; Lieberwirth, Ingo; Kockrick, Emanuel; Frind, Robert; Kaskel, Stefan; Weiss, Clemens K.; Landfester, Katharina

2011-04-01

Cerium(IV) oxide nanoparticles were synthesized using an inverse miniemulsion technique with cerium nitrate hexahydrate as precursor. The resulting nanocrystallites are as small as 5 nm with a specific surface area of 158 m2 g - 1 after calcination at 400 °C. With the addition of cetyltrimethylammonium bromide (CTAB) or (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)) triblock copolymers (PEO-PPO-PEO) as template in the miniemulsion droplets, the specific surface area can be increased up to 255 m2 g - 1. The miniemulsions were characterized by dynamic light scattering (DLS) and the obtained oxides were examined by x-ray diffraction (XRD), nitrogen sorption (BET and BJH), and transmission electron microscopy (TEM). The catalytic activity of the resulting ceria was investigated for the temperature-programmed oxidation (TPO) of methane.

A novel particle engineering technology to enhance dissolution of poorly water soluble drugs: spray-freezing into liquid.

PubMed

Rogers, True L; Nelsen, Andrew C; Hu, Jiahui; Brown, Judith N; Sarkari, Marazban; Young, Timothy J; Johnston, Keith P; Williams, Robert O

2002-11-01

A novel cryogenic spray-freezing into liquid (SFL) process was developed to produce microparticulate powders consisting of an active pharmaceutical ingredient (API) molecularly embedded within a pharmaceutical excipient matrix. In the SFL process, a feed solution containing the API was atomized beneath the surface of a cryogenic liquid such that the liquid-liquid impingement between the feed and cryogenic liquids resulted in intense atomization into microdroplets, which were frozen instantaneously into microparticles. The SFL micronized powder was obtained following lyophilization of the frozen microparticles. The objective of this study was to develop a particle engineering technology to produce micronized powders of the hydrophobic drug, danazol, complexed with hydroxypropyl-beta-cyclodextrin (HPbetaCD) and to compare these SFL micronized powders to inclusion complex powders produced from other techniques, such as co-grinding of dry powder mixtures and lyophilization of bulk solutions. Danazol and HPbetaCD were dissolved in a water/tetrahydrofuran cosolvent mixture prior to SFL processing or slow freezing. Identical quantities of the API and HPbetaCD used in the solutions were co-ground in a mortar and pestle and blended to produce a co-ground physical mixture for comparison. The powder samples were characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy, surface area analysis, and dissolution testing. The results provided by DSC, XRD, and FTIR suggested the formation of inclusion complexes by both slow-freezing and SFL. However, the specific surface area was significantly higher for the latter. Dissolution results suggested that equilibration of the danazol/HPbetaCD solution prior to SFL processing was required to produce the most soluble conformation of the resulting inclusion complex following SFL. SFL micronized powders exhibited better dissolution profiles than the slowly frozen aggregate powder. Results indicated that micronized SFL inclusion complex powders dissolved faster in aqueous dissolution media than inclusion complexes formed by conventional techniques due to higher surface areas and stabilized inclusion complexes obtained by ultra-rapid freezing.

One Step Assembly of Thin Films of Carbon Nanotubes on Screen Printed Interface for Electrochemical Aptasensing of Breast Cancer Biomarker.

PubMed

Nawaz, Muhammad Azhar Hayat; Rauf, Sajid; Catanante, Gaelle; Nawaz, Mian Hasnain; Nunes, Gilvanda; Marty, Jean Louis; Hayat, Akhtar

2016-10-06

Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer-Emmett- Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications.

One Step Assembly of Thin Films of Carbon Nanotubes on Screen Printed Interface for Electrochemical Aptasensing of Breast Cancer Biomarker

PubMed Central

Nawaz, Muhammad Azhar Hayat; Rauf, Sajid; Catanante, Gaelle; Nawaz, Mian Hasnain; Nunes, Gilvanda; Louis Marty, Jean; Hayat, Akhtar

2016-01-01

Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications. PMID:27782067

Distributions of clay minerals in surface sediments of the middle Bay of Bengal: Source and transport pattern

NASA Astrophysics Data System (ADS)

Li, Jingrui; Liu, Shengfa; Shi, Xuefa; Feng, Xiuli; Fang, Xisheng; Cao, Peng; Sun, Xingquan; Wenxing, Ye; Khokiattiwong, Somkiat; Kornkanitnan, Narumol

2017-08-01

The clay mineral contents in 110 surface sediment samples collected from the middle of the Bay of Bengal were analyzed by X-ray diffraction (XRD) to investigate the provenance and transport patterns. The illite content was highest, followed by chlorite, kaolinite and then smectite, with average weight percent distributions of 52%, 22%, 14% and 12%, respectively. Illite and chlorite had similar distribution pattern, with higher contents in the northern and central areas and lower contents in the southern area, whereas smectite showed the opposite distribution pattern. Kaolinite show no obvious higher or lower areas and the southern ;belt; was one of the highest content areas. Based on the spatial distribution characteristics and cluster analysis results, the study area can be classified into two provinces. Province I covers the southwestern area and contains high concentrations of illite and smectite sediments. Province II covers most sites and is also characterized by high concentrations of illite, but the weight percent of smectite is only half of that of province I. According to a quantitative estimate using end-member clay minerals contents, the relative contributions from the Himalayan source and the Indian source are 63% and 37% on average, respectively. Integrative analysis indicates that the hydrodynamic environment in the study area, especially the turbidity and surface monsoonal circulation, plays an important role in the spatial distribution and dispersal of the clay fraction in the sediments. The sediments in province I are mainly from the Indian source transported by the East Indian Coastal Current (EICC) and the surface monsoon circulation with minor contributions from the Himalayan source while the sediments in province II are mainly from the Himalayan source transported by turbidity and surface monsoonal circulation with little contribution from Indian river materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jomekian, A.; Faculty of Chemical Engineering, Iran University of Science and Technology; Behbahani, R.M., E-mail: behbahani@put.ac.ir

Ultra porous ZIF-8 particles synthesized using PEO/PA6 based poly(ether-block-amide) (Pebax 1657) as structure directing agent. Structural properties of ZIF-8 samples prepared under different synthesis parameters were investigated by laser particle size analysis, XRD, N{sub 2} adsorption analysis, BJH and BET tests. The overall results showed that: (1) The mean pore size of all ZIF-8 samples increased remarkably (from 0.34 nm to 1.1–2.5 nm) compared to conventionally synthesized ZIF-8 samples. (2) Exceptional BET surface area of 1869 m{sup 2}/g was obtained for a ZIF-8 sample with mean pore size of 2.5 nm. (3) Applying high concentrations of Pebax 1657 to themore » synthesis solution lead to higher surface area, larger pore size and smaller particle size for ZIF-8 samples. (4) Both, Increase in temperature and decrease in molar ratio of MeIM/Zn{sup 2+} had increasing effect on ZIF-8 particle size, pore size, pore volume, crystallinity and BET surface area of all investigated samples. - Highlights: • The pore size of ZIF-8 samples synthesized with Pebax 1657 increased remarkably. • The BET surface area of 1869 m{sup 2}/gr obtained for a ZIF-8 synthesized sample with Pebax. • Increase in temperature had increasing effect on textural properties of ZIF-8 samples. • Decrease in MeIM/Zn{sup 2+} had increasing effect on textural properties of ZIF-8 samples.« less

Use of glancing angle X-ray powder diffractometry to depth-profile phase transformations during dissolution of indomethacin and theophylline tablets.

PubMed

Debnath, Smita; Predecki, Paul; Suryanarayanan, Raj

2004-01-01

The purpose of this study was (i) to develop glancing angle x-ray powder diffractometry (XRD) as a method for profiling phase transformations as a function of tablet depth; and (ii) to apply this technique to (a) study indomethacin crystallization during dissolution of partially amorphous indomethacin tablets and to (b) profile anhydrate --> hydrate transformations during dissolution of theophylline tablets. The intrinsic dissolution rates of indomethacin and theophylline were determined after different pharmaceutical processing steps. Phase transformations during dissolution were evaluated by various techniques. Transformation in the bulk and on the tablet surface was characterized by conventional XRD and scanning electron microscopy, respectively. Glancing angle XRD enabled us to profile these transformations as a function of depth from the tablet surface. Pharmaceutical processing resulted in a decrease in crystallinity of both indomethacin and theophylline. When placed in contact with the dissolution medium, while indomethacin recrystallized, theophylline anhydrate rapidly converted to theophylline monohydrate. Due to intimate contact with the dissolution medium, drug transformation occurred to a greater extent at or near the tablet surface. Glancing angle XRD enabled us to depth profile the extent of phase transformations as a function of the distance from the tablet surface. The processed sample (both indomethacin and theophylline) transformed more rapidly than did the corresponding unprocessed drug. Several challenges associated with the glancing angle technique, that is, the effects of sorbed water, phase transformations during the experimental timescale, and the influence of phase transformation on penetration depth, were addressed. Increased solubility, and consequently dissolution rate, is one of the potential advantages of metastable phases. This advantage is negated if, during dissolution, the metastable to stable transformation rate > dissolution rate. Glancing angle XRD enabled us to quantify and thereby profile phase transformations as a function of compact depth. The technique has potential utility in monitoring surface reactions, both chemical decomposition and physical transformations, in pharmaceutical systems.

Comparison of titanium soaked in 5 M NaOH or 5 M KOH solutions

PubMed Central

Kim, Christina; Kendall, Matthew R.; Miller, Matthew A.; Long, Courtney L.; Larson, Preston R.; Humphrey, Mary Beth; Madden, Andrew S.; Tas, A. Cuneyt

2012-01-01

Commercially pure titanium plates/coupons and pure titanium powders were soaked for 24 h in 5 M NaOH and 5 M KOH solutions, under identical conditions, over the temperature range of 37° to 90°C. Wettability of the surfaces of alkali-treated cpTi coupons were studied by using contact angle goniometry. cpTi coupons soaked in 5 M NaOH or 5 M KOH solutions were found to have hydrophilic surfaces. Hydrous alkali titanate nanofibers and nanotubes were identified with SEM/EDXS and grazing incidence XRD. Surface areas of Ti powders increased >50–220 times, depending on the treatment, when soaked in the above solutions. A solution was developed to coat amorphous calcium phosphate, instead of hydroxyapatite, on Ti coupon surfaces. In vitro cell culture tests were performed with osteoblast-like cells on the alkali-treated samples. PMID:23565038

KOH-activated multi-walled carbon nanotubes as platinum supports for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

He, Chaoxiong; Song, Shuqin; Liu, Jinchao; Maragou, Vasiliki; Tsiakaras, Panagiotis

In the present investigation, multi-walled carbon nanotubes (MWCNTs) thermally treated by KOH were adopted as the platinum supporting material for the oxygen reduction reaction electrocatalysts. FTIR and Raman spectra were used to investigate the surface state of MWCNTs treated by KOH at different temperatures (700, 800, and 900 °C) and showed MWCNTs can be successfully functionalized. The structural properties of KOH-activated MWCNTs supported Pt were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their electrochemical performance was evaluated by the aid of cyclic voltammetry (CV) and rotating disk electrode (RDE) voltammetry. According to the experimental findings of the present work, the surrface of MWCNTs can be successfully functionalized with oxygen-containing groups after activation by KOH, favoring the good dispersion of Pt nanoparticles with narrow size distribution. The as-prepared Pt catalysts supported on KOH treated MWCNTs at higher temperature, possess higher electrochemical surface area and exhibit desirable activity towards oxygen reduction reaction (ORR). More precisely, it has been found that the electrochemical active area of Pt/MWCNTs-900 is approximately two times higher than that of Pt/MWCNTs. It can be concluded that KOH activation is an effective way to decorate MWCNTs' surface with oxygen-containing groups and bigger surface area, which makes them more suitable as electrocatalyst support materials.

Nanoporous activated carbon derived from Lapsi (Choerospondias axillaris) seed stone for the removal of arsenic from water.

PubMed

Rajbhandari, Rinita; Shrestha, Lok Kumar; Pradhananga, Raja Ram

2012-09-01

Activated carbons were prepared from Lapsi (Choerospondias axillaris) seed stone by zinc chloride (ZnCl2) activation at three different Lapsi seed powder (LSP):ZnCl2 ratios: 1:0.5 (AC-0.5), 1:1 (AC-1), and 1:2 (AC-2). The properties of these activated carbons (ACs), including effective surface areas, pore volumes, and pore size distributions were characterized from N2 adsorption-desorption isotherms. The ACs obtained were essentially nanoporous (including both micro- and mesoporous) with effective surface area ranging from 1167 to 1328 m2/g. Fourier-transform infrared (FTIR) spectroscopy showed the presence of functional groups on the surface of ACs. Scanning electron microscopy (SEM) images showed a high pore development in the ACs. X-ray diffraction (XRD) patterns showed that, in addition to the amorphous structure, ACs contains crystalline ZnO formed during the carbonization. Presence of amorphous carbon is further confirmed by Raman scattering, where we observed only D and G bands. Iron impregnated nanoporous AC has been found to be very effective for arsenic removal from ground water; amount of arsenic is decreased from ca. 200 ppb to 10 ppb. These experimental results indicate the potential use of Lapsi seed as a precursor material for the preparation of high surface area nanoporous activated carbons.

X-ray Photoelectron Spectroscopy study of CaV1-xMoxO3-δ

NASA Astrophysics Data System (ADS)

Belyakov, S. A.; Kuznetsov, M. V.; Shkerin, S. N.

2018-06-01

An investigation was carried out on perovskite-based derivatives of CaV1-xMoxO3-δ using X-ray Photoelectron Spectroscopy (XPS). According to the XRD pattern, the area of homogeneity covers the region from x = 0 to x = 0.6. Wide XPS-peaks of Ca, V, Mo and O are observed, signalling that elements are presented in multiple states. A model for explaining the large chemical shifts of XPS peaks due to different charging effects on different parts of the sample surface is proposed.

Hydrothermal synthesis of porous triphasic hydroxyapatite/(alpha and beta) tricalcium phosphate.

PubMed

Vani, R; Girija, E K; Elayaraja, K; Prakash Parthiban, S; Kesavamoorthy, R; Narayana Kalkura, S

2009-12-01

A novel, porous triphasic calcium phosphate composed of nonresorbable hydroxyapatite (HAp) and resorbable tricalcium phosphate (alpha- and beta-TCP) has been synthesized hydrothermally at a relatively low temperature. The calcium phosphate precursor for hydrothermal treatment was prepared by gel method in the presence of ascorbic acid. XRD, FT-IR, Raman analyses confirmed the presence of HAp/TCP. The surface area and average pore size of the samples were found to be 28 m2/g and 20 nm, respectively. The samples were found to be bioactive in simulated body fluid (SBF).

Structure, morphology and reducibility of ceria-doped zirconia

NASA Astrophysics Data System (ADS)

Aribi, Koubra; Soltani, Zohra; Ghelamallah, Madani; Granger, Pascal

2018-03-01

Zr1-xCexOx has been prepared by hydrolysis, in neutral medium, starting from rough ZrO2 and CeO2 materials as simple and cheaper synthesis method compared to sol-gel routes. The oxy-hydroxide precursors thus obtained were calcined under air at 450 °C, 900 °C and 1200 °C. The impact of those thermal treatments on the structure, texture and related redox properties has been investigated. Higher specific surface area than those observed on ceria were observed after calcination at low temperature, i.e., 450 °C. Above that temperature thermal sintering occurs having a detrimental effect on the specific surface area related to crystal growth more accentuated on CeO2. The formation of several Zrsbnd Ce mixed oxide phases formed by incorporation and substitution of Zr in the structure of ceria was characterized. A complete loss of specific surface area is noticeable after calcination at 1200 °C. XRD and SEM analysis revealed the formation of two mixed oxides structure, i.e. Ce2Zr2O7.04 and Ce2Zr2O7 corresponding to different redox behavior evidenced from H2-TPR experiments.

DC Electric Arc Furnace Application for Production of Nickel-Boron Master Alloys

NASA Astrophysics Data System (ADS)

Alkan, Murat; Tasyürek, Kerem Can; Bugdayci, Mehmet; Turan, Ahmet; Yücel, Onuralp

2017-09-01

In this study, nickel-boron (Ni-B) alloys were produced via a carbothermic reduction starting from boric acid (H3BO3) with high-purity nickel oxide (NiO), charcoal, and wood chips in a direct current arc furnace. In electric arc furnace experiments, different starting mixtures were used, and their effects on the chemical compositions of the final Ni-B alloys were investigated. After the reduction and melting stages, Ni-B alloys were obtained by tapping from the bottom of the furnace. The samples from the designated areas were also taken and analyzed. The chemical composition of the final alloys and selected samples were measured with wet chemical analysis. The Ni-B alloys had a composition of up to 14.82 mass% B. The phase contents of the final alloys and selected samples were measured using x-ray diffraction (XRD). The XRD data helped predict possible reactions and reaction mechanisms. The material and energy balance calculations were made via the XRD Rietveld and chemical compositions. Nickel boride phases started to form 600 mm below the surface. The targeted NiB phase was detected at the tapping zone of the crucible (850-900 mm depth). The energy consumption was 1.84-4.29 kWh/kg, and the electrode consumption was 10-12 g/kg of raw material charged.

[Preparation of large area Al-ZnO thin film by DC magnetron sputtering].

PubMed

Jiao, Fei; Liao, Cheng; Han, Jun-Feng; Zhou, Zhen

2009-03-01

Solar cells of p-CIS/n-buffer/ZnO type, where CIS is (CuInS2, CuInSe2 or intermediates, are thin-film-based devices for the future high-efficiency and low-cost photovoltaic devices. As important thin film, the properties of Al-doped ZnO (AZO) directly affect the parameter of the cell, especially for large volume. In the present paper, AZO semiconductor transparent thin film on soda-lime glass was fabricated using cylindrical zinc-aluminum target, which can not only lower the cost of the target but also make the preparation of large area AZO thin film more easily. Using the DC magnet sputtering techniques and rolling target, high utilization efficiency of target was achieved and large area uniform and directional film was realized. An introduction to DC magnet sputtering techniques for large area film fabrication is given. With different measurement methods, such as X-ray diffraction (XRD) and scan electron microscope (SEM), we analyzed large size film's structure, appearance, and electrical and optical characteristics. The XRD spectrum indicated that the AZO film shows well zinc-blende structure with a preferred (002) growth and the c-axis is oriented normal to the substrate plane. The lattice constant is 5.603 9 nm and the mismatch with CdS thin film is only 2 percent. It absolutely satisfied the demand of the GIGS solar cell. The cross-section of the AZO thin film indicates the columnar structure and the surface morphology shows that the crystal size is about 50 nm that is consistent with the result of XRD spectrum. By the optical transmission curve, not only the high transmission rate over 85 percent in the visible spectrum between 400 nm and 700 nm was showed but also the band gap 3.1 eV was estimated. And all these parameters can meet the demand of the large area module of GIGS solar cell. The result is that using alloy target and Ar gas, and controlling the appropriate pressure of oxygen, we can get directional, condensed, uniform, high transmitting rate, low resistance and large size (300 mm x 300 mm) AZO film.

Estimation of lattice strain in nanocrystalline RuO2 by Williamson-Hall and size-strain plot methods

NASA Astrophysics Data System (ADS)

Sivakami, R.; Dhanuskodi, S.; Karvembu, R.

2016-01-01

RuO2 nanoparticles (RuO2 NPs) have been successfully synthesized by the hydrothermal method. Structure and the particle size have been determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). UV-Vis spectra reveal that the optical band gap of RuO2 nanoparticles is red shifted from 3.95 to 3.55 eV. BET measurements show a high specific surface area (SSA) of 118-133 m2/g and pore diameter (10-25 nm) has been estimated by Barret-Joyner-Halenda (BJH) method. The crystallite size and lattice strain in the samples have been investigated by Williamson-Hall (W-H) analysis assuming uniform deformation, deformation stress and deformation energy density, and the size-strain plot method. All other relevant physical parameters including stress, strain and energy density have been calculated. The average crystallite size and the lattice strain evaluated from XRD measurements are in good agreement with the results of TEM.

Cyclic Oxidation and Hot Corrosion Behavior of Nickel-Iron-Based Superalloy

NASA Astrophysics Data System (ADS)

Chellaganesh, D.; Adam Khan, M.; Winowlin Jappes, J. T.; Sathiyanarayanan, S.

2018-01-01

The high temperature oxidation and hot corrosion behavior of nickel-iron-based superalloy are studied at 900 ° and 1000 °C. The significant role of alloying elements with respect to the exposed medium is studied in detail. The mass change per unit area was catastrophic for the samples exposed at 1000 °C and gradual increase in mass change was observed at 900 °C for both the environments. The exposed samples were further investigated with SEM, EDS and XRD analysis to study the metallurgical characteristics. The surface morphology has expressed the in situ nature of the alloy and its affinity toward the environment. The EDS and XRD analysis has evidently proved the presence of protective oxides formation on prolonged exposure at elevated temperature. The predominant oxide formed during the exposure at high temperature has a major contribution toward the protection of the samples. The nickel-iron-based superalloy is less prone to oxidation and hot corrosion when compared to the existing alloy in gas turbine engine simulating marine environment.

Synthesis and characterization of SBA-3, SBA-15, and SBA-1 nanostructured catalytic materials.

PubMed

Anunziata, Oscar A; Beltramone, Andrea R; Martínez, Maria L; Belon, Lizandra López

2007-11-01

A highly ordered large pore mesoporous silica molecular sieve SBA-3, SBA-15, Al-SBA-15, and SBA-1, were developed and characterized by XRD, BET, FTIR, SEM, and NMR-MAS. The catalytic materials were synthesized using different raw materials and operation conditions. These materials contain a regular arrangement of uniform channels with diameters between 1.8 and 10 nm, high specific surface area and high specific pore volume. The designed methods were effective for the synthesis, presenting each mesostructured materials, patterns of XRD and other characteristics corresponding to the reported ones in literature. The new route employed to synthesize Al-SBA-15, generates a catalyst with only aluminum in tetrahedral form, according to the data of (27)Al NMR-MAS. However, several reports indicated that the coordination of the Al atoms changes below the Si/Al ratio of 45, presenting peaks corresponding to penta and hexa-coordinated aluminum, which are absent in our samples (Si/Al = 50 and 33).

Synthesis of ZnO nanopencils using wet chemical method and its investigation as LPG sensor

NASA Astrophysics Data System (ADS)

Shimpi, Navinchandra G.; Jain, Shilpa; Karmakar, Narayan; Shah, Akshara; Kothari, D. C.; Mishra, Satyendra

2016-12-01

ZnO nanopencils (NPCs) were prepared by a novel wet chemical process, using triethanolamine (TEA) as a mild base, which is relatively simple and cost effective method as compared to hydrothermal method. ZnO NPCs were characterized using powder X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy in mid-IR and far-IR regions, X-ray Photoelectron Spectroscopy (XPS), UV-vis (UV-vis) absorption spectroscopy, room temperature Photoluminescence (PL) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). ZnO NPCs obtained, were highly pure, uniform and monodispersed.XRD pattern indicated hexagonal unit cell structure with preferred orientation along the c-axis. Sensing behaviour of ZnO NPCs was studied towards Liquefied Petroleum Gas (LPG) at different operating temperatures. The study shows that ZnO NPCs were most sensitive and promising candidate for detection of LPG at 250 °C with gas sensitivity > 60%. The high response towards LPG is due to high surface area of ZnO NPCs and their parallel alignment.

Eco-friendly and green synthesis of BiVO4 nanoparticle using microwave irradiation as photocatalayst for the degradation of Alizarin Red S

NASA Astrophysics Data System (ADS)

Abraham, S. Daniel; David, S. Theodore; Bennie, R. Biju; Joel, C.; Kumar, D. Sanjay

2016-06-01

Bismuth vanadate (BiVO4) nanocrystals have been successfully synthesised using microwave-assisted combustion synthesis (MCS), and characterised using Fourier transform infrared (FT-IR) and Raman spectra, surface area analysis (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray analysis (EDX), diffused reflectance spectroscopy (DRS) and Photoluminescence (PL) spectroscopy. The XRD results confirmed the formation of monoclinic bismuth vanadate. The formations of BiO & VO43-vibrations were ascertained from FT-IR data. The morphology of hallow internal structural micro entities were confirmed by SEM. The optical properties were determined by DRS and PL spectra. Hence, the influence of the preparation methods on the structure, morphology and optical activities of bismuth vanadate was investigated systematically. Photocatalytic degradation (PCD) of Alizarin Red S (ARS), an effective disrupting chemical in aqueous medium was investigated using BiVO4 nanoparticles. The kinetics of PCD was found to follow pseudo first-order.

Effect of sulfate ions on the crystallization and photocatalytic activity of TiO2/diatomite composite photocatalyst

NASA Astrophysics Data System (ADS)

Zhang, Jinjun; Wang, Xiaoyan; Wang, Jimei; Wang, Jing; Ji, Zhijiang

2016-01-01

TiO2 nanoparticles were immobilized on diatomite by hydrolysis-deposition method using titanium tetrachloride as precursor. The effect of sulfate ions on the crystallization and photocatalytic activity of TiO2/diatomite composite photocatalyst was characterized by TG-DSC, XRD, BET surface area, SEM, FT-IR spectroscopy, XPS and UV-vis diffuse reflectance spectra. The results indicate that addition of a small amount of sulfate ions promotes the formation of anatase phase and inhibits the transformation from anatase to rutile. On the other hand, sulfate ions immobilized on the surface of TiO2/diatomite have strong affinity for electrons, capturing the photo-generated electrons, which hinders the recombination of electrons and holes.

Effects of Laser Shock Processing on Morphologies and Mechanical Properties of ANSI 304 Stainless Steel Weldments Subjected to Cavitation Erosion

PubMed Central

Zhang, Lei; Lu, Jin-Zhong; Zhang, Yong-Kang; Ma, Hai-Le; Luo, Kai-Yu; Dai, Feng-Ze

2017-01-01

Effects of laser shock processing (LSP) on the cavitation erosion resistance of laser weldments were investigated by optical microscope (OM), scanning electron microscope (SEM) observations, roughness tester, micro hardness tester, and X-ray diffraction (XRD) technology. The morphological microstructures were characterized. Cumulative mass loss, incubation period, erosion rate, and damaged surface areas were monitored during cavitation erosion. Surface roughness, micro-hardness, and residual stress were measured in different zones. Results showed that LSP could improve the damage of morphological microstructures and mechanical properties after cavitation erosion. The compressive residual stresses were generated during the process of LSP, which was an effective guarantee for the improvement of the above mentioned properties. PMID:28772652

Nano-Crystalline Diamond Films with Pineapple-Like Morphology Grown by the DC Arcjet vapor Deposition Method

NASA Astrophysics Data System (ADS)

Li, Bin; Zhang, Qin-Jian; Shi, Yan-Chao; Li, Jia-Jun; Li, Hong; Lu, Fan-Xiu; Chen, Guang-Chao

2014-08-01

A nano-crystlline diamond film is grown by the dc arcjet chemical vapor deposition method. The film is characterized by scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD) and Raman spectra, respectively. The nanocrystalline grains are averagely with 80 nm in the size measured by XRD, and further proven by Raman and HRTEM. The observed novel morphology of the growth surface, pineapple-like morphology, is constructed by cubo-octahedral growth zones with a smooth faceted top surface and coarse side surfaces. The as-grown film possesses (100) dominant surface containing a little amorphous sp2 component, which is far different from the nano-crystalline film with the usual cauliflower-like morphology.

Synthesis and characterization of Ni doped ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Tamgadge, Y. S.; Gedam, P. P.; Ganorkar, R. P.; Mahure, M. A.; Pahurkar, V. G.; Muley, G. G.

2018-05-01

In this paper, we present synthesis of L-valine assisted surface modification of Ni doped ZnO nanoparticles (NPs) using chemical precipitation method. Samples were calcined at 500oC for 2h. Uncalcined and calcined samples were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet-visible (UV-vis) spectroscopy. Ni doped ZnO NPs with average particle size of 8 nm have been successfully obtained using L-valine as surface modifying agent. Increase in the particle size was observed after the calcination. XRD and TEM studies confirmed the purity, surface morphology and hexagonal wurtzite crystal structure of ZnO NPs. UV-vis spectroscopy indicated the blue shift of excitons absorption wavelength and surface modification by L-valine.

The observation of the physicochemical change of rock under freeze-thawing experiment: CLSM, XRD and ICP analysis

NASA Astrophysics Data System (ADS)

Choi, J.; Chae, B.; Chon, C.; Jeong, J.

2013-12-01

Abstract : In order to understand the progress of the physical weathering of rock sample, we managed freeze-thawing experiment at temperature of up to 40C from -20C taking into account of South Korea. In this study, the time was held by two hours the temperature of the maximum (40C) and minimum (-20C) and the experiments were carried out at intervals of one hour rising and falling. We have run the experiment about 120 cycle with the cycle of -20C from 40C experiment. We measured the physical properties of rock samples after each 20 cycle has elapsed by using confocal laser scanning microscope (CLSM) and observed changes in roughness of rock samples surface. We also analyzed the mineral of rock sample using the XRD analysis and observing the change in chemical composition of solution used in the experiment by using ICP analysis. Through the above process, we observed physico-chemical changes in the rock sample due to freeze-thaw cycles. To analysis of the line roughness parameter we used set by the 10 vertical and horizontal cross section line on the surface and surface roughness parameter was analyzed by using the area on the surface. Through such a process, while the freeze-thawing experiment is advanced, it was studied how the physical roughness and chemical composition were changed. As a result, it was possible to observe a change in the mineral component of the particular dissolved in the solution and it was able to observe the characteristic changes of the parameters of the roughness of the lines and surfaces.

Synthesis of LaVO4/TiO2 heterojunction nanotubes by sol-gel coupled with hydrothermal method for photocatalytic air purification.

PubMed

Zou, Xuejun; Li, Xinyong; Zhao, Qidong; Liu, Shaomin

2012-10-01

With the aim of improving the effective utilization of visible light, the LaVO(4)/TiO(2) heterojunction nanotubes were fabricated by sol-gel coupled with hydrothermal method. The photocatalytic ability was demonstrated through catalytic removal of gaseous toluene species. The nanotube samples were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), surface photovoltage (SPV), Raman spectra and N(2) adsorption-desorption measurements. The characterization results showed that the samples with high specific surface areas were of typical nanotubular morphology, which would lead to the high separation and transfer efficiency of photo induced electron-hole pairs. The as-prepared nanotubes exhibited high photocatalytic activity in decomposing toluene species under visible light irradiation with fine photochemical stability. The enhanced photocatalytic performance of LaVO(4)/TiO(2) nanotubes might be attributed to the matching band potentials, the interconnected heterojunction of LaVO(4) versus TiO(2), and the large specific surface areas of nanotubes. Copyright © 2012 Elsevier Inc. All rights reserved.

Preparation of nanobiochar as magnetic solid acid catalyst by pyrolysis-carbonization from oil palm empty fruit bunches

NASA Astrophysics Data System (ADS)

Jenie, S. N. Aisyiyah; Kristiani, Anis; Kustomo, Simanungkalit, Sabar; Mansur, Dieni

2017-11-01

Nanomaterials based on carbon exhibits unique properties, both physical and chemical, that can be utilized in various application, including catalyst. These nanomaterials were prepared through pyrolysis-carbonization process of biomass, oil palm empty fruit bunches. The effect of carbonization temperature in range of 500°C-600°C were also studied. The magnetic nanobiochar samples, MBC, were sulfonated by using sulfuric acid to increase their properties as solid acid catalyst. Their chemical and physical properties were characterized by Surface Area Analyzer and Porositymeter, X-Ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infra-Red. The magnetic biochar samples obtained from carbonization at 873 K, MBC02-SO3H, was proven to have higher surface area, crystallinity properties and surface chemical composition after sulfonation process, which were confirmed by the BET, XRD and FT-IR analysis. Moreover, sample MBC02-SO3H exhibit promising catalytic acitivity in a catalysed esterification reaction, producing an ester yield of 64%. The result from this work opens new opportunities for the development of magnetic heterogenous acid catalyst from biomass waste.

Synthesis and characterization of TiO2/graphitic carbon nanocomposites with enhanced photocatalytic performance

NASA Astrophysics Data System (ADS)

Wanag, Agnieszka; Kusiak-Nejman, Ewelina; Kowalczyk, Łukasz; Kapica-Kozar, Joanna; Ohtani, Bunsho; Morawski, Antoni W.

2018-04-01

In this paper titanium dioxide carbon modification with benzene as a carbon source is presented. A TiO2/graphitic carbon nanocomposites were synthesized by thermal modification in the presence of benzene vapours at different temperature (300-700 °C). The new materials were characterized by a various techniques, such as: X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV-vis/DR), surface-enhanced Raman spectroscopy. BET specific surface area was also measured. The photocatalytic activity of obtained nanocomposites was measured by the decomposition of acetic acid and methylene blue under UV-vis irradiation. The results show that photocatalytic activity increasing with increase in carbon concentration and temperature of modification. It can be noted that adsorption degree has a very high impact on methylene blue decomposition. The highest photocatalytic activity was found for the photocatalyst modified at 600 °C contains 1.13 wt% of carbon. It should be noted that, the influence of crystallite size, crystal structure changes and specific surface area for photocatalytic activity are presented.

Maltodextrin: A consummate carrier for spray-drying of xylooligosaccharides.

PubMed

Zhang, Liangqing; Zeng, Xianhai; Fu, Nan; Tang, Xing; Sun, Yong; Lin, Lu

2018-04-01

The aim of this study was to evaluate the influence of spray-drying on the powder qualities and microstructures of prebiotic xylooligosaccharides (XOS). The relationships between glass transition temperature (T g ) and XOS retention, moisture content, drying yield as well as specific surface area under different inlet air temperatures and maltodextrin concentrations were investigated. Antioxidant activity retention, hygroscopicity, color attributes, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) of the spray-dried XOS product were also assessed. The results indicated that an increase in inlet air temperature decreased the moisture content, hence the T g value was increased. Higher maltodextrin concentration increased the T g value, and was attributed to the molecular weight increase. The wall deposition was a tendency to occur when the temperature beyond the T g , reduced the drying yield. Higher temperature and wall deposition promoted the decomposition of XOS into monosaccharide. The crust formation rate of droplets and stickiness of microparticles were affected by T g , and hence, influenced the specific surface area. The antioxidant activity retention of XOS exhibited a concentration-dependent behavior. The hygroscopicity of the microparticles could be reduced by both of the low inlet air temperature and high maltodextrin concentration. According to the results of color attributes, XRD and SEM, the particles were colorless and amorphous, and tended to become more spherical and scattered with the addition of maltodextrin. The FT-IR analysis confirmed that no chemical reaction occurred between XOS and agent, which indicated that maltodextrin is a promising carrier for producing bioactive XOS powder. Copyright © 2018 Elsevier Ltd. All rights reserved.

Adsorption of Cd2+ ions on plant mediated SnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Haq, Sirajul; Rehman, Wajid; Waseem, Muhammad; Shahid, Muhammad; Mahfooz-ur-Rehman; Hussain Shah, Khizar; Nawaz, Mohsan

2016-10-01

Plant mediated SnO2 nanoparticles were synthesized by using SnCl4.5H2O as a precursor material. The nanoparticles were then characterized for BET surface area measurements, energy dispersive x-rays (EDX), scanning electron microscopy (SEM), UV-vis diffuse reflectance (DRS) spectra and x-rays diffraction (XRD) analysis. The successful synthesis of SnO2 nanoparticles was confirmed by EDX analysis. The particle sizes were in the range 19-27 nm whereas the crystallite size computed from XRD measurement was found to be 19.9 nm. Batch adsorption technique was employed for the removal of Cd2+ ions from aqueous solution. The sorption studies of Cd2+ ions were performed at pHs 4 and 6. The equilibrium concentration of Cd2+ ions was determined by atomic absorption spectrometer (flame mode). The uptake of Cd2+ ions was affected by initial concentration, pH and temperature of the electrolytic solution. It was observed that the adsorption of Cd2+ ions enhanced with increase in the initial concentration of Cd2+ ions whereas a decrease in the percent adsorption was detected. From the thermodynamic parameters, the adsorption process was found spontaneous and endothermic in nature. The n values confirmed 2:1 exchange mechanism between surface protons and Cd2+ ions.

Porous silicon-copper phthalocyanine heterostructure based photoelectrochemical cell

NASA Astrophysics Data System (ADS)

A. Betty, C.; N, Padma; Arora, Shalav; Survaiya, Parth; Bhattacharya, Debarati; Choudhury, Sipra; Roy, Mainak

2018-01-01

A hybrid solar cell consisting of nanostructured p-type porous silicon (PS) deposited with visible light absorbing dye, Copper Phthalocyanine (CuPc) has been prepared in the photoelectrochemical cell configuration. P-type PS with (100) and (111) orientations which have different porous structures were used for studying the effects of the substrate morphology on the cell efficiency. Heterostructures were prepared by depositing three different thicknesses of CuPc for optimizing the cell efficiency. Structural and surface characterizations were studied using XRD, Raman, SEM and AFM on the PS-CuPc heterostructure. XRD spectrum on both plane silicon and porous silicon indicates the π-π stacking of CuPc with increased disorder for CuPc film on porous silicon. Electrochemical characterizations under sun light type radiation have been carried out to evaluate the photosensitivity of the heterostructure. Between the two different substrates, (100) PS gives better photocurrent, possibly due to the higher surface area and lower series resistance of the structure. Among the (100) PS substrates, (100) PS with 15 nm CuPc film gives Voc more than 1 V resulting in higher efficiency for the cell. The study suggests the scope for optimization of solar cell efficiency using various combinations of the substrate structure and thickness of the sensitizing layer.

Experimental and modeling study on charge storage/transfer mechanism of graphene-based supercapacitors

NASA Astrophysics Data System (ADS)

Ban, Shuai; Jing, Xie; Zhou, Hongjun; Zhang, Lei; Zhang, Jiujun

2014-12-01

A symmetrical graphene-based supercapacitor is constructed for studying the charge-transfer mechanism within the graphene-based electrodes using both experiment measurements and molecular simulation. The in-house synthesized graphene is characterized by XRD, SEM and BET measurements for morphology and surface area. It is observed that the electric capacity of graphene electrode can be reduced by both high internal resistance and limited mass transfer. Computer modeling is conducted at the molecular level to characterize the diffusion behavior of electrolyte ions to the interior of electrode with emphasis on the unique 2D confinement imposed by graphene layers. Although graphene powder poses a moderate internal surface of 400 m2 g-1, the capacitance performance of graphene electrode can be as good as that of commercial activated carbon which has an overwhelming surface area of 1700 m2 g-1. An explanation to this abnormal correlation is that graphene material has an intrinsic capability of adaptively reorganizing its microporous structure in response to intercalation of ions and immergence of electrolyte solvent. The accessible surface of graphene is believed to be dramatically enlarged for ion adsorption during the charging process of capacitor.

Anodized Steel Electrodes for Supercapacitors.

PubMed

Sagu, Jagdeep S; Wijayantha, K G Upul; Bohm, Mallika; Bohm, Siva; Kumar Rout, Tapan

2016-03-09

Steel was anodized in 10 M NaOH to enhance its surface texture and internal surface area for application as an electrode in supercapacitors. A mechanism was proposed for the anodization process. Field-emission gun scanning electron microscopy (FEGSEM) studies of anodized steel revealed that it contains a highly porous sponge like structure ideal for supercapacitor electrodes. X-ray photoelectron spectroscopy (XPS) measurements showed that the surface of the anodized steel was Fe2O3, whereas X-ray diffraction (XRD) measurements indicated that the bulk remained as metallic Fe. The supercapacitor performance of the anodized steel was tested in 1 M NaOH and a capacitance of 18 mF cm(-2) was obtained. Cyclic voltammetry measurements showed that there was a large psueudocapacitive contribution which was due to oxidation of Fe to Fe(OH)2 and then further oxidation to FeOOH, and the respective reduction of these species back to metallic Fe. These redox processes were found to be remarkably reversible as the electrode showed no loss in capacitance after 10000 cycles. The results demonstrate that anodization of steel is a suitable method to produce high-surface-area electrodes for supercapacitors with excellent cycling lifetime.

Detachment strength of human osteoblasts cultured on hydroxyapatite with various surface roughness. Contribution of integrin subunits.

PubMed

Kokkinos, Petros A; Koutsoukos, Petros G; Deligianni, Despina D

2012-06-01

Hydroxyapatite (HA) has been widely used as a bone substitute in dental, maxillofacial and orthopaedic surgery and as osteoconductive bone substitute or precoating of pedicle screws and cages in spine surgery. The aim of the present study was to investigate the osteoblastic adhesion strength on HA substrata with different surface topography and biochemistry (pre-adsorption of fibronectin) after blocking of specific integrin subunits with monoclonal antibodies. Stoichiometric HA was prepared by precipitation followed by ageing and characterized by SEM, EDX, powder XRD, Raman spectroscopy, TGA, and specific surface area analysis. Human bone marrow derived osteoblasts were cultured on HA disc-shaped substrata which were sintered and polished resulting in two surface roughness grades. For attachment evaluation, cells were incubated with monoclonal antibodies and seeded for 2 h on the substrata. Cell detachment strength was determined using a rotating disc device. Cell detachment strength was surface roughness, fibronectin preadsorption and intergin subunit sensitive.

X-Ray Diffraction for In-Situ Mineralogical Analysis of Planetesimals.

NASA Astrophysics Data System (ADS)

Sarrazin, P.; Blake, D. F.; Dera, P.; Downs, R. T.; Taylor, J.

2017-12-01

X-ray diffraction (XRD) is a general purpose technique for definitive, quantitative mineralogical analysis. When combined with XRF data for sample chemistry, XRD analyses yield as complete a characterization as is possible by any spacecraft-capable techniques. The MSL CheMin instrument, the first XRD instrument flown in space, has been used to establish the quantitative mineralogy of the Mars global soil, to discover the first habitable environment on another planet, and to provide the first in-situ evidence of silicic volcanism on Mars. CheMin is now used to characterize the depositional and diagenetic environments associated with the mudstone sediments of lower strata of Mt. Sharp. Conventional powder XRD requires samples comprised of small grains presented in random orientations. In CheMin, sample cells are vibrated to cause loose powder to flow within the cell, driven by granular convection, which relaxes the requirement for fine grained samples. Nevertheless, CheMin still requires mechanisms to collect, crush, sieve and deliver samples before analysis. XTRA (Extraterrestrial Regolith Analyzer) is an evolution of CheMin intended to analyze fines in as-delivered surface regolith, without sample preparation. Fine-grained regolith coats the surfaces of most airless bodies in the solar system, and because this fraction is typically comminuted from the rocky regolith, it can often be used as a proxy for the surface as a whole. HXRD (Hybrid-XRD) is concept under development to analyze rocks or soils without sample preparation. Like in CheMin, the diffracted signal is collected with direct illumination CCD's. If the material is sufficiently fine-grained, a powder XRD pattern of the characteristic X-ray tube emission is obtained, similar to CheMin or XTRA. With coarse grained crystals, the white bremsstrahlung radiation of the tube is diffracted into Laue patterns. Unlike typical Laue applications, HXRD uses the CCD's capability to distinguish energy and analyze the "colors" of each Laue spot, which enable phase identification. The concept was demonstrated with prototypes and dedicated crystallographic software was developed for identification the minerals responsible for the Laue patterns. High TRL subsystems are under development for future deployment opportunities of these new XRD instruments.

Study the oxidation kinetics of uranium using XRD and Rietveld method

NASA Astrophysics Data System (ADS)

Zhang, Yanzhi; Guan, Weijun; Wang, Qinguo; Wang, Xiaolin; Lai, Xinchun; Shuai, Maobing

2010-03-01

The surface oxidation of uranium metal has been studied by X-ray diffraction (XRD) and Rietveld method in the range of 50~300°C in air. The oxidation processes are analyzed by XRD to determine the extent of surface oxidation and the oxide structure. The dynamics expression for the formation of UO2 was derived. At the beginning, the dynamic expression was nonlinear, but switched to linear subsequently for uranium in air and humid oxygen. That is, the growth kinetics of UO2 can be divided into two stages: nonlinear portion and linear portion. Using the kinetic data of linear portion, the activation energy of reaction between uranium and air was calculated about 46.0 kJ/mol. However the content of oxide as a function of time was linear in humid helium ambience. Contrast the dynamics results, it prove that the absence of oxygen would accelerate the corrosion rate of uranium in the humid gas. We can find that the XRD and Rietveld method are a useful convenient method to estimate the kinetics and thermodynamics of solid-gas reaction.

Synthesis, characterization and catalytic activity of indium substituted nanocrystalline Mobil Five (MFI) zeolite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shah, Kishor Kr.; Nandi, Mithun; Talukdar, Anup K., E-mail: anup_t@sify.com

2015-06-15

Highlights: • In situ modification of the MFI zeolite by incorporation of indium. • The samples were characterized by XRD, FTIR, TGA, UV–vis (DRS), SAA, EDX and SEM. • The incorporation of indium was confirmed by XRD, FT-IR, UV–vis (DRS), EDX and TGA. • Hydroxylation of phenol reaction was studied on the synthesized catalysts. - Abstract: A series of indium doped Mobil Five (MFI) zeolite were synthesized hydrothermally with silicon to aluminium and indium molar ratio of 100 and with aluminium to indium molar ratios of 1:1, 2:1 and 3:1. The MFI zeolite phase was identified by XRD and FT-IRmore » analysis. In XRD analysis the prominent peaks were observed at 2θ values of around 6.5° and 23° with a few additional shoulder peaks in case of all the indium incorporated samples suggesting formation of pure phase of the MFI zeolite. All the samples under the present investigation were found to exhibit high crystallinity (∼92%). The crystallite sizes of the samples were found to vary from about 49 to 55 nm. IR results confirmed the formation of MFI zeolite in all cases showing distinct absorbance bands near 1080, 790, 540, 450 and 990 cm{sup −1}. TG analysis of In-MFI zeolites showed mass losses in three different steps which are attributed to the loss due to adsorbed water molecules and the two types TPA{sup +} cations. Further, the UV–vis (DRS) studies reflected the position of the indium metal in the zeolite framework. Surface area analysis of the synthesized samples was carried out to characterize the synthesized samples The analysis showed that the specific surface area ranged from ∼357 to ∼361 m{sup 2} g{sup −1} and the pore volume of the synthesized samples ranged from 0.177 to 0.182 cm{sup 3} g{sup −1}. The scanning electron microscopy studies showed the structure of the samples to be rectangular and twinned rectangular shaped. The EDX analysis was carried out for confirmation of Si, Al and In in zeolite frame work. The catalytic activities of the synthesized samples were investigated with respect to hydroxylation of phenol, in which catechol and hydroquinone were found to be the major products. It is observed that under all reaction conditions catechol selectivity was higher than the hydroquinone selectivity. In-MFI zeolites were successfully synthesized and were used as an effective catalyst for the hydroxylation of phenol to synthesize catechol and hydroquinone as the major product.« less

Chemical and morphological characterization of TSP and PM2.5 by SEM-EDS, XPS and XRD collected in the metropolitan area of Monterrey, Mexico

NASA Astrophysics Data System (ADS)

González, Lucy T.; Rodríguez, F. E. Longoria; Sánchez-Domínguez, M.; Leyva-Porras, C.; Silva-Vidaurri, L. G.; Acuna-Askar, Karim; Kharisov, B. I.; Villarreal Chiu, J. F.; Alfaro Barbosa, J. M.

2016-10-01

Total suspended particles (TSP) and particles smaller than 2.5 μm (PM2.5) were collected at four sites in the metropolitan area of Monterrey (MAM) in Mexico. The samples were characterized by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM). In order to determine the possible sources of emissions of atmospheric particulate matter, a principal component analysis (PCA) was performed. The XRD results showed that the major crystalline compounds found in the TPS were CaCO3 and SiO2; while in the PM2.5 CaSO4 was found. The XPS analysis showed that the main elements found on the surface of the particles were C, O, Si, Ca, S, and N. The deconvolution carried out on the high-resolution spectra for C1s, S2p and N1s, showed that the aromatics, sulfates and pyrrolic-amides were the main groups contributing to the signal of these elements, respectively. The C-rich particles presented a spherical morphology, while the Ca- and Si-based particles mostly showed a prismatic shape. The PCA analysis together with the results obtained from the characterization techniques, suggested that the main contributors to the CaCO3 particles collected in the PM were most probably produced and emitted into the atmosphere by local construction industries and exploitation of rich-deposits of calcite. Meanwhile, the SiO2 found in the MAM originated from the suspension of geological material abundant in the region, and the carbon particles were mainly produced by the combustion of fossil fuels.

Role of Exposed Surfaces on Zinc Oxide Nanostructures in the Catalytic Ethanol Transformation.

PubMed

Morales, María V; Asedegbega-Nieto, Esther; Iglesias-Juez, Ana; Rodríguez-Ramos, Inmaculada; Guerrero-Ruiz, Antonio

2015-07-08

For a series of nanometric ZnO materials, the relationship between their morphological and surface functionalities and their catalytic properties in the selective decomposition of ethanol to yield acetaldehyde was explored. Six ZnO solids were prepared by a microemulsion-precipitation method and the thermal decomposition of different precursors and compared with a commercial sample. All these materials were characterized intensively by XRD and SEM to obtain their morphological specificities. Additionally, surface area determinations and IR spectroscopy were used to detect differences in the surface properties. The density of acid surface sites was determined quantitatively using an isopropanol dehydration test. Based on these characterization studies and on the results of the catalytic tests, it has been established that ZnO basal surfaces seem to be responsible for the production of ethylene as a minor product as well as for secondary reactions that yield acetyl acetate. Furthermore, one specific type of exposed hydroxyl groups appears to govern the surface catalytic properties. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Higher Alcohols via Syngas on Cu/Zn/Si Catalysts. Effect of Polyethylene Glycol Content

NASA Astrophysics Data System (ADS)

Cui, Rong-Ji; Yan, Xing; Fan, Jin-Chuan; Huang, Wei

2018-05-01

Cu/Zn/Si catalysts with different polyethylene glycol (PEG) content were prepared by a complete liquid-phase method, and characterized by XRD, H2-TPR, N2-adsorption, and XPS. The influence of PEG content on the higher alcohols synthesis from syngas was investigated. The results showed that addition of PEG can influence the texture and surface properties of the catalysts, and therefore affect their activity and product distribution. With an increase in PEG content, BET surface area, Cu crystallite size and surface active ingredient content of the catalysts first increased and then decreased, the CO conversion had similar variation tendency. However, the pore volume and pore diameter of the catalyst increased, and the binding energy of the active component and the content of Cu2O decreased, which resulted in higher catalyst selectivity towards higher alcohols. The highest C2+OH selectivity in total alcohols was 60.6 wt %.

A study of thermal properties of sodium titanate nanotubes synthesized by microwave-assisted hydrothermal method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Preda, Silviu, E-mail: predas01@yahoo.co.uk; Rutar, Melita; Jožef Stefan International Postgraduate School, Jamova cesta 39, SI-1000 Ljubljana

2015-11-15

Highlights: • The microwave-assisted hydrothermal route was used for titanate nanotubes synthesis. • Conversion to single-phase nanotube morphology completes after 8 h reaction time. • The nanotube morphology is stable up to 600 °C, as determined by in-situ XRD and SEM. • Sodium ions migrate to the surface due to thermal motion and structure condensation. - Abstract: Sodium titanate nanotubes (NaTiNTs) were synthesized by microwave-assisted hydrothermal treatment of commercial TiO{sub 2}, at constant temperature (135 °C) and different irradiation times (15 min, 1, 4, 8 and 16 h). The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electronmore » microscopy, differential scanning calorimetry and specific surface area measurements. The irradiation time turned out to be the key parameter for morphological control of the material. Nanotubes were observed already after 15 min of microwave irradiation. The analyses of the products irradiated for 8 and 16 h confirm the complete transformation of the starting TiO{sub 2} powder to NaTiNTs. The nanotubes are open ended with multi-wall structures, with the average outer diameter of 8 nm and specific surface area up to 210 m{sup 2}/g. The morphology, surface area and crystal structure of the sodium titanate nanotubes synthesized by microwave-assisted hydrothermal method were similar to those obtained by conventional hydrothermal method.« less

Fabrication of dense and porous Li2ZrO3 nanofibers with electrospinning method

NASA Astrophysics Data System (ADS)

Yuan, Kangkang; Jin, Xiaotong; Xu, Chonghe; Wang, Xinqiang; Zhang, Guanghui; Zhu, Luyi; Xu, Dong

2018-06-01

Lithium zirconate (Li2ZrO3) has been extensively studied as CO2 capture material, electrolyte material and coating material. Most of the previous studies were focused on the powder structure, while seldom taking a consideration of fiber structure. In the present work, dense and porous Li2ZrO3 nanofibers with surface area of 16 m2 g-1 were prepared by electrospinning method. IR spectral results showed that lithium carbonate was the intermediate for the formation of Li2ZrO3. The phase transformation of Li2ZrO3 underwent the pathway of amorphous precursor fibers, tetragonal zirconia and Li2CO3, tetragonal Li2ZrO3, and monoclinic Li2ZrO3. XRD and XPS results further suggested that Li2O diffusion from the fiber body to surface occurred for Li2ZrO3 nanofibers when heat-treated above 900 °C, and the tetragonal Li2ZrO3 with high surface area could be obtained at 800 °C. Bamboo structure appeared both for the dense and porous nanofibers heat-treated at 1000 °C. The high surface area and high thermal stability of tetragonal phase of Li2ZrO3 make it a promising candidate in CO2 absorption, electrolyte and coating material.

The dual role of sulfur-containing amino acids in the synthesis of IV-VI semiconductor nanocrystals: a mechanochemical approach.

PubMed

Baláž, Peter; Baláž, Matej; Caplovičová, Mária; Zorkovská, Anna; Caplovič, Lubomír; Psotka, Miroslav

2014-01-01

PbS@cystine nanocrystals were synthesized mechanochemically, with lead acetate and L-cystine being used as the lead and sulfur precursors, respectively. The resulting nanocrystals are 22-34 nm in size, well-faceted and octahedral in shape. Characterization by XRD, FT-IR, NMR, FE-SEM, EDS, TEM (HRTEM) and surface area measurement methods showed that the particles are single, defect-free crystals with a high crystallinity. Furthermore, the crystals were prepared using a solvent-free procedure that was performed under ambient temperature and atmospheric pressure.

Synthesis of porous NiO/CeO2 hybrid nanoflake arrays as a platform for electrochemical biosensing

NASA Astrophysics Data System (ADS)

Cui, Jiewu; Luo, Jinbao; Peng, Bangguo; Zhang, Xinyi; Zhang, Yong; Wang, Yan; Qin, Yongqiang; Zheng, Hongmei; Shu, Xia; Wu, Yucheng

2015-12-01

Porous NiO/CeO2 hybrid nanoflake arrays fabricated by a facile hydrothermal method were employed as substrates for electrochemical biosensors. The resulting NiO/CeO2 hybrid nanoflake arrays with a large specific surface area and good biocompatibility presented an excellent platform for electrochemical biosensing.Porous NiO/CeO2 hybrid nanoflake arrays fabricated by a facile hydrothermal method were employed as substrates for electrochemical biosensors. The resulting NiO/CeO2 hybrid nanoflake arrays with a large specific surface area and good biocompatibility presented an excellent platform for electrochemical biosensing. Electronic supplementary information (ESI) available: Optical photographs of the as-prepared samples, SEM, TEM, EDS, XRD and BET data of the samples are presented, I-t curves of glucose biosensors based on NiO and NiO/CeO2 NFAs, EIS results of different electrodes. See DOI: 10.1039/c5nr05924k

The influence of Ce doping of titania on the photodegradation of phenol.

PubMed

Martin, Marcela V; Villabrille, Paula I; Rosso, Janina A

2015-09-01

Pure and cerium-doped [0.05, 0.1, 0.3, 0.5, and 1.0 Ce nominal atomic % (at.%)] TiO2 was synthesized by the sol-gel method. The obtained catalysts were characterized by X-ray diffraction (XRD), UV-visible diffused reflectance spectroscopy (DRS), Raman, and BET surface area measurement. The photocatalytic activity of synthesized samples for the oxidative degradation of phenol in aqueous suspension was investigated. The content of Ce in the catalysts increases both the transition temperature for anatase to rutile phase transformation and the specific surface area, and decreases the crystallite size of anatase phase, the crystallinity, and the band gap energy value. The material with higher efficiency corresponds to 0.1 Ce nominal at.%. Under irradiation with 350 nm lamps, the degradation of phenol could be described as an exponential trend, with an apparent rate constant of (9.1 ± 0.6) 10(-3) s(-1) (r(2) = 0.98). Hydroquinone was identified as the main intermediate.

Microstructure and thermal conductivity of surfactant-free NiO nanostructures

NASA Astrophysics Data System (ADS)

Sahoo, Pranati; Misra, Dinesh K.; Salvador, Jim; Makongo, Julien P. A.; Chaubey, Girija S.; Takas, Nathan J.; Wiley, John B.; Poudeu, Pierre F. P.

2012-06-01

High purity, nanometer sized surfactant-free nickel oxide (NiO) particles were produced in gram scale using a solution combustion method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), gas pycnometry and gas adsorption analysis (BET). The average particle size of the as-synthesized NiO increases significantly with the preheating temperature of the furnace, while the specific surface area decreases. A BET specific surface area of ∼100 m2/g was obtained for NiO nanoparticles with size as small as 3 nm synthesized at 300 °C. The thermal conductivity (κ) of pressed pellets of the synthesized NiO nanoparticles obtained using spark plasma sintering (SPS) and uniaxial hot pressing is drastically decreased (∼60%) compared to that of NiO single crystal. This strong reduction in κ with particle size suggests the suitability of the synthesized surfactant-free NiO nanoparticles for use as nanoinclusions when designing high performance materials for waste heat recovery.

Characterization of leaf waste based biochar for cost effective hydrogen sulphide removal from biogas.

PubMed

Sahota, Shivali; Vijay, Virendra Kumar; Subbarao, P M V; Chandra, Ram; Ghosh, Pooja; Shah, Goldy; Kapoor, Rimika; Vijay, Vandit; Koutu, Vaibhav; Thakur, Indu Shekhar

2018-02-01

Installation of decentralized units for biogas production along with indigenous upgradation systems can be an effective approach to meet growing energy demands of the rural population. Therefore, readily available leaf waste was used to prepare biochar at different temperatures and employed for H 2 S removal from biogas produced via anaerobic digestion plant. It is found that biochar prepared via carbonization of leaf waste at 400 °C effectively removes 84.2% H 2 S (from 1254 ppm to 201 ppm) from raw biogas for 25 min in a continuous adsorption tower. Subsequently, leaf waste biochar compositional, textural and morphological properties before and after H 2 S adsorption have been analyzed using proximate analysis, CHNS, BET surface area, FTIR, XRD, and SEM-EDX. It is found that BET surface area, pore size, and textural properties of leaf waste biochar plays a crucial role in H 2 S removal from the biogas. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical degradation of trimethyl phosphate as surrogate for organo-phosporus pesticides on nanostructured metal oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Štengl, Václav, E-mail: stengl@iic.cas.cz; Henych, Jiří; Grygar, Tomáš

Nanostructured TiO{sub 2} and mixed oxides of Ti and Fe, Hf, In, Mn or Zr -were prepared by homogeneous hydrolysis of aqueous solution of metal sulphates with urea. The oxides were characterised by X-ray powder diffraction (XRD), scanning electron microscopy, particle size distribution, surface area and porosity. The oxide materials consists of a few nanometre primary crystals (mainly anatase) arranged in a few micrometre regular spherical agglomerates with specific surface area 133–511 m{sup 2} g{sup −1}. The FTIR diffuse spectroscopy was used for monitoring chemical degradation of trimethylphosphate (TMP) as a surrogate for organo-phosphorus pesticides under ambient and higher temperatures.more » Undoped TiO{sub 2} and Ti,Mn-mixed oxide were most active in cleavage (hydrolysis) of CH{sub 3}O from TMP at room temperature and 100 °C. Cleavage of CH{sub 3}O in the other studied mixed oxides was not complete until temperature exceeds the boiling point of TMP.« less

Synthesis of MoS2/rGO nanosheets hybrid materials for enhanced visible light assisted photocatalytic activity

NASA Astrophysics Data System (ADS)

Pal, Shreyasi; Dutta, Shibsankar; De, Sukanta

2018-04-01

A facile hydrothermal method has been adopted to synthesize pure MoS2 nanosheets and MoS2/rGO nanosheets hybrid. The samples were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (HRTEM), X-ray diffraction spectroscopy (XRD), Brunauer-Emmett-Teller (BET). The photocatalytic performance and reusability of MoS2 nanosheets and MoS2/rGO hybrids was evaluated by discoloring of RhB under visible light irradiation. Results indicated that MoS2/rGO photocatalysts with large surface area of 69.5 m2 g-1 could completely degrade 50 mL of 8 mg L-1 RhB aqueous solution in 90 min with excellent recycling and structural stability as compared with pure MoS2 nanosheets (53%). Such enhanced performance could be explained due to the high surface area, enhanced light absorption and the increased dye adsorptivity and reduced electron-hole pair recombination with the presence of rGO.

A high selective methanol gas sensor based on molecular imprinted Ag-LaFeO3 fibers.

PubMed

Rong, Qian; Zhang, Yumin; Wang, Chao; Zhu, Zhongqi; Zhang, Jin; Liu, Qingju

2017-09-21

Ag-LaFeO 3 molecularly imprinted polymers (ALMIPs) were fabricated, which provided special recognition sites to methanol. Then ALMIPs fiber 1, fiber 2 and fiber 3 were prepared using filter paper, silk and carbon fibers template, respectively. Based on the observation of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and Nitrogen adsorption surface area analyzer (BET), the structure, morphology and surface area of the fibers were characterized. The ALMIPs fibers (fiber 1, fiber 2 and fiber 3) show excellent selectivity and good response to methanol. The responses to 5 ppm methanol and the optimal operating temperature of ALMIPs fibers are 23.5 and 175 °C (fiber 1), 19.67 and 125 °C (fiber 2), 17.59 and 125 °C (fiber 3), and a lower response (≤10, 3, 2) to other test gases including formaldehyde, acetone, ethanol, ammonia, gasoline and benzene was measured, respectively.

Facile hydrothermal synthesis of mesoporous In2O3 nanoparticles with superior formaldehyde-sensing properties

NASA Astrophysics Data System (ADS)

Zhang, Su; Song, Peng; Yang, Zhongxi; Wang, Qi

2018-03-01

Mesoporous In2O3 nanoparticles were successfully synthesized via a facile, template free, and low-cost hydrothermal method. Their morphology and structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal and thermogravimetry analysis (DSC-TG), and N2 adsorption-desorption analyses. The results reveal that mesoporous In2O3 nanoparticles with a size range of 40-60 nm, possess plenty of pores, and average pore size is about 5 nm. Importantly, the mesoporous structure, large specific surface area, and small size endow the mesoporous In2O3 nanoparticles with highly sensing performance for formaldehyde detection. The response value to 10 ppm HCHO is 20 at an operating temperature of 280 °C, and the response and recovery time are 4 and 8 s, respectively. It is expected that the mesoporous In2O3 nanoparticles with large specific surface area and excellent sensing properties will become a promising functional material in monitoring and detecting formaldehyde.

Cobalt and sulfur co-doped nano-size TiO2 for photodegradation of various dyes and phenol.

PubMed

Siddiqa, Asima; Masih, Dilshad; Anjum, Dalaver; Siddiq, Muhammad

2015-11-01

Various compositions of cobalt and sulfur co-doped titania nano-photocatalyst are synthesized via sol-gel method. A number of techniques including X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Rutherford backscattering spectrometry (RBS), thermal gravimetric analysis (TGA), Raman, N2 sorption, electron microscopy are used to examine composition, crystalline phase, morphology, distribution of dopants, surface area and optical properties of synthesized materials. The synthesized materials consisted of quasispherical nanoparticles of anatase phase exhibiting a high surface area and homogeneous distribution of dopants. Cobalt and sulfur co-doped titania demonstrated remarkable structural and optical properties leading to an efficient photocatalytic activity for degradation of dyes and phenol under visible light irradiations. Moreover, the effect of dye concentration, catalyst dose and pH on photodegradation behavior of environmental pollutants and recyclability of the catalyst is also examined to optimize the activity of nano-photocatalyst and gain a better understanding of the process. Copyright © 2015. Published by Elsevier B.V.

Studies on the sensing behaviour of nanocrystalline CuGa(2)O(4) towards hydrogen, liquefied petroleum gas and ammonia.

PubMed

Biswas, Soumya Kanti; Sarkar, Arpita; Pathak, Amita; Pramanik, Panchanan

2010-06-15

In the present article, the gas sensing behaviour of nanocrystalline CuGa(2)O(4) towards H(2), liquefied petroleum gas (LPG) and NH(3) has been reported for the first time. Nanocrystalline powders of CuGa(2)O(4) having average particle sizes in the range of 30-60nm have been prepared through thermal decomposition of an aqueous precursor solution comprising copper nitrate, gallium nitrate and triethanol amine (TEA), followed by calcination at 750 degrees C for 2h. The synthesized nanocrystalline CuGa(2)O(4) powders have been characterised through X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM) study, energy dispersive X-ray (EDX) analysis and BET (Brunauer-Emmett-Teller) surface area measurement. The synthesized CuGa(2)O(4) having spinel structure with specific surface area of 40m(2)/g exhibits maximum sensitivity towards H(2), LPG, and NH(3) at 350 degrees C.

Titania nanotube powders obtained by rapid breakdown anodization in perchloric acid electrolytes

NASA Astrophysics Data System (ADS)

Ali, Saima; Hannula, Simo-Pekka

2017-05-01

Titania nanotube (TNT) powders are prepared by rapid break down anodization (RBA) in a 0.1 M perchloric acid (HClO4) solution (Process 1), and ethylene glycol (EG) mixture with HClO4 and water (Process 2). A study of the as-prepared and calcined TNT powders obtained by both processes is implemented to evaluate and compare the morphology, crystal structure, specific surface area, and the composition of the nanotubes. Longer TNTs are formed in Process 1, while comparatively larger pore diameter and wall thickness are obtained for the nanotubes prepared by Process 2. The TNTs obtained by Process 1 are converted to nanorods at 350 °C, while nanotubes obtained by Process 2 preserve tubular morphology till 350 °C. In addition, the TNTs prepared by an aqueous electrolyte have a crystalline structure, whereas the TNTs obtained by Process 2 are amorphous. Samples calcined till 450 °C have XRD peaks from the anatase phase, while the rutile phase appears at 550 °C for the TNTs prepared by both processes. The Raman spectra also show clear anatase peaks for all samples except the as-prepared sample obtained by Process 2, thus supporting the XRD findings. FTIR spectra reveal the presence of O-H groups in the structure for the TNTs obtained by both processes. However, the presence is less prominent for annealed samples. Additionally, TNTs obtained by Process 2 have a carbonaceous impurity present in the structure attributed to the electrolyte used in that process. While a negligible weight loss is typical for TNTs prepared from aqueous electrolytes, a weight loss of 38.6% in the temperature range of 25-600 °C is found for TNTs prepared in EG electrolyte (Process 2). A large specific surface area of 179.2 m2 g-1 is obtained for TNTs prepared by Process 1, whereas Process 2 produces nanotubes with a lower specific surface area. The difference appears to correspond to the dimensions of the nanotubes obtained by the two processes.

Evaluation of accessible mineral surface areas for improved prediction of mineral reaction rates in porous media

NASA Astrophysics Data System (ADS)

Beckingham, Lauren E.; Steefel, Carl I.; Swift, Alexander M.; Voltolini, Marco; Yang, Li; Anovitz, Lawrence M.; Sheets, Julia M.; Cole, David R.; Kneafsey, Timothy J.; Mitnick, Elizabeth H.; Zhang, Shuo; Landrot, Gautier; Ajo-Franklin, Jonathan B.; DePaolo, Donald J.; Mito, Saeko; Xue, Ziqiu

2017-05-01

The rates of mineral dissolution reactions in porous media are difficult to predict, in part because of a lack of understanding of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area used in reactive transport models for porous media are typically ad hoc and often based on average grain size, increased to account for surface roughness or decreased by several orders of magnitude to account for reduced surface reactivity of field as opposed to laboratory samples. In this study, accessible mineral surface areas are determined for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan) using a multi-scale image analysis based on synchrotron X-ray microCT, SEM QEMSCAN, XRD, SANS, and FIB-SEM. This analysis not only accounts for accessibility of mineral surfaces to macro-pores, but also accessibility through connected micro-pores in smectite, the most abundant clay mineral in this sample. While the imaging analysis reveals that most of the micro- and macro-pores are well connected, some pore regions are unconnected and thus inaccessible to fluid flow and diffusion. To evaluate whether mineral accessible surface area accurately reflects reactive surface area a flow-through core experiment is performed and modeled at the continuum scale. The core experiment is performed under conditions replicating the pilot site and the evolution of effluent solutes in the aqueous phase is tracked. Various reactive surface area models are evaluated for their ability to capture the observed effluent chemistry, beginning with parameter values determined as a best fit to a disaggregated sediment experiment (Beckingham et al., 2016) described previously. Simulations that assume that all mineral surfaces are accessible (as in the disaggregated sediment experiment) over-predict the observed mineral reaction rates, suggesting that a reduction of RSA by a factor of 10-20 is required to match the core flood experimental data. While the fit of the effluent chemistry (and inferred mineral dissolution rates) greatly improve when the pore-accessible mineral surface areas are used, it was also necessary to include highly reactive glass phases to match the experimental observations, in agreement with conclusions from the disaggregated sediment experiment. It is hypothesized here that the 10-20 reduction in reactive surface areas based on the limited pore accessibility of reactive phases in core flood experiment may be reasonable for poorly sorted and cemented sediments like those at the Nagaoka site, although this reflects pore rather than larger scale heterogeneity.

Characteristics of nano-sized yttria powder synthesized by a polyvinyl alcohol solution route at low temperature.

PubMed

Lee, Sang-Jin; Jung, Choong-Hwan

2012-01-01

Nano-sized yttria (Y2O3) powders were successfully synthesized at a low temperature of 400 degrees C by a simple polymer solution route. PVA polymer, as an organic carrier, contributed to an atom-scale homogeneous precursor gel and it resulted in fully crystallized, nano-sized yttria powder with high specific surface area through the low temperature calcination. In this process, the content of PVA, calcination temperature and heating time affected the microstructure and crystallization behavior of the powders. The development of crystalline phase and the final particle size were strongly dependant on the oxidation reaction from the polymer burn-out step and the PVA content. In this paper, the PVA solution technique for the fabrication of nano-sized yttria powders is introduced. The effects of PVA content and holding time on the powder morphology and powder specific surface area are also studied. The characterization of the synthesized powders is examined by using XRD, DTA/TG, SEM, TEM and nitrogen gas adsorption. The yttria powder synthesized from the PVA content of 3:1 ratio and calcined at 400 degrees C had a crystallite size of about 20 nm or less with a high surface areas of 93.95-120.76 m2 g(-1).

Construction of Zinc Oxide into Different Morphological Structures to Be Utilized as Antimicrobial Agent against Multidrug Resistant Bacteria

PubMed Central

Elkady, M. F.; Shokry Hassan, H.; Hafez, Elsayed E.; Fouad, Ahmed

2015-01-01

Nano-ZnO has been successfully implemented in particles, rods, and tubes nanostructures via sol-gel and hydrothermal techniques. The variation of the different preparation parameters such as reaction temperature, time, and stabilizer agents was optimized to attain different morphological structures. The influence of the microwave annealing process on ZnO crystallinity, surface area, and morphological structure was monitored using XRD, BET, and SEM techniques, respectively. The antimicrobial activity of zinc oxide produced in nanotubes structure was examined against four different multidrug resistant bacteria: Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) strains. The activity of produced nano-ZnO was determined by disc diffusion technique and the results revealed that ZnO nanotubes recorded high activity against the studied strains due to their high surface area equivalent to 17.8 m2/g. The minimum inhibitory concentration (MIC) of ZnO nanotubes showed that the low concentrations of ZnO nanotubes could be a substitution for the commercial antibiotics when approached in suitable formula. Although the annealing process of ZnO improves the degree of material crystallinity, however, it declines its surface area and consequently its antimicrobial activity. PMID:26451136

Synthesis and characterization of mesoporous ZnS with narrow size distribution of small pores

NASA Astrophysics Data System (ADS)

Nistor, L. C.; Mateescu, C. D.; Birjega, R.; Nistor, S. V.

2008-08-01

Pure, nanocrystalline cubic ZnS forming a stable mesoporous structure was synthesized at room temperature by a non-toxic surfactant-assisted liquid liquid reaction, in the 9.5 10.5 pH range of values. The appearance of an X-ray diffraction (XRD) peak in the region of very small angles (˜ 2°) reveals the presence of a porous material with a narrow pore size distribution, but with an irregular arrangement of the pores, a so-called worm hole or sponge-like material. The analysis of the wide angle XRD diffractograms shows the building blocks to be ZnS nanocrystals with cubic structure and average diameter of 2 nm. Transmission electron microscopy (TEM) investigations confirm the XRD results; ZnS crystallites of 2.5 nm with cubic (blende) structure are the building blocks of the pore walls with pore sizes from 1.9 to 2.5 nm, and a broader size distribution for samples with smaller pores. Textural measurements (N2 adsorption desorption isotherms) confirm the presence of mesoporous ZnS with a narrow range of small pore sizes. The relatively lower surface area of around 100 m2/g is attributed to some remaining organic molecules, which are filling the smallest pores. Their presence, confirmed by IR spectroscopy, seems to be responsible for the high stability of the resulting mesoporous ZnS as well.

Few layered vanadyl phosphate nano sheets-MWCNT hybrid as an electrode material for supercapacitor application

NASA Astrophysics Data System (ADS)

Dutta, Shibsankar; De, Sukanta

2016-05-01

It have been already seen that 2-dimensional nano materials are the suitable choice for the supercapacitor application due to their large specific surface area, electrochemical active sites, micromechanical flexibility, expedite ion migration channel properties. Free standing hybrid films of functionalized MWCNT (- COOH group) and α-Vanadyl phosphates (VOPO42H2O) are prepared by vacuum filtering. The surface morphology and microstructure of the samples are studied by transmission electron microscope, field emission scanning electron microscope, XRD, Electrochemical properties of hybrid films have been investigated systematically in 1M Na2SO4 aqueous electrolyte. The hybrid material exhibits a high specific capacitance 236 F/g with high energy density of 65.6 Wh/Kg and a power density of 1476 W/Kg.

Design and synthesis of inorganic/organic hybrid electrochemical materials

NASA Astrophysics Data System (ADS)

Harreld, John H.

An ambient pressure method for drying sol-gel materials is developed to synthesize high porosity (80--90%), high surface area vanadium oxide and silica aerogel materials (150--300 and 1000 m2/g for vanadium pentoxide and silica, respectively). The synthesis approach uses liquid exchange to replace the pore fluid with a low surface tension, nonpolar solvent which reduces the capillary pressures developed during drying. The Good-Girifalco interaction parameter is used to calculate pore stresses resulting from drying silica gels from various liquids. Vanadium oxide/polypyrrole hybrid aerogels are prepared using three strategies. These approaches focus on either sequential or consecutive polymerization of the inorganic and organic networks. Microcomposite aerogels are synthesized by encapsulating a dispersion of preformed polypyrrole in a vanadium pentoxide gel. In the second approach, pyrrole is polymerized and doped within the pore volume of preformed vanadium pentoxide gel. When the inorganic and organic precursors are polymerized simultaneously, the resulting gels exhibited a nanometer scaled microstructure with homogeneous distributions of either phases. Through this route, a suitable microstructure and composition for a lithium secondary battery cathode is obtained. Lithiated aerogels of hydrated nickel, cobalt, and mixed nickel-cobalt oxides are synthesized from lithium hydroxide and transition metal acetate precursors. The XRD analyses indicate that the nickel containing gels exhibit a lithium deficiency (less than 1 Li/transition metal. By increasing the concentration of the lithium precursor the lithium content in nickel oxides is increased, and additional base solution is no longer required to catalyze gelation. A non-hydrolytic sol-gel approach is utilized to create tin oxide and tin-aluminum binary oxide aerogels with high porosity (90%) and high surface area (300 m2/g). XRD data from single phase tin oxide aerogel indicates the growth of SnO2 crystallites between 150--400°C in air, accompanied by a reduction in surface area (30 m2/g). Heated tin oxide aerogel exhibits comparable reversible specific capacity (390 mAh/g) as that of commercial SnO2 (420 mAh/g). Amorphous tin oxide aerogel is stabilized to higher temperatures when aluminum oxide is incorporated into the structure. The tin oxide phase remains electrochemically active towards lithium insertion and exhibits excellent reversibility during cycling.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pariona, Moises Meza, E-mail: mmpariona@uepg.br; Teleginski, Viviane; Santos, Kelly dos

Laser beam welding has recently been incorporated into the fabrication process of aircraft and automobile structures. Surface roughness is an important parameter of product quality that strongly affects the performance of mechanical parts, as well as production costs. This parameter influences the mechanical properties such as fatigue behavior, corrosion resistance, creep life, etc., and other functional characteristics such as friction, wear, light reflection, heat transmission, lubrification, electrical conductivity, etc. The effects of laser surface remelting (LSR) on the morphology of Al-Fe aerospace alloys were examined before and after surface treatments, using optical microscopy (OM), scanning electron microscopy (SEM), low-angle X-raymore » diffraction (LA-XRD), atomic force microscopy (AFM), microhardness measurements (Vickers hardness), and cyclic voltammetry. This analysis was performed on both laser-treated and untreated sanded surfaces, revealing significant differences. The LA-XRD analysis revealed the presence of alumina, simple metals and metastable intermetallic phases, which considerably improved the microhardness of laser-remelted surfaces. The morphology produced by laser surface remelting enhanced the microstructure of the Al-Fe alloys by reducing their roughness and increasing their hardness. The treated surfaces showed passivity and stability characteristics in the electrolytic medium employed in this study. - Highlights: Black-Right-Pointing-Pointer The samples laser-treated and untreated showed significant differences. Black-Right-Pointing-Pointer The La-XRD revealed the presence of alumina in Al-1.5 wt.% Fe. Black-Right-Pointing-Pointer The laser-treated reducing the roughness and increasing the hardness. Black-Right-Pointing-Pointer The laser-treated surfaces showed characteristic passive in the electrolytic medium. Black-Right-Pointing-Pointer The laser-treated is a promising technique for applications technological.« less

Surface characteristics and bioactivity of oxide film on titanium metal formed by thermal oxidation.

PubMed

Park, Yeong-Joon; Song, Ho-Jun; Kim, In; Yang, Hong-So

2007-04-01

In this study, we characterized the surface of oxide film formed on titanium metal through the use of thermal treatment and investigated the effect of surface characteristics on the bioactivity of titanium. The as-received sample group was prepared by polishing and cleaning CP-Ti as a control group, and thermally oxidized sample groups were prepared by heat treating at 530, 600, 700, 800, 900, and 1000 degrees C respectively. Micro-morphology, crystalline structure, chemical composition, and binding state were evaluated using FE-SEM, XRD, and XPS. The bioactivity of sample groups was investigated by observing the degree of calcium phosphate formation from immersion testing in MEM. The surface characterization tests showed that hydroxyl group content in titanium oxide film was increased, as the density of titanium atoms was high and the surface area was large. In MEM immersion test, initial calcium phosphate formation was dependent upon the thickness of titanium oxide, and resultant calcium phosphate formation depended on the content of the hydroxyl group of the titanium oxide film surface.

Study on the surface sulfidization behavior of smithsonite at high temperature

NASA Astrophysics Data System (ADS)

Lv, Jin-fang; Tong, Xiong; Zheng, Yong-xing; Xie, Xian; Wang, Cong-bing

2018-04-01

Surface sulfidization behavior of smithsonite at high temperature was investigated by X-ray powder diffractometer (XRD) along with thermodynamic calculation, X-ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA). The XRD and thermodynamic analyses indicated that the smithsonite was decomposed into zincite at high temperatures. After introducing a small amount of pyrite, artificial sulfides were formed at surface of the obtained zincite. The XPS analyses revealed that the sulfide species including zinc sulfide and zinc disulfide were generated at the zincite surface. The EPMA analyses demonstrated that the film of sulfides was unevenly distributed at the zincite surface. The average concentration of elemental sulfur at the sample surface increased with increasing of pyrite dosage. A suitable mole ratio of FeS2 to ZnCO3 for the surface thermal modification was determined to be about 0.3. These findings can provide theoretical support for improving the process during which the zinc recovery from refractory zinc oxide ores is achieved by xanthate flotation.

Surface modification of hydroxyapatite nanoparticles by poly( L-phenylalanine) via ROP of L-phenylalanine N-carboxyanhydride (Pha-NCA)

NASA Astrophysics Data System (ADS)

Dai, Yanfeng; Xu, Min; Wei, Junchao; Zhang, Haobin; Chen, Yiwang

2012-01-01

The surface of hydroxyapatite nanoparticles was modified by poly(L-phenylalanine) via the ring opening polymerization (ROP) of L-phenylalanine N-carboxyanhydride. The preparation procedure was monitored by Fourier transform infrared spectroscopy (FTIR), and the modified hydroxyapatite was characterized by thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). The results showed that the surface grafting amounts of poly(L-phenylalanine) on HA ranging from 20.26% to 38.92% can be achieved by tuning the reaction condition. The XRD patterns demonstrated that the crystalline structure of the modified hydroxyapatite was nearly the same with that of HA, implying that the ROP was an efficient surface modification method. The MTT assay proved that the biocompatibility of modified HA was very good, which showed the potential application of modified HA in bone tissue engineering.

SILAR derived CdO films: Effect of triethanolamine on the surface morphology and optical bandgap energy

NASA Astrophysics Data System (ADS)

Sahin, B.; Aydin, R.

2018-07-01

Nanostructured CdO films have been successfully synthesized with different ratios of surfactant triethanolamine (TEA) under SILAR condition. The influence of addition of TEA on the physical properties of CdO nanoparticles was studied. The surface morphology of the films was studied by metallurgical microscope and SEM analysis. Surface topography of the film was studied by AFM. The structural properties of the samples were studied by X-ray diffraction (XRD). The XRD studies confirm that the deposited CdO films has cubic structure (111) preferred orientation with well-crystallinity and purity. The optical bandgap energy was estimated based on the UV-vis spectroscopies which were obtained in the range of 2.16 eV-2.46 eV. Our study is encouraging to get enhanced surface topography by surfactant TEA.

Anti-bacteria activity of carbon nanotubes grown on trimetallic catalyst

NASA Astrophysics Data System (ADS)

Ibrahim, S. O.; Abdulkareem, A. S.; Isah, K. U.; Ahmadu, U.; Bankole, M. T.; Kariim, I.

2018-06-01

Trimetallic catalyst was prepared using wet impregnation method to produce carbon nanotubes (CNTs) through the method of catalytic chemical vapor deposition (CCVD). Characterization of the developed catalyst and CNTs were carried out using thermogravimetric analysis (TGA), x-ray diffraction (XRD), specific surface area Brunauer-Emmett-Teller (BET), Fourier-transform infrared spectroscopy (FTIR), high-resolution scanning electron microscopy (HRSEM)/energy dispersive x-ray spectroscopy (EDS) and high-resolution transmission electron microscopy (HRTEM)/selected area electron diffraction (SAED). The BET and TGA analysis indicated that the catalyst has a high surface area and is thermally stable. The FTIR of the developed catalyst shows notable functional group with presence of unbound water. The HRSEM of the catalyst revealed agglomerated, homogeneous and porous particles while the HRSEM/HRTEM of the produced CNTs gave the formation of long strand of multiwalled carbon nanotubes (MWCNTs), and homogeneous crystalline fringe like structure with irregular diameter. EDS revealed the dominance of carbon in the elemental composition. XRD/SAED patterns of the catalyst suggest high dispersion of the metallic particles in the catalyst mixture while that of the CNTs confirmed that the produced MWCNTs were highly graphitized and crystalline in nature with little structural defects. The anti-bacteria activity of the produced MWCNTs on Klebsiella pneumoneae, Escherichia coli, and Pseudomonas aeruginosa was also carried out. It was observed that the produced MWCNTs have an inhibitory property on bacteria; Escherichia coli and Klebsiella pneumoneae from zero day ( and ) through to twelfth day (Nil count) respectively. It has no effect on Pseudomonas aeruginosa with too numerous to count at zero-sixth day, but a breakdown in its growth at ninth-twelfth day (). This study implied that MWCNTs with varying diameter and well-ordered nano-structure can be produced from catalyst via CCVD method, and it can be recommended that the MWCNTs can be used to treat infected media contaminated with Klebsiella pneumoneae, Escherichia coli, and Pseudomonas aeruginosa.

Molten salt method of preparation and cathodic studies on layered-cathode materials Li(Co0.7Ni0.3)O2 and Li(Ni0.7Co0.3)O2 for Li-ion batteries

NASA Astrophysics Data System (ADS)

Reddy, M. V.; Tung, Bui Dang; Yang, Lu; Quang Minh, Nguyen Dang; Loh, K. P.; Chowdari, B. V. R.

2013-03-01

Layered compounds, Li(Co0.7Ni0.3)O2 (I) and Li(Ni0.7Co0.3)O2(II) were prepared by molten salt method in temperature ranging from 650 to 950 °C. The effect of morphology, crystal structure and electrochemical properties of materials were evaluated by X-Ray Diffraction (XRD), Scanning Electron Microscopy and Brunauer-Emmett-Teller surface area, cyclic voltammetry (CV) and galvanostatic cycling. XRD pattern shows a hexagonal type structure with lattice parameters of a˜2.828 Å, c˜14.096 Å for I and a˜2.851 Å, c˜14.121 Å for II prepared in oxygen flow. The surface area of the compounds, I and II are 1.74 and 0.75 m2 g-1 respectively. CV studies show a main anodic peak occur at ˜3.8-3.94 V vs. Li and a cathodic peak occur at ˜3.6-3.7 V vs. Li. Galvanostatic cycling studies are carried out at a current rate of 30 mA g-1 in the voltage range of 2.5-4.3 V, at room temperature. Li(Co0.7Ni0.3)O2 prepared at 750 °C in air show a reversible capacity of 145 mAh g-1 at the 1st discharge cycle and 13% capacity fading between 2 and 56 cycles, whereas Li(Ni0.7Co0.3)O2 reheated in the presence of oxygen deliver a high and stable reversible capacity of 165 mAh g-1 at the end of 60th cycle.

Effective reduction in the nanoparticle sizes of NiO obtained via the pyrolysis of nickel malonate precursor modified using oleylamine surfactant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lontio Fomekong, Roussin, E-mail: lonforou@yahoo.fr; Institut de la Matière Condensée et des Nanosciences, Université Catholique de Louvain, Croix du Sud 1, 1348 Louvain-La-Neuve; Ngolui Lambi, John

2016-09-15

Nickel oxide nanoparticles were synthesized via thermal decomposition of two precursors, the first, a simple nickel malonate and the second, a nickel malonate modified by oleylamine, a surfactant, both having been synthesized by precipitation. While FTIR, TGA and ToF-SIMS were used to characterize the two precursors and to show the presence of oleylamine in the modified precursor, XRD, SEM, TEM and BET were employed to investigate the structure, the morphology and the specific surface area of the decomposition products obtained after pyrolysis. The results showed that the modification of nickel malonate by oleylamine was effective. The XRD results, which showedmore » a cubic structure for the NiO obtained, suggest with SEM an important particle size reduction (at least 54%) when oleylamine was used to modify the nickel malonate precursor. The SEM images also showed a well-defined spherical nanoparticle morphology in both cases, not affected by the presence of oleylamine. The TEM also confirmed the reduction of particle size and their spherical nature but at the same time showed that, in the presence of oleylamine, there was no agglomeration resulting in a more uniform particle size distribution. The specific surface area of the NiO obtained by the oleylamine-modified precursor was 4.7 times larger than that obtained with the regular precursor. This again confirms the particle size reduction. - Highlights: • Nickel malonate precursor has been synthesized by precipitation method. • This precursor was successfully modified by a surfactant (oleylamine). • NiO was identified as the decomposition products of the previous precursors. • Oleylamine has provoked around 54% of particle size reduction of the NiO.« less

Exploration of geo-mineral compounds in granite mining soils using XRD pattern data analysis

NASA Astrophysics Data System (ADS)

Koteswara Reddy, G.; Yarakkula, Kiran

2017-11-01

The purpose of the study was to investigate the major minerals present in granite mining waste and agricultural soils near and away from mining areas. The mineral exploration of representative sub-soil samples are identified by X-Ray Diffractometer (XRD) pattern data analysis. The morphological features and quantitative elementary analysis was performed by Scanning Electron Microscopy-Energy Dispersed Spectroscopy (SEM-EDS).The XRD pattern data revealed that the major minerals are identified as Quartz, Albite, Anorthite, K-Feldspars, Muscovite, Annite, Lepidolite, Illite, Enstatite and Ferrosilite in granite waste. However, in case of agricultural farm soils the major minerals are identified as Gypsum, Calcite, Magnetite, Hematite, Muscovite, K-Feldspars and Quartz. Moreover, the agricultural soils neighbouring mining areas, the minerals are found that, the enriched Mica group minerals (Lepidolite and Illite) the enriched Orthopyroxene group minerals (Ferrosilite and Enstatite). It is observed that the Mica and Orthopyroxene group minerals are present in agricultural farm soils neighbouring mining areas and absent in agricultural farm soils away from mining areas. The study demonstrated that the chemical migration takes place at agricultural farm lands in the vicinity of the granite mining areas.

Kaolinite-supported nanoscale zero-valent iron for removal of Pb2+ from aqueous solution: reactivity, characterization and mechanism.

PubMed

Zhang, Xin; Lin, Shen; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

2011-05-01

The use of nanoscale zero-valent iron (nZVI) to remediate contaminated groundwater is limited due to its lack of durability and mechanical strength. To address this issue, 20% (w/w) nZVI was loaded onto kaolinite as a support material (K-nZVI). More than 96% of Pb(2+) was removed from aqueous solution using K-nZVI at an initial condition of 500 mg/L Pb(2+) within 30 min under the conditions of 10 g/L of K-nZVI, pH 5.10 and a temperature of 30 °C. To understand the mechanism of removal of Pb(2+), various techniques were implemented to characterize K-nZVI. Scanning electron microscopy (SEM) indicated that K-nZVI had a suitable dispersive state with a lower aggregation, where the mean specific surface area and average particle size as determined by the BET-N(2) method and X-ray diffraction (XRD), were 26.11 m(2)/g and 44.3 nm, respectively. The results obtained from XRD, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) indicated that a small number of iron oxides formed on the surface of K-nZVI, suggesting that free Pb(2+) was adsorbed onto K-nZVI and subsequently reduced to Pb(0). Copyright © 2011 Elsevier Ltd. All rights reserved.

Lithium modified zeolite synthesis for conversion of biodiesel-derived glycerol to polyglycerol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayoub, Muhammad, E-mail: muhammad.ayoub@petronas.com.my; Abdullah, Ahmad Zuhairi, E-mail: chzuhairi@usm.my; Inayat, Abrar, E-mail: abrar.inayat@petronas.com.my

Basic zeolite has received significant attention in the catalysis community. These zeolites modified with alkaline are the potential replacement for existing zeolite catalysts due to its unique features with added advantages. The present paper covers the preparation of lithium modified zeolite Y (Li-ZeY) and its activity for solvent free conversion of biodiesel-derived glycerol to polyglycerol via etherification process. The modified zeolite was well characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Nitrogen Adsorption. The SEM images showed that there was no change in morphology of modified zeolite structure after lithium modification. XRD patterns showed that the structure ofmore » zeolite was sustained after lithium modification. The surface properties of parent and modified zeolite was also observed N{sub 2} adsortion-desorption technique and found some changes in surface area and pore size. In addition, the basic strength of prepared materials was measured by Hammet indicators and found that basic strength of Li-ZeY was highly improved. This modified zeolite was found highly thermal stable and active heterogamous basic catalyst for conversion of solvent free glycerol to polyglycerol. This reaction was conducted at different temperatures and 260 °C was found most active temperature for this process for reaction time from 6 to 12 h over this basic catalyst in the absence of solvent.« less

Thermal, structural, functional, optical and magnetic studies of pure and Ba doped CdO nanoparticles.

PubMed

Sivakumar, S; Venkatesan, A; Soundhirarajan, P; Khatiwada, Chandra Prasad

2015-12-05

In this research, a chemical precipitation method was used to synthesize undoped and doped cadmium oxide nanoparticles and studied by TG-DTA, XRD, FT-IR, SEM, with EDX and antibacterial activities, respectively. The melting points, thermal stability and the kinetic parameters like entropy (ΔS), enthalpy (ΔH), Gibb's energy (ΔG), activation energy (E), frequency factor (A) were evaluated from TG-DTA measurements. X-ray diffraction analysis (XRD) brought out the information about the synthesized products exist in spherical in shape with cubic structure. The functional groups and band area of the samples were established by Fourier transform infrared (FT-IR) spectroscopy. The direct and indirect band gap energy of pure and doped samples were determined by UV-Vis-DRS. The surface morphological, elemental compositions and particles sizes were evaluated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Finally, antibacterial activities indicated the Gram-positive and Gram-negative bacteria are more active in transporter, dehydrogenize and periplasmic enzymatic activities of pure and doped samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Efficient photo-catalytic degradation of malachite green using nickel tungstate material as photo-catalyst.

PubMed

Helaïli, N; Boudjamaa, A; Kebir, M; Bachari, K

2017-03-01

The present study focused on the evaluation of photo-catalytic and photo-electrochemical properties of the photo-catalyst based on nickel tungstate material prepared by a nitrate method through the degradation of malachite green (MG) dye's. The effect of catalyst loading and dye concentration was examined. Physico-chemical, optical, electrical, electrochemical, and photo-electrochemical properties of the prepared material were analyzed by X-ray diffraction (XRD), fourier transform-infrared spectroscopy (FTIR), BET analysis, optical reflectance diffuse (DR), scanning electron microscopy (SEM/EDX), electrical conductivity, cyclic voltammetry (CV), current intensity, mott-shottky, and nyquist. XRD revealed the formation of monoclinic structure with a small particle size. BET surface area of the sample was around 10 m 2 /g. The results show that the degradation of MG was more than 80%, achieved after 3 h of irradiation at pH 4.6 and with a catalyst loading of 75 mg. Also, it was found that the dye photo-degradation obeyed the pseudo-first order kinetic via Langmuir Hinshelwood model.

Al3+ ions dependent structural and magnetic properties of Co-Ni nano-alloys.

PubMed

Kadam, R H; Alone, Suresh T; Gaikwad, Anil S; Birajdar, A P; Shirsath, Sagar E

2014-06-01

Ferrite samples with a chemical formula Co0.5Ni0.5Al(x)Fe(2-x)O4 (where x = 0.0, 0.25, 0.5, 0.75 and 1.0) were synthesized by sol-gel auto-combustion method. The synthesized samples were annealed at 600 degrees C for 4 h. An analysis of X-ray diffraction (XRD) patterns reveals the formation of single phase cubic spinel structure. The lattice parameter decreased linearly with the increasing Al content x. Nano size of the powders were confirmed by the transmission electron micrographs (TEM). Particle size, bulk density decreased whereas specific surface area and porosity of the samples increased with the Al substitution. Cation distribution of constituent ions shows linear dependence of Al substitution. Based on the cation distribution obtained from XRD data, structural parameters such as lattice parameters, ionic radii of available sites and the oxygen parameter 'u' is calculated. Saturation magnetization (M(s)), magneton number (n(B)) and coercivity (H(c)) decreased with the Al substitution. Possible explanation for the observed structural and magnetic behavior with various Al content are discussed.

Tetramethylene glycol mediated hydrothermal synthesis of defect-rich SnO2 nanoparticles for fast adsorption and degradation of MB dye

NASA Astrophysics Data System (ADS)

Rani, Barkha; Jadhao, Charushila Vasant; Sahu, Niroj Kumar

2018-04-01

Defect-rich pristine tin oxide nanoparticles (SnO2 NPs) with high colloidal stability have been synthesized by tetramethylene glycol (TMG) mediated hydrothermal process and characterized by XRD, TEM, Zeta Potential, PL spectroscopy and porosity measurement techniques. XRD result suggests the formation of rutile phase of SnO2 with average crystallite size of 2.65 nm. TMG act as a structure directing agent assist in the formation of network like structure of SnO2 NPs as confirmed from TEM. Significant blue shifts in the UV absorption spectrum as that of the bulk and defect bands in the PL spectrum are observed. The nanomaterial possesses very high surface area of 263.102 m2/g and large pore volume. The above properties strongly influence the photocatalytic degradation of methylene blue dye. Very fast adsorption and 96% degradation (under UV irradiation) has been achieved when 10 ppm methylene blue solutions is catalysed by 20 mg SnO2 NPs which pave the way for potential environmental application.

Estimation of lattice strain in nanocrystalline RuO2 by Williamson-Hall and size-strain plot methods.

PubMed

Sivakami, R; Dhanuskodi, S; Karvembu, R

2016-01-05

RuO2 nanoparticles (RuO2 NPs) have been successfully synthesized by the hydrothermal method. Structure and the particle size have been determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). UV-Vis spectra reveal that the optical band gap of RuO2 nanoparticles is red shifted from 3.95 to 3.55eV. BET measurements show a high specific surface area (SSA) of 118-133m(2)/g and pore diameter (10-25nm) has been estimated by Barret-Joyner-Halenda (BJH) method. The crystallite size and lattice strain in the samples have been investigated by Williamson-Hall (W-H) analysis assuming uniform deformation, deformation stress and deformation energy density, and the size-strain plot method. All other relevant physical parameters including stress, strain and energy density have been calculated. The average crystallite size and the lattice strain evaluated from XRD measurements are in good agreement with the results of TEM. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis of Carbon Nano Materials Originated from Waste Cooking Oil Using a Nebulized Spray Pyrolysis

NASA Astrophysics Data System (ADS)

Arie, A. A.; Hadisaputra, L.; Susanti, R. F.; Devianto, H.; Halim, M.; Enggar, R.; Lee, J. K.

2017-07-01

Synthesis of nanocarbon on snake fruit-peel’s activated carbon from waste cooking oil palm was conducted by a nebulized spray pyrolysis process (NSP) by varying the processing temperature from 650 to 750 °C. Ferrocene was used as a catalyst with constant concentration of 0.015 g/ml of carbon source. The structure of nanocarbon was studied by using scanning electron microscope (SEM),x-ray diffraction (XRD), surface area analyzer and Raman spectroscopy. SEM results showed that the structures of carbon products was in the the form of carbon nanopsheres (CNS). XRD and Raman analysis confirmed the CNS structure. The carbon producs were then tested as electrode’s materials for lithium ion capacitors (LIC) by cyclic voltammetry (CV) instruments. From the CV results the specific capacitance was estimated as 79.57 F / g at a scan rate of 0.1 mV / s and voltage range from 2.5 - 4 V. This study shows that the nano carbons synthesized from the waste cooking oil can be used as prospective electrode materials for LIC.

In-situ growth of ZIF-8 on layered double hydroxide: Effect of Zn/Al molar ratios on their structural, morphological and adsorption properties.

PubMed

Yang, Yingli; Yan, Xinlong; Hu, Xiaoyan; Feng, Rui; Zhou, Min

2017-11-01

In-situ growth of Zeolite imidazolate frameworks (ZIFs) on layered double hydroxides (LDHs) to form porous composites is a promising and challenging strategy to develop materials for separation application. Herein, the Zn-Al LDH with different Zn/Al molar ratios was prepared and used as matrix for the growth of ZIF-8 on its surface. The resulting composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 physisorption, thermogravimetric (TG), scanning electron microscope (SEM) and elemental analysis followed by testing for As V removal from aqueous solution. Results showed that ZIF-8 could form on the surface of LDH with different Zn/Al molar ratios. At low Zn/Al molar ratios, the morphology and surface area of the ZIF/LDH composites and the content of ZIF-8 in the composites were little affected by the Zn/Al molar ratio. With increasing Zn/Al molar ratio, ZIF-8/LDH exhibited a lower surface area, which resulted from reduced content of ZIF-8 caused by impurities generated in the LDH matrix. All ZIF-8/LDH samples showed high As V adsorption capacity, which was significantly higher than that of pure LDH or ZIF-8. Copyright © 2017 Elsevier Inc. All rights reserved.

Chemical etching mechanism and properties of microstructures in sapphire modified by femtosecond laser

NASA Astrophysics Data System (ADS)

Liu, Manyu; Hu, Youwang; Sun, Xiaoyan; Wang, Cong; Zhou, Jianying; Dong, Xinran; Yin, Kai; Chu, Dongkai; Duan, Ji'an

2017-01-01

Sapphire, with extremely high hardness, high-temperature stability and wear resistance, often corroded in molten KOH at 300 °C after processing. The fabrication of microstructures on sapphire substrate performed by femtosecond laser irradiation combined with KOH solution chemical etching at room temperature is presented. It is found that this method reduces the harsh requirements of sapphire corrosion. After femtosecond irradiation, the sapphire has a high corrosion speed at room temperature. Through the analysis of Raman spectrum and XRD spectrum, a novel insight of femtosecond laser interaction with sapphire (α-Al2O3) is proposed. Results indicated that grooves on sapphire surface were formed by the lasers ablation removal, and the groove surface was modified in a certain depth. The modified area of the groove surface was changed from α-Al2O3 to γ-Al2O3. In addition, the impacts of three experimental parameters, laser power, scanning velocities and etching time, on the width and depth of microstructures are investigated, respectively. The modified area dimension is about 2 μm within limits power and speed. This work could fabricate high-quality arbitrary microstructures and enhance the performance of sapphire processing.

Microstructure and corrosion resistance of sputter-deposited titanium-chromium alloy coatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landolt, D.; Robyr, C.; Mettraux, P.

1998-10-01

Titanium, chromium, and titanium-chromium alloy coatings were sputter-deposited to study their corrosion behaviors in relation to microstructure and composition. Silicon substrates were used to study the effect of alloying on intrinsic corrosion resistance of the coating materials, and brass substrates were used to study the effect of alloying on the penetrating porosity of the coatings. Corrosion behavior was characterized using linear sweep voltammetry. The crystal structure of the coatings was examined by x-ray diffraction (XRD) and the microstructure by scanning electron microscopy (SEM). Electrochemical impedance spectroscopy (EIS) was used to estimate the real surface area of the coatings. Results showedmore » alloying of titanium with chromium greatly influenced microstructure of the coatings. Alloying led to deposits of higher apparent density and, in some cases, to an x-ray amorphous structure. Alloy coatings showed significantly lower corrosion currents than the constituting metals. The effect was attributed to a smoother surface topography. When corrected of differences in real surface area, the intrinsic corrosion rate of the alloy coatings did not differ significantly from that of the constituting metals. Alloy coatings deposited on brass exhibited a lower porosity than titanium or chromium metal coatings produced under identical conditions.« less

FABRICATION AND OPTOELECTRONIC PROPERTIES OF MgxZn1-xO ULTRATHIN FILMS BY LANGMUIR-BLODGETT TECHNOLOGY

NASA Astrophysics Data System (ADS)

Tang, Dongyan; Feng, Qian; Jiang, Enying; He, Baozhu

2012-08-01

By transferring MgxZn1-xO sol and stearic acid onto a hydrophilic silicon wafer or glass plate, the Langmuir-Blodgett (LB) multilayers of MgxZn1-xO (x:0, 0.2, 0.4) were deposited. After calcinations at 350°C for 0.5 h and at 500°C for 3 h, MgxZn1-xO ultrathin films were fabricated. The optimized parameters for monolayer formation and multilayer deposition were determined by the surface pressure-surface (Π-A) area and the transfer coefficient, respectively. The expended areas of stearic acid with MgxZn1-xO sols under Π-A isotherms inferred the interaction of stearic acid with MgxZn1-xO sols during the formation of monolayer at air-water interface. X-ray diffraction (XRD) was used to determine the crystal structures of MgxZn1-xO nanoparticles and ultrathin films. The surface morphologies of MgxZn1-xO ultrathin films were observed by scanning probe microscopy (AFM). And the optoelectronic properties of MgxZn1-xO were detected and discussed based on photoluminescence (PL) spectra.

Measurement of clay surface areas by polyvinylpyrrolidone (PVP) sorption and its use for quantifying illite and smectite abundance

USGS Publications Warehouse

Blum, A.E.; Eberl, D.D.

2004-01-01

A new method has been developed for quantifying smectite abundance by sorbing polyvinylpyrrolidone (PVP) on smectite particles dispersed in aqueous solution. The sorption density of PVP-55K on a wide range of smectites, illites and kaolinites is ~0.99 mg/m2, which corresponds to ~0.72 g of PVP-55K per gram of montmorillonite. Polyvinylpyrrolidone sorption on smectites is independent of layer charge and solution pH. PVP sorption on SiO2, Fe2O3 and ZnO normalized to the BET surface area is similar to the sorption densities on smectites. γ-Al2O3, amorphous Al(OH)3 and gibbsite have no PVP sorption over a wide range of pH, and sorption of PVP by organics is minimal. The insensitivity of PVP sorption densities to mineral layer charge, solution pH and mineral surface charge indicates that PVP sorption is not localized at charged sites, but is controlled by more broadly distributed sorption mechanisms such as Van der Waals’ interactions and/or hydrogen bonding. Smectites have very large surface areas when dispersed as single unit-cell-thick particles (~725 m2/g) and usually dominate the total surface areas of natural samples in which smectites are present. In this case, smectite abundance is directly proportional to PVP sorption. In some cases, however, the accurate quantification of smectite abundance by PVP sorption may require minor corrections for PVP uptake by other phases, principally illite and kaolinite. Quantitative XRD can be combined with PVP uptake measurements to uniquely determine the smectite concentration in such samples.

Thermal effect of Zn quantum dots grown on Si(111): competition between relaxation and reconstraint

NASA Astrophysics Data System (ADS)

Kao, Li-Chi; Huang, Bo-Jia; Zheng, Yu-En; Tu, Kai-Teng; Chiu, Shang-Jui; Ku, Ching-Shun; Lo, Kuang Yao

2018-01-01

Zn dots are potential solutions for metal contacts in future nanodevices. The metastable states that exist at the interface between Zn quantum dots and oxide-free Si(111) surfaces can suppress the development of the complete relaxation and increase the size of Zn dots. In this work, the actual heat consumption of the structural evolution of Zn dots resulting from extrinsic thermal effect was analyzed. Zn dots were coherently grown on oxide-free Si(111) through magnetron RF sputtering. A compensative optical method combined with reflective second harmonic generation and synchrotron x-ray diffraction (XRD) was developed to statistically analyze the thermal effect on the Zn dot system. Pattern matching (3 m) between the Zn and oxide-free Si(111) surface enabled Si(111) to constrain Zn dots from a liquid to solid phase. Annealing under vacuum induced smaller, loose Zn dots to be reconstrained by Si(111). When the size of the Zn dots was in the margin of complete relaxation, the Zn dot was partially constrained by potential barriers (metastable states) between Zn(111) and one of the six in-planes of Si〈110〉. The thermal disturbance exerted by annealing would enable partially constrained ZnO/Zn dots to overcome the potential barrier and be completely relaxed, which is obvious on the transition between Zn(111) and Zn(002) peak in synchrotron XRD. Considering the actual irradiated surface area of dots array in a wide-size distribution, the competition between reconstrained and relaxed Zn dots on Si(111) during annealing was statistically analyzed.

Residual stresses in continuous graphite fiber Al metal matrix composites

NASA Technical Reports Server (NTRS)

Park, Hun Sub; Zong, Gui Sheng; Marcus, Harris L.

1988-01-01

The residual stresses in graphite fiber reinforced aluminum (Gr/Al) composites with various thermal histories are measured using X-ray diffraction (XRD) methods. The XRD stress analysis is based on the determination of lattice strains by precise measurements of the interplanar spacings in different directions of the sample. The sample is a plate consisting of two-ply P 100 Gr/Al 6061 precursor wires and Al 6061 overlayers. Prior to XRD measurement, the 6061 overlayers are electrochemically removed. In order to calibrate the relationship between stress magnitude and lattice spacing shift, samples of Al 6061 are loaded at varying stress levels in a three-point bend fixture, while the stresses are simultaneously determined by XRD and surface-attached strain gages. The stresses determined by XRD closely match those determined by the strain gages. Using these calibrations, the longitudinal residual stresses of P 100 Gr/Al 6061 composites are measured for various heat treatments, and the results are presented.

Fabrication and characterization of a novel hydrophobic CaCO3 grafted by hydroxylated poly(vinyl chloride) chains

NASA Astrophysics Data System (ADS)

Bao, Lixia; Yang, Simei; Luo, Xin; Lei, Jingxin; Cao, Qiue; Wang, Jiliang

2015-12-01

The hydroxylated PVC (PVC-OH) was successfully synthesized by a suspension polymerization of vinyl chloride (VC), butyl acrylate (BA) and hydroxyethyl acrylate (HEA). Novel hydrophobic CaCO3 was then prepared by a urethane formation reaction between methylene diphenyl diisocyanate (MDI) and the sbnd OH groups both in the PVC-OH chains and on the surface of pristine CaCO3 particles. The effect of the PVC-OH content on the grafting ratio of treated CaCO3 particles was extensively investigated. Combining the result of Fourier transform infrared (FTIR) with that of water contact angle, it can be concluded that the hydrophobicity of CaCO3 had been efficiently improved by the PVC-OH segments grafted on the surface of CaCO3 particles. X-ray diffraction (XRD), thermal gravity analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM) were also used to study crystalline behaviors, thermal stability and surface morphology of the modified CaCO3 particles, respectively. The change of specific surface area implying surface modification was investigated as well.

The Structure and Infrastructure of the Global Nanotechnology Literature

DTIC Science & Technology

2005-01-01

transmiss.electron.microscopi 1.3%, morpholog 1.2%, zn 1.0%, cd 1.0%, microscopi 1.0%, synthesi 0.9%, diffract.xrd 0.8%, electron 0.8%, powder 0.8%, surfact 0.8...film 2.3%, product 2.3%, hydrotherm 1.1%, tem 1.0%, synthes 0.9%, reaction 0.9%, xrd 0.9%, layer 0.8%, zn 0.8%, surfac 0.7%, cd 0.7%, magnet 0.7...0.5%, sol.gel 0.5%, thick 0.5%, materi 0.5%, laser 0.5%, reaction 0.5%, capac 0.4%, synthesi 0.4%, thin 0.4%, surfac 0.4%, nanowir 0.4%, nanoparticl

Astrobiological Significance of Definitive Mineralogical Analysis of Martian Surface Samples Using the CheMin XRD/XRF Instrument

NASA Technical Reports Server (NTRS)

Feldman, S. M.; Blake, D. F.; Sarrazin, P.; Bish, D. L.; Chipera, S. J.; Vaniman, D. T.; Collins, S.

2004-01-01

The search for evidence of habitability, or of extant or extinct life on Mars, will initially be a search for evidence of past or present conditions supportive of life. The three key requirements for the emergence of life are thought to be liquid water; a suitable energy source; and chemical building blocks. CheMin is a miniaturized XRD/XRF (X-Ray diffraction / X-ray fluorescence) instrument which has been developed for definitive mineralogic analysis of soils and rocks on the Martian surface. The CheMin instrument can provide information that is highly relevant to each of these habitability requirements as summarized below.

Facile synthesis of mesoporous spinel NiCo2O4 nanostructures as highly efficient electrocatalysts for urea electro-oxidation

NASA Astrophysics Data System (ADS)

Ding, Rui; Qi, Li; Jia, Mingjun; Wang, Hongyu

2014-01-01

Mesoporous spinel nickel cobaltite (NiCo2O4) nanostructures were synthesized via a facile chemical deposition method coupled with a simple post-annealing process. The physicochemical properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. The electrocatalytic performances were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit typical agglomerate mesoporous nanostructures with a large surface area (190.1 m2 g-1) and high mesopore volume (0.943 cm3 g-1). Remarkably, the NiCo2O4 shows much higher catalytic activity, lower overpotential, better stability and greater tolerance towards urea electro-oxidation compared to those of cobalt oxide (Co3O4) synthesized by the same procedure. The NiCo2O4 electrode delivers a current density of 136 mA cm-2 mg-1 at 0.7 V (vs. Hg/HgO) in 1 M KOH and 0.33 M urea electrolytes accompanied with a desirable stability. The impressive electrocatalytic activity is largely ascribed to the high intrinsic electronic conductivity, superior mesoporous nanostructures and rich surface Ni active species of the NiCo2O4 materials, which can largely boost the interfacial electroactive sites and charge transfer rates for urea electro-oxidation, indicating promising applications in future wastewater remediation, hydrogen production and fuel cells.Mesoporous spinel nickel cobaltite (NiCo2O4) nanostructures were synthesized via a facile chemical deposition method coupled with a simple post-annealing process. The physicochemical properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. The electrocatalytic performances were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit typical agglomerate mesoporous nanostructures with a large surface area (190.1 m2 g-1) and high mesopore volume (0.943 cm3 g-1). Remarkably, the NiCo2O4 shows much higher catalytic activity, lower overpotential, better stability and greater tolerance towards urea electro-oxidation compared to those of cobalt oxide (Co3O4) synthesized by the same procedure. The NiCo2O4 electrode delivers a current density of 136 mA cm-2 mg-1 at 0.7 V (vs. Hg/HgO) in 1 M KOH and 0.33 M urea electrolytes accompanied with a desirable stability. The impressive electrocatalytic activity is largely ascribed to the high intrinsic electronic conductivity, superior mesoporous nanostructures and rich surface Ni active species of the NiCo2O4 materials, which can largely boost the interfacial electroactive sites and charge transfer rates for urea electro-oxidation, indicating promising applications in future wastewater remediation, hydrogen production and fuel cells. Electronic supplementary information (ESI) available: XRD patterns of NO and CO; XRD patterns and XPS profiles of CO; SEM images of CO; BET plots of CO; XPS quantitative analysis of NCO; a comparison of N2 sorption data between NCO and CO; the fitted values of impedimetric parameters of NCO and CO electrodes. See DOI: 10.1039/c3nr05359h

Silver nanoparticles anchored reduced graphene oxide for enhanced electrocatalytic activity towards methanol oxidation

NASA Astrophysics Data System (ADS)

Kumar, Sanjeev; Mahajan, Mani; Singh, Rajinder; Mahajan, Aman

2018-02-01

In this report, silver nanoparticles (Ag NPs) anchored reduced graphene oxide (rGO) sheets (rGO/Ag) nanohybrid has been explored as anode material in direct methanol fuel cells (DMFCs). The synthesized rGO/Ag nanohybrid is characterized by XRD, XPS, FTIR spectroscopy and HRTEM techniques. Cyclic voltammograms demonstrate that the rGO/Ag nanohybrid exhibits higher electrocatalytic activity in comparison to rGO sheets for methanol oxidation reaction (MOR). This enhancement is attributed to the synergetic effect produced by the presence of more active sites provided by Ag NPs anchored on a conducting network of large surface area rGO sheets.

Micro-emulsion-assisted synthesis of ZnS nanospheres and their photocatalytic activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Yao; He Xiaoyan; Cao Minhua

2008-11-03

ZnS nanospheres with rough surface were synthesized by using a micro-emulsion-assisted solvothemal process. The molar ratio of [water]/[surfactant] played an important role in controlling the size of the ZnS nanospheres. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), field emission-scanning electron microscope (FE-SEM), and selected area electron diffraction (SAED) were used for the characterization of the resulting ZnS nanospheres. A possible formation mechanism was proposed. These ZnS nanospheres exhibited a good photocatalytic activity for degradation of an aqueous p-nitrophenol solution and the total organic carbon (TOC) of the degradation product has also been investigated.

CuO urchin-nanostructures synthesized from a domestic hydrothermal microwave method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keyson, D.; Laboratorio de Ensino de Ciencias, DME Universidade Federal da Paraiba, PB; Volanti, D.P.

This letter reports the synthesis of CuO urchin-nanostructures by a simple and novel hydrothermal microwave method. The formation and growth of urchin-nanostructures is mainly affected by the addition of polyethylene glycol (PEG). The hierarchical malachite particles are uniform spheres with a diameter of 0.7-1.9 {mu}m. CuO urchin-nanostructures were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FEG-SEM) and nitrogen adsorption (BET). The specific surface area of the CuO nanostructured microspheres was about 170.5 m{sup 2}/g. A possible mechanism for the formation of such CuO urchin-nanostructures is proposed.

A simple approach for large-area fabrication of Ag nanorings

NASA Astrophysics Data System (ADS)

Yuan, Zhi-hao; Zhou, Wei; Duan, Yue-qin; Bie, Li-jian

2008-02-01

A simple and low-cost method based on a two-step heat treatment of AgNO3/SiO2 film has been developed for fabricating metal Ag nanoring arrays. The as-prepared nanorings have an inner diameter of 70-250 nm and an average wall thickness (namely wire diameter) of approximately 30 nm with a number density of approximately 109 cm-2 on the surface of the SiO2 matrix. X-ray diffraction (XRD) results reveal that these nanorings exhibit a face-centered cubic crystal structure. Furthermore, a new growth mechanism, namely a molten metal bubble as a self-template, is tentatively proposed for Ag nanorings.

Ultrasensitive ppb-level NO2 gas sensor based on WO3 hollow nanosphers doped with Fe

NASA Astrophysics Data System (ADS)

Zhang, Ziyue; haq, Mahmood; Wen, Zhen; Ye, Zhizhen; Zhu, Liping

2018-03-01

WO3 mesoporous hollow nanospheres doped with Fe synthesized by a facile method have mesoporous hollow nanospherical like morphology, small grain size (10 nm), high crystalline quality and ultrahigh surface area (165 m2/g). XRD spectra and Raman spectra indicate the Fe doping leading to the smaller cell parameters as compared to pure WO3, and the slight distortion in the crystal lattice produces a number of defects, making it a better candidate for gas sensing. XPS analysis shows that Fe-doped WO3 mesoporous hollow nanospheres have more oxygen vacancies than pure WO3, which is beneficial to the adsorption of oxygen and NO2 and its surface reaction. The gas sensor based on Fe-WO3 exhibited excellent low ppb-level (10 ppb) NO2 detecting performance and outstanding selectivity.

Unpredictable adsorption and visible light induced decolorization of nano rutile for the treatment of crystal violet

NASA Astrophysics Data System (ADS)

Dong, Yanling; Liu, Yang; Lu, Dingze; Zheng, Feng; Fang, Pengfei; Zhang, Haining

2017-04-01

Photocatalysts containing different ratios of anatase and rutile are prepared via heat treatment of Degussa P-25 titania. X-ray diffraction (XRD), Bruuauer-Emmett-Teller (BET), ultraviolet-visible light diffuse reflectance spectra (DRS), Raman spectra (Raman), positron annihilation lifetime spectra (PAL) and temperature-programmed desorption (TPD) are applied to investigate the phase composition of the synthesized catalysts. Using crystal violet (CV) as the target pollutant, the unexpected visible light decolorization of rutile is observed. Despite the decreased specific surface area, the as-synthesized rutile samples exhibit much higher adsorption capability of CV than P-25 does, which in turn leads to improved photoreaction efficiency. Since the rutile samples can't absorb the visible light, the degradation under visible light irradiation is attributed to self-sensitization of CV on the surface of rutile.

Few layered vanadyl phosphate nano sheets-MWCNT hybrid as an electrode material for supercapacitor application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dutta, Shibsankar; De, Sukanta, E-mail: sukanta.physics@presiuniv.ac.in

It have been already seen that 2-dimensional nano materials are the suitable choice for the supercapacitor application due to their large specific surface area, electrochemical active sites, micromechanical flexibility, expedite ion migration channel properties. Free standing hybrid films of functionalized MWCNT (– COOH group) and α-Vanadyl phosphates (VOPO{sub 4}2H{sub 2}O) are prepared by vacuum filtering. The surface morphology and microstructure of the samples are studied by transmission electron microscope, field emission scanning electron microscope, XRD, Electrochemical properties of hybrid films have been investigated systematically in 1M Na{sub 2}SO{sub 4} aqueous electrolyte. The hybrid material exhibits a high specific capacitance 236more » F/g with high energy density of 65.6 Wh/Kg and a power density of 1476 W/Kg.« less

Salt efflorescence due to water-rock interaction on the surface of tuff cave in the Yoshimi-Hyakuana Historic Site, central Japan

NASA Astrophysics Data System (ADS)

Oguchi, Chiaki T.; Kodama, Shogo; Mohammad, Rajib; Tharanga Udagedara, Dashan

2016-04-01

Artificial cave walls in Yoshimi Hyakuana Historic Site have been suffering from salt weathering since 1945 when the caves were made. To consider the processes of weathering and subsequent crystallization of secondary minerals, water-rock experiment using tuff from this area was performed. Rocks, surface altered materials, groundwater and rainwater were collected, and chemical and mineralogical characteristics of those samples were investigated. The XRD and SEM-EDS analyses were carried out for the solid samples and ICP-OES analysis was performed for the solution generated from the experiment, groundwater and rainwater. Gypsum is detected in original tuff, and on grey and whiter coloured altered materials. General chemical changes were observed on this rock. However, it is found that purple and black altered materials were mainly made due to microbiological processes.

The Synthesis of Silicon Carbide in Rhombohedral Form with Different Chemicals

NASA Astrophysics Data System (ADS)

KARİPER, İ. AFŞIN

2017-06-01

This study describes the attempt at producing silicon carbide using a simpler and less costly method. Within the study, XRD, EDX, and FTIR analyses were performed to determine the structural properties of the product, and SEM analyses were used to identify its surface properties. The characteristics such as porosity and surface area were determined through BET analysis. The starting reagents were compared with the product using FTIR analysis, whereas the product was compared with a sample of SiC procured from a supplier who manufactures high-purity products through BET analysis. In EDX analysis, approximately 72 pct Si and 28 pct C were identified. The vibrational peaks of the synthesized product (characteristics Si-C bonds) were observed at around 1076 cm-1 (FTIR analysis). At the same time, the outcomes were compared with major publications in the literature.

Surface characterization studies of walnut-shell biochar catalysts for simultaneously removing of organic sulfur from yellow phosphorus tail gas

NASA Astrophysics Data System (ADS)

Song, Xin; Li, Kai; Ning, Ping; Wang, Chi; Sun, Xin; Tang, Lihong; Ruan, Haotian; Han, Shuang

2017-12-01

The influences of different preparation conditions for surface characteristics on removing organic sulfur were studied. From BET, XRD, FTIR, DRIFTS, TG/DTA, CO2-TPD results, it can be seen that these preparation conditions had great influences on the pore structure, specific surface area, crystal structure and surface functional groups. The micropore volume, amorphous structure and alkalinity site strength played major roles in desulfurization process. H2S was oxidized by oxygen containing functional groups, such as sbnd COO, sbnd Cdbnd O. H2O molecule could be converted into some groups, such as sbnd CH and Csbnd OH groups, and promoted the hydrolysis reaction. The strong alkalinity site was the key factor for chemical adsorption and hydrolysis. H2O molecule, sbnd CH, Csbnd OH groups promoted the hydrolysis reaction and sbnd COO, sbnd Cdbnd O groups promoted the oxidation of H2S on the surface of WSB. Meanwhile, the main desulfurization process over WSB after carbonization was adsorption and it changed to hydrolysis reaction after activation on the surface of WSB. Furthermore, the reaction mechanism was investigated by DRIFTS measurement according to the change of surface functional groups.

Effect of Arsenic on the Formation and Adsorption Property of Ferric Hydroxide Precipitates in ZVI Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Xing; Xi, Beidou; Zhao, Ying

Treatment of arsenic by zerovalent iron (ZVI) has been studied extensively. However, the effect of arsenic on the formation of ferric hydroxide precipitates in the ZVI treatment has not been investigated. We discovered that the specific surface area (ca. 187 m2/g) and arsenic content (ca. 67 mg/g) of the suspended solids (As-containing solids) generated in the ZVI treatment of arsenic solutions were much higher than the specific surface area (ca. 37 m2/g) and adsorption capacity (ca.12 mg/g) of the suspended solids (As-free solids) generated in the arsenic-free solutions. Arsenic in the As-containing solids was much more stable than the adsorbedmore » arsenic in As-free solids. XRD, SEM, TEM, and selected area electron diffraction (SAED) analyses showed that the As-containing solids consisted of amorphous nanoparticles, while the As-free solids were composed of micron particles with weak crystallinity. Extended X-ray absorption fine structure (EXAFS) analysis determined that As(V) was adsorbed on the As-containing suspended solids and magnetic solid surfaces through bidentate binuclear complexation; and As(V) formed a mononuclear complex on the As-free suspended solids. The formation of the surface As(V) complexes retarded the bonding of free FeO6 octahedra to the oxygen sites on FeO6 octahedral clusters and prevented the growth of the clusters and their development into 3-dimensional crystalline phases.« less

Martensitic phase transformations in the nanostructured surface layers induced by mechanical attrition treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ni Zhichun; Wang Xiaowei; Wu Erdong

2005-12-01

Conversion electron Moessbauer spectroscopy (CEMS) and x-ray diffraction (XRD) analysis have been used to investigate the relationship between characteristics of phase transformation and the treatment time in surface nanocrystallized 316L stainless steel induced by surface mechanical attrition treatment (SMAT). A similar trend of development of the martensitic phase upon the treatment time has been observed from both CEMS and XRD measurements. However, in the CEMS measurement, two types of martensite phase with different magnetic hyperfine fields are revealed. Based on a random distribution of the non-iron coordinating atoms, a three-element theoretical model is developed to illustrate the difference of twomore » types of martensite phase. The calculated results indicate the segregation of the non-iron atoms associated with SMAT treatment.« less

Effects of Laser Re-melting on the Corrosion Properties of HVOF Coatings

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Toor, I. H.; Patel, F.; Baig, M. A.

2013-05-01

HVOF coating of Inconel 625 powder on carbon steel is carried out. Laser melting of the resulting coating is realized to improve coating structural integrity. Morphological and microstructural changes are examined in the coating prior and after laser treatment process using scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction (XRD). The residual stress developed is measured on the surface vicinity of the laser-treated coating using the XRD technique. The corrosion resistance of the laser-treated and untreated coating surfaces is measured, incorporating the potentiodynamic tests in 0.5 M NaCl aqueous solution. It is found that laser treatment reduces the pores and produces cellular structures with different sizes and orientations in the coating. Laser-controlled melting improves the corrosion resistance of the coating surface.

Plasma Sprayed Hydroxyapatite Coatings: Influence of Spraying Power on Microstructure

NASA Astrophysics Data System (ADS)

Mohd, S. M.; Abd, M. Z.; Abd, A. N.

2010-03-01

The plasma sprayed hydroxyapatite (HA) coatings are used on metallic implants to enhance the bonding between the implant and bone in human body. The coating process was implemented at different spraying power for each spraying condition. The coatings formed from a rapid solidification of molten and partly molten particles that impact on the surface of substrate at high velocity and high temperature. The study was concentrated on different spraying power that is between 23 to 31 kW. The effect of different power on the coatings microstructure was investigated using scanning electron microscope (SEM) and phase composition was evaluated using X-ray diffraction (XRD) analysis. The coatings surface morphology showed distribution of molten, partially melted particles and some micro-cracks. The produced coatings were found to be porous as observed from the cross-sectional morphology. The coatings XRD results indicated the presence of crystalline phase of HA and each of the patterns was similar to the initial powder. Regardless of different spraying power, all the coatings were having similar XRD patterns.

Study on growth of large area mercuric iodide polycrystalline film and its x-ray imaging

NASA Astrophysics Data System (ADS)

Xu, Gang; Guo, Yanfei; Xi, Zengzhe; Gu, Zhi; Zhang, Lan; Yu, Wentao; Ma, Xuming; Li, Bo

2014-11-01

Tetragonal mercuric iodide, as a group of wide band gap semiconductors, has been widely investigation during most of the last half-century, applied on room-temperature X-ray and gamma-ray spectrometers. Up to the present, Mercuric iodide (HgI2) is still thought to be one of the most outstanding vitality semiconductor materials because of its wide band gap, for which the device was required to be high resistivity, high atomic number, adequate mechanical strength, long carrier lifetimes and high mobility-lifetime produces. Now, HgI2 polycrystalline films are being developed as a new detector technology for digital x-ray imaging. In this research, HgI2 polycrystalline films with different surface areas of 1 and 36 cm2 were grown by vapor sublimation method within a self-design growth furnace. XRD, SEM and J-V analysis were used to characterize the properties of these as-grown films. The results of XRD show that the ratio of (001) / (hkl) on all as-grown films is amount to be 90% for the area of 1 cm2 films. Grain size of 1 cm2 films was measured to be 120-150 μm. Their electrical resistivity were also determined to be about 1011 Ω·cm operated at the bias voltage of ~100 V by I-V characteristic measurement. Utilizing the polycrystalline film with the area of 36 cm2 deposited on TFT, we then prepared the direct image detector after capsulation for non-corrosive steel screw imaging. The results indicated that profile of screw was distinctly exhibited in digital x-ray imaging systems.

Effect of oxygen partial pressure on oxidation of Mo-metal

NASA Astrophysics Data System (ADS)

Sharma, Rabindar Kumar; Kumar, Prabhat; Singh, Megha; Gopal, Pawar; Reddy, G. B.

2018-05-01

This report explains the effect of oxygen partial pressure (PO2 ) on oxidation of Mo-metal in oxygen plasma. XRD results indulge that oxide layers formed on Mo-surfaces at different oxygen partial pressures have two different oxide phases (i.e. orthorhombic MoO3 and monoclinic Mo8O23). Intense XRD peaks at high pressure (i.e. 2.0×10-1 Torr) points out the formation of thick oxide layer on Mo-surface due to presence of large oxygen species in chamber and less oxide volatilization. Whereas, at low PO2 (6.5×10-2 and 7.5×10-2 Torr.) the reduced peak strength is owing to high oxide volatilization rate. SEM micrographs and thickness measurements also support XRD results and confirm that the optimum -2value of PO2 to deposited thicker and uniform oxide film on glass substrate is 7.5×10-2 Torr through plasma assistedoxidation process. Further to study the compositional properties, EDX of the sample M2 (the best sample) is carried out, which confirms that the stoichiometric ratio is less than 3 (i.e. 2.88). Less stoichiometric ratio again confirms the presence of sub oxides in oxide layers on Mo metal as evidenced by XRD results. All the observed results are well in consonance with each other.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saw, C K

To date a global kinetic rate law has not been written to accurately describe solid-solid phase transformations of HMX and TATB where contributions from grain size effects, binder contents, and impurity levels are explicitly defined. Our recent work presented at the 2001 SCCM topical APS meeting, Atlanta, GA, demonstrated one can not confidently use the second harmonic generation (SHG) diagnostic to study energetic material phase transitions where non-uniform grain size distributions are present. For example, in HMX, the early arrival of SHG before the XRD in the SHG/XRD simultaneous high temperature experiment clearly indicates the partial molecular conversion from centrosymmetricmore » to non-centrosymmetric without any structural changes as exhibit by the XRD pattern. This conversion is attributed to the changes of the surface molecules due to the differences in potential between the surface and the bulk. The present paper reports on accurate XRD measurements following changes of {beta}-HMX to {delta}-HMX at elevated temperature. The results are compared for sample with 2 different grain sizes for HMX. We report accurate temperature dependent lattice parameters and hence volume and linear thermal expansion coefficients along each crystallographic axis. We have also conducted kinetic studies of the behavior of 2 grain-sizes of HMX and concluded that their kinetics, are drastically different.« less

Experimentally Shocked and Altered Basalt: Laboratory Analogs for Calibration of Mars Remote Sensing and In Situ Data

NASA Technical Reports Server (NTRS)

Bell, M. S.

2015-01-01

Calciumphosphate (likely chloroapatite) is formed in the alteration experiments and is more abundant in the altered and shocked sample probably due to increased surface area exposed to alteration fluids resulting from shock damage in the form of both brittle and structural deformation to the starting material (Figs 1 & 3). Apatite forms in basic conditions so the closed system alteration experiment must be buffered by the basalt starting material to create a fluid chemistry environment evolving from neutral at the start to alkaline after 21 days at 160 C. Plagioclase feldspar in the unshocked sample (Fig. 2) has undergone a solid-state transformation to maskelynite, a disordered phase that is not manifest in the XRD pattern of the shocked sample (Fig.4). Olivine and ulvospinel that are present in the starting material can be detected by XRD in the shocked and altered sample (Fig. 4). Tungsten from the sample holder used in the shock experiments dominates the XRD pattern of the shocked and altered sample (Fig. 4). Samples were weighed after the alteration experiments to determine mass loss and predict the amount of material available for the planned analyses from the shock experiments. Within the constraints of these experiments, mass loss is negligible. The samples will next be characterized by Moessbauer and Vis-Near IR spectroscopy, the results of which will be compared to the Mars Exploration Rovers and Mars Reconnaissance Orbiter data sets respectively.

Synthesis, characterization, and catalytic activity of type 2 crystalline titanates prepared with supercritical drying

NASA Astrophysics Data System (ADS)

Al-Adwani, Hamad A. H.

Supercritically dried silico-alumino-titanate (Si-Al-Ti) mixed oxides (T2CT) were successfully synthesized by a sol-gel method with hydrothermal synthesis temperatures less than 200°C and autogenic pressure. High-surface-area T2CT aerogels with meso- to macroporosity were obtained. All solid products, after calcination at 450°C, are semicrystalline. In addition, successful scale-up of T2CT synthesis in a one-gallon reactor yielding 500 g was achieved. Surface areas, pore volumes, and average pore diameters are greatly influenced by the drying method. Supercritical drying had no effect on the crystalline or molecular structure of the materials. The synthesized materials were characterized by means of nitrogen physisorption, X-ray diffraction (XRD), thermal analysis, and diffuse reflectance FTIR spectroscopy. The addition of different amounts of phosphorous and antimony affected neither the textural nor the structural aspects of T2CT. However, a decrease in surface area occurred. The catalytic activity of these materials was evaluated after being loaded with nickel and molybdenum by the incipient wetness method. Cyclohexene hydrogenation and thiophene hydrodesulfurization reactions are used in the catalytic activity study. The activities of some of the catalyst prepared in this study are in the same range as the commercial catalyst, Shell 324, but with lower metal loadings than the commercial catalysts. Thus, more efficient use of Mo and Ni was observed.

Novel mesoporous FeAl bimetal oxides for As(III) removal: Performance and mechanism.

PubMed

Ding, Zecong; Fu, Fenglian; Cheng, Zihang; Lu, Jianwei; Tang, Bing

2017-02-01

In this study, novel mesoporous FeAl bimetal oxides were successfully synthesized, characterized, and employed for As(III) removal. Batch experiments were conducted to investigate the effects of Fe/Al molar ratio, dosage, and initial solution pH values on As(III) removal. The results showed that the FeAl bimetal oxide with Fe/Al molar ratio 4:1 (shorten as FeAl-4) can quickly remove As(III) from aqueous solution in a wide pH range. The FeAl-4 before and after reaction with As(III) was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED), Brunauer-Emmett-Teller (BET) surface area measurement, and X-ray photoelectron spectroscopy (XPS). The BET results showed that the original FeAl-4 with a high surface area of 223.9 m 2 /g was a mesoporous material. XPS analysis indicated that the surface of FeAl-4 possessed a high concentration of M-OH (where M represents Fe and Al), which was beneficial to the immobility of As(III). The excellent performance of FeAl-4 makes it a potentially attractive material for As(III) removal from aqueous solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kapoor, Seema; Batra, Uma; Kohli, Suchita

Hydroxyapatite (HAP) ceramics have been recognized as substitute materials for bone and teeth in orthopedic and dentistry field due to their chemical and biological similarity to human hard tissue. The nanosized and nanocrystalline forms of HAP have great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This paper reports the synthesis of biomimetic nano-hydroxyapatite (HAP) by sol-gel method using calcium nitrate tetrahydrate (CNT) and potassium dihydrogen phosphate (KDP) as calcium and phosphorus precursors, respectively to obtain a desired Ca/P ratio of 1.67. Deionized water was used as a diluting mediamore » for HAP sol preparation and ammonia was used to adjust the pH to 11. After aging, the HAP gel was dried at 55 deg. C and sintered to different temperatures (200 deg. C, 400 deg. C, 600 deg. C, 800 deg. C, 1000 deg. C and 1200 deg. C). The dried and sintered powders were characterized for phase composition using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The particle size and morphology was studied using transmission electron microscopy (TEM). The thermal behavior of the dried HAP nanopowder was studied in the temperature range of 55 deg. C to 1000 deg. C using thermal gravimetric analyser (TGA). The BET surface area of absorbance was determined by Nitrogen adsorption using Brunauer-Emmett-Teller (BET) method. The presence of characteristic peaks of the phosphate and OH groups in FTIR spectrums confirmed the formation of pure HAP in dried as well as sintered powders. XRD results also confirmed the formation of stoichiometric nano-HAP. Sintering revealed that with increase in temperature, both the crystallinity and crystallite size of nano-HAP particles increased. The synthesized nano-HAP powder was found to be stable upto 1000 deg. C without any additional phase other than HAP, whereas peak of {beta}-TCP (tricalcium phosphate) was observed at 1200 deg. C. Photomicrograph of TEM showed that the nanopowder sintered at 600 deg. C is composed of hydroxyapatite nanoparticles (26.0-45.6 nm), which is well in agreement with the crystallite size calculated using XRD data. TGA study showed the thermal stability of the synthesized nano-HAP powder. The BET surface area decreased with increase in sintering temperature.« less

Charting the relationship between phase type-surface area-interactions between the constituent atoms and oxygen reduction activity of Pd–Cu nanocatalysts inside fuel cells by in operando high-energy X-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maswadeh, Yazan; Shan, Shiyao; Prasai, Binay

The activity and stability of nanoalloy catalysts for chemical reactions driving devices for clean energy conversion, in particular the oxygen reduction reaction (ORR), depend critically on optimizing major structural characteristics of the nanoalloys, such as the phase composition, surface area and bonding interactions between the constituent atoms, for the harsh operating conditions inside the devices. The effort requires good knowledge of the potential effect of changes in these characteristics on the catalytic functionality of the nanoalloys and, hence, on the devices' performance. We present the results from an in operando high-energy X-ray diffraction (HE-XRD) study on the concurrent changes inmore » the structural characteristics and ORR activity of Pd–Cu nanoalloy catalysts as they function at the cathode of a proton exchange membrane fuel cell (PEMFC). We find that the as-prepared Pd–Cu nanoalloys with a chemical composition close to Pd1Cu1 are better ORR catalysts in comparison with Pd1Cu2, i.e. Pd-poor, and Pd3Cu1, i.e. Pd-rich, nanoalloys. Under operating conditions though, the former suffers a big loss in ORR activity appearing as a slow-mode oscillation in the current output of the PEMFC. Losses in ORR activity suffered by the latter also exhibit sudden drops and rises during the PEMFC operation. Through atomic pair distribution function (PDF) analysis of the in operando HE-XRD data, we identify the structural changes of Pd–Cu alloy NPs that are behind the peculiar decay of their ORR activity. The results uncover the instant link between the ever-adapting structural state of ORR nanocatalysts inside an operating PEMFC and the performance of the PEMFC. Besides, our results indicate that, among others, taking control over the intra-particle diffusion of metallic species in nanoalloy catalysts may improve the performance of PEMFCs significantly and, furthermore, in operando HE-XRD can be an effective tool to guide the effort. Finally, we argue that, though showing less optimal ORR activity in the as-prepared state, monophase Pd–Cu alloy catalysts with a composition ranging between Pd1Cu1 and Pd3Cu1 may deliver optimal performance inside operating PEMFCs.« less

Highly surface-roughened quasi-spherical silver powders in back electrode paste for silicon solar cells

NASA Astrophysics Data System (ADS)

Yin, Peng; Liu, Shouchao; Li, Qiuying; Chen, Xiaolei; Guo, Weihong; Wu, Chifei

2017-08-01

In our work, highly surface-roughened quasi-spherical silver powders with controllable size and superior dispersibility, which have narrow size distribution and relatively high tap density, were successfully prepared by reducing silver nitrate with ascorbic acid in aqueous solutions. Gum arabic (AG) was selected as dispersant to prevent the agglomeration of silver particles. Furthermore, the effects of preparation conditions on the characteristics of the powders were systematically investigated. By varying the concentration of the reactants, dosage of dispersant, the feeding modes, synthesis temperature and the pH value of the mixture solution of silver nitrate and AG, the resulted silver particles displayed controllable size, different morphologies and surface roughness. The spherical silver powder with mean particle size of 1.20 µm, tap density of 4.1 g cm-3 and specific area value of 0.46 m2 g-1 was prepared by adjusting preparation conditions. The AG absorbed on the surface preventing the silver particles from diffusion and aggregation was proved by the ultraviolet spectra. Observations of SEM images showed that the as-prepared silver powders were relatively monodisperse silver spheres with highly roughened surface and the particle size was controllable from 1 µm to 5 µm, specific surface area value from approximately 0.2 m2 g-1 to 0.8 m2 g-1. X-ray diffraction (XRD) patterns, energy dispersive spectroscopy (EDS), x-ray photoelectron spectra (XPS) and thermal gravity analysis (TGA) demonstrated high crystallinity and purity of the obtained silver powders.

A simple large-scale synthesis of mesoporous In2O3 for gas sensing applications

NASA Astrophysics Data System (ADS)

Zhang, Su; Song, Peng; Yan, Huihui; Yang, Zhongxi; Wang, Qi

2016-08-01

In this paper, large-scale mesoporous In2O3 nanostructures were synthesized by a facile Lewis acid catalytic the furfural alcohol resin (FAR) template route for the high-yield. Their morphology and structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal and thermogravimetry analysis (DSC-TG) and the Brunauer-Emmett-Teller (BET) approach. The as-obtained mesoporous In2O3 nanostructures possess excellent mesoporous and network structure, which increases the contact area with the gases, it is conducive for adsorption-desorption of gas on the surface of In2O3. The In2O3 particles and pores were both about 15 nm and very uniform. In gas-sensing measurements with target gases, the gas sensor based on mesoporous In2O3 nanostructures showed a good response, short response-recovery time, good selectivity and stability to ethanol. These properties are due to the large specific surface area of mesoporous structure. This synthetic method could use as a new design concept for functional mesoporous nanomaterials and for mass production.

Synthesis, characterization and photoactivity of bi-crystalline mesoporous TiO2

NASA Astrophysics Data System (ADS)

Nguyen, Dongthanh; Wang, Wei; Long, Haibo; Ru, Hongqiang

2016-03-01

Mesoporous titania (meso-TiO2) has received extensive attention owing to its versatile potential applications. This paper reports a low-temperature templating approach for the fabrication of meso-TiO2 using the peroxo titanic acid (PTA) sol as precursor and Pluronic P123 as nonionic template. The TGA, XRD, N2 sorption, FE-SEM and HRTEM were used to characterize the obtained samples. The results showed that meso-TiO2 with high surface area up to 163 m2·g-1 and large pore volume of 0.65 cm3·g-1 can be obtained. The mesopore sizes can be varied between 13 and 20 nm via this synthesis approach. The amount of P123 and the calcination conditions were found to have great influence on the mesoporous and crystalline structures of meso-TiO2. The photocatalytic activity testing clearly shows that the high surface area and bi-crystallinity phases of meso-TiO2 play important roles in enhancing photocatalytic properties of meso-TiO2 in photo-decomposing Rhodamine B in water.

Conversion of "Waste Plastic" into Photocatalytic Nanofoams for Environmental Remediation.

PubMed

de Assis, Geovania C; Skovroinski, Euzébio; Leite, Valderi D; Rodrigues, Marcelo O; Galembeck, André; Alves, Mary C F; Eastoe, Julian; de Oliveira, Rodrigo J

2018-03-07

Plastic debris is a major environmental concern, and to find effective ways to reuse polystyrene (PS) presents major challenges. Here, it is demonstrated that polystyrene foams impregnated with SnO 2 are easily generated from plastic debris and can be applied to photocatalytic degradation of dyes. SnO 2 nanoparticles were synthesized by a polymeric precursor method, yielding specific surface areas of 15 m 2 /g after heat treatment to 700 °C. Crystallinity, size, and shape of the SnO 2 particles were assessed by X-ray diffraction (XRD) and transmission electron microscopy (TEM), demonstrating the preparation of crystalline spherical nanoparticles with sizes around 20 nm. When incorporated into PS foams, which were generated using a thermally induced phase separation (TIPS) process, the specific surface area increased to 48 m 2 /g. These PS/SnO 2 nanofoams showed very good efficiency for photodegradation of rhodamine B, under UV irradiation, achieving up to 98.2% removal. In addition the PS/SnO 2 nanofoams are shown to retain photocatalytic activity for up to five reuse cycles.

MgCoAl and NiCoAl LDHs synthesized by the hydrothermal urea hydrolysis method: Structural characterization and thermal decomposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chagas, L.H., E-mail: lhchagas-prometro@inmetro.gov.br; Instituto Nacional de Metrologia Qualidade e Tecnologia, Divisão de Metrologia de Materiais, 25250-020 Duque de Caxias, RJ; De Carvalho, G.S.G.

Highlights: • We synthesized MgCoAl and NiCoAl LDHs by the urea hydrolysis method. • Aluminum rich and crystalline materials have been formed. • The calcination of the LDHs generated mixed oxides with high surface areas. - Abstract: Layered double hydroxides (LDHs) with Mg/Co/Al and Ni/Co/Al were synthesized for the first time by the urea hydrolysis method. The experimental conditions promoted aluminum rich and crystalline materials. The formation of LDHs was investigated by powder X-ray diffraction (XRD), chemical analysis, solid state nuclear magnetic resonance with magic angle spinning ({sup 27}Al-MAS-NMR), simultaneous thermogravimetric/differential thermal analysis (TGA/DTA), FTIR spectroscopy, scanning electron microscopy (SEM),more » and N{sub 2} adsorption–desorption experiments. A single phase corresponding to LDH could be obtained in all the investigated compositions. Thermal calcination of these LDHs at 500 °C resulted in the formation of solid solutions in which Al{sup 3+} was dissolved. All the calcined materials have rock-salt like structures and high surface areas.« less

Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

PubMed Central

Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

2017-01-01

Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time. PMID:28429740

Preparation and characterization of uniform nanosized cephradine by combination of reactive precipitation and liquid anti-solvent precipitation under high gravity environment.

PubMed

Zhong, Jie; Shen, Zhigang; Yang, Yan; Chen, Jianfeng

2005-09-14

In this work, a novel direct method, which was combined with reactive precipitation and liquid anti-solvent precipitation under high gravity environment, had been developed to prepare nanosized cephradine with narrow particle size distribution. Compared with commercial crude cephradine, the prepared cephradine showed a significant decrease in particle size, a significant increase in the specific surface area and shorter dissolving time when used for injection. The characteristic particle size was between 200-400 nm. The specific surface area increased from 2.95 to 10.87 m2/g after micronization. When the amount of L-arginin decreased from 0.25 to 0.18 g, the mixture of nanosized cephradine and L-arginine could still dissolve in 1 min. The X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analysis indicated that the physical characteristics and molecular states remained unchanged after the recrystallization process. This method had potential application in industrial fields because of its low cost, efficient processing and the ease of scaling-up.

Removal of trichloroethylene by zerovalent iron/activated carbon derived from agricultural wastes.

PubMed

Su, Yuh-fan; Cheng, Yu-ling; Shih, Yang-hsin

2013-11-15

Activated carbon (AC) and zerovalent iron (ZVI) have been widely used in the adsorption and dehalogenation process, respectively, for the removal of organic compounds in environmental treatments. This study aims to prepare ZVI/AC derived from an agricultural waste, coir pith, through simple one-step pyrolysis. The effect of activation temperature and time on the surface area, iron content, and zerovalent iron ratio of ZVI/AC was systemically investigated. The results indicated that the activation of AC by FeSO4 significantly increased surface area of AC and distributed elemental iron over the AC. The X-ray diffraction (XRD), electron spectroscopy for chemical analysis (ESCA), and X-ray absorption near edge structure (XANES) spectra of ZVI/AC revealed that zerovalent iron was present. As compared to AC without FeSO4 activation, ZVI/AC increased the trichloroethylene removal rate constant by 7 times. The dechlorination ability of ZVI/AC was dominated by the zerovalent iron content. We have shown that lab-made ZVI/AC from coir pith can effectively adsorb and dehalogenate the chlorinated compounds in water. Copyright © 2013 Elsevier Ltd. All rights reserved.

Transition metal ions effect on the properties and photocatalytic activity of nanocrystalline TiO2 prepared in an ionic liquid.

PubMed

Ghasemi, S; Rahimnejad, S; Setayesh, S Rahman; Rohani, S; Gholami, M R

2009-12-30

TiO(2) and transition metal (Cr, Mn, Fe, Co, Ni, Cu, and Zn) doped TiO(2) nanoparticles were synthesized by the sol-gel method using 2-hydroxylethylammonium formate as an ionic liquid. All the prepared samples were calcined at 500 degrees C and characterized by X-ray diffraction (XRD), BET surface area determination, energy dispersive X-ray (EDX) analysis, diffuse reflectance spectroscopy (DRS), and Fourier transformed infrared (FT-IR) techniques. The studies revealed that transition metal (TM) doped nanoparticles have smaller crystalline size and higher surface area than pure TiO(2). Dopant ions in the TiO(2) structure caused significant absorption shift into the visible region. The results of photodegradation of Acid Blue92 (AB92) in aqueous medium under UV light showed that photocatalytic activity of TiO(2) nanoparticles was significantly enhanced by the presence of some transition metal ions. Chemical Oxygen Demand (COD) of dye solutions were done at regular intervals gave a good idea about mineralization of dye.

Novel methods of stabilization of Raney-Nickel catalyst for fuel-cell electrodes

NASA Astrophysics Data System (ADS)

Al-Saleh, M. A.; Sleem-Ur-Rahman; Kareemuddin, S. M. M. J.; Al-Zakri, A. S.

Two new methods of stabilizing Raney-Nickel (Raney-Ni) catalyst for making fuel-cell anodes were studied. In the first method, the catalyst was oxidized with aqueous H 2O 2 solution, while in the second, oxygen/air (O 2/air) was used in a slurry reactor. Effects of different concentrations of H 2O 2 (5-25 wt.%) and different pressures (10-20 psig) of gas were investigated. The stabilized catalyst was characterized using BET surface area, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The catalyst was used in fuel-cell anodes and the electrochemical performance was determined in an alkaline half-cell. The results were compared with electrodes prepared using conventionally stabilized catalysts. The hydrogen peroxide-treated catalyst has higher BET surface area and produces electrodes with lower polarization. In addition to this, H 2O 2 treatment is convenient, fast and needs simple equipment which involves no instrumentation. Use of oxygen in a slurry reactor to stabilize the catalyst is also convenient but electrode performance is relatively poor.

Preparation of InYO3 catalyst and its application in photodegradation of molasses fermentation wastewater.

PubMed

Qin, Zuzeng; Liang, Yi; Liu, Zili; Jiang, Weiqing

2011-01-01

An InYO3 photocatalyst was prepared through a precipitation method and used for the degradation of molasses fermentation wastewater. The InYO3 photocatalyst characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, surface area and porosimetry. Energy band structures and density of states were achieved using the Cambridge Serial Total Energy package (CASTEP). The results indicated that the photodegradation of molasses fermentation wastewater was significantly enhanced in the presence of InYO3 when compared with PbWO4. The calcination temperature was found to have a significant effect on the photocatalytic activity of InYO3. Specifically, InYO3 calcined at 700 degrees C had a considerably larger surface area and lower reflectance intensity and showed higher photocatalytic activity. The mathematical simulation results indicated that InYO3 is a direct band gap semiconductor, and its conduction band is composed of In 5p and Y 4d orbitals, whereas its valence band is composed of O 2p and In 5s orbitals.

Nanocrystalline TiO₂ Composite Films for the Photodegradation of Formaldehyde and Oxytetracycline under Visible Light Irradiation.

PubMed

Wei, Min; Peng, Xue-Lei; Liu, Qi-Sheng; Li, Fang; Yao, Ming-Ming

2017-06-14

In order to effectively photodegradate organic pollutants, ZnO composite and Co-B codoped TiO₂ films were successfully deposited on glass substrates via a modified sol-gel method and a controllable dip-coating technique. Combining with UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL) analyses, the multi-modification could not only extend the optical response of TiO₂ to visible light region but also decrease the recombination rate of electron-hole pairs. XRD results revealed that the multi-modified TiO₂ film had an anatase-brookite biphase heterostructure. FE-SEM results indicated that the multi-modified TiO₂ film without cracks was composed of smaller round-like nanoparticles compared to pure TiO₂. BET surface area results showed that the specific surface area of pure TiO₂ and the multi-modified TiO₂ sample was 47.8 and 115.8 m²/g, respectively. By degradation of formaldehyde and oxytetracycline, experimental results showed that the multi-modified TiO₂ film had excellent photodegradation performance under visible light irradiation.

Influence of hydrothermal synthesis parameters on the properties of hydroxyapatite nanoparticles.

PubMed

Kuśnieruk, Sylwia; Wojnarowicz, Jacek; Chodara, Agnieszka; Chudoba, Tadeusz; Gierlotka, Stanislaw; Lojkowski, Witold

2016-01-01

Hydroxyapatite (HAp) nanoparticles of tunable diameter were obtained by the precipitation method at room temperature and by microwave hydrothermal synthesis (MHS). The following parameters of the obtained nanostructured HAp were determined: pycnometric density, specific surface area, phase purity, lattice parameters, particle size, particle size distribution, water content, and structure. HAp nanoparticle morphology and structure were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray diffraction measurements confirmed crystalline HAp was synthesized, which was pure in terms of phase. It was shown that by changing the synthesis parameters, the diameter of HAp nanoparticles could be controlled. The average diameter of the HAp nanoparticles was determined by Scherrer's equation via the Nanopowder XRD Processor Demo web application, which interprets the results of specific surface area and TEM measurements using the dark-field technique. The obtained nanoparticles with average particle diameter ranging from 8-39 nm were characterized by having homogeneous morphology with a needle shape and a narrow particle size distribution. Strong similarities were found when comparing the properties of some types of nanostructured hydroxyapatite with natural occurring apatite found in animal bones and teeth.

Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

NASA Astrophysics Data System (ADS)

Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

2017-04-01

Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time.

Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane.

PubMed

Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

2017-04-21

Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time.

Structural and morphological study of Fe-doped Bi-based superconductor

NASA Astrophysics Data System (ADS)

Singh, Yadunath; Kumar, Rohitash

2018-05-01

In the present work, we report the study of iron-doped Bi-based superconductor sample with stoichiometric composition of Bi2Sr2Can-1(Cu1-x Fex)3O2n+4 where n=3 and x = 0.7. This sample was prepared by grinding the precursor oxides in the Ball mill for 6 hours continuous at the rate of 400 rpm for a proper mixing and to obtain the required grain size. Then the solid-state reaction method was used to prepare the sample. X-ray diffraction (XRD) and scanning electron microscopy (SEM) in combination with energy dispersive X-ray fluorescence analysis (EDX) were performed for determination of the crystal structure, surface morphology and trace the material elements of samples, respectively. The surface microscopy data were collected over a selected area of the surface of the material and a two-dimensional image generated that displays spatial variations in properties including chemical characterization and orientation of materials.

Electrochemical Properties of Graphene Oxide/Resol Composites as Electrode Materials for Supercapacitor Applications.

PubMed

Park, Geon Woo; Jeon, Sang Kwon; Yang, Jin Yong; Choi, Sung Dae; Kim, Geon Joong

2016-05-01

RGO/Resol carbon composites were prepared from a mixture of reduced GO and a low-molecular-weight phenolic resin (Resol) solution. The effects of the calcination temperature, amount of Resol added and KOH treatment on the electrochemical performance of the RGO/Resol composites were investigated. The physical and electrochemical properties of the composite materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) surface areas measurements, and cyclic voltammetry (CV). The relationships between their physical properties and their electrochemical performance were examined for use as super-capacitors (SCs). The RGO/Resol composite calcined at 400 degrees C after the KOH loading showed dramatically improved electrochemical properties, showing a high BET surface and capacitance of 2190 m2/g and 220 F/g, respectively. The RGO/Resol composites calcined after the KOH treatment showed much better capacitor performance than those treated only thermally at the same temperature without KOH impregnation. The fabrication of high surface electrodes was essential for improving the SCs properties.

Nanoscale Fe/Ag particles activated persulfate: optimization using response surface methodology.

PubMed

Silveira, Jefferson E; Barreto-Rodrigues, Marcio; Cardoso, Tais O; Pliego, Gema; Munoz, Macarena; Zazo, Juan A; Casas, José A

2017-05-01

This work studied the bimetallic nanoparticles Fe-Ag (nZVI-Ag) activated persulfate (PS) in aqueous solution using response surface methodology. The Box-Behnken design (BBD) was employed to optimize three parameters (nZVI-Ag dose, reaction temperature, and PS concentration) using 4-chlorophenol (4-CP) as the target pollutant. The synthesis of nZVI-Ag particles was carried out through a reduction of FeCl 2 with NaBH 4 followed by reductive deposition of Ag. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area. The BBD was considered a satisfactory model to optimize the process. Confirmatory tests were carried out using predicted and experimental values under the optimal conditions (50 mg L -1 nZVI-Ag, 21 mM PS at 57 °C) and the complete removal of 4-CP achieved experimentally was successfully predicted by the model, whereas the mineralization degree predicted (90%) was slightly overestimated against the measured data (83%).

Characterization of terrestrial hydrothermal alteration products with Mars analog instrumentation: Implications for current and future rover investigations

NASA Astrophysics Data System (ADS)

Black, Sarah R.; Hynek, Brian M.

2018-06-01

Interpretation of Martian geology relies heavily on our understanding of terrestrial analog deposits and our ability to obtain comprehensive and accurate mineralogical compositions. Many previous studies of terrestrial hydrothermal deposits relied on limited datasets and/or did not use instruments analogous to those deployed on Mars. We analyzed 100 hydrothermally altered basalts from Costa Rica, Nicaragua, and Iceland with Mars analog Visible to Short Wave Infrared (VSWIR) spectroscopy, X-ray Diffraction (XRD), and Raman laser spectrometry. Alteration mineralogy consisted of amorphous and crystalline SiO2 (cristobalite, tridymite, quartz), Ca/Al/Fe/Mg-sulfates (gypsum, anhydrite, alunite, jarosite, hexahydrite, alunogen), Fe-, Ti-, and Mg-oxides/hydroxides (hematite, goethite, anatase/brookite, brucite), elemental sulfur, and phyllosilicates (montmorillonite, kaolinite). Results indicate VSWIR is best suited for identification of X-ray amorphous materials such as hydrated SiO2 and phyllosilicates, while XRD is best utilized for highly ordered crystalline materials such as sulfates, crystalline SiO2 polymorphs, elemental sulfur, and Mg-hydroxides identification. Surprisingly, XRD had the lowest identification rates for Fe-oxides/hydroxides (42% compared to 61% and 75% for VNIR and Raman, respectively), and nearly equal identification rates as VSWIR for kaolinite (76% for VSWIR, 71% for XRD). Identification of phyllosilicates in XRD, while possible, is not as effective as VSWIR without extensive sample preparation. Our observed identification rates may be attributed to the relative abundance of materials-Fe-oxides/hydroxides being present as surface coatings, the presence of large amounts of kaolinite in some samples, and an increased particle size for kaolinite relative to other clays. Elemental sulfur and Fe- and Ti-oxides/hydroxides were more readily identified with Raman. With NASA's current focus on habitability, hydrothermally altered areas-which we know to host a wide range of microbial life here on Earth-are of high interest and it is likely that future rovers will encounter similar mineral assemblages. Therefore, future rovers would benefit from using a combination of these methods and expanding the VSWIR sampling range to the full 300-2500 nm to conduct a comprehensive mineralogical investigation.

A study of structural and mechanical properties of nano-crystalline tungsten nitride film synthesis by plasma focus

NASA Astrophysics Data System (ADS)

Hussnain, Ali; Singh Rawat, Rajdeep; Ahmad, Riaz; Hussain, Tousif; Umar, Z. A.; Ikhlaq, Uzma; Chen, Zhong; Shen, Lu

2015-02-01

Nano-crystalline tungsten nitride thin films are synthesized on AISI-304 steel at room temperature using Mather-type plasma focus system. The surface properties of the exposed substrate against different deposition shots are examined for crystal structure, surface morphology and mechanical properties using X-ray diffraction (XRD), atomic force microscope, field emission scanning electron microscope and nano-indenter. The XRD results show the growth of WN and WN2 phases and the development of strain/stress in the deposited films by varying the number of deposition shots. Morphology of deposited films shows the significant change in the surface structure with different ion energy doses (number of deposition shots). Due to the effect of different ion energy doses, the strain/stress developed in the deposited film leads to an improvement of hardness of deposited films.

Surface morphological properties of Ag-Al2O3 nanocermet layers using dip-coating technique

NASA Astrophysics Data System (ADS)

Muhammad, Nor Adhila; Suhaimi, Siti Fatimah; Zubir, Zuhana Ahmad; Daud, Sahhidan

2017-12-01

Ag-Al2O3 nanocermet layer was deposited on Cu coated glass substrate using dip-coating technique. The aim of this study was to observe the surface morphology properties of Ag-Al2O3 nanocermet layers after annealing process at 350°C in H2. The surface morphology of Ag-Al2O3 nanocermet will be characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-Ray Diffractometer (XRD), respectively. The results show that nearly isolated Ag particles having a large and small size were present in the Al2O3 dielectric matrix after annealing process. The face centered cubic crystalline structure of Ag nanoparticles inclusion in the amorphous alumina dielectric matrix was confirmed using XRD pattern and supported by EDX spectra analysis.

Synthesis and characterization of aluminosilicate catalyst impregnated by nickel oxide

NASA Astrophysics Data System (ADS)

Maulida, Iffana Dani; Sriatun, Taslimah

2015-09-01

Aluminosilicate as a catalyst has been synthesized by pore-engineering using CetylTrimethylAmmonium-Bromide (CTAB) as templating agent. It can produce bigger aluminosilicate pore therefore it will be more suitable for bulky molecule. The aims of this research are to synthesize aluminosilicate supported by Nickel, using CTAB surfactant as templating agent for larger pore radius than natural zeolite and characterize the synthesis product, consist of total acid sites and surface area characteristic. This research has been done with following steps. First, making sodium silicate and sodium aluminate. Second, aluminosilicate was synthesized by direct methods, calcined at 550, 650 and 750°C variation temperature, characterized product by X-RD and FTIR spectrometer. Third, NiCl2 was impregnated to the aluminosilicate that has the best cristallinity and main TO4 functional groups product (550 sample). Variation of NiCl2:aluminosilicate (w/w) ratio were 25%:75%, 50%:50% and 75%:25%. Last but not least characterization of catalytic properties was performed. It comprised total acidity test (gravimetric method) and Surface Area Analyzer. The result shows that the product synthesized by direct method at 550oC calcination temperature has the best cristallinity and main functional groups of TO4. The highest total acid sites was 31.6 mmole/g (Imp-A sample). Surface Area Analyzer shows that Imp-B sample has the best pore distribution and highest total pore volume and specific surface area with value 32.424 cc/g and 46.8287 m2/g respectively. We can draw the conclusion that the most potential catalyst is Imp-A sample compared to Imp-B and Imp-C because it has the highest total acid sites. However the most effective catalyst used for product selectivity was Imp-B sample among all samples.

Single-step uncalcined N-TiO2 synthesis, characterizations and its applications on alachlor photocatalytic degradations

NASA Astrophysics Data System (ADS)

Suwannaruang, Totsaporn; Wantala, Kitirote

2016-09-01

The aims of this research were to synthesize nitrogen doped TiO2 (N-TiO2) photocatalysts produced by hydrothermal technique and to test the degradation performance of alachlor by photocatalytic process under UV irradiations in the effect of aging temperature and time in the preparation process. The characterizations of synthesized TiO2 such as specific surface area, particle size, phase structure and elements were analyzed by using the Brunauer-Emmett-Teller (BET) technique, Transmission Electron Microscopy (TEM), X-ray Diffractometer (XRD) and Energy Dispersive X-ray spectrometer (EDX), respectively. The Central Composite Design (CCD) was used to design the experiment to determine the optimal condition, main effects and their interactions by using specific surface area, percent alachlor removal and observed first-order rate constant as responses. The kinetic reactions of alachlor degradation were explained by using Langmuir-Hinshelwood expression to confirm the reaction took place on the surface of photocatalyst. The results showed that the effect of aging temperatures was significant on surface area, whereas aging time was insignificant. Additionally, the square term of aging temperature and interaction term were shown significant on the specific surface area as well. The highest specific surface area from response surface at aging temperature between 150-175 °C and aging time between 6-13 h was found in a range of 100-106 m2/g. The average particle size of TiO2 was similar to crystallite size. Therefore, it can be concluded that one particle has only one crystal. The element analysis has shown 10% of nitrogen in TiO2 structure that the energy band-gap about 2.95 eV was found. Although, the effects of aging temperature and time on percent alachlor removal and observed first-order rate constants were insignificant, both terms were significant in term of the square for alachlor photocatalytic degradation. The optimal condition of both responses was achieved at an aging temperature of 145 °C and aging time of 12 h.

Nanoscale Zero-Valent Iron (NZVI) supported on sineguelas waste for Pb(II) removal from aqueous solution: kinetics, thermodynamic and mechanism.

PubMed

Arshadi, M; Soleymanzadeh, M; Salvacion, J W L; SalimiVahid, F

2014-07-15

In this study, the synthesis and characterization of a new adsorbent containing nanoscale zerovalent iron particles (NZVI) decorated sineguelas waste (S-NaOH-NZVI) from agriculture biomass was investigated for the adsorption/reduction of inorganic pollution such as Pb(II) ions. The combination of ZVI particles on the surface of sineguelas waste can help to overcome the disadvantage of ultra-fine powders which may have strong tendency to agglomerate into larger particles, resulting in an adverse effect on both effective surface area and catalyst performance. The synthesized materials were characterized with different methods such as FT-IR, BET, XRD, TEM and pHPZC. Good dispersion of NZVI particles (ca. 10-70nm) on the sineguelas waste was observed. The effects of various parameters, such as contact time, pH, concentration, adsorbent dosage and temperature were studied. The adsorption of Pb(II) ions has been studied in terms of pseudo-first- and second-order kinetics, and the Freundlich, Langmuir and Langmuir-Freundlich isotherms models have also been used to the equilibrium adsorption data. The adsorption kinetics followed the mechanism of the pseudo-second-order equation. The thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the adsorption of Pb(II) ions were feasible, spontaneous and endothermic at 25-80°C. XRD analysis indicated the presence of Pb(0) on the S-NaOH-NZVI surface. This study suggests that the modified sineguelas waste by NZVI particles can be prepared at low cost and the materials are environmentally benign for the removal of Pb(II) ions, and likely many other heavy metal ions, from water. Copyright © 2014 Elsevier Inc. All rights reserved.

Quaternary M{sub 0.25}Cu{sub 0.25}Mg{sub 0.5}Fe{sub 2}O{sub 4} (M = Ni, Zn, Co, Mn) ferrite oxides: Synthesis, characterization and magnetic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciocarlan, Radu George; Laboratory of Adsorption and Catalysis, Department of Chemistry, University of Antwerpen; Pui, Aurel, E-mail: aurel@uaic.ro

2016-09-15

Highlights: • Superparamagnetic quaternary nanoferrite (M{sub 0.25}Cu{sub 0.25}Mg{sub 0.5}Fe{sub 2}O{sub 4,} where M = Mn, Zn, Co, Ni) were obtained. • C, O, H and metals were observed by XPS analysis. • Phases purity were confirmed by XRD diffraction and crystallite size (3–10 nm) were determind. - Abstract: We report the synthesis of M{sub 0.25}Cu{sub 0.25}Mg{sub 0.5}Fe{sub 2}O{sub 4} (where M = Mn, Zn, Co, Ni) nanoparticles using the coprecipitation method in the presence of carboxymethyl cellulose (CMC) as the in-situ surfactant. The crystalline structure and surface morphology were examined by means of X-ray diffraction (XRD) and scanning electron microscopymore » (SEM) and it was established that the average diameter of the magnetic nanoparticles (MNPs) is in the range of 3–10 nm. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) show that the MNPs are activated by the hydrophilic groups of the surfactant, which coat them and enhance their stability. The vibrating sample magnetometry measurements show the superparamagnetic behavior of the nanoparticles. Due to their small crystallite size, which implies large surface area, and their functionalization with organic groups, the obtained nanoparticles could have medical and catalytic applications.« less

Beneficial use of meat and bone meal combustion residue: "an efficient low cost material to remove lead from aqueous effluent".

PubMed

Deydier, Eric; Guilet, Richard; Sharrock, Patrick

2003-07-04

Meat and bone meal (MBM) combustion residues, a natural apatite-rich substance, was evaluated as a low cost substitute for hydroxyapatite in lead sequestration from water effluents. The thermal behaviour of crude meat and bone meal was followed by TGA and 24% inorganic residue was collected. The resulting ashes were characterised by powder X-ray diffraction (XRD), particle size distribution, specific surface area (BET), and elemental analysis confirming apatite contents, with high level of phosphate (56.3%) and calcium (36.8%). Mechanism and kinetics of lead removal by this bioinorganic material were investigated and compared to mechanisms and kinetics involved with synthetic apatite. Batch metal removal experiments were carried out with 500 and 1500ppm (mg/kg) Pb(2+) solutions. Lead concentration, calcium and pH were monitored. We observed that the mechanism is similar to that occurring for pure apatite, and involved both surface complexation and calcium hydroyapatite (CaHA), Ca(10)(PO(4))(6)(OH)(2), dissolution followed by less soluble Pb(10)(PO(4))(6)(OH)(2) precipitation, as confirmed by XRD analysis of ashes after incubation with lead solution. Our results show that this natural apatite-rich material removes in a few minutes a large quantity of lead (275mg/g capacity) which remains however lower than the theoretical maximum capacity (if calcium were totally substituted by lead). Meat and bone meal combustion residues represent a valuable alternative apatite source for environmental application.

Photocatalytic degradation of methylene blue on Sn-doped titania nanoparticles synthesized by solution combustion route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhange, P.D., E-mail: pallavi.ncl@gmail.com; Awate, S.V.; Gholap, R.S.

2016-04-15

Highlights: • Series of Sn-doped titania nanoparticles were prepared by solution combustion synthesis method. • Sn-doped titania nanoparticles were tested for degradation of MB under UV light irradiation. • The maximum Sn doping in the TiO{sub 2} lattice is found to be less than 10%. • The crystallite size decreases with increase in the Sn content. • The doping of Sn into TiO{sub 2} lattice hinders the recombination of electrons and holes thus enhance the photocatalytic activity. - Abstract: Series of tin-doped titania nanoparticles with varying tin content in the range 0–20 mol% have been prepared by solution combustion synthesismore » route using urea as a fuel. The structure, surface morphology and optical activity of Sn-doped TiO{sub 2} nanoparticles were investigated by various analytical techniques such as powder XRD, SEM, TEM, UV–vis and N{sub 2} adsorption study. The crystalline structures of the various phases were studied by rietveld refinement of the XRD data. The photocatalytic performance of Sn-doped titania nanoparticles were tested for degradation of MB under UV and visible light irradiation. The results reveal that the photocatalytic activity increases with increase in tin content which may be due to decrease in crystallite size with increase in surface area. The doping of Sn into TiO{sub 2} lattice hinders the recombination of electrons and holes thus enhance the quantum efficiency of photocatalytic reaction.« less

The alcohol-sensing behaviour of SnO2 nanorods prepared by a facile solid state reaction

NASA Astrophysics Data System (ADS)

Gao, F.; Ren, X. P.; Wan, W. J.; Zhao, Y. P.; Li, Y. H.; Zhao, H. Y.

2017-02-01

SnO2 nanorods with the range of 12-85 nm in diameter were fabricated by a facile solid state reaction in the medium of NaCl-KCl mixture at room temperature and calcined at 600, 680, 760 and 840 oC, respectively. The XRD, TEM and XPS were employed to characterize the structure and morphology of the SnO2 nanorods. The influence of the calcination temperature on the gas sensing behaviour of the SnO2 nanorods with different diameter was investigated. The result showed that all the sensors had good response to alcohol. The response of the gracile nanorods prepared at a low calcined temperature demonstrated significantly better than the thick nanorods prepared at a high calcined temperature. The mechanism was attributed to the nonstoichiometric ratio of Sn/O and larger surface area of the gracile nanorods to enhance the oxygen surface adsorption.

A facile hydrothermal approach to synthesize rGO/BiVO4 photocatalysts for visible light induced degradation of RhB dye

NASA Astrophysics Data System (ADS)

Pal, Shreyasi; Dutta, Shibsankar; De, Sukanta

2018-05-01

RGO/BiVO4 composites were synthesized by a simple hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) and surface analysis (BET). The photocatalytic activity of the as-prepared samples was evaluated by studying the degradation of model dyes rhodamine B (RhB) under visible light. The prepared rGO/BiVO4 composites exhibited higher photocatalytic activity for the degradation of RhB with a maximum removal rate of 86% under visible light irradiation under visible-light irradiation than pure BiVO4 nanoparticles (63%). This behavior could be associated to their higher specific surface area (BET), increased light absorption intensity and the degradation of electron-hole pair recombination in BiVO4 with the introduction of the rGO.

Modified fly ash from municipal solid waste incineration as catalyst support for Mn-Ce composite oxides

NASA Astrophysics Data System (ADS)

Chen, Xiongbo; Liu, Ying; Yang, Ying; Ren, Tingyan; Pan, Lang; Fang, Ping; Chen, Dingsheng; Cen, Chaoping

2017-08-01

Fly ash from municipal solid waste incineration was modified by hydrothermal treatment and used as catalyst support for Mn-Ce composite oxides. The prepared catalyst showed good activity for the selective catalytic reduction (SCR) of NO by NH3. A NO conversion of 93% could be achieved at 300 °C under a GHSV of 32857 h-1. With the help of characterizations including XRD, BET, SEM, TEM, XPS and TPR, it was found that hydrothermal treatment brought a large surface area and abundant mesoporous to the modified fly ash, and Mn-Ce composite oxides were highly dispersed on the surface of the support. These physical and chemical properties were the intrinsic reasons for the good SCR activity. This work transformed fly ash into high value-added products, providing a new approach to the resource utilization and pollution control of fly ash.

Production of nanotubes in delignified porous cellulosic materials after hydrolysis with cellulase.

PubMed

Koutinas, Αthanasios Α; Papafotopoulou-Patrinou, Evgenia; Gialleli, Angelika-Ioanna; Petsi, Theano; Bekatorou, Argyro; Kanellaki, Maria

2016-08-01

In this study, tubular cellulose (TC), a porous cellulosic material produced by delignification of sawdust, was treated with a Trichoderma reesei cellulase in order to increase the proportion of nano-tubes. The effect of enzyme concentration and treatment duration on surface characteristics was studied and the samples were analyzed with BET, SEM and XRD. Also, a composite material of gelatinized starch and TC underwent enzymatic treatment in combination with amylase (320U) and cellulase (320U) enzymes. For TC, the optimum enzyme concentration (640U) led to significant increase of TC specific surface area and pore volume along with the reduction of pore diameter. It was also shown that the enzymatic treatment did not result to a significant change of cellulose crystallinity index. The produced nano-tubular cellulose shows potential for application to drug and chemical preservative delivery systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Facile fabrication of Cu(II)-porphyrin MOF thin films from tetrakis(4-carboxyphenyl)porphyrin and Cu(OH)2 nanoneedle array

NASA Astrophysics Data System (ADS)

La, Duong Duc; Thi, Hoai Phuong Nguyen; Kim, Yong Shin; Rananaware, Anushri; Bhosale, Sheshanath V.

2017-12-01

Herein, we report a facile synthetic protocol to grow thin films of Cu(II) tetrakis(4-carboxyphenyl)porphyrin (CuTCPP) metal-organic frameworks (MOF) from a tetrakis(4-carboxyphenyl)porphyrin (H2TCPP) solution and the copper hydroxide (Cu(OH)2) nanoneedle array formed on a Cu substrate at room temperature. The formations of Cu-centered TCPP ligands and crystalline platelet-like Cu MOFs were successfully probed by SEM, XRD, FTIR, UV-vis and XPS. The formation process from Cu(OH)2 was monitored by using SEM images obtained at different reaction times during the first 24 h, thus suggesting the reaction pathway of Cu(OH)2 dissolution followed by the reprecipitation of CuTCPP MOFs at a near surface. In addition, the CuTCPP MOFs exhibited a high specific surface area of 408 m2/g.

Functionalization of CNTs surface with phosphonuim based deep eutectic solvents for arsenic removal from water

NASA Astrophysics Data System (ADS)

AlOmar, Mohamed Khalid; Alsaadi, Mohammed Abdulhakim; Hayyan, Maan; Akib, Shatirah; Hashim, Mohd Ali

2016-12-01

Herein, we present the use of deep eutectic solvent (DES) as functionalization agents for carbon nanotubes (CNTs) to form novel adsorbents for removal of arsenic ions (As3+) from water. Two DESs systems were prepared using methyltriphenylphosphonium bromide (MTPB) and benzyltriphenylphosphonium chloride (BTPC) as salts, in conjugation with glycerol (Gly) as a hydrogen bond donor. The resulting novel adsorbents were characterized using thermogravimetric analysis (TGA), Zeta potential, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, XRD, EDX, FESEM, and BET surface area. Optimization studies were carried out utilizing RSM-CCD experimental design to estimate the optimum removal conditions for each adsorbent. The adsorption experimental data of both adsorbents were found to fit well with pseudo-second-order kinetics model, as well as with Langmuir and Freundlich adsorption isotherm models. The maximum adsorption capacity of a MTPB-DES-functionalized CNTs adsorbent was 23.4 mg/g.

Enhancement in surface area and magnetization of CoFe2O4 nanoparticles for targeted drug delivery application

NASA Astrophysics Data System (ADS)

Kale, Swati B.; Somvanshi, Sandeep B.; Sarnaik, M. N.; More, S. D.; Shukla, S. J.; Jadhav, K. M.

2018-05-01

This paper reports facile synthesis, characterizations by X-ray diffraction and scanning electron microscopy and magnetic behaviour of cobalt ferrite nanoparticles. Cobalt ferrite nanoparticles were prepared by sol-gel auto combustion technique using glycine as a fuel. Phase purity and nanocrystalline nature of the prepared sample was confirmed through X-ray diffraction technique. No extra peak other than cubic spinel structure was observed in the XRD pattern. The crystallite size calculated by using Scherrer's formula is of the order of 21.6 nm indicating the nanocrystalline nature of the prepared cobalt ferrite sample. The surface morphological studies were carried out using scanning electron microscope (SEM). SEM image shows homogeneous, agglomerated particles with sponge-like form. The saturation magnetization, coercivity and remenance magnetization obtained by hysteresis curve clearly gives the evidence of excellent and enhanced magnetic behaviour.

Natural manganese ore catalyst for low-temperature selective catalytic reduction of NO with NH3 in coke-oven flue gas.

PubMed

Zhu, Baozhong; Yin, Shoulai; Sun, Yunlan; Zhu, Zicheng; Li, Jiaxin

2017-11-01

Different types of manganese ore raw materials were prepared for use as catalysts, and the effects of different manganese ore raw materials and calcination temperature on the NO conversion were analyzed. The catalysts were characterized by XRF, XRD, BET, XPS, H 2 -TPR, NH 3 -TPD, and SEM techniques. The results showed that the NO conversion of calcined manganese ore with a Mn:Fe:Al:Si ratio of 1.51:1.26:0.34:1 at 450 °C reached 80% at 120 °C and 98% at 180~240 °C. The suitable proportions and better dispersibility of active ingredients, larger BET surface area, good reductibility, a lot of acid sites, contents of Mn 4+ and Fe 3+ , and surface-adsorbed oxygen played important roles in improving the NO conversion.

Diagnosing x-ray power and energy of tungsten wire array z-pinch with a flat spectral response x-ray diode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Kun-lun; Ren, Xiao-dong; Huang, Xian-bin, E-mail: caephxb2003@aliyun.com

2015-11-15

Fast z-pinch is a very efficient way of converting electromagnetic energy to radiation. With an 8-10 MA current on primary test stand facility, about 1 MJ electromagnetic energy is delivered to vacuum chamber, which heats z-pinch plasma to radiate soft x-ray. To develop a pulsed high power x-ray source, we studied the applicability of diagnosing x-ray power from tungsten wire array z-pinch with a flat spectral response x-ray diode (FSR-XRD). The detector was originally developed to diagnose radiation of a hohlraum in SG-III prototype laser facility. It utilized a gold cathode XRD and a specially configured compound gold filter tomore » yield a nearly flat spectral response in photon energy range of 0.1-4 keV. In practice, it was critical to avoid surface contamination of gold cathode. It is illustrated that an exposure of an XRD to multiple shots caused a significant change of response. Thus, in diagnosing x-ray power and energy, we used each XRD in only one shot after calibration. In a shot serial, output of FSR-XRD was compared with output of a nickel bolometer. In these shots, the outputs agreed with each other within their uncertainties which were about 12% for FSR-XRD and about 15% for bolometer. Moreover, the ratios between the FSR-XRD and the bolometer among different shots were explored. In 8 shots, the standard deviation of the ratio was 6%. It is comparable to XRD response change of 7%.« less

Nanostructured KTaTeO6 and Ag-doped KTaTeO6 Defect Pyrochlores: Promising Photocatalysts for Dye Degradation and Water Splitting

NASA Astrophysics Data System (ADS)

Venkataswamy, Perala; Sudhakar Reddy, CH.; Gundeboina, Ravi; Sadanandam, Gullapelli; Veldurthi, Naveen Kumar; Vithal, M.

2018-03-01

In this study, the nanostructured parent KTaTeO6 (KTTO) and Ag-doped KTaTeO6 (ATTO) catalysts with defect pyrochlore structure were prepared by solid-state and ion-exchange methods, respectively. The synthesized materials were characterized by various techniques to determine their chemical composition, morphology and microstructural features. The XRD studies show that both KTTO and ATTO have cubic structure (space group Fd3m) with high crystallinity. The doping of Ag altered the BET surface area of parent KTTO. The nano nature of the samples was studied by TEM images. A considerable red-shift in the absorption edge is observed for ATTO compared to KTTO. Incorporation of Ag+ in the KTTO lattice is clearly identified from EDX, elemental mapping and XPS results. Degradation of methyl violet and solar water splitting reactions were used to access the photocatalytic activity of KTTO and ATTO. The results obtained suggest that compared to KTTO, the ATTO showed higher photocatalytic activity in both cases. The favourable properties such as high surface area, more surface hydroxyl groups, stronger light absorption in visible region and narrower band gap energy were supposed to be the reasons for the high activity observed in ATTO.

Effect of particle size of calcium phosphate based bioceramic drug delivery carrier on the release kinetics of ciprofloxacin hydrochloride: an in vitro study

NASA Astrophysics Data System (ADS)

Sasikumar, Swamiappan

2013-09-01

Hydroxyapatite (HAP) is the constituent of calcium phosphate based bone cement and it is extensively used as a bone substitute and drug delivery vehicle in various biomedical applications. In the present study we investigated the release kinetics of ciprofloxacin loaded HAP and analyzed its ability to function as a targeted and sustained release drug carrier. Synthesis of HAP was carried out by combustion method using tartaric acid as a fuel and nitric acid as an oxidizer. Powder XRD and FTIR techniques were employed to characterize the phase purity of the drug carrier and to verify the chemical interaction between the drug and carrier. The synthesized powders were sieve separated to make two different drug carriers with different particle sizes and the surface topography of the pellets of the drug carrier was imaged by AFM. Surface area and porosity of the drug carrier was carried out using surface area analyzer. The in-vitro drug release kinetics was performed in simulated body fluid, at 37.3°C. The amount of ciprofloxacin released is measured using UV-visible spectroscopy following the characteristic λ max of 278 nm. The release saturates around 450 h which indicates that it can be used as a targeted and sustained release carrier for bone infections.

Biotemplated Synthesis of Anatase Titanium Dioxide Nanoparticles via Lignocellulosic Waste Material

PubMed Central

Bagheri, Samira; Abd Hamid, Sharifah Bee

2014-01-01

Anatase titanium dioxide nanoparticles (TiO2-NPs) were synthesized by sol-gel method using rice straw as a soft biotemplate. Rice straw, as a lignocellulosic waste material, is a biomass feedstock which is globally produced in high rate and could be utilized in an innovative approach to manufacture a value-added product. Rice straw as a reliable biotemplate has been used in the sol-gel method to synthesize ultrasmall sizes of TiO2-NPs with high potential application in photocatalysis. The physicochemical properties of titanium dioxide nanoparticles were investigated by a number of techniques such as X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), ultraviolet visible spectra (UV-Vis), and surface area and pore size analysis. All results consensually confirmed that particle sizes of synthesized titanium dioxide were template-dependent, representing decrease in the nanoparticles sizes with increase of biotemplate concentration. Titanium dioxide nanoparticles as small as 13.0 ± 3.3 nm were obtained under our experimental conditions. Additionally, surface area and porosity of synthesized TiO2-NPs have been enhanced by increasing rice straw amount which results in surface modification of nanoparticles and potential application in photocatalysis. PMID:25126547

Catalytic activity of nanostructured Au: Scale effects versus bimetallic/bifunctional effects in low-temperature CO oxidation on nanoporous Au

PubMed Central

Wang, Lu-Cun; Zhong, Yi; Jin, Haijun; Widmann, Daniel; Weissmüller, Jörg

2013-01-01

Summary The catalytic properties of nanostructured Au and their physical origin were investigated by using the low-temperature CO oxidation as a test reaction. In order to distinguish between structural effects (structure–activity correlations) and bimetallic/bifunctional effects, unsupported nanoporous gold (NPG) samples prepared from different Au alloys (AuAg, AuCu) by selective leaching of a less noble metal (Ag, Cu) were employed, whose structure (surface area, ligament size) as well as their residual amount of the second metal were systematically varied by applying different potentials for dealloying. The structural and chemical properties before and after 1000 min reaction were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The catalytic behavior was evaluated by kinetic measurements in a conventional microreactor and by dynamic measurements in a temporal analysis of products (TAP) reactor. The data reveal a clear influence of the surface contents of residual Ag and Cu species on both O2 activation and catalytic activity, while correlations between activity and structural parameters such as surface area or ligament/crystallite size are less evident. Consequences for the mechanistic understanding and the role of the nanostructure in these NPG catalysts are discussed. PMID:23503603

Photocatalytic reduction of NO with NH3 using Si-doped TiO2 prepared by hydrothermal method.

PubMed

Jin, Ruiben; Wu, Zhongbiao; Liu, Yue; Jiang, Boqiong; Wang, Haiqiang

2009-01-15

A series of Si-doped TiO2 (Si/TiO2) photocatalysts supported on woven glass fabric were prepared by hydrothermal method for photocatalytic reduction of NO with NH3. The photocatalytic activity tests were carried out in a continuous Pyrex reactor with the flow rate of 2000mL/min under UV irradiation (luminous flux: 1.1x10(4)lm, irradiated catalyst area: 160cm2). The photocatalysts were characterized by X-ray diffraction (XRD), BET, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectrophotometer, transmission electron microscopy (TEM), photoluminescence (PL) and temperature-programmed desorption (TPD). The experiment results showed that NO conversion on Si/TiO2 at 323K could exceed 60%, which was about 50% higher than that on Degussa P25 and pure TiO2. With the doping of Si, photocatalysts with smaller crystal size, larger surface area and larger pore volume were obtained. It was also found that Ti-O-Si bands were formed on the surface of Si/TiO2 and that the surface hydroxyl concentration was greatly increased. As a result, total acidity and NH3 chemisorption amount were enhanced for Si/TiO2 leading to its photocatalytic activity improvement.

Removal of copper (II) ion from aqueous solution using zeolite Y synthesized from rice husk ash: Equilibrium and kinetic study

NASA Astrophysics Data System (ADS)

Tuyen, Nguyen Thi Kim; Nhan, Do Nguyen Thanh; Nhat, Trieu Thi; An, Ngo Thanh; Long, Nguyen Quang

2017-09-01

Zeolite Y was synthesized from silica of rice-husk ash using hydrothermal process. The crystalline structure FAU of zeolite Y was characterized by X-ray diffraction (XRD). Surface's area of the catalyst was determined by physic-adsorption method using BET model. The zeolite was examined for possibility of Cu2+ adsorbent by an ion-exchange mechanism. Various adsorption isotherm models, such as Langmuir, Freundlich and Dubinin-Radushkevich were tested for equilibrium study. The integration method was applied to find out the possible kinetic equation of the Cu2+ adsorption on the zeolite Y which obtained from cheap and locally available rice husk ash.

Dye adsorption into transition metal-doped zinc oxide nanoparticles supported on natural zeolites to solve wastewater issue

NASA Astrophysics Data System (ADS)

Indra Pratiwi, Margaretha; Afifah, Nur; Saleh, Rosari

2017-03-01

In this work, Fe-doped zinc oxide/natural zeolite (Fe:ZnO/NZ) nanocomposites were prepared using the co-precipitation method with various NZ amounts. The nanocomposites were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis and thermogravimetric analysis (TGA). The nanocomposites were used to remove methylene blue (MB) dye from an aqueous solution. The effect of various NZ amounts and initial MB concentration were tested. The Pseudo-first-order and pseudo-second-order kinetic models were used to explain the adsorption mechanism. The Langmuir and the Freundlich isotherm models were used to fit the adsorption isotherms of the nanocomposites.

Visible Light Photocatalysis via CdS/ TiO 2 Nanocomposite Materials

DOE PAGES

Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

2006-01-01

Nmore » anostructured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers, and selective reduction/oxidation of different classes of organic compounds. In the present paper, we have carried out a systematic synthesis of nanostructured CdS- TiO 2 via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS- TiO 2 nanocomposites are determined using XRD and SEM-EDS techniques. The visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water suspension.« less

Effects of Polyethylene Glycol and Citric Acid on Preparation and Hydrodechlorination Activity of Molybdenum Phosphide

NASA Astrophysics Data System (ADS)

Liu, Xiaomeng; Lu, Shaoxiang; Xu, Hanghui; Ren, Lili

2018-07-01

Molybdenum phosphide (MoP), modified by polyethylene glycol (PEG) and citric acid (CA), exhibited 2 to 3 times superior activity than the MoP modified by CA alone. And the optimal activity temperature was reduced from 500 to 450oC. The catalyst was fully characterized by a variety of techniques including X-ray diffraction (XRD), N2 adsorption-desorption isotherm, scanning electron microscopy (SEM), transmission electron microscopy (TEM). The results showed that the addition of PEG and CA increased the surface area of MoP and decreased the particle size of MoP. Furthermore, the reaction mechanism also has been discussed by combining the activity data and characterization results.

Surface restructuring of red mud to produce FeO x (OH) y sites and mesopores for the efficient complexation/adsorption of β-lactam antibiotics.

PubMed

Pinto, Paula S; Lanza, Giovani D; Souza, Mayra N; Ardisson, José D; Lago, Rochel M

2018-03-01

In this work, iron oxide in the red mud (RM) waste was restructured to produce mesopores with surface [FeO x (OH) y ] sites for the efficient complexation/adsorption of β-lactam antibiotics. Red mud composed mainly by hematite was restructured by an acid/base process followed by a thermal treatment at 150-450 °C (MRM150, MRM200, MRM300, and MRM450) and fully characterized by Mössbauer, XRD, FTIR, BET, SEM, CHN, and thermogravimetric analyses. The characterization data showed a highly dispersed Fe 3+ oxyhydroxy phase, which was thermally dehydrated to a mesoporous α-Fe 2 O 3 with surface areas in the range of 141-206 m 2  g -1 . These materials showed high efficiencies (21-29 mg g -1 ) for the adsorption of β-lactam antibiotics, amoxicillin, cephalexin, and ceftriaxone, and the data was better fitted by the Langmuir model isotherm (R 2  = 0.9993) with monolayer adsorption capacity of ca. 39 mg g -1 for amoxicillin. Experiments such as competitive adsorption in the presence of phosphate and H 2 O 2 decomposition suggested that the β-lactamic antibiotics might be interacting with surface [FeO x (OH) y ] species by a complexation process. Moreover, the OH/Fe ratio, BET surface area and porosity indicated that this complexation is occurring especially on [FeO x (OH) y ] surf sites contained in the mesopore space.

Investigating the Influence of Temperature on the Kaolinite-Base Synthesis of Zeolite and Urease Immobilization for the Potential Fabrication of Electrochemical Urea Biosensors.

PubMed

Anderson, David Ebo; Balapangu, Srinivasan; Fleischer, Heidimarie N A; Viade, Ruth A; Krampa, Francis D; Kanyong, Prosper; Awandare, Gordon A; Tiburu, Elvis K

2017-08-08

Temperature-dependent zeolite synthesis has revealed a unique surface morphology, surface area and pore size which influence the immobilization of urease on gold electrode supports for biosensor fabrication. XRD characterization has identified zeolite X (Na) at all crystallization temperatures tested. However, N₂ adsorption and desorption results showed a pore size and pore volume of zeolite X (Na) 60 °C, zeolite X (Na) 70 °C and zeolite X (Na) 90 °C to range from 1.92 nm to 2.45 nm and 0.012 cm³/g to 0.061 cm³/g, respectively, with no significant differences. The specific surface area of zeolite X (Na) at 60, 70 and 90 °C was 64 m²/g, 67 m²/g and 113 m²/g, respectively. The pore size, specific surface area and pore volumes of zeolite X (Na) 80 °C and zeolite X (Na) 100 °C were dramatically increased to 4.21 nm, 295 m²/g, 0.762 cm³/g and 4.92 nm, 389 m²/g, 0.837 cm³/g, in that order. The analytical performance of adsorbed urease on zeolite X (Na) surface was also investigated using cyclic voltammetry measurements, and the results showed distinct cathodic and anodic peaks by zeolite X (Na) 80 °C and zeolite X (Na) 100 °C. These zeolites' molar conductance was measured as a function of urea concentration and gave an average polynomial regression fit of 0.948. The findings in this study suggest that certain physicochemical properties, such as crystallization temperature and pH, are critical parameters for improving the morphological properties of zeolites synthesized from natural sources for various biomedical applications.

Investigating the Influence of Temperature on the Kaolinite-Base Synthesis of Zeolite and Urease Immobilization for the Potential Fabrication of Electrochemical Urea Biosensors

PubMed Central

Anderson, David Ebo; Balapangu, Srinivasan; Fleischer, Heidimarie N. A.; Viade, Ruth A.; Awandare, Gordon A.; Tiburu, Elvis K.

2017-01-01

Temperature-dependent zeolite synthesis has revealed a unique surface morphology, surface area and pore size which influence the immobilization of urease on gold electrode supports for biosensor fabrication. XRD characterization has identified zeolite X (Na) at all crystallization temperatures tested. However, N2 adsorption and desorption results showed a pore size and pore volume of zeolite X (Na) 60 °C, zeolite X (Na) 70 °C and zeolite X (Na) 90 °C to range from 1.92 nm to 2.45 nm and 0.012 cm3/g to 0.061 cm3/g, respectively, with no significant differences. The specific surface area of zeolite X (Na) at 60, 70 and 90 °C was 64 m2/g, 67 m2/g and 113 m2/g, respectively. The pore size, specific surface area and pore volumes of zeolite X (Na) 80 °C and zeolite X (Na) 100 °C were dramatically increased to 4.21 nm, 295 m2/g, 0.762 cm3/g and 4.92 nm, 389 m2/g, 0.837 cm3/g, in that order. The analytical performance of adsorbed urease on zeolite X (Na) surface was also investigated using cyclic voltammetry measurements, and the results showed distinct cathodic and anodic peaks by zeolite X (Na) 80 °C and zeolite X (Na) 100 °C. These zeolites’ molar conductance was measured as a function of urea concentration and gave an average polynomial regression fit of 0.948. The findings in this study suggest that certain physicochemical properties, such as crystallization temperature and pH, are critical parameters for improving the morphological properties of zeolites synthesized from natural sources for various biomedical applications. PMID:28786961

Effects of Al(3+) doping on the structure and properties of goethite and its adsorption behavior towards phosphate.

PubMed

Li, Wei; Wang, Longjun; Liu, Fan; Liang, Xiaoliang; Feng, Xionghan; Tan, Wenfeng; Zheng, Lirong; Yin, Hui

2016-07-01

Al substitution in goethite is common in soils, and has strong influence on the structure and physicochemical properties of goethite. In this research, a series of Al-doped goethites were synthesized, and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The adsorption behavior of these samples towards PO4(3-) was also investigated. Characterization results demonstrated that increasing Al content in goethite led to a reduction in crystallinity, increase in specific surface area (SSA), and morphology change from needle-like to granular. Rietveld structure refinement revealed that the lattice parameter a remained almost constant and b slightly decreased, but c was significantly reduced, and the calculated crystal density increased. EXAFS analysis demonstrated that the Fe(Al)-O distance in the structure of the doped goethites was almost the same, but the Fe-Fe(Al) distance decreased with increasing Al content. Surface analysis showed that, with increasing Al content, the content of OH groups on the mineral surface increased. The adsorption of phosphate per unit mass of Al-doped goethite increased, while adsorption per unit area decreased owing to the decrease of the relative proportion of (110) facets in the total surface area of the minerals. The results of this research facilitate better understanding of the effect of Al substitution on the structure and properties of goethite and the cycling of phosphate in the environment. Copyright © 2016. Published by Elsevier B.V.

Crystal Structure Variations of Sn Nanoparticles upon Heating

NASA Astrophysics Data System (ADS)

Mittal, Jagjiwan; Lin, Kwang-Lung

2018-04-01

Structural changes in Sn nanoparticles during heating below the melting point have been investigated using differential scanning calorimetry (DSC), x-ray diffraction (XRD) analysis, electron diffraction (ED), and high-resolution transmission electron microscopy (HRTEM). DSC revealed that the heat required to melt the nanoparticles (28.43 J/g) was about half compared with Sn metal (52.80 J/g), which was attributed to the large surface energy contribution for the nanoparticles. ED and XRD analyses of the Sn nanoparticles revealed increased intensity for crystal planes having large interplaner distances compared with regular crystal planes with increasing heat treatment temperature (HTT). HRTEM revealed an increase in interlayer spacing at the surface and near joints between nanoparticles with the HTT, leading to an amorphous structure of nanoparticles at the surface at 220°C. These results highlight the changes that occur in the morphology and crystal structure of Sn nanoparticles at the surface and in the interior with increase of the heat treatment temperature.

Synthesis, structural and magnetic properties of Mg0.6Zn0.4CrxFe2-xO4 (0.0 ≤ x ≤ 2.0) nano ferrite

NASA Astrophysics Data System (ADS)

Verma, R.; Kane, S. N.; Raghuvanshi, S.; Satalkar, M.; Modak, S. S.; Mazaleyrat, F.

2018-05-01

Present study reports, effect on structural, magnetic properties of Cr doped Mg-Zn nano-ferrite: Mg0.6Zn0.4CrxFe2-xO4 (0.0≤ x≤2.0), synthesized by sol-gel auto combustion method. X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques were utilized to monitor the effect of Cr substitution on structural, magnetic properties, and correlation between them. XRD confirms the formation of single phase spinel nano ferrite with particle size ranging between 3.9 - 40.5 nm, whereas EDS confirms the formation of the estimated ferrite composition. Distribution of Mg, Zn, Cr, Fe cations on tetrahedral (A), octahedral (B) site show mixed spinel structure. Increase of Cr content leads to increase of specific surface area (4.35 - 28.28 m2/g), decrease of experimental saturation magnetization at 300 K (varies between 0.57 - 40.95 Am2/kg), and theoretical magnetization at 0 K (range between 13.37 - 56.77 Am2/kg). Observed changes in coercivity values reflect soft magnetic nature of the studied ferrites.

Sulfur Nanoparticles Synthesis and Characterization from H2S Gas, Using Novel Biodegradable Iron Chelates in W/O Microemulsion

NASA Astrophysics Data System (ADS)

Deshpande, Aniruddha S.; Khomane, Ramdas B.; Vaidya, Bhalchandra K.; Joshi, Renuka M.; Harle, Arti S.; Kulkarni, Bhaskar D.

2008-06-01

Sulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+ malic acid chelate (0.05 M aqueous solution) was studied in w/o microemulsion containing cyclohexane, Triton X-100 and n-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system is nearly uniform in size (average particle size 10 nm) and narrow particle size distribution (in range of 5 15 nm) as compared to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%). Moreover, sulfur nanoparticles synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi) than that of colloidal sulfur.

Ultrasound assisted synthesis of WO3-ZnO nanocomposites for brilliant blue dye degradation.

PubMed

Hunge, Y M; Yadav, A A; Mathe, V L

2018-07-01

The present work deals with the preparation of WO 3 and WO 3 -ZnO nanocomposites in presence of ultrasonic irradiation, and its use in the sonocatalytic degradation of brilliant blue dye. WO 3 -ZnO nanocomposite is prepared using one step in-situ ultrasound assisted method. The successfully prepared WO 3 and WO 3 -ZnO nanocomposites were characterized using different characterization techniques such as XRD, Raman, BET, FE-SEM and EDS. The XRD pattern reveals that the formation of monoclinic and hexagonal crystal structures of WO 3 and ZnO respectively. BET study shows that WO 3 -ZnO nanocomposite have maximum surface area than that of the WO 3 . EDS study confirms the formation of WO 3 -ZnO nanocomposites. Further the use of the prepared WO 3 and WO 3 -ZnO nanocomposites as a sonocatalyst for the degradation of brilliant blue dye. The rate constant (k) was evaluated as a function of the initial concentration of brilliant blue dye. It is found that WO 3 -ZnO nanocomposites exhibits maximum sonocatalytic activity as compared to WO 3 photocatalyst. Copyright © 2018 Elsevier B.V. All rights reserved.

The preparation and characterization of novel Pt/C electrocatalysts with controlled porosity and cluster size

DOE PAGES

Coker, Eric N.; Steen, William A.; Miller, Jeffrey T.; ...

2007-05-23

Small platinum clusters have been prepared in zeolite hosts through ion exchange and controlled calcination/reduction processes. In order to enable electrochemical application, the pores of the Pt-zeolite were filled with electrically conductive carbon via infiltration with carbon precursors, polymerization, and pyrolysis. The zeolite host was then removed by acid washing, to leave a Pt/C electrocatalyst possessing quasi-zeolitic porosity and Pt clusters of well-controlled size. The electrocatalysts were characterized by TEM, XRD, EXAFS, nitrogen adsorption and electrochemical techniques. Depending on the synthesis conditions, average Pt cluster sizes in the Pt/C catalysts ranged from 1.3 to 2.0 nm. The presence of orderedmore » porosity/structure in the catalysts was evident in TEM images as lattice fringes, and in XRD as a low-angle diffraction peak with d-spacing similar to the parent zeolite. The catalysts possess micro- and meso-porosity, with pore size distributions that depend upon synthesis variables. Finally, electroactive surface areas as high as 112 m 2 g Pt -1 have been achieved in Pt/C electrocatalysts which show oxygen reduction performance comparable to standard industrial catalysts.« less

Composite electrodes of activated carbon derived from cassava peel and carbon nanotubes for supercapacitor applications

NASA Astrophysics Data System (ADS)

Taer, E.; Iwantono, Yulita, M.; Taslim, R.; Subagio, A.; Salomo, Deraman, M.

2013-09-01

In this paper, a composite electrode was prepared from a mixture of activated carbon derived from precarbonization of cassava peel (CP) and carbon nanotubes (CNTs). The activated carbon was produced by pyrolysis process using ZnCl2 as an activation agent. A N2 adsorption-desorption analysis for the sample indicated that the BET surface area of the activated carbon was 1336 m2 g-1. Difference percentage of CNTs of 0, 5, 10, 15 and 20% with 5% of PVDF binder were added into CP based activated carbon in order to fabricate the composite electrodes. The morphology and structure of the composite electrodes were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The SEM image observed that the distribution of CNTs was homogeneous between carbon particles and the XRD pattern shown the amorphous structure of the sample. The electrodes were fabricated for supercapacitor cells with 316L stainless steel as current collector and 1 M sulfuric acid as electrolyte. An electrochemical characterization was performed by using an electrochemical impedance spectroscopy (EIS) method using a Solatron 1286 instrument and the addition of CNTs revealed to improve the resistant and capacitive properties of supercapacitor cell.

Optical and structural properties of Mo-doped NiTiO3 materials synthesized via modified Pechini methods

NASA Astrophysics Data System (ADS)

Pham, Thanh-Truc; Kang, Sung Gu; Shin, Eun Woo

2017-07-01

In this study, molybdenum (Mo)-doped nickel titanate (NiTiO3) materials were successfully synthesized as a function of Mo content through a modified Pechini method followed by a solvothermal treatment process. Various characterization methods were employed to investigate the optical and structural properties of the materials. XRD patterns clearly showed that the NiTiO3 structure maintained a single phase with no observed crystalline structure transformations, even after the addition of 10 wt.% Mo. In the Raman spectra and XRD patterns, peak positions shifted with a change in Mo content, confirming that the NiTiO3 lattice was doped with Mo. On the other hand, Mo doping of NiTiO3 materials changed their optical properties. DRS-UV demonstrated that the addition of Mo increased photon absorption within the UV region. Relaxation processes were inhibited by Mo doping, which was evident in the PL spectra. Structural properties of the prepared materials were studied via FE-SEM and HR-TEM. The measured surface area increased proportionally with Mo content due to a reduction in grain size of the materials.

The equation of state of 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one determined via in-situ optical microscopy and interferometry measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stavrou, Elissaios, E-mail: stavrou1@llnl.gov; Zaug, Joseph M., E-mail: zaug1@llnl.gov; Bastea, Sorin

2016-04-07

Quasi-hydrostatic high-pressure equations of state (EOS) are typically determined, for crystalline solids, by measuring unit-cell volumes using x-ray diffraction (XRD) techniques. However, when characterizing low-symmetry materials with large unit cells, conventional XRD approaches may become problematic. To overcome this issue, we examined the utility of a “direct” approach toward determining high pressure material volume by measuring surface area and sample thickness using optical microscopy and interferometry (OMI), respectively. We have validated this experimental approach by comparing results obtained for 2,4,6-triamino-1,3,5-trinitrobenzene TATB with an EOS determined from synchrotron XRD measurements; and, a good match is observed. We have measured the high pressure EOS of 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one (α-NTO) upmore » to 28 GPa. No high-pressure XRD EOS data have been published on α-NTO, probably due to its complex crystal structure. The results of this study suggest that OMI is a reliable and versatile alternative for determining EOSs, especially when conventional methodologies are impractical.« less

Identification of corrosion product on medium carbon steel under the exposure of Banda Aceh’s atmosphere

NASA Astrophysics Data System (ADS)

Thalib, Sulaiman; Ikhsan, Muharil; Fonna, Syarizal; Huzni, Syifaul; Ridha, Syahrir

2018-05-01

This research was conducted to study the form of corrosion products of medium carbon steel under the exposure of Banda Aceh’s atmosphere. The medium carbon steel samples which the size based on ASTM G 50 were exposed in open areas around the Engineering Faculty, Syiah Kuala University, Darussalam - Banda Aceh, Aceh province, Indonesia. The study was carried out from January through December 2016. The corrosion product formed on the surface of the samples was studied using X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) method. Measurements of weight loss due to atmospheric corrosion as a basis for calculating corrosion rates was referring to ASTM G1. Corrosion product found based on XRD analysis was lepidocrocite (FeO2, γ-FeOOH) and goethite (FeO2, α-FeOOH). The results agreed with SEM analysis that also indicates to lepidocrocite and goethite. The corrosion rate for twelve months showed that the highest rate occurs in the period of March-April that was 0.024 mpy. During twelve months exposure, the corrosion products consist of lepidocrocite and goethite. Significant changes began to occur in the eighth month, where the product of corrosion was almost entirely goethite.

Sulfur Nanoparticles Synthesis and Characterization from H2S Gas, Using Novel Biodegradable Iron Chelates in W/O Microemulsion

PubMed Central

2008-01-01

Sulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+–malic acid chelate (0.05 M aqueous solution) was studied in w/o microemulsion containing cyclohexane, Triton X-100 andn-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system is nearly uniform in size (average particle size 10 nm) and narrow particle size distribution (in range of 5–15 nm) as compared to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%). Moreover, sulfur nanoparticles synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi) than that of colloidal sulfur.

Thickness dependence of crystal and optical characterization on ZnO thin film grown by atomic layer deposition

NASA Astrophysics Data System (ADS)

Baek, Seung-Hye; Lee, Hyun-Jin; Lee, Sung-Nam

2018-06-01

We studied the thickness dependence of the crystallographic and optical properties of ZnO thin films grown on c-plane sapphire substrate using atomic layer deposition. High-resolution X-ray diffraction (HR-XRD) revealed two peaks at 34.5° and 36.2° in the initial growth stage of ZnO on the sapphire substrate, corresponding to the (002) and (101) ZnO planes, respectively. However, as the thickness of the ZnO film increased, the XRD intensity of the (002) ZnO peak increased drastically, compared with that of the (101) ZnO peak. This indicated that (002) and (101) ZnO were simultaneously grown on the c-plane sapphire substrate in the initial growth stage, and that (002) ZnO was predominantly grown with the increase in the thickness of ZnO film. The ZnO thin film presented an anisotropic surface structure at the initial stage, whereas the isotropic surface morphology was developed with an increase in the film thickness of ZnO. These observations were consistent with the HR-XRD results.

Biochar composites with nano zerovalent iron and eggshell powder for nitrate removal from aqueous solution with coexisting chloride ions.

PubMed

Ahmad, Munir; Ahmad, Mahtab; Usman, Adel R A; Al-Faraj, Abdullah S; Abduljabbar, Adel S; Al-Wabel, Mohammad I

2017-09-18

Biochar (BC) was produced from date palm tree leaves and its composites were prepared with nano zerovalent iron (nZVI-BC) and hen eggshell powder (EP-BC). The produced BC and its composites were characterized by SEM, XRD, BET, and FTIR for surface structural, mineralogical, and chemical groups and tested for their efficiency for nitrate removal from aqueous solutions in the presence and absence of chloride ions. The incidence of graphene and nano zerovalent iron (Fe 0 ) in the nZVI-BC composite was confirmed by XRD. The nZVI-BC composite possessed highest surface area (220.92 m 2  g -1 ), carbon (80.55%), nitrogen (3.78%), and hydrogen (11.09%) contents compared to other materials. Nitrate sorption data was fitted well to the Langmuir (R 2  = 0.93-0.98) and Freundlich (R 2  = 0.90-0.99) isotherms. The sorption kinetics was adequately explained by the pseudo-second-order, power function, and Elovich models. The nZVI-BC composite showed highest Langmuir predicted sorption capacity (148.10 mg g -1 ) followed by EP-BC composite (72.77 mg g -1 ). In addition to the high surface area, the higher nitrate removal capacity of nZVI-BC composite could be attributed to the combination of two processes, i.e., chemisorption (outer-sphere complexation) and reduction of nitrate to ammonia or nitrogen by Fe 0 . The appearance of Fe-O stretching and N-H bonds in post-sorption FTIR spectra of nZVI-BC composite suggested the occurrence of redox reaction and formation of Fe compound with N, such as ferric nitrate (Fe(NO 3 ) 3 ·9H 2 O). Coexistence of chloride ions negatively influenced the nitrate sorption. The decrease in nitrate sorption with increasing chloride ion concentration was observed, which could be due to the competition of free active sites on the sorbents between nitrate and chloride ions. The nZVI-BC composite exhibited higher nitrate removal efficiency compared to other materials even in the presence of highest concentration (100 mg L -1 ) of coexisting chloride ion.

Tailoring pore properties of MCM-48 silica for selective adsorption of CO2.

PubMed

Kim, Sangil; Ida, Junichi; Guliants, Vadim V; Lin, Jerry Y S

2005-04-07

Four different types of amine-attached MCM-48 silicas were prepared and investigated for CO(2) separation from N(2). Monomeric and polymeric hindered and unhindered amines were attached to the pore surface of the MCM-48 silica and characterized with respect to their CO(2) sorption properties. The pore structures and amino group content in these modified silicas were investigated by XRD, FT-IR, TGA, N(2) adsorption/desorption at 77 K and CHN/Si analysis, which confirmed that in all cases the amino groups were attached to the pore surface of MCM-48 at 1.5-5.2 mmol/g. The N(2) adsorption/desorption analysis showed a considerable decrease of the pore volume and surface area for the MCM-48 silica containing a polymeric amine (e.g., polyethyleneimine). The CO(2) adsorption rates and capacities of the amine-attached MCM-48 samples were studied employing a sorption microbalance. The results obtained indicated that in addition to the concentration of surface-attached amino groups, specific interactions between CO(2) and the surface amino groups, and the resultant pore structure after amine group attachment have a significant impact on CO(2) adsorption properties of these promising adsorbent materials.

Synthesis and characterization of protocatechuic acid-loaded gadolinium-layered double hydroxide and gold nanocomposite for theranostic application

NASA Astrophysics Data System (ADS)

Usman, Muhammad Sani; Hussein, Mohd Zobir; Kura, Aminu Umar; Fakurazi, Sharida; Masarudin, Mas Jaffri; Saad, Fathinul Fikri Ahmad

2018-03-01

A theranostic nanocomposite was developed using anticancer agent, protocatechuic acid (PA) and magnetic resonance imaging (MRI) contrast agent gadolinium nitrate (Gd) for simultaneous delivery using layered double hydroxide (LDH) as the delivery agent. Gold nanoparticles (AuNPs) were adsorbed on the surface of the LDH, which served as a complementary contrast agent. Based on the concept of supramolecular chemistry (SPC) and multimodal delivery system (MDS), the PA and Gd guests were first intercalated into the LDH host and subsequently AuNPs were surface adsorbed as the third guest. The nanohybrid developed was named MAPGAu. The MAPGAu was exposed to various characterizations at different stages of synthesis, starting with XRD analysis, which was used to confirm the intercalation episode and surface adsorption of the guest molecules. Consequently, FESEM, Hi-TEM, XRD, ICP-OES, CHNS, FTIR and UV-Vis analyses were done on the nanohybrids. The result of XRD analysis indicated successful intercalation of the Gd and PA as well the adsorption of AuNPs. The UV-Vis release study showed 90% of the intercalated drug was released at pH 4.8, which is the pH of the cancer cells. The FESEM and TEM micrographs obtained equally confirmed the formation of MAGPAu nanocomposite, with AuNPs conspicuously deposited on the LDH surface. The cytotoxicity study of the nanohybrid also showed insignificant toxicity to normal cell lines and significant toxicity to cancer cell lines. The developed MAGPAu nanocomposite has shown prospects for future theranostic cancer treatment.

Facile electrocatalytic redox of hemoglobin by flower-like gold nanoparticles on boron-doped diamond surface.

PubMed

Li, Mingfang; Zhao, Guohua; Geng, Rong; Hu, Huikang

2008-11-01

The flower-like gold nanoparticles together with spherical and convex polyhedron gold nanoparticles were fabricated on boron-doped diamond (BDD) surface by one-step and simple electrochemical method through easily controlling the applied potential and the concentration of HAuCl(4). The recorded X-ray diffraction (XRD) patterns confirmed that these three shapes of gold nanoparticles were dominated by different crystal facets. The cyclic voltammetric results indicated that the morphology of gold nanoparticles plays big role in their electrochemical behaviors. The direct electrochemistry of hemoglobin (Hb) was realized on all the three different shapes of nanogold-attached BDD surface without the aid of any electron mediator. In pH 4.5 acetate buffer solutions (ABS), Hb showed a pair of well defined and quasi-reversible redox peaks. However, the results obtained demonstrated that the redox peak potential, the average surface concentration of electroactive heme, and the electron transfer rates of Hb are greatly dependent upon the surface morphology of gold nanoparticles. The electron transfer rate constant of hemoglobin over flower-like nanogold/BDD electrode was more than two times higher than that over spherical and convex polyhedron nanogold. The observed differences may be ascribed to the difference in gold particle characteristics including surface roughness, exposed surface area, and crystal structure.

Methyl parathion detection in vegetables and fruits using silver@graphene nanoribbons nanocomposite modified screen printed electrode

NASA Astrophysics Data System (ADS)

Govindasamy, Mani; Mani, Veerappan; Chen, Shen-Ming; Chen, Tse-Wei; Sundramoorthy, Ashok Kumar

2017-04-01

We have developed a sensitive electrochemical sensor for Organophosphorus pesticide methyl parathion (MP) using silver particles supported graphene nanoribbons (Ag@GNRs). The Ag@GNRs nanocomposite was prepared through facile wet chemical strategy and characterized by TEM, EDX, XRD, Raman, UV-visible, electrochemical and impedance spectroscopies. The Ag@GNRs film modified screen printed carbon electrode (SPCE) delivers excellent electrocatalytic ability to the reduction of MP. The Ag@GNRs/SPCE detects sub-nanomolar concentrations of MP with excellent selectivity. The synergic effects between special electrocatalytic ability of Ag and excellent physicochemical properties of GNRs (large surface area, high conductivity, high area-normalized edge-plane structures and abundant catalytic sites) make the composite highly suitable for MP sensing. Most importantly, the method is successfully demonstrated in vegetables and fruits which revealed its potential real-time applicability in food analysis.

Spherical V-Fe-MCM-48: The Synthesis, Characterization and Hydrothermal Stability.

PubMed

Qian, Wang; Wang, Haiqing; Chen, Jin; Kong, Yan

2015-04-14

Spherical MCM-48 mesoporous sieve co-doped with vanadium and iron was successfully synthesized via one-step hydrothermal method. The material was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, inductively coupled plasma (ICP), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis spectra, and X-ray photoelectron spectra (XPS) techniques. Results indicated that the V-Fe-MCM-48 showed an ordered 3D cubic mesostructure with spherical morphology, narrow pore size distribution and high specific surface area. Most of vanadium and iron atoms existing as tetrahedral V 4+ and Fe 3+ species were co-doped into the silicate framework. The particle sizes of V-Fe-MCM-48 were smaller and the specific area was much higher than those of of V-MCM-48. Additionally, the synthesized V-Fe-MCM-48 exhibited improved hydrothermal stability compared with the pure MCM-48.

Spherical V-Fe-MCM-48: The Synthesis, Characterization and Hydrothermal Stability

PubMed Central

Qian, Wang; Wang, Haiqing; Chen, Jin; Kong, Yan

2015-01-01

Spherical MCM-48 mesoporous sieve co-doped with vanadium and iron was successfully synthesized via one-step hydrothermal method. The material was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, inductively coupled plasma (ICP), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis spectra, and X-ray photoelectron spectra (XPS) techniques. Results indicated that the V-Fe-MCM-48 showed an ordered 3D cubic mesostructure with spherical morphology, narrow pore size distribution and high specific surface area. Most of vanadium and iron atoms existing as tetrahedral V4+ and Fe3+ species were co-doped into the silicate framework. The particle sizes of V-Fe-MCM-48 were smaller and the specific area was much higher than those of of V-MCM-48. Additionally, the synthesized V-Fe-MCM-48 exhibited improved hydrothermal stability compared with the pure MCM-48. PMID:28788030

The effect of surface charge on photocatalytic degradation of methylene blue dye using chargeable titania nanoparticles.

PubMed

Azeez, Fadhel; Al-Hetlani, Entesar; Arafa, Mona; Abdelmonem, Yasser; Nazeer, Ahmed Abdel; Amin, Mohamed O; Madkour, Metwally

2018-05-08

Herein, a simple approach based on tailoring the surface charge of nanoparticles, NPs, during the preparation to boost the electrostatic attraction between NPs and the organic pollutant was investigated. In this study, chargeable titania nanoparticles (TiΟ 2 NPs) were synthesized via a hydrothermal route under different pH conditions (pH = 1.6, 7.0 and 10). The prepared TiΟ 2 NPs were fully characterized via various techniques including; transmission electron microscopy (TEM), X-ray diffraction (XRD), N 2 adsorption/desorption, X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible spectroscopy (UV-Vis) and dynamic light scattering (DLS). The influence of the preparation pH on the particle size, surface area and band gap was investigated and showed pH-dependent behavior. The results revealed that upon increasing the pH value, the particle size decreases and lead to larger surface area with less particles agglomeration. Additionally, the effect of pH on the surface charge was monitored by XPS to determine the amount of hydroxyl groups on the TiO 2 NPs surface. Furthermore, the photocatalytic activity of the prepared TiΟ 2 NPs towards methylene blue (MB) photodegradation was manifested. The variation in the preparation pH affected the point of zero charge (pH PZC ) of TiO 2 NPs, subsequently, different photocatalytic activities based on electrostatic interactions were observed. The optimum efficiency obtained was 97% at a degradation rate of 0.018 min -1 using TiO 2 NPs prepared at pH 10.

Reduction Expansion Synthesis as Strategy to Control Nitrogen Doping Level and Surface Area in Graphene

PubMed Central

Canty, Russell; Gonzalez, Edwin; MacDonald, Caleb; Osswald, Sebastian; Zea, Hugo; Luhrs, Claudia C.

2015-01-01

Graphene sheets doped with nitrogen were produced by the reduction-expansion (RES) method utilizing graphite oxide (GO) and urea as precursor materials. The simultaneous graphene generation and nitrogen insertion reactions are based on the fact that urea decomposes upon heating to release reducing gases. The volatile byproducts perform two primary functions: (i) promoting the reduction of the GO and (ii) providing the nitrogen to be inserted in situ as the graphene structure is created. Samples with diverse urea/GO mass ratios were treated at 800 °C in inert atmosphere to generate graphene with diverse microstructural characteristics and levels of nitrogen doping. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the microstructural features of the products. The effects of doping on the samples structure and surface area were studied by X-ray diffraction (XRD), Raman Spectroscopy, and Brunauer Emmet Teller (BET). The GO and urea decomposition-reduction process as well as nitrogen-doped graphene stability were studied by thermogravimetric analysis (TGA) coupled with mass spectroscopy (MS) analysis of the evolved gases. Results show that the proposed method offers a high level of control over the amount of nitrogen inserted in the graphene and may be used alternatively to control its surface area. To demonstrate the practical relevance of these findings, as-produced samples were used as electrodes in supercapacitor and battery devices and compared with conventional, thermally exfoliated graphene. PMID:28793618

Mineralogy of mine waste at the Vermont Asbestos Group mine, Belvidere Mountain, Vermont

USGS Publications Warehouse

Levitan, D.M.; Hammarstrom, J.M.; Gunter, M.E.; Seal, R.R.; Chou, I.-Ming; Piatak, N.M.

2009-01-01

Samples from the surfaces of waste piles at the Vermont Asbestos Group mine in northern Vermont were studied to determine their mineralogy, particularly the presence and morphology of amphiboles. Analyses included powder X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and Raman spectroscopy. Minerals identified by XRD were serpentine-group minerals, magnetite, chlorite, quartz, olivine, pyroxene, and brucite; locally, mica and carbonates were also present. Raman spectroscopy distinguished antigorite and chrysotile, which could not be differentiated using XRD. Long-count, short-range XRD scans of the (110) amphibole peak showed trace amounts of amphibole in most samples. Examination of amphiboles in tailings by optical microscopy, SEM, and EPMA revealed non-fibrous amphiboles compositionally classified as edenite, magnesiohornblende, magnesiokatophorite, and pargasite. No fibrous amphibole was found in the tailings, although fibrous tremolite was identified in a sample of host rock. Knowledge of the mineralogy at the site may lead to better understanding of potential implications for human health and aid in designing a remediation plan.

Variable-focus microscopy and UV surface dissolution imaging as complementary techniques in intrinsic dissolution rate determination.

PubMed

Ward, Adam; Walton, Karl; Box, Karl; Østergaard, Jesper; Gillie, Lisa J; Conway, Barbara R; Asare-Addo, Kofi

2017-09-15

This work reports a novel approach to the assessment of the surface properties of compacts used in Surface Dissolution Imaging (SDI). SDI is useful for determining intrinsic dissolution rate (IDR), an important parameter in early stage drug development. Surface topography, post-compaction and post-SDI run, have been measured using a non-contact, optical, three-dimensional microscope based on focus variation, the Alicona Infinite Focus Microscope, with the aim of correlating the IDRs to the surface properties. Ibuprofen (IBU) was used as a model poorly-soluble drug. DSC and XRD were used to monitor possible polymorphic changes that may have occurred post-compaction and post-SDI run. IBUs IDR decreased from 0.033mg/min/cm 2 to 0.022mg/min/cm 2 from 10 to 20min, respectively, during the experiment. XRD and DSC showed no form changes during the SDI run. The surface topography images showed that a distinct imprint was embossed on the surfaces of some compacts which could affect IDRs. Surface parameter values were associated with the SDI experiments which showed strong correlations with the IDR values. The variable-focus microscope can be used as a complimentary tool in the determination of IDR values from the SDI. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Surface Morphology and Hardness Analysis of TiCN Coated AA7075 Aluminium Alloy

NASA Astrophysics Data System (ADS)

Srinath, M. K.; Ganesha Prasad, M. S.

2017-12-01

Successful titanium carbonitride (TiCN) coating on AA7075 plates using the PVD technique depends upon many variables, including temperature, pressure, incident angle and energy of the reactive ions. Coated specimens have shown an increase in their surface hardness of 2.566 GPa. In this work, an attempt to further augment the surface hardness and understand its effects on the surface morphology was performed through heat treatments at 500°C for different duration of times. Specimen's heat treated at 500°C for 1 h exhibited a maximum surface hardness of 6.433 GPa, corresponding to an increase of 92.07%. The XRD results showed the presence of Al2Ti and AlTi3N and indicate the bond created between them. Unit cell lattice parameters in the XRD data are calculated using Bragg's law. The SEM images exhibit increasing crack sizes as the heat treatment time is increased. From the studies, the heat treatment duration can be optimized to 1 h, which exhibited an augmented surface hardness, as further increases in durations caused a drop in the surface hardness. The heat treatment effectively modified the surface hardness. Equations providing the relationships that temperature and time have with the reaction parameters are presented.

Adequacy of surface analytical tools for studying the tribology of ceramics

NASA Technical Reports Server (NTRS)

Sliney, H. E.

1986-01-01

Surface analytical tools are very beneficial in tribological studies of ceramics. Traditional methods of optical microscopy, XRD, XRF, and SEM should be combined with newer surface sensitive techniques especially AES and XPS. ISS and SIMS can also be useful in providing additional compositon details. Tunneling microscopy and electron energy loss spectroscopy are less known techniques that may also prove useful.

Microwave-Assisted Synthesis of Perovskite SrSnO 3 Nanocrystals in Ionic Liquids for Photocatalytic Applications

DOE PAGES

Alammar, Tarek; Hamm, Ines; Grasmik, Viktoria; ...

2017-06-05

Nanosized SrSnO 3 photocatalysts have been successfully synthesized by microwave synthesis in various ionic liquids (ILs) followed by a heat treatment process to optimize the materials’ crystallinity. The influence of the ILs with various cations such as 1-butyl-3-methylimidazolium ([C 4mim] +), 6-bis(3-methylimidazolium-1-yl)hexane ([C 6(mim) 2] 2+), butylpyridinium ([C 4Py] +), and tetradecyltrihexylphosphonium ([P 66614] +) and bis(trifluoromethanesulfonyl)amide ([Tf 2N] -) as the anion on the structure, crystallization, and morphology of the products was investigated. The samples were characterized by X-ray diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), surface area analysis by gas adsorption, X-ray photoelectron spectroscopy (XPS), diffuse reflectancemore » UV–vis spectroscopy, and Raman and IR spectroscopy. According to structure characterization by XRD and Raman spectroscopy all samples crystallized phase-pure in the orthorhombic GdFeO 3 perovskite structure type. SEM reveals that, on the basis of the IL, the obtained SrSnO 3 nanoparticles exhibit different morphologies and sizes. Rod-shaped particles are formed in [C 4mim][Tf 2N], [C 6(mim) 2][Tf 2N] 2, and [P 66614][Tf 2N]. However, the particle dimensions and size distribution vary depending on the IL and range from quite thin and long needlelike particles with a narrow size distribution obtained in [P 66614][Tf 2N] to relatively larger particles with a broader size distribution obtained in [C 6(mim) 2][Tf 2N] 2. In contrast, in [C 4Py][Tf 2N] nanospheres with a diameter of about 50 nm form. For these particles the highest photocatalytic activity was observed. Our investigations indicate that the improved photocatalytic activity of this material results from the synergistic effect of the relatively large surface area associated with nanosize and an appropriate energy band structure.« less

RIS4E at Kilauea's December 1974 Flow: Chemical, mineralogical and spectral characteristics of Hawaiian basaltic alteration products measured with portable instruments

NASA Astrophysics Data System (ADS)

Young, K. E.; Rogers, D.; Dyar, M. D.; Ito, G.; Yant, M.; McAdam, A.; Bleacher, J. E.; Glotch, T. D.

2015-12-01

A major objective of the SSERVI RIS4E (Remote, In-situ, and Synchrotron Studies for Science and Exploration) investigation is to evaluate the performance of portable chemical and mineralogical instruments in a variety of planetary volcanic analog settings. To that end, we used a suite of true/proxy portable instruments (XRF, LIBS, XRD, near-IR and mid-IR spectrometers), to measure the chemical and spectral characteristics of young basaltic flows (erupted December 1974, or D1974) within the southwest rift zone of Kilauea, Hawaii. The D1974 lavas exhibit multiple flow morphologies and textures, and have undergone alteration by a variety of processes, including acid weathering, oxidation and devitrification. The mineralogy, chemistry and infrared spectral properties of select samples from these altered surfaces have been well characterized by previous groups using high resolution (e.g. SEM, TEM) and/or laboratory measurements (XRD, Mossbauer, infrared). Typical alteration products include coatings of Fe-Ti-oxide +/- an overlying silica-rich coating. Coatings are commonly discontinuous and vary in color. Oxidation fronts are also present, most visible as reddish brown discoloration along the edges of broken and uplifted flow crusts. The previous detailed characterizations provide the basis for evaluating instrument performance and also allow us to assess areas where portable instruments can contribute new information to current understanding. These areas include characterizing the spatial variability in alteration chemistry/mineralogy, relating chemical/mineralogical properties to texture and context, and comparing chemical/mineralogical variations with infrared spectral properties. Because infrared spectra are commonly used to assess compositional variations of a site remotely, either from the ground or from orbit, relating changes in chemistry and mineralogy to spectral variations is particularly important. Last, the D1974 site provides an excellent location to test the performance of portable chemical instruments on coated surfaces of variable texture. Results from this multi-technique approach will be presented at the meeting.

Rapid synthesis of Ti-MCM-41 by microwave-assisted hydrothermal method towards photocatalytic degradation of oxytetracycline.

PubMed

Chen, Hanlin; Peng, Yen-Ping; Chen, Ku-Fan; Lai, Chia-Hsiang; Lin, Yung-Chang

2016-06-01

This study employed microwave-assisted hydrothermal method to synthesize Ti-MCM-41, which are mesoporous materials with a high surface area and excellent photocatalytic ability. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-Vis) were employed. The XRD findings showed that Ti-MCM-41 exhibited a peak at 2θ of 2.2°, which was attributed to the hexagonal MCM-41 structure. The BET (Brunauer-Emmett-Teller) results agreed with the TEM findings that Ti-MCM-41 has a pore size of about 3-5nm and a high surface area of 883m(2)/g. FTIR results illustrated the existence of Si-O-Si and Si-O-Ti bonds in Ti-MCM-41. The appearance of Ti 2p peaks in the XPS results confirmed the FTIR findings that the Ti was successfully doped into the MCM-41 structure. Zeta (ζ)-potential results indicated that the iso-electric point (IEP) of Ti-MCM-41 was at about pH3.02. In this study, the photocatalytic degradation of oxytetracycline (OTC) at different pH was investigated under Hg lamp irradiation (wavelength 365nm). The rate constant (K'obs) for OTC degradation was 0.012min(-1) at pH3. Furthermore, TOC (total organic carbon) and high resolution LC-MS (liquid chromatography-mass spectrometry) analyses were conducted to elucidate the possible intermediate products and degradation pathway for OTC. The TOC removal efficiency of OTC degradation was 87.0%, 74.4% and 50.9% at pH3, 7 and 10, respectively. LC-MS analysis results showed that the degradation products from OTC resulted from the removal of functional groups from the OTC ring. Copyright © 2016. Published by Elsevier B.V.

Fabrication of multicolor fluorescent polyvinyl alcohol through surface modification with conjugated polymers by oxidative polymerization

NASA Astrophysics Data System (ADS)

Hai, Thien An Phung; Sugimoto, Ryuichi

2018-06-01

A simple method for the preparation of multicolor polyvinyl alcohol (PVA) by chemical oxidative polymerization is introduced. The PVA surface was successfully modified with conjugated polymers composed of 3-hexylthiophene (3HT) and fluorene (F). The incorporation of the 3HT/F copolymer onto the PVA surface was confirmed by Fourier-transform infrared (FT-IR), ultraviolet-visible (UV-vis), and fluorescence spectroscopies, X-ray diffraction (XRD), as well as thermogravimetric analysis (TGA), contact angle, and field-emission scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray (EDX) analysis. Different 3HT/F ratios on the PVA surface result in optical properties that include multicolor-emission and absorption behavior. The color of the resultant (3HT/F)-g-PVA shifted from red to blue, and the quantum yield increased with increasing F content. The surface hydrophobicity of the modified PVA increased significantly through grafting with the conjugated polymers, with the water contact angle increasing by 30° compared to pristine PVA. The PVA XRD peaks were less intense following surface modification. Thermogravimetric analyses reveal that the thermal stability of the PVA decreases as a result of grafting with the 3HT/F copolymers.

Synthesis of Copper-Based Nanostructured Catalysts on SiO2-Al2O3, SiO2-TiO2, and SiO2-ZrO2 Supports for NO Reduction.

PubMed

Namkhang, Pornpan; Kongkachuichay, Paisan

2015-07-01

The selective catalytic reduction of NO over a series of Cu-based catalysts supported on modified silica including SiO2-Al2O3, SiO2-TiO2, and SiO2-ZrO2 prepared via a sol-gel process and a flame spray pyrolysis (FSP) was studied. The prepared catalysts were characterized by means of TEM, XRD, XRF, TPR, and nitrogen physisorption measurement techniques, to determine particle diameter, morphology, crystallinity, phase composition, copper reducibility, surface area, and pore size of catalysts. The particles obtained from sol-gel method were almost spherical while the particles obtained from the FSP were clearly spherical and non-porous nanosized particles. The effects of Si:Al, Si:Ti, and Si:Zr molar ratio of precursor were identified as the domain for different crystalline phase of materials. It was clearly seen that a high SiO2 content inhibited the crystallization of materials. The BET surface area of catalysts obtained from sol-gel method was higher than that from the FSP and it shows that surface area increased with increasing SiO2 molar ratio due to high surface area from SiO2. The catalyst performances were tested for the selective catalytic reduction of NO with H2. It was found that the catalyst prepared over 7 wt% Cu on Si02-Al2O3 support was the most active compared with the others which converted NO as more than 70%. Moreover, the excess copper decreased the performance of NO reduction, due to the formation of CuO agglomeration covered on the porous silica as well as the alumina surface, preventing the direct contact of CO2 and AL2O3.

Influence of the physico-chemical properties of CeO 2-ZrO 2 mixed oxides on the catalytic oxidation of NO to NO 2

NASA Astrophysics Data System (ADS)

Atribak, Idriss; Guillén-Hurtado, Noelia; Bueno-López, Agustín; García-García, Avelina

2010-10-01

Commercial and home-made Ce-Zr catalysts prepared by co-precipitation were characterised by XRD, Raman spectroscopy, N 2 adsorption at -196 °C and XPS, and were tested for NO oxidation to NO 2. Among the different physico-chemical properties characterised, the surface composition seems to be the most relevant one in order to explain the NO oxidation capacity of these Ce-Zr catalysts. As a general trend, Ce-Zr catalysts with a cerium-rich surface, that is, high XPS-measured Ce/Zr atomic surface ratios, are more active than those with a Zr-enriched surface. The decrease in catalytic activity of the Ce-Zr mixed oxided upon calcinations at 800 °C with regard to 500 °C is mainly attributed to the decrease in Ce/Zr surface ratio, that is, to the surface segregation of Zr. The phase composition (cubic or t'' for Ce-rich compositions) seems not to be a direct effect on the catalytic activity for NO oxidation in the range of compositions tested. However, the formation of a proper solid solution prevents important surface segregation of Zr upon calcinations at high temperature. The effect of the BET surface area in the catalytic activity for NO oxidation of Ce-Zr mixed oxides is minor in comparison with the effect of the Ce/Zr surface ratio.

Understanding the effect of surface/bulk defects on the photocatalytic activity of TiO2: anatase versus rutile.

PubMed

Yan, Junqing; Wu, Guangjun; Guan, Naijia; Li, Landong; Li, Zhuoxin; Cao, Xingzhong

2013-07-14

The sole effect of surface/bulk defects of TiO2 samples on their photocatalytic activity was investigated. Nano-sized anatase and rutile TiO2 were prepared by hydrothermal method and their surface/bulk defects were adjusted simply by calcination at different temperatures, i.e. 400-700 °C. High temperature calcinations induced the growth of crystalline sizes and a decrease in the surface areas, while the crystalline phase and the exposed facets were kept unchanged during calcination, as indicated by the characterization results from XRD, Raman, nitrogen adsorption-desorption, TEM and UV-Vis spectra. The existence of surface/bulk defects in calcined TiO2 samples was confirmed by photoluminescence and XPS spectra, and the surface/bulk defect ratio was quantitatively analyzed according to positron annihilation results. The photocatalytic activity of calcined TiO2 samples was evaluated in the photocatalytic reforming of methanol and the photocatalytic oxidation of α-phenethyl alcohol. Based on the characterization and catalytic results, a direct correlation between the surface specific photocatalytic activity and the surface/bulk defect density ratio could be drawn for both anatase TiO2 and rutile TiO2. The surface defects of TiO2, i.e. oxygen vacancy clusters, could promote the separation of electron-hole pairs under irradiation, and therefore, enhance the activity during photocatalytic reaction.

Calcination Conditions on the Properties of Porous TiO2 Film

NASA Astrophysics Data System (ADS)

Zhang, Wenjie; Pei, Xiaobei; Bai, Jiawei; He, Hongbo

2014-03-01

Porous TiO2 films were deposited on SiO2 precoated glass-slides by sol-gel method using PEG1000 as template. The strongest XRD diffraction peak at 2θ = 25.3° is attributed to [101] plane of anatase TiO2 in the film. The increases of calcination temperature and time lead to stronger diffraction peak intensity. High transmittance and blue shift of light absorption edge are the properties of the film prepared at high calcination temperature. The average pore size of the films increases with the increasing calcination temperature as the result of TiO2 crystalline particles growing up and aggregation, accompanied with higher specific surface area. Photocatalytic activity of porous TiO2 films increases with the increasing calcination temperature. The light absorption edge of the films slightly moves to longer wavelength region along with the increasing calcination time. The mesoporous film calcinated at 500 °C for 2 h has the highest transmittance, the maximum surface area, and the maximum total pore volume. Consequently, the optimum degradation activity is achieved on the porous TiO2 film calcinated at 500 °C for 2 h.

A one-step thermal decomposition method to prepare anatase TiO2 nanosheets with improved adsorption capacities and enhanced photocatalytic activities

NASA Astrophysics Data System (ADS)

Li, Wenting; Shang, Chunli; Li, Xue

2015-12-01

Anatase TiO2 nanosheets (NSs) with high surface area have been prepared via a one-step thermal decomposition of titanium tetraisopropoxide (TTIP) in oleylamine (OM), and their adsorption capacities and photocatalytic activities are investigated by using methylene blue (MB) and methyl orange (MO) as model pollutants. During the synthesis procedure, only one type of surfactant, oleylamine (OM), is used as capping agents and no other solvents are added. Structure and properties of the TiO2 NSs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption analysis, UV-vis spectrum, X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) methods. The results indicate that the TiO2 NSs possess high surface area up to 378 m2 g-1. The concentration of capping agents is found to be a key factor controlling the morphology and crystalline structure of the product. Adsorption and photodegradation experiments reveal that the prepared TiO2 NSs possess high adsorption capacities of model pollutants MB and high photocatalytic activity, showing that TiO2 NSs can be used as efficient pollutant adsorbents and photocatalytic degradation catalysts of MB in wastewater treatment.

Preparation and Characterization of Ato Nanoparticles by Coprecipitation with Modified Drying Method

NASA Astrophysics Data System (ADS)

Liu, Shimin; Liang, Dongdong; Liu, Jindong; Jiang, Weiwei; Liu, Chaoqian; Ding, Wanyu; Wang, Hualin; Wang, Nan

Antimony-doped tin oxide (ATO) nanoparticles were prepared by coprecipitation by packing drying and traditional direct drying (for comparison) methods. The as-prepared ATO nanoparticles were characterized by TG, XRD, EDS, TEM, HRTEM, BET, bulk density and electrical resistivity measurements. Results indicated that the ATO nanoparticles obtained by coprecipitation with direct drying method featured hard-agglomerated morphology, high bulk density, low surface area and low electrical resistivity, probably due to the direct liquid evaporation during drying, the fast shrinkage of the precipitate, the poor removal efficiency of liquid molecules and the hard agglomerate formation after calcination. Very differently, the ATO product obtained by the packing and drying method featured free-agglomerated morphology, low bulk density, high surface area and high electrical resistivity ascribed probably to the formed vapor cyclone environment and liquid evaporation-resistance, avoiding fast liquid removal and improving the removal efficiency of liquid molecules. The intrinsic formation mechanism of ATO nanoparticles from different drying methods was illustrated based on the dehydration process of ATO precipitates. Additionally, the packing and drying time played key roles in determining the bulk density, morphology and electrical conductivity of ATO nanoparticles.

ZnO nanostructures with different morphology for enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Peter, I. John; Praveen, E.; Vignesh, G.; Nithiananthi, P.

2017-12-01

ZnO nanomaterials of different morphologies have been synthesized and the effect of morphology on Photocatalytic activity on natural dye has been investigated. Crystalline size and lattice strain of the synthesized particles are determined by XRD analysis and Williamson-Hall (W-H) method respectively. All other important physical parameters such as strain, stress and energy density values are also calculated using W-H analysis using different models such as uniform deformation model, uniform deformation stress model and uniform deformation energy density model. A shift in the peak of FTIR spectrum of ZnO is observed due to morphology effects. The SEM analysis reveals that the synthesized ZnO nanoparticles appear as flake, rod and dot. ZnO quantum dot exhibits higher photocatalytic activity comparing to the other morphologies. Larger surface area, high adsorption rate, large charge separation and the slow recombination of electrons/holes in ZnO dots establish dots as favorable morphology for good photocatalysis. Among the three, ZnO quantum dot shows three-times enhancement in the kinetic rate constants of photocatalysis. The results confirm that availability of specific (active) surface area, photocatalytic potential and quantum confinement of photo-induced carriers differ with morphology.

Fabrication of meso-porous BiOI sensitized zirconia nanoparticles with enhanced photocatalytic activity under simulated solar light irradiation

NASA Astrophysics Data System (ADS)

Vignesh, K.; Suganthi, A.; Min, Bong-Ki; Kang, Misook

2015-01-01

In this present work, BiOI sensitized zirconia (BiOI-ZrO2) nanoparticles were fabricated using a precipitation-deposition method. The physicochemical characteristics of BiOI/ZrO2 were studied through X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), BET-surface area, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis-DRS) and photoluminescence (PL) spectroscopy techniques. The absorption maximum of ZrO2 was shifted to the visible region after sensitization with BiOI. BET-surface area results inferred that the prepared hetero-junctions were meso-porous in nature. The photocatalytic activity of BiOI-ZrO2 for the degradation of methyl violet (MV) dye under simulated solar light irradiation was investigated in detail. 3% BiOI-ZrO2 exhibited the highest photocatalytic performance (98% of MV degradation) when compared with ZrO2 and BiOI. The enhancement in the photocatalytic activity of BiOI-ZrO2 is ascribed to the sensitization effect of BiOI, suppression of electron-hole recombination and the formation of p-n hetero-junction.

Li-cycling properties of molten salt method prepared nano/submicrometer and micrometer-sized CuO for lithium batteries.

PubMed

Reddy, M V; Yu, Cai; Jiahuan, Fan; Loh, Kian Ping; Chowdari, B V R

2013-05-22

We report the synthesis of CuO material by molten salt method at a temperature range, 280 to 950 °C for 3 h in air. This report includes studies on the effect of morphology, crystal structure and electrochemical properties of CuO prepared at different temperatures. Obtained CuO was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area methods. Samples prepared at ≥410 °C showed a single-phase material with a lattice parameter value of a = 4.69 Å, b = 3.43 Å, c = 5.13 Å and surface area values are in the range 1.0-17.0 m(2) g(-1). Electrochemical properties were evaluated via cyclic voltammetry (CV) and galvanostatic cycling studies. CV studies showed a minor difference in the peak potentials depending on preparation temperature and all compounds exhibit a main anodic peak at ~2.45 V and cathodic peaks at ~0.85 V and ~1.25 V vs Li. CuO prepared at 750 °C showed high and stable capacity of ~620 mA h g(-1) at the end of 40th cycle.

Solvothermal and electrochemical synthetic method of HKUST-1 and its methane storage capacity

NASA Astrophysics Data System (ADS)

Wahyu Lestari, Witri; Adreane, Marisa; Purnawan, Candra; Fansuri, Hamzah; Widiastuti, Nurul; Budi Rahardjo, Sentot

2016-02-01

A comparison synthetic strategy of Metal-Organic Frameworks, namely, Hongkong University of Techhnology-1 {HKUST-1[Cu3(BTC)]2} (BTC = 1,3,5-benzene-tri-carboxylate) through solvothermal and electrochemical method in ethanol:water (1:1) has been conducted. The obtained material was analyzed using powder X-ray diffraction, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermo-Gravimetric Analysis (TGA) and Surface Area Analysis (SAA). While the voltage in the electrochemical method are varied, ranging from 12 to 15 Volt. The results show that at 15 V the texture of the material has the best degree of crystallinity and comparable with solvothermal product. This indicated from XRD data and supported by the SEM image to view the morphology. The thermal stability of the synthesized compounds is up to 320 °C. The shape of the nitrogen sorption isotherm of the compound corresponds to type I of the IUPAC adsorption isotherm classification for microporous materials with BET surface area of 629.2 and 324.3 m2/g (for solvothermal and electrochemical product respectively) and promising for gas storage application. Herein, the methane storage capacities of these compounds are also tested.

Selenite sorption by carbonate substituted apatite

DOE PAGES

Moore, Robert C.; Rigali, Mark J.; Brady, Patrick

2016-08-31

The sorption of selenite, SeO 3 2–, by carbonate substituted hydroxylapatite was investigated using batch kinetic and equilibrium experiments. The carbonate substituted hydroxylapatite was prepared by a precipitation method and characterized by SEM, XRD, FT-IR, TGA, BET and solubility measurements. The material is poorly crystalline, contains approximately 9.4% carbonate by weight and has a surface area of 210.2 m 2/g. Uptake of selenite by the carbonated hydroxylapatite was approximately an order of magnitude higher than the uptake by uncarbonated hydroxylapatite reported in the literature. Distribution coefficients, K d, determined for the carbonated apatite in this work ranged from approximately 4200more » to over 14,000 L/kg. A comparison of the results from kinetic experiments performed in this work and literature kinetic data indicates the carbonated apatite synthesized in this study sorbed selenite 23 times faster than uncarbonated hydroxylapatite based on values normalized to the surface area of each material. Furthermore, the results indicate carbonated apatite is a potential candidate for use as a sorbent for pump-and-treat technologies, soil amendments or for use in permeable reactive barriers for the remediation of selenium contaminated sediments and groundwaters.« less

Sustainable Blended Cements-Influences of Packing Density on Cement Paste Chemical Efficiency.

PubMed

Knop, Yaniv; Peled, Alva

2018-04-18

This paper addresses the development of blended cements with reduced clinker amount by partial replacement of the clinker with more environmentally-friendly material (e.g., limestone powders). This development can lead to more sustainable cements with reduced greenhouse gas emission and energy consumption during their production. The reduced clicker content was based on improved particle packing density and surface area of the cement powder by using three different limestone particle diameters: smaller (7 µm, 3 µm) or larger (70 µm, 53 µm) than the clinker particles, or having a similar size (23 µm). The effects of the different limestone particle sizes on the chemical reactivity of the blended cement were studied by X-ray diffraction (XRD), thermogravimetry and differential thermogravimetry (TG/DTG), loss on ignition (LOI), isothermal calorimetry, and the water demand for reaching normal consistency. It was found that by blending the original cement with limestone, the hydration process and the reactivity of the limestone itself were increased by the increased surface area of the limestone particles. However, the carbonation reaction was decreased with the increased packing density of the blended cement with limestone, having various sizes.

Fabrication of Co0.5Ni0.5CrxFe2-xO4 materials via sol-gel method and their characterizations

NASA Astrophysics Data System (ADS)

Kadam, R. H.; Birajdar, A. P.; Alone, Suresh T.; Shirsath, Sagar E.

2013-02-01

Co0.5Ni0.5CrxFe2-xO4 nanoparticles have been designed by the sol-gel auto combustion method, using nitrates of the respective metal ions, and citric acid as the starting materials. The process takes only a few minutes to obtain as-received Cr-substituted Co-Ni ferrite powders. X-ray diffraction (XRD), vibrational sample magnetometer (VSM), transmission electron microscopy (TEM) are utilized in order to study the effect of variation in the Cr3+ substitution and its impact on particle size, lattice constant, specific surface area, cation distribution and magnetic properties. Lattice parameter, particle size found to decrease with increasing Cr3+ content, whereas specific surface area showed increasing trend with the Cr3+ substitution. Cation distribution indicates that the Cr, Co and Ni ions show preference toward octahedral [B] site, whereas Fe occupies both tetrahedral (A) and octahedral [B] sites. Saturation magnetization (MS) decreased from 65.1 to 40.6 emu/g with the increase in Cr3+ substitution. However, Coercivity increased from 198 to 365 Oe with the Cr3+ substitution.

Catalytic oxidation of soot on mesoporous ceria-based mixed oxides with cetyltrimethyl ammonium bromide (CTAB)-assisted synthesis.

PubMed

Zhu, Hongjian; Xu, Jing; Yichuan, Yuge; Wang, Zhongpeng; Gao, Yibo; Liu, Wei; Yin, Henan

2017-12-15

Mesoporous ceria and transition metal-doped ceria (M 0.1 Ce 0.9 O 2 (M=Mn, Fe, Co, Cu)) catalysts were synthesized via CTAB-assisted method. The physicochemical properties of the prepared catalysts were characterized by XRD, DLS analysis, SEM, BET, Raman, H 2 -TPR and in situ DRIFT techniques. The catalytic activity tests for soot oxidation were performed under tight contact of soot/catalyst mixtures in the presence of O 2 and NO+O 2 , respectively. The obtained results show that mesoporous ceria-based solid solutions can be formed with large surface areas and small crystallite size. Transition metals doping enhances the oxygen vacancies and improves redox properties of the solids, resulting in the increased NO oxidation capacity and NO x adsorption capacity. The soot oxidation activity in the presence of O 2 is enhanced by doping transition metal, which may be related to their high surface area, increased oxygen vacancies and improved redox properties. The soot combustion is accelerated by the NO 2 -assisted mechanism under NO+O 2 atmosphere, facilitating an intimate contact between the soot and the catalyst. Copyright © 2017 Elsevier Inc. All rights reserved.

Characteristics of supported nano-TiO2/ZSM-5/silica gel (SNTZS): photocatalytic degradation of phenol.

PubMed

Zainudin, Nor Fauziah; Abdullah, Ahmad Zuhairi; Mohamed, Abdul Rahman

2010-02-15

Photocatalytic degradation of phenol was investigated using the supported nano-TiO(2)/ZSM-5/silica gel (SNTZS) as a photocatalyst in a batch reactor. The prepared photocatalyst was characterized using XRD, TEM, FT-IR and BET surface area analysis. The synthesized photocatalyst composition was developed using nano-TiO(2) as the photoactive component and zeolite (ZSM-5) as the adsorbents, all supported on silica gel using colloidal silica gel binder. The optimum formulation of SNTZS catalyst was observed to be (nano-TiO(2):ZSM-5:silica gel:colloidal silica gel=1:0.6:0.6:1) which giving about 90% degradation of 50mg/L phenol solution in 180 min. The SNTZS exhibited higher photocatalytic activity than that of the commercial Degussa P25 which only gave 67% degradation. Its high photocatalytic activity was due to its large specific surface area (275.7 m(2)/g), small particle size (8.1 nm), high crystalline quality of the synthesized catalyst and low electron-hole pairs recombination rate as ZSM-5 adsorbent was used. The SNTZS photocatalyst synthesized in this study also has been proven to have an excellent adhesion and reusability.

Adsorbent for hydroquinone removal based on graphene oxide functionalized with magnetic cyclodextrin-chitosan.

PubMed

Li, Leilei; Fan, Lulu; Sun, Min; Qiu, Huamin; Li, Xiangjun; Duan, Huimin; Luo, Chuannan

2013-07-01

Magnetic cyclodextrin-chitosan/graphene oxide (CCGO) with high surface area was synthesized via a simple chemical bonding method. The characteristics results of FTIR, SEM, TEM and XRD showed that CCGO was prepared. The large saturation magnetization (22.35 emu/g) of the synthesized nanoparticles allows fast separation of the CCGO from liquid suspension. These composites could efficiently remove hydroquinone from simulated wastewater with a facile subsequent solid-liquid separation because of their large area, abundant hydroxyl and amino groups with handy operation, and hydrophobicity. The hydroquinone removal process was found to obey the Freundlich adsorption model and its kinetics followed pseudo-second-order rate equation. The hydroquinone removal mechanism of CCGO might be attributed to the electrostatic adsorption of hydroquinone in the form of negatively charged hydroquinone by positively charged chitosan, accompanying hydroquinone absorbed by cavities of the cyclodextrin, and forming hydrogen bonds between hydroquinone and the hydroxyl groups on the surface of CCGO. The used CCGO could be recovered with ethanol. This study provides a promising nanostructured adsorbent with easy separation property for heavy metal ions removal. Copyright © 2013 Elsevier B.V. All rights reserved.

Phase study and surface morphology of beta-alumina

NASA Astrophysics Data System (ADS)

Tak, S. K.

2018-05-01

Beta alumina ceramic is well known as a polycrystalline ceramic material. The characteristic crystal structure of beta-alumina makes it useful as a separator in sodium sulphur batteries and other electrochemical devices requiring the passage of sodium ions. β"-alumina powders for this study were prepared by zeta process. The pellets were sintered at different microwave power levels and power schedule to optimize the sintering conditions to obtain preferred β" phase with improved microstructure. Phase identification was studied by X-ray diffraction (XRD). XRD analysis shows increase in β'' phase as the sintering temperature was increased from 1400°C to 1600°C. Surface morphology of the pellets was carried out by Scanning Electron microscopy (SEM). SEM studies revealed the formation and growth of platelet grains with interconnected porosity.

Synthesis, structural, thermal and Hirshfeld surface analysis of novel [1,2,4]triazolo[3,4-b][1,3,4] thiadiazine carrying 1,4-benzothiazine-3-one moiety

NASA Astrophysics Data System (ADS)

Shruthi, C.; Ravindrachary, V.; Guruswamy, B.; Lokanath, N. K.; Kumara, Karthik; Goveas, Janet

2018-05-01

Needle shaped single crystal of the title compound was grown by slow evaporation solution growth technique using ethanol as solvent. The grown single crystal was characterized using FT-IR, Single crystal XRD and Thermal analysis. The FT-IR spectrum confirms the molecular structure and identifies the different functional groups present in the compound. Single crystal XRD study reveals that the crystallized compound belongs to the monoclinic crystal system with P21/c space group and the corresponding cell parameters were identified. The thermal stability of the material was determined using both TGA and DTA analysis. The intermolecular interaction of each individual atom in the crystal lattice was estimated using Hirshfeld surface and finger print analysis.

SAPO-34/AlMCM-41, as a novel hierarchical nanocomposite: preparation, characterization and investigation of synthesis factors using response surface methodology

NASA Astrophysics Data System (ADS)

Roohollahi, Hossein; Halladj, Rouein; Askari, Sima; Yaripour, Fereydoon

2018-06-01

SAPO-34/AlMCM-41, as a new hierarchical nanocomposite was successfully synthesized via hydrothermal and dry-gel conversion. In an experimental and statistical study, effect of five input parameters including synthesis period, drying temperature, NaOH/Si, water/dried-gel and SAPO% were investigated on range-order degree of mesochannels and the relative crystallinity. X-ray diffraction (XRD) patterns were recorded to characterize the ordered AlMCM-41 and crystalline SAPO-34 structures. Nitrogen adsorption-desorption technique, scanning electron microscopy (SEM), field-emission SEM (FESEM) equipped with an energy-dispersive X-ray spectroscopy (EDS-Map) and transmission electron microscopy (TEM) were used to study the textural properties, morphology and surface elemental composition. Two reduced polynomials were fitted to the responses with good precision. Further, based on analysis of variances, SAPO% and time duration of dry-gel conversion were observed as the most effective parameters on the composite structure. The hierarchical porosity, narrow pore size distribution, high external surface area and large specific pore volume were of interesting characteristics for this novel nanocomposite.

TiO2-PANI/Cork composite: A new floating photocatalyst for the treatment of organic pollutants under sunlight irradiation.

PubMed

Sboui, Mouheb; Nsib, Mohamed Faouzi; Rayes, Ali; Swaminathan, Meenakshisundaram; Houas, Ammar

2017-10-01

A novel photocatalyst based on TiO 2 -PANI composite supported on small pieces of cork has been reported. It was prepared by simple impregnation method of the polyaniline (PANI)-modified TiO 2 on cork. The TiO 2 -PANI/Cork catalyst shows the unique feature of floating on the water surface. The as-synthesized catalyst was characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectra (UV-vis DRS) and the Brunauer-Emmett-Teller (BET) surface area analysis. Characterization suggested the formation of anatase highly dispersed on the cork surface. The prepared floating photocatalyst showed high efficiency for the degradation of methyl orange dye and other organic pollutants under solar irradiation and constrained conditions, i.e., no-stirring and no-oxygenation. The TiO 2 -PANI/Cork floating photocatalyst can be reused for at least four consecutive times without significant decrease of the degradation efficiency. Copyright © 2017. Published by Elsevier B.V.

EDTA functionalized magnetic nanoparticle as a multifunctional adsorbent for Congo red dye from contaminated water

NASA Astrophysics Data System (ADS)

Sahoo, Jitendra Kumar; Rath, Juhi; Dash, Priyabrat; Sahoo, Harekrushna

2017-05-01

The present work reports the applicability of magnetite iron nanoparticles (Fe3O4) functionalized with ethylenediaminetetraacetic acid (EDTA) as an efficient adsorbent for the removal of Congo red (CR) dye from contaminated water. Magnetic nanoparticles (Fe3O4) are prepared by chemical precipitation method in which Fe2+ and Fe3+ salt from aqueous solution were reacted in presence of ammonia solution. The surface of Fe3O4 nanoparticle was first coated with (3-aminopropyl) triethoxy silane (APTES) by a salinization reaction and then linked with EDTA via reaction between -NH2 and -COOH to form well dispersed surface functionalised biocompatible magnetic nanoparticles. The obtained EDTA functionalized magnetic nanoparticles are characterized in terms of their morphological, XRD, BET surface area analysis, Fourier transform infrared spectroscopy (FT-IR) and Vibrating sample magnetometer (VSM). The adsorption of CR on Fe3O4-APTES-EDTA nanocomposite corresponds well to the Langmuir model and the Freundlich model respectively. The adsorption processes for CR followed the pseudo-second-order model.

Facile Synthesis of Self-Assembled Flower-Like Mesoporous Zinc Oxide Nanoflakes for Energy Applications

NASA Astrophysics Data System (ADS)

Saranya, P. E.; Selladurai, S.

Flower-shaped self-assembled zinc oxide (ZnO) nanoflakes were successfully synthesized via a temperature-controlled hydrothermal method. The crystallinity and phase formation of the compound were determined from powder X-ray diffraction (PXRD) result. Surface morphology investigations reveal the self-assembled ZnO nanoflakes to form a spherical flower-like structure. In addition, the particle size was determined from high-resolution transmission electron microscope measurement as 18nm which is in accord with XRD and UV results. X-ray photo electron spectroscopy studies reveal the chemical composition and oxidation state of the ZnO nanoparticle. The specific surface area was calculated, and mesoporous nature was confirmed using Brunauer-Emmett-Teller analysis. Results support the superior interaction between the electrode and electrolyte ions through surface pores. Capacitive performance of the ZnO electrode material was determined using cyclic voltammetry and galvanostatic charge/discharge studies, and a maximum specific capacitance of 322F/g was obtained at 5mV/sec. Electrochemical impedance spectrum reveals the materials fast charge transfer kinetics.

Nonlinear electronic transport and enhanced catalytic behavior caused by native oxides on Cu nanowires

NASA Astrophysics Data System (ADS)

Hajimammadov, Rashad; Csendes, Zita; Ojakoski, Juha-Matti; Lorite, Gabriela Simone; Mohl, Melinda; Kordas, Krisztian

2017-09-01

Electrical transport properties of individual nanowires (both in axial and transversal directions) and their random networks suggest rapid oxidation when Cu is exposed to ambient conditions. The oxidation process is elucidated by thorough XRD, XPS and Raman analyzes conducted for a period of 30 days. Based on the obtained experimental data, we may conclude that first, cuprous oxide and copper hydroxide form that finally transform to cupric oxide. In electrical applications, oxidation of copper is not a true problem as long as thin films or bulk metal is concerned. However, as highlighted in our work, this is not the case for nanowires, since the oxidized surface plays quite important role in the contact formation and also in the conduction of percolated nanowire networks. On the other hand, by taking advantage of the mixed surface oxide states present on the nanowires along with their large specific surface area, we tested and found excellent catalytic activity of the oxidized nanowires in phenol oxidation, which suggests further applications of these materials in catalysis.

Zirconium doped nano-dispersed oxides of Fe, Al and Zn for destruction of warfare agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stengl, Vaclav, E-mail: stengl@uach.cz; Houskova, Vendula; Bakardjieva, Snejana

2010-11-15

Zirconium doped nano dispersive oxides of Fe, Al and Zn were prepared by a homogeneous hydrolysis of the respective sulfate salts with urea in aqueous solutions. Synthesized metal oxide hydroxides were characterized using Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX). These oxides were taken for an experimental evaluation of their reactivity with sulfur mustard (HD or bis(2-chloroethyl)sulfide), soman (GD or (3,3'-Dimethylbutan-2-yl)-methylphosphonofluoridate) and VX agent (S-[2-(diisopropylamino)ethyl]-O-ethyl-methylphosphonothionate). The presence of Zr{sup 4+} dopant can increase both the surface area and the surface hydroxylation of the resultingmore » doped oxides, decreases their crystallites' sizes thereby it may contribute in enabling the substrate adsorption at the oxide surface thus it can accelerate the rate of degradation of warfare agents. Addition of Zr{sup 4+} converts the product of the reaction of ferric sulphate with urea from ferrihydrite to goethite. We found out that doped oxo-hydroxides Zr-FeO(OH) - being prepared by a homogeneous hydrolysis of ferric and zirconium oxo-sulfates mixture in aqueous solutions - exhibit a comparatively higher degradation activity towards chemical warfare agents (CWAs). Degradation of soman or VX agent on Zr-doped FeO(OH) containing ca. 8.3 wt.% of zirconium proceeded to completion within 30 min.« less

Pseudocapacitive performance of electrodeposited porous Co3O4 film on electrophoretically modified graphite electrodes with carbon nanotubes

NASA Astrophysics Data System (ADS)

Kazazi, Mahdi; Sedighi, Ali Reza; Mokhtari, Mohammad Amin

2018-05-01

A facile and efficient two-step procedure was developed for the fabrication of a high-performance and binder-free cobalt oxide-carbon nanotubes (CO/CNT) pseudocapacitive electrode. First, CNTs were deposited on the surface of a chemically activated graphite sheet by cathodic electrophoretic deposition technique from their ethanolic suspension. In the next step, a thin film of cobalt oxide was electrodeposited on the CNTs coated graphite substrate by a galvanostatic method, followed by a thermal treatment in air. The structure and morphology of the prepared cobaltite electrode with and without CNT interlayer were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and nitrogen adsorption-desorption measurement. The results indicated that Co3O4 nanoparticles were uniformly attached on the surface of CNTs, to form a porous-structured CO/CNT composite electrode with a high specific surface area of 144.9 m2 g-1. Owing to the superior electrical conductivity of CNTs, high surface area and open porous structure, and improved integrity of the electrode structure, the composite electrode delivered a high areal capacitance of 4.96F cm-2 at a current density of 2 mA cm-2, a superior rate performance (64.7% capacitance retention from 2 mA cm-2 to 50 mA cm-2), as well as excellent cycling stability (91.8% capacitance retention after 2000 cycles), which are higher than those of the pure cobaltite electrode.

Soil formation in the Tsauchab Valley, Namibia

NASA Astrophysics Data System (ADS)

Eden, Marie; Bens, Oliver; Ramisch, Arne; Schwindt, Daniel; Völkel, Jörg

2016-04-01

The BMBF-funded project GeoArchives (Spaces) investigates soils and sediments in Southern Africa. A focus area lies on the Tsauchab Valley (Namibia), South of the Naukluft mountain range (24°26'40'' S, 16°10'40'' E). On a gently sloping alluvial fan facing East towards the river, the surface is characterized by a desert pavement covering soils used as farmland. The landscape units were mapped and the area at the lower slope of a hill was divided into three units: a rinsing surface and a gravel plain, separated by a channel. On these surfaces soil profiles were excavated. Profile description followed the German system (Bodenkundliche Kartieranleitung KA 5) and disturbed samples were taken at various depths and analysed in the lab. Undisturbed soil cores with a volume of 100 cm³ were taken just below the surface at a depth of ~1-6 cm. Lab analyses included texture and gravel content, colour, pH, electrical conductivity, carbonates, CNS, cation exchange capacity, pedogenic oxides, main and trace elements (XRF), and clay mineral distribution (XRD). Undisturbed samples were used to determine soil water retention curve, air permeability and bulk density. The profiles revealed moderately developed cambic soils rich in clay minerals and with total carbon contents ranging up to 1.8 %, bearing shrubs and after episodic rainfall a dense grass vegetation. Their genesis is discussed and interpreted in the context of the landscape and climate history of this semi-desert environment.

Synthesis and characterization of intercalated polyaniline-clay nanocomposite using supercritical CO2

NASA Astrophysics Data System (ADS)

Abdelraheem, A.; El-Shazly, A. H.; Elkady, M. F.

2018-05-01

Lately, supercritical CO2 (SCCO2) have been getting great interest. It can be used in numerous applications because it is environmentally friendly, safe, comparatively low cost, and nonflammable. One of its applications is being a solvent in the synthesis of polymeric-clay nanocomposite. In this paper, intercalated polyaniline-clay nanocomposite (PANC) was prepared using SCCO2. The intercalation structure of polyaniline chains between clay layers was verified by various characterization techniques. Scanning electron microscope and transmission electron microscope (SEM-TEM) were used to show the morphology of the synthesized nanocomposite. The molecular structure of PANC nanocomposite was confirmed using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The BET surface area and the conductivity of the nanocomposite were determined.

Catalytic performance of Mn 3O 4 and Co 3O 4 nanocrystals prepared by sonochemical method in epoxidation of styrene and cyclooctene

NASA Astrophysics Data System (ADS)

Askarinejad, Azadeh; Bagherzadeh, Mojtaba; Morsali, Ali

2010-09-01

A simple sonochemical method was developed to synthesis uniform sphere-like Co 3O 4 and Mn 3O 4 nanocrystals. Epoxidation of styrene and cyclooctene by anhydrous tert-butyl hydroperoxide over the prepared Co 3O 4 and Mn 3O 4 nanocatalysts was investigated. The results of conversion activity were compared with bulk Co 3O 4 and Mn 3O 4. Under optimized reaction conditions, the nanocatalysts showed a superior catalytic performance as compared to the bulk catalysts. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and BET surface area, were used to characterize and investigate the nanocatalysts.

Photodegradation of methyl red under visible light by mesoporous carbon nitride

NASA Astrophysics Data System (ADS)

Hu, Yueyue; Zhang, Min; Xiao, Zaozao; Jiang, Tao; Yan, Bing; Li, Jian

2018-02-01

Mesoporous carbon nitride (mpg-C3N4) with tunable microstructure has been successfully prepared through a simple polymerization reaction of cyanamide by a nano hard-templating approach. The obtained materials have been characterized using X-ray diffraction (XRD), N2 adsorption, and Fourier transform infrared (FT-IR) spectroscopy. The results show that the pore diameter of the mpg-C3N4 materials can be easily tuned from 3.8 to 10.5 nm. The mpg-C3N4 materials are demonstrated to exhibit much higher visible light photocatalytic activity than that of g-C3N4 for the degradation of aqueous methyl red (MR). The high surface areas and large pore volume contributed to the efficient visible light photocatalytic activity.

Pt nanoparticle-reduced graphene oxide nanohybrid for proton exchange membrane fuel cells.

PubMed

Park, Dae-Hwan; Jeon, Yukwon; Ok, Jinhee; Park, Jooil; Yoon, Seong-Ho; Choy, Jin-Ho; Shul, Yong-Gun

2012-07-01

A platinum nanoparticle-reduced graphene oxide (Pt-RGO) nanohybrid for proton exchange membrane fuel cell (PEMFC) application was successfully prepared. The Pt nanoparticles (Pt NPs) were deposited onto chemically converted graphene nanosheets via ethylene glycol (EG) reduction. According to the powder X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) analysis, the face-centered cubic Pt NPs (3-5 nm in diameter) were homogeneously dispersed on the RGO nanosheets. The electrochemically active surface area and PEMFC power density of the Pt-RGO nanohybrid were determined to be 33.26 m2/g and 480 mW/cm2 (maximum values), respectively, at 75 degrees C and at a relative humidity (RH) of 100% in a single-cell test experiment.

Preparation of zeolite supported TiO{sub 2}, ZnO and ZrO{sub 2} and the study on their catalytic activity in NO{sub x} reduction and 1-pentanol dehydration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fatimah, Is

Preparation of zeolite supported TiO{sub 2}, ZnO and ZrO{sub 2} and their catalytic activity was studied. Activated natural zeolite from Indonesia was utilized for the preparation and catalytic activity test on NO{sub x} reduction by NH{sub 3} and also 1-pentanol dehydration were examined. Physicochemical characterization of materials was studied by x-ray diffraction (XRD) measurement, scanning electron microscope, solid acidity determination and also gas sorption analysis. The results confirmed that the preparation gives some improvements on physicochemical characters suitable for catalysis mechanism in those reactions. Solid acidity and specific surface area contributed significantly to the activity.

Influence of Oxidation Treatments and Surface Finishing on the Electrochemical Behavior of Ni-20Cr HVOF Coatings

NASA Astrophysics Data System (ADS)

Ruiz-Luna, H.; Porcayo-Calderon, J.; Alvarado-Orozco, J. M.; Mora-García, A. G.; Martinez-Gomez, L.; Trápaga-Martínez, L. G.; Muñoz-Saldaña, J.

2017-12-01

The low-temperature electrochemical behavior of HVOF Ni-20Cr coatings was assessed. The coatings were evaluated in different conditions including as-sprayed, as-ground, and heat-treated in air and argon atmospheres. A detailed analysis of the coatings was carried out by means of XRD, SEM, and EPMA, prior and after the corrosion test. The corrosion rate was analyzed in a NaCl solution saturated with CO2. Results demonstrate that the use of a low-oxygen partial pressure favors the formation of a Cr2O3 layer on the surface of the coatings. According to the electrochemical results, the lower corrosion rates were obtained for the heat-treated coatings irrespective of the surface finishing, being the ground and argon heat-treated condition that shows the best corrosion performance. This behavior is due to the synergistic effect of the low-pressure heat treatment and the grinding processes. The grinding promotes a more homogeneous reaction area without surface heterogeneities such as voids, and the pre-oxidation treatment decreases the porosity content of the coating and also allows the growing of a Cr-rich oxide scale which acts as a barrier against the ions of the aqueous solution.

[Preparation and catalytic activity of surface-modification CNTs/TiO2 composite photocatalysts].

PubMed

Wang, Huan-Ying; Li, Wen-Jun; Chang, Zhi-Dong; Zhou, Hua-Lei; Guo, Hui-Chao

2011-09-01

A novel kind of carbon nanotubes/titanium dioxide (CNTs/TiO2) composite photocatalyst was prepared by a modified sol-gel method in which the nanoscaled TiO2 particles were uniformly deposited on the CNTs modified with poly(vinyl pyrrolidone) (PVP). The composites were characterized by a range of analytical techniques including high resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results show the successful covering of the CNTs with PVP, forming core-shell structure. The nanoscaled TiO2 particles were uniformly deposited on the surface of CNTs reducing the bare CNTs which avoid losing the absorption and scattering of photons. The combination of CNTs and TiO2 particles imply the enhanced interactions between the CNTs and TiO2 interface which possibly becomes heterojunction. The composites become mesoporous crystalline TiO2 (anatase) clusters after annealing at 500 degrees C, and the surface area increases obviously. The photocatalytic activities of surface modification CNTs/TiO2 (smCNTs/TiO2) composites are extremely enhanced from the results of the photodegradation of methylene blue (MB).

Effects of copper-precursors on the catalytic activity of Cu/graphene catalysts for the selective catalytic oxidation of ammonia

NASA Astrophysics Data System (ADS)

Li, Jingying; Tang, Xiaolong; Yi, Honghong; Yu, Qingjun; Gao, Fengyu; Zhang, Runcao; Li, Chenlu; Chu, Chao

2017-08-01

Different copper-precursors were used to prepare Cu/graphene catalysts by an impregnation method. XRD, Raman spectra, TEM, BET, XPS, H2-TPR, NH3-TPD, DRIFTS and catalytic activity test were used to characterize and study the effect of precursors on the catalytic activity of Cu/graphene catalysts for NH3-SCO reaction. The large specific surface area of Cu/graphene catalysts and high dispersion of the metal particles on the graphene caused the well catalytic activity of NH3-SCO reaction. Compared to Cu/GE(AC), Cu/GE(N) showed better catalytic performance, and the complete NH3 removal efficiency was obtained at 250 °C with N2 selectivity of 85%. The copper-precursors had influence on the distribution of surface Cu species and further affected the catalytic activity of Cu/GE catalysts. The more amount of surface Cu species and highly dispersed CuO particles on the graphene surface formed by using copper nitrate as precursor could significantly improve the reducibility of catalysts and enhance NH3 adsorption, thereby improving the catalytic activity of Cu/graphene catalyst.

Hot Corrosion Behavior of Ti-48Al and Ti-48Al-2Cr Intermetallic Alloys Produced by Electric Current Activated Sintering

NASA Astrophysics Data System (ADS)

Garip, Y.; Ozdemir, O.

2018-06-01

In this study, Ti-48Al and Ti-48Al-2Cr (at. pct) intermetallic alloys were produced by electric current activated sintering (ECAS). In order to characterize the phase formation and microstructures of these alloys, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis were used. The XRD result shows that the intermetallic alloys are composed of γ-TiAl and α 2-Ti3Al phases. The microstructure is dense with a low amount of porosity. The hot corrosion behavior of intermetallic alloys was carried out in a salt mixture of 25 wt pct K2SO4 and 75 wt pct Na2SO4 at 700 °C for 180 hours. The morphology of corroded surfaces was observed by SEM-EDS and XRD. Corrosion phases were identified as TiO2 and Al2O3. Well-adhering oxide scale was detected on the corroded sample surface at the end of 180 hours, and no spallation was observed. In addition, a parabolic curve was obtained at the weight change rate vs time.

Surface photoelectric and visible light driven photocatalytic properties of zinc antimonate-based photocatalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Shaojun; Li, Guoqiang; Zhang, Yang

2013-03-15

Highlights: ► N-doped and pristine ZnSb{sub 2}O{sub 6} photocatalysts were synthesized by a facile method. ► N-doped ZnSb{sub 2}O{sub 6} shows a significant enhanced visible light photocatalytic activity. ► The N-doped ZnSb{sub 2}O{sub 6} shows the reduced surface photovoltage signals. - Abstract: The N-doped and pristine ZnSb{sub 2}O{sub 6} photocatalysts were synthesized by a facile method. The samples were characterized by X-ray diffraction (XRD), UV–vis spectroscopy, surface photovoltage spectroscopy and scanning electron microscopy. The photocatalytic activities of the prepared samples were evaluated from the degradation of rhodamine B (RhB) under full arc and visible light irradiation of Xe lamp. Themore » XRD and UV–vis results indicated that the N-doping did not change the crystal structure, but decrease the band gap in comparison with the pristine one. The N-doped ZnSb{sub 2}O{sub 6} shows the reduced surface photovoltage signals and the significantly enhanced photocatalytic activity under two irradiation conditions.« less

Structure evolution of zinc oxide thin films deposited by unbalance DC magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aryanto, Didik, E-mail: didi027@lipi.go.id; Materials Research Group, Physics Department, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah; Marwoto, Putut

Zinc oxide (ZnO) thin films are deposited on corning glass substrates using unbalanced DC magnetron sputtering. The effect of growth temperature on surface morphology and crystallographic orientation of ZnO thin film is studied using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The surface morphology and crystallographic orientation of ZnO thin film are transformed against the increasing of growth temperature. The mean grain size of film and the surface roughness are inversely and directly proportional towards the growth temperature from room temperature to 300 °C, respectively. The smaller grain size and finer roughness of ZnO thin film are obtainedmore » at growth temperature of 400 °C. The result of AFM analysis is in good agreement with the result of XRD analysis. ZnO thin films deposited in a series of growth temperatures have hexagonal wurtzite polycrystalline structures and they exhibit transformations in the crystallographic orientation. The results in this study reveal that the growth temperature strongly influences the surface morphology and crystallographic orientation of ZnO thin film.« less

Effect of black clay soil moisture on the electrochemical behavior of API X70 pipeline steel

NASA Astrophysics Data System (ADS)

Hendi, R.; Saifi, H.; Belmokre, K.; Ouadah, M.; Smili, B.; Talhi, B.

2018-03-01

The effect of moisture content variation (20–100 wt.%) on the electrochemical behavior of API X70 pipeline steel buried in the soil of Skikda (East of Algeria) was studied using electrochemical techniques, scanning electron microscopy (SEM), X ray diffraction analysis (XRD) and weight loss measurement. The electrochemical measurements showed that the corrosion current Icorr is directly proportional to the moisture content up to 50 wt.%, beyond this content, this value becomes almost constant. The result were confirmed by electrochemical impedance spectroscopy; the capacitance of the double layer formed on the surface is the highest at 50 wt.%. A single time constant was detected by plotting the Bode diagrams. The steel surface degradation has been appreciated using the scanning electron microscopy observations. A few pitting corrosion at 20 wt.% moisture, followed by more degradation at 50 wt.% have been revealed. However, when the moisture amount exceeded 50 wt.%, the surface became entirely covered by a corrosion product. XRD analysis revealed the dominance of FeOOH and Fe3O4 phases on steel surface for a moisture content of 50 wt.%.

Laser irradiation effects on the surface, structural and mechanical properties of Al-Cu alloy 2024

NASA Astrophysics Data System (ADS)

Yousaf, Daniel; Bashir, Shazia; Akram, Mahreen; kalsoom, Umm-i.-; Ali, Nisar

2014-02-01

Laser irradiation effects on surface, structural and mechanical properties of Al-Cu-Mg alloy (Al-Cu alloy 2024) have been investigated. The specimens were irradiated for various fluences ranging from 3.8 to 5.5 J/cm2 using an Excimer (KrF) laser (248 nm, 18 ns, 30 Hz) under vacuum environment. The surface and structural modifications of the irradiated targets have been investigated by scanning electron microscope (SEM) and X-ray diffractometer (XRD), respectively. SEM analysis reveals the formation of micro-sized craters along the growth of periodic surface structures (ripples) at their peripheries. The size of the craters initially increases and then decreases by increasing the laser fluence. XRD analysis shows an anomalous trend in the peak intensity and crystallite size of the specimen irradiated for various fluences. A universal tensile testing machine and Vickers microhardness tester were employed in order to investigate the mechanical properties of the irradiated targets. The changes in yield strength, ultimate tensile strength and microhardness were found to be anomalous with increasing laser fluences. The changes in the surface and structural properties of Al-Cu alloy 2024 after laser irradiation have been associated with the changes in mechanical properties.

Dissolution Rates of Allophane, FE-Containing Allophane, and Hisingerite and Implications for Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Ralston, S. J.; Hausrath, E. M.; Tschauner, O.; Rampe, E. B.; Christoffersen, R.

2018-01-01

Investigations with the CheMin Xray Diffractometer (XRD) onboard the Curiosity rover in Gale Crater demonstrate that all rock and soil samples measured to date contain approximately 15-70 weight percentage X-ray amorphous materials. The diffuse scattering hump from the X-ray amorphous materials in CheMin XRD patterns can be fit with a combination of allophane, ferrihydrite, and rhyolitic and basaltic glass. Because of the iron-rich nature of Mars' surface, Fe-rich poorly-crystalline phases, such as hisingerite, may be present in addition to allophane.

The effect of nanoparticles size on photocatalytic and antimicrobial properties of Ag-Pt/TiO2 photocatalysts

NASA Astrophysics Data System (ADS)

Zielińska-Jurek, Anna; Wei, Zhishun; Wysocka, Izabela; Szweda, Piotr; Kowalska, Ewa

2015-10-01

Ag-Pt-modified TiO2 nanocomposites were synthesized using the sol-gel method. Bimetallic modified TiO2 nanoparticles exhibited improved photocatalytic activity under visible-light irradiation, better than monometallic Ag/TiO2 and Pt/TiO2 nanoparticles (NPs). All modified powders showed localized surface plasmon resonance (LSPR) in visible region. The photocatalysts' characteristics by X-ray diffractometry (XRD), scanning transmission electron microscopy (STEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption (BET method for specific surface area) showed that sample with the highest photocatalytic activity had anatase structure, about 93 m2/g specific surface area, maximum plasmon absorption at ca. 420 nm and contained small NPs of silver of 6 nm and very fine platinum NPs of 3 nm. The photocatalytic activity was estimated by measuring the decomposition rate of phenol in 0.2 mM aqueous solution under Vis and UV/vis light irradiation. It was found that size of platinum was decisive for the photocatalytic activity under visible light irradiation, i.e., the smaller Pt NPs were, the higher was photocatalytic activity. While, antimicrobial activities, estimated for bacteria Escherichia coli and Staphylococcus aureus, and pathogenic fungi belonging to Candida family, were only observed for photocatalysts containing silver, i.e., Ag/TiO2 and Ag-Pt/TiO2 nanocomposites.

Synthesis and CO{sub 2} adsorption study of modified MOF-5 with multi-wall carbon nanotubes and expandable graphite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ullah, Sami, E-mail: samichemist1@gmail.com, E-mail: azmibustam@petronas.com.my, E-mail: azmish@petronas.com.my, E-mail: lkhlfh@gmail.com, E-mail: hmurshid@gmail.com, E-mail: nadiariazz@gmail.com; Bustam, M. A., E-mail: samichemist1@gmail.com, E-mail: azmibustam@petronas.com.my, E-mail: azmish@petronas.com.my, E-mail: lkhlfh@gmail.com, E-mail: hmurshid@gmail.com, E-mail: nadiariazz@gmail.com; Shariff, A. M., E-mail: samichemist1@gmail.com, E-mail: azmibustam@petronas.com.my, E-mail: azmish@petronas.com.my, E-mail: lkhlfh@gmail.com, E-mail: hmurshid@gmail.com, E-mail: nadiariazz@gmail.com

2014-10-24

MOF-5 was synthesized by solvothermal method and its reactivation under anhydrous conditions. This research is conducted to investigate the effect of MOF-5 and MOF-5 modified with multi-wall carbon nanotubes (MWCNTs) and expandable graphite (EG) on the performance of CO{sub 2} adsorption. The synthesized MOFs were characterized using Field emission scanning electron microscopy (FESEM) for surface morphology, Thermogravimetric analysis (TGA) for thermal stability, X-ray diffraction (XRD) for crystals plane, Brunauer-Emmet-Teller (BET) for surface area and CO{sub 2} adsorption. The result had showed that the modified MOF-5 enhanced the CO{sub 2} adsorption compared to the pure MOF-5. The increment in the CO{submore » 2} uptake capacities of MOF materials was attributed to the decrease in the pore size and enhancement of micropore volume of MOF-5 by multi-walled carbon nanotube and EG incorporation. The BET surface area of the synthesized MOF-5@MWCNTs is more than MOF-5. The CO{sub 2} sorption capacities of MOF-5 and MOF-5@MWCNTs were observed to increase from 0.00008 to 0.00048 mol g-1 at 298 K and 1 bar. The modified MOF-5@MWCNTs resulted in the highest CO{sub 2} adsorption followed by the modified MOF-5@ EG and lastly, MOF-5.« less

Study of structural, surface and hydrogen storage properties of boric acid mediated metal (sodium)-organic frameworks

NASA Astrophysics Data System (ADS)

Ozer, Demet; Köse, Dursun A.; Sahin, Onur; Oztas, Nursen A.

2018-04-01

Three boric acid mediated metal organic frameworks were synthesized by solution method with using succinic acid, fumaric acid and acetylene dicarboxylic acid as a ligand source and sodium as a metal source. The complexes were characterized by FT-IR, powder XRD, elemental analyses and single crystal measurements. The complexes with the formula, C4H18B2Na2O14, C4H16B2Na2O14 and C4H14B2Na2O14 were successfully obtained. BET surface area of complexes were calculated and found as 13.474 m2/g for catena-(tetrakis(μ2-hydroxo)-(μ2-trihydrogen borate)-(μ2-succinato)-di-sodium boric acid solvate), 1.692 m2/g for catena-(tetrakis(μ2-hydroxo)-(μ2-trihydrogen borate)-(μ2-fumarato)-di-sodium boric acid solvate) and 5.600 m2/g for catena-(tetrakis(μ2-hydroxo)-(μ2-trihydrogen borate)-(μ2-acetylenedicarboxylato)-di-sodium boric acid solvate). Hydrogen storage capacities of the complexes were also studied at 77 K 1 bar pressure and found as 0.108%, 0.033%, 0.021% by mass. When different ligands were used, the pore volume, pore width and surface area of the obtained complexes were changed. As a consequence, hydrogen storage capacities also changed.

Effects of Small Polar Molecules (MA+ and H2O) on Degradation Processes of Perovskite Solar Cells.

PubMed

Ma, Chunqing; Shen, Dong; Qing, Jian; Thachoth Chandran, Hrisheekesh; Lo, Ming-Fai; Lee, Chun-Sing

2017-05-03

Degradation mechanisms of methylammonium lead halide perovskite solar cells (PSCs) have drawn much attention recently. Herein, the bulk and surface degradation processes of the perovskite were differentiated for the first time by employing combinational studies using electrochemical impedance spectroscopy (EIS), capacitance frequency (CF), and X-ray diffraction (XRD) studies with particular attention on the roles of small polar molecules (MA + and H 2 O). CF study shows that short-circuit current density of the PSCs is increased by H 2 O at the beginning of the degradation process coupled with an increased surface capacitance. On the basis of EIS and XRD analysis, we show that the bulk degradation of PSCs involves a lattice expansion process, which facilitates MA + ion diffusion by creating more efficient channels. These results provide a better understanding of the roles of small polar molecules on degradation processes in the bulk and on the surface of the perovskite film.

Antioxidation performance of poly(vinyl alcohol) modified poly(vinylidene fluoride) membranes

NASA Astrophysics Data System (ADS)

Wang, Daohui; Li, Xianfeng; Li, Qing; Liu, Zhen; Li, Nana; Huang, Qinglin; Zhang, Yufeng; Xiao, Changfa

2018-03-01

Commercial poly(vinylidene fluoride) (PVDF) membranes were modified by dip-coating and crosslinking hydrophilic poly(vinyl alcohol) (PVA) on the membrane surface. The antioxidation performance of the modified PVDF membranes was evaluated via exposing the modified membranes to sodium hypochlorite and potassium permanganate solutions for 5-30 days, respectively. The evaluation was based on the influences of the two oxidants on the permeability, rejection, and hydrophility of the modified membranes, which were characterized by water flux, ink rejection, water contact angle, x-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, and x-ray diffraction (XRD) measurements. The XPS and water contact angle results show that the hydrophilicity of PVDF membranes was significantly improved when PVA was crosslinked on the surface of PVDF membranes. When the modified membranes had been treated with sodium hypochlorite or potassium permanganate for 30 days, the permeability and hydrophilicity were basically maintained and the rejection was slightly decreased. XPS and XRD indicated that some of PVAs coated on the membrane surface could be oxidized and peeled.

Enhancement of the fatigue performance of Ti-6Al-4V implant products

NASA Astrophysics Data System (ADS)

Wimalasiri, Dematapaksha H. R. J.

Implants surgery, in particular hip implants, is fast becoming a routine, popular approach for curing diseases such as, osteoarthritis and rheumatic arthritis. However one potential problem with the insertion of a metal implant is that of the risk of fatigue failure. Numerous factors affect the propensity of a metal to fatigue, none more so than the physical and stress state of the surface. This research is focused on an assessment of the role of manufacturing processes on the fatigue performance of hip implants made from a Ti-6Al-4V alloy. The role of surface defects, surface residual stresses and material microstructural properties which influence fatigue performance were examined. Characterization of the implant material and of the processes involved in actual hip implant manufacturing were conducted. Rotating bend fatigue testing using hour glass shaped specimens was conducted to evaluate the fatigue performance at selected manufacturing stages. The surface roughness/defects and residual stresses were measured prior to conducting fatigue tests. A variation of fatigue limit, attributed to variations of surface roughness and surface residual stress was observed. The influence of parameters such as, stress ratio and mean stress effect, variation of fracture mechanics parameters (e.g. DeltaK[th]) and the limiting threshold conditions for different stages of cracks were investigated in the context of Kitagawa-Takahashi (K-T) type diagrams. Experimental data was used to develop models which were used to calculate, (i). fatigue life at respective stress amplitude and, (ii). the fatigue limit of components with known surface roughness/defect size and residual stress. To evaluate material crack growth properties a surface replication method was used. The output from both models showed good correlation with experimental data. Comprehensive fractography was conducted using optical, secondary electron, and infinite focus microscopy to support the results obtained from fatigue testing. Analysis was performed on in-vivo hip implant failure data covering the last 12 years. Fatigue failures occur in two locations on the implant stem, namely the cone area and the neck area. These two locations were investigated separately to identify the factors, such as; the category of implant most vulnerable to failure, service life, design features, fixation with the host bone, crack initiation features and propagation details. An attempt was made to compare in-vivo fatigue features with experimental fatigue results. X-ray diffraction (XRD) was used to investigate the surface residual stresses resulting from different manufacturing processes. The results were confirmed and software and hardware settings were calibrated in accordance with the results obtained from XRD analysis conducted at National Physical Laboratories (NPL), UK. Surface roughness measurements were also conducted using stylus type surface profilometer. The knowledge gained from this research can be used to understand the causes and modes of in-vivo fatigue failure of hip implants made of Ti-6Al-4V. Understanding the fatigue/mechanical properties of the implant material enables recommendations and optimization of good practice in manufacturing to eliminate in-vivo fatigue failures.

Evaluation of Cation Migration in Lanthanum Strontium Cobalt Ferrite Solid Oxide Fuel Cell Cathodes via In-operando X-ray Diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardy, John S.; Coyle, Christopher A.; Bonnett, Jeff F.

2018-01-28

Anode-supported SOFCs with LSCF-6428 cathodes were operated at various temperatures for hundreds of hours in dry or humid (~3% water) cathode air with continuous cathode XRD. Additionally, one cell in dry air was held at OCV and another had 12% CO2 added to the humid air. Long cumulative XRD count times allowed identification of minor phases at <0.1 wt%. In humid air, performance improved during the first couple of hundred hours and Fe-rich Fe,Co spinel XRD peaks gradually shifted to lower angles while nano-nodules formed on LSCF surfaces. With 12% CO2 added, performance degraded after initial activation, unlike without CO2,more » where stability followed activation. In CO2, LSCF XRD peaks shifted indicating gradual decomposition. In dry air, fast initial degradation that decelerated over time occurred at constant current while the cell at OCV was stable. At OCV and 750°C or at constant current and 700°C in dry air, Fe-rich spinel XRD peaks shifted more slowly than in humid air tests; Co-rich Fe,Co spinel peaks shifted to higher angles; and SEM discovered smaller nano-nodules on LSCF than after humid air tests. At constant current at 750°C and 800°C in dry air, no nano-nodules or gradual changes in the XRD patterns were discovered.« less

[X-ray diffraction (XRD) and near infrared spectrum (NIR) analysis of the soil overlying the Bairendaba deposit of the Inner Mongolia Grassland].

PubMed

Luo, Song-ying; Cao, Jian-jin; Wu, Zheng-quan

2014-08-01

The soil samples uniformly overlying the Bairendaba deposit of the Inner Mongolia grassland were collected, and ana- lyzed with X-ray diffraction (XRD) and near infrared spectrum (NIR), for exploring the origins of the soil from the, grassland mining area and the relationship with the underground rock. The results show that the samp]s consist of quartz, graphite, carbonate, hornblende, mica, chlorite, montmorillonite, illite, berlinite, diaspore, azurite, hen tite, etc. These indicate that the soil samples were not only from the weathering products of the surface rock, but also from the underground rock mass and the alteration of the wall rock. The azurite and the hematite contained in the soil, mainly coming from the oxidation zone of the orebodies, can be used as the prospecting marks. The alteration mineral assemblage is mainly chlorite-illite-montmorillonite and it experienced the alteration process of potassic alteration-->silicification-->carbonatization-->silk greisenization-->clayization. Also, the wall rock alteration and the physical weathering processes can be accurately restored by analyzing the combination of the alteration minerals, which can provide important reference information for the deep ore prospecting and the ore deposit genesis study, improving the rate of the prospecting. The XRD and NIR with the characteristics of the economy and quickness can be used for the identification of mineral composition of soil, and in the study of mineral and mineral deposits. Especially, NIR has its unique superiority, that is, its sample request is low, and it can analyze a batch of samples quickly. With the development of INR, it will be more and more widely applied in geological field, and can play an important role in the ore exploration.

Studies the alterations of biochemical and mineral contents in bone tissue of mus musculus due to aluminum toxicity and the protective action of desferrioxamine and deferiprone by FTIR, ICP-OES, SEM and XRD techniques.

PubMed

Sivakumar, S; Khatiwada, Chandra Prasad; Sivasubramanian, J

2014-05-21

The present study has attempt to analyze the changes in the biochemical and mineral contents of aluminum intoxicated bone and determine the protective action of desferrioxamine (DFO) and deferiprone (DFP) by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), and scanning electron microscopy (SEM) techniques for four groups of animals such as control (Group I), aluminum intoxicated (Group II), Al+DFP (Group III) and Al+DFO+DFP (Group IV) treated groups respectively. The FTIR spectra of the aluminum intoxicated bone showed significant alteration in the biochemical constituents. The bands ratio at I1400/I877 significantly decreased from control to aluminum, but enhanced it by Al+DFP to Al+DFO+DFP treated bone tissue for treatments of 16 weeks. This result suggests that DFO and DFP are the carbonate inhibitor, recovered from chronic growth of bone diseases and pathologies. The alteration of proteins profile indicated by Amide I and Amide II, where peak area values decreased from control to aluminum respectively, but enhanced by treated with DFP (p.o.) and DFO+DFP (i.p.) respectively. The XRD analysis showed a decrease in crystallinity due to aluminum toxicity. Further, the Ca, Mg, and P contents of the aluminum exposed bone were less than those of the control group, and enhanced by treatments with DFO and DFP. The concentrations of trace elements were found by ICP-OES. Therefore, present study suggests that due to aluminum toxicity severe loss of bone minerals, decrease in the biochemical constituents and changes in the surface morphology. Copyright © 2014 Elsevier B.V. All rights reserved.

Phase transformation during surface ablation of cobalt-cemented tungsten carbide with pulsed UV laser

NASA Astrophysics Data System (ADS)

Li, T.; Lou, Q.; Dong, J.; Wei, Y.; Liu, J.

Surface ablation of cobalt-cemented tungsten carbide hard metal has been carried out in this work using a 308 nm, 20 ns XeCl excimer laser. Surface microphotography and XRD, as well as an electron probe have been used to investigate the transformation of phase and microstructure as a function of the pulse-number of laser shots at a laser fluence of 2.5 J/cm2. The experimental results show that the microstructure of cemented tungsten carbide is transformed from the original polygonal grains of size 3 μm to interlaced large, long grains with an increase in the number of laser shots up to 300, and finally to gross grains of size 10 μm with clear grain boundaries after 700 shots of laser irradiation. The crystalline structure of the irradiated area is partly transformed from the original WC to βWC1-x, then to αW2C and CW3, and finally to W crystal. It is suggested that the undulating `hill-valley' morphology may be the result of selective removal of cobalt binder from the surface layer of the hard metal. The formation of non-stoichiometric tungsten carbide may result from the escape of elemental carbon due to accumulated heating of the surface by pulsed laser irradiation.

Correlation between the microstructures of graphite oxides and their catalytic behaviors in air oxidation of benzyl alcohol.

PubMed

Geng, Longlong; Wu, Shujie; Zou, Yongcun; Jia, Mingjun; Zhang, Wenxiang; Yan, Wenfu; Liu, Gang

2014-05-01

A series of graphite oxide (GO) materials were obtained by thermal treatment of oxidized natural graphite powder at different temperatures (from 100 to 200 °C). The microstructure evolution (i.e., layer structure and surface functional groups) of the graphite oxide during the heating process is studied by various characterization means, including XRD, N2 adsorption, TG-DTA, in situ DRIFT, XPS, Raman, TEM and Boehm titration. The characterization results show that the structures of GO materials change gradually from multilayer sheets to a transparent ultrathin 2D structure of the carbon sheets. The concentration of surface COH and HOCO groups decrease significantly upon treating temperature increasing. Benzyl alcohol oxidation with air as oxidant source was carried out to detect the catalytic behaviors of different GO materials. The activities of GO materials decrease with the increase of treating temperatures. It shows that the structure properties, including ultrathin sheets and high specific surface area, are not crucial factors affecting the catalytic activity. The type and amount of surface oxygen-containing functional groups of GO materials tightly correlates with the catalytic performance. Carboxylic groups on the surface of GO should act as oxidative sites for benzyl alcohol and the reduced form could be reoxidized by molecular oxygen. Copyright © 2014 Elsevier Inc. All rights reserved.

Influence of sulfurization temperature on Cu2ZnSnS4 absorber layer on flexible titanium substrates for thin film solar cells

NASA Astrophysics Data System (ADS)

Gokcen Buldu, Dilara; Cantas, Ayten; Turkoglu, Fulya; Gulsah Akca, Fatime; Meric, Ece; Ozdemir, Mehtap; Tarhan, Enver; Ozyuzer, Lutfi; Aygun, Gulnur

2018-02-01

In this study, the effect of sulfurization temperature on the morphology, composition and structure of Cu2ZnSnS4 (CZTS) thin films grown on titanium (Ti) substrates has been investigated. Since Ti foils are flexible, they were preferred as a substrate. As a result of their flexibility, they allow large area manufacturing and roll-to-roll processes. To understand the effects of sulfurization temperature on the CZTS formation on Ti foils, CZTS films fabricated with various sulfurization temperatures were investigated with several analyses including x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy and Raman scattering. XRD measurements showed a sharp and intense peak coming from the (112) planes of the kesterite type lattice structure (KS), which is strong evidence for good crystallinity. The surface morphologies of our thin films were investigated using SEM. Electron dispersive spectroscopy was also used for the compositional analysis of the thin films. According to these analysis, it is observed that Ti foils were suitable as substrates for the growth of CZTS thin films with desired properties and the sulfurization temperature plays a crucial role for producing good quality CZTS thin films on Ti foil substrates.

Effect of sulfuric acid concentration of bentonite and calcination time of pillared bentonite

NASA Astrophysics Data System (ADS)

Mara, Ady; Wijaya, Karna; Trisunaryati, Wega; Mudasir

2016-04-01

An activation of natural clay has been developed. Activation was applied by refluxing the natural bentonite in variation of the sulfuric acid concentration and calcination time of pillared bentonite (PLC). Calcination was applied using oven in microwave 2,45 GHz. Determination of acidity was applied by measuring the amount of adsorbed ammonia and pyridine. Morphological, functional groups and chrystanility characterizations were analyzed using SEM, TEM, FTIR and XRD. Porosity was analyzed using SSA. The results showed that the greater of the concentration of sulfuric acid and calcination time was, the greater the acidity of bentonite as well as the pore diameter were. FTIR spectra showed no fundamental changes in the structure of the natural bentonite, SEM, and TEM images were showing an increase in space or field due to pillarization while the XRD patterns showed a shift to a lower peak. Optimization was obtained at a concentration of 2 M of sulfuric acid and calcination time of 20 minutes, keggin ion of 2.2 and suspension of 10 mmol, respectively each amounted to 11.7490 mmol/gram of ammonia and 2.4437 mmol/gram of pyridine with 154.6391 m2/gram for surface area, 0.130470 m3/gram of pore volume and 3.37484 nm of pore diameter.

Moessbauer Characterization of Magnetite/Polyaniline Magnetic Nanocomposite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, Anselmo F. R.; Faria, Fernando S. E. D. V.; Lopez, Jorge L.

2010-12-02

Aniline surface coated Fe{sub 3}O{sub 4} nanoparticles have been successfully synthesized by UV irradiation varying the time and the acid media (HCl, HNO{sub 3}, or H{sub 2}SO{sub 4}). The synthesized material represents a promising platform for application in nerve regeneration. XRD patterns are consistent with the crystalline structure of magnetite. Nevertheless, for UV irradiation times longer than 2 h, extra XRD lines reveal the presence of goethite. The mean crystallite size of uncoated particles is estimated to be 25.4 nm, meanwhile that size is reduced to 19.9 nm for the UV irradiated sample in HCl medium for 4 h. Moessbauermore » spectra of uncoated nanoparticles reveal the occurrence of thermal relaxation at room temperature, while the 77 K-Moessbauer spectrum suggests the occurrence of electron localization effects similar to that expected in bulk magnetite. The Mossbauer spectra of UV irradiated sample in HCl medium during 4 h, confirms the presence of the goethite phase. For this sample, the thermal relaxation is more evident, since the room temperature spectrum shows larger spectral area for the nonmagnetic component due to the smaller crystallite size. Meanwhile, the 77 K-Moessbauer spectrum suggests the absence of the electron localization effect above 77 K.« less

Characterization of the carbonaceous materials obtained from different agro-industrial wastes.

PubMed

Ensuncho-Muñoz, A E; Carriazo, J G

2015-01-01

This paper reports the preparation and characterization of carbonaceous materials obtained from three types of vegetable wastes provided by agricultural industries. Soft carbonization (280°C) and H3PO4-activation procedures were used to convert the agricultural wastes to carbon powders with high adsorbent capacities. This process is excellent for eliminating and exploiting the huge masses (many tons) of vegetable residues remaining after each harvest every year in several Colombian agro-industries. The powders were characterized by X-ray diffraction (XRD), IR spectroscopy, scanning electron microscopy (SEM), and N2-adsorption isotherms. XRD and IR verified the formation of carbons, and SEM showed small particles (20-500 µm) with characteristic morphology for each type of residue used and abundant cavities of different sizes. The N2-adsorption analyses showed that the carbons had high adsorption capacities with important surface area values and large pore volumes. The use of the activated carbonaceous materials as adsorbent of azo dyes (allura red and sunset yellow) from aqueous solutions was evaluated. The results showed a good adsorption capacity indicating the potentiality of these materials as pollutant adsorbents in food industry wastewaters. These results indicate that these powders can be used as potential adsorbents for different gaseous or liquid pollutants.

Role of different chelating agent in synthesis of copper doped tin oxide (Cu-SnO2) nanoparticles

NASA Astrophysics Data System (ADS)

Saravanakumar, B.; Anusiya, A.; Rani, B. Jansi; Ravi, G.; Yuvakkumar, R.

2018-05-01

An attempt was made to synthesis the copper doped tin oxide (Cu-SnO2) nanoparticles by adopting different chelating agents (NaOH, KOH and C2H2O4) by Sol-gel process. The synthesized products were characterized by XRD, Photoluminescence (PL), Infra- Red (FTIR) and SEM analysis. The XRD confirms the formation of Cu-SnO2 shows the maximum peak at 33.8° with lattice plane (101). The PL peak at 361 and 382 nm due to the recombination of electron in conduction band to valence band infers the optical properties. The IR spectra correspond to the peak at 551 and 620 cm-1 attributed to the characteristics peak for Cu-SnO2 nanoparticles. The SEM images for all three Cu-SnO2 nanoparticles formed by three chelating agent (NaOH, KOH and C2H2O4) facilitates the formation mechanism and the chelating agent Oxalic acid results in formation of nano flowers with diverse layers orientated in random direction. Further SEM studies reveal that, the Cu-SnO2 nanoparticles formed by oxalic acid could posses high surface area with large number layered structured enables the better electrochemical properties and its applications.

Synthesis of nanocrystalline zirconia by amorphous citrate route: structural and thermal (HTXRD) studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhagwat, Mahesh; Ramaswamy, Veda

Nanocrystalline zirconia powder with a fairly narrow particle size distribution has been synthesized by the amorphous citrate route. The sample obtained has a high BET surface area of 89 m{sup 2} g{sup -1}. Rietveld refinement of the powder X-ray diffraction (XRD) profile of the zirconia sample confirms stabilization of zirconia in the tetragonal phase with around 8% monoclinic impurity. The data show the presence of both anionic as well as cationic vacancies in the lattice. Crystallite size determined from XRD is 8 nm and is in close agreement with the particle size determined by TEM. The in situ high temperature-X-raymore » diffraction (HTXRD) study revealed high thermal stability of the mixture till around 1023 K after which the transformation of tetragonal phase into the monoclinic phase has been seen as a function of temperature till 1473 K. This transformation is accompanied by an increase in the crystallite size of the sample from 8 to 55 nm. The thermal expansion coefficients are 9.14 x 10{sup -6} K{sup -1} along 'a'- and 15.8 x 10{sup -6} K{sup -1} along 'c'-axis. The lattice thermal expansion coefficient in the temperature range 298-1623 K is 34.6 x 10{sup -6} K{sup -1}.« less

Interface morphology of a Cr(001)/Fe(001) superlattice determined by scanning tunneling microscopy and x-ray diffraction: A comparison

NASA Astrophysics Data System (ADS)

Schmidt, C. M.; Bürgler, D. E.; Schaller, D. M.; Meisinger, F.; Güntherodt, H.-J.; Temst, K.

2001-01-01

A Cr(001)/Fe(001) superlattice with ten bilayers grown by molecular beam epitaxy on a Ag(001) substrate is studied by in situ scanning tunneling microscopy (STM) and ex situ x-ray diffraction (XRD). Layer-resolved roughness parameters determined from STM images taken in various stages of the superlattice fabrication are compared with average values reported in the literature or obtained from the fits of our XRD data. Good agreement is found for the rms roughnesses describing vertical roughness and for the lateral correlation lengths characterizing correlated as well as uncorrelated interface roughness if peculiarities of STM and XRD are taken into account. We discuss in detail (i) the possible differences between the STM topography of a free surface and the morphology of a subsequently formed interface, (ii) contributions due to chemical intermixing at the interfaces, (iii) the comparison of XRD parameters averaged over all interfaces versus layer-resolved STM parameters, and (iv) the question of the coherent field of view for the determination of rms values.

Influence of smectite suspension structure on sheet orientation in dry sediments: XRD and AFM applications.

PubMed

Zbik, Marek S; Frost, Ray L

2010-06-15

The structure-building phenomena within clay aggregates are governed by forces acting between clay particles. Measurements of such forces are important to understand in order to manipulate the aggregate structure for applications such as dewatering of mineral processing tailings. A parallel particle orientation is required when conducting XRD investigation on the oriented samples and conduct force measurements acting between basal planes of clay mineral platelets using atomic force microscopy (AFM). To investigate how smectite clay platelets were oriented on silicon wafer substrate when dried from suspension range of methods like SEM, XRD and AFM were employed. From these investigations, we conclude that high clay concentrations and larger particle diameters (up to 5 microm) in suspension result in random orientation of platelets in the substrate. The best possible laminar orientation in the clay dry film, represented in the XRD 001/020 intensity ratio of 47 was obtained by drying thin layers from 0.02 wt.% clay suspensions of the natural pH. Conducted AFM investigations show that smectite studied in water based electrolytes show very long-range repulsive forces lower in strength than electrostatic forces from double-layer repulsion. It was suggested that these forces may have structural nature. Smectite surface layers rehydrate in water environment forms surface gel with spongy and cellular texture which cushion approaching AFM probe. This structural effect can be measured in distances larger than 1000 nm from substrate surface and when probe penetrate this gel layer, structural linkages are forming between substrate and clay covered probe. These linkages prevent subsequently smooth detachments of AFM probe on way back when retrieval. This effect of tearing new formed structure apart involves larger adhesion-like forces measured in retrieval. It is also suggested that these effect may be enhanced by the nano-clay particles interaction. 2010 Elsevier Inc. All rights reserved.

Functional electrospun membranes

NASA Astrophysics Data System (ADS)

Ognibene, G.; Fragalà, M. E.; Cristaldi, D. A.; Blanco, I.; Cicala, G.

2016-05-01

In this study we combined electrospun PES nanofibers with ZnO nanostructures in order to obtain a hierarchical nanostructured hybrid material to be use for active water filtration membranes. It benefits of flexibility and high surface area of the polymeric nanofibers as well as of additional functionalities of ZnOnanostructures. First, randomly oriented nanofibers with diameters of 716nm ±365 nm were electrospun on a glass fibers substrate from a solution of PES and DMF-TOL(1:1). ZnO nanorods were grown onto the surface of electrospun PES fibers by a Chemical Bath Deposition (CBD) process. It was preceed by a seeding process necessary to form nucleation sites for the subsequent radially aligned growth of ZnO nanowires. The morfology of the fibers and the effect of the seeding time have been analysed by SEM. The amount of ZnO nanowires grown over electrospun nanofibers was determined as 45% by weight. The high purity and crystallinity of the asobtained products are confirmed by XRD since all reflection peaks can be indexed to hexagonal wurtzite ZnO.

A simple and low temperature process for super-hydrophilic rutile TiO 2 thin films growth

NASA Astrophysics Data System (ADS)

Mane, R. S.; Joo, Oh-Shim; Min, Sun-Ki; Lokhande, C. D.; Han, Sung-Hwan

2006-11-01

We investigate an environmentally friendly aqueous solution system for rutile TiO2 violet color nanocrystalline thin films growth on ITO substrate at room temperature. Film shows considerable absorption in visible region with excitonic maxima at 434 nm. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), UV-vis, water surface contact angle and energy dispersive X-ray analysis (EDX) techniques in addition to actual photo-image that shows purely rutile phase of TiO2 with violet color, super-hydrophilic and densely packed nanometer-sized spherical grains of approximate diameter 3.15 ± 0.4 nm, characterize the films. Band gap energy of 4.61 eV for direct transition was obtained for the rutile TiO2 films. Film surface shows super-hydrophilic behavior, as exhibited water contact angle was 7°. Strong visible absorption (not due to chlorine) leaves future challenge to use these films in extremely thin absorber (ETA) solar cells.

Silicon carbide ceramic membranes

NASA Astrophysics Data System (ADS)

Suwanmethanond, Varaporn

This dissertation focuses on the preparation of silicon carbide (SiC) ceramic membranes on SiC substrates. An original technique of SiC porous substrate preparation using sintering methods was developed during the work for the completion of the dissertation. The resulting SiC substrates have demonstrated high porosity, high internal surface area, well interconnected surface pore network and, at the same time, good thermal, chemical and mechanical stability. In a further development, sol-gel techniques were used to deposit micro-porous SiC membranes on these SiC porous substrates. The SiC membranes were characterized by a variety of techniques: ideal gas selectivity (He and N2), XRD, BET, SEM, XPS, and AFM. The characterization results confirmed that the asymmetric sol-gel SiC membranes were of high quality, with no cracks or pinholes, and exhibiting high resistance to corrosion and high hydro-thermal stability. In conclusion, the SiC ceramic membrane work was successfully completed. Two publications in international peer reviewed journals resulted out of this work.

Optimization of Fe2+ Removal from Coal Mine Wastewater using Activated Biochar of Colocasia esculenta.

PubMed

Banerjee, Soumya; LaminKa-Ot, Augustine; Joshi, S R; Mandal, Tamal; Halder, Gopinath

2017-09-01

  The present study investigates the sorptive removal of Fe2+ from simulated coal mine waste water using steam activated biochar (SABC) developed from the roots of Colocasia esculenta. The process was optimized by response surface methodology (RSM) under the influence of pH, temperature, adsorbent dosage and contact time at a constant shaking speed of 180 rpm with an initial concentration of 3 mg/L. The uptake performance of the biosorbent was assessed following a 24 full factorial experimental matrix developed by central composite design approach. Adsorbent was characterised by SEM, EDAX, XRD and B.E.T surface area analyzer. Maximum removal of 72.96% of Fe2+ was observed at pH 7.75, temperature 37.5 °C, adsorbent dosage 1.5 g/L for a time period of 180 mins. The study suggested that SABC prepared from roots of Colocasia esculenta could be used as an efficient and cost effective sorbent for removal of Fe2+ from coal mine wastewater.

Native defects in silver orthophosphate and their effects on photocatalytic activity under visible light irradiation

NASA Astrophysics Data System (ADS)

Sulaeman, Uyi; Hermawan, Dadan; Andreas, Roy; Abdullah, Ahmad Zuhairi; Yin, Shu

2018-01-01

Native defects in silver orthophosphate could be generated by simple co-precipitation method under ethanol-aqueous solution using AgNO3 and Na2HPO4.12H2O. AgNO3 ethanol-aqueous solution with the ethanol contents of 0%, 25%, 50%, 75%, 90% and 100% was reacted with Na2HPO4 aqueous solution. The produced catalysts were characterized using XRD, DRS, FE-SEM, BET specific surface area and XPS. The increase of ethanol content in the synthesis process decreased the Ag/P atomic ratio of Ag3PO4. The native defects of silver vacancy might be generated on the surface of Ag3PO4. The activity of Ag3PO4 for Rhodamine B degradation dramatically increased by 5.8 times higher compared to that of the pristine Ag3PO4. The defect states of Ag vacancies enhanced the separation of electron-hole pairs, leading to the improvement of photocatalytic activity.

Sol-gel synthesis and adsorption properties of mesoporous manganese oxide

NASA Astrophysics Data System (ADS)

Ivanets, A. I.; Kuznetsova, T. F.; Prozorovich, V. G.

2015-03-01

Sol-gel synthesis of mesoporous xerogels of manganese oxide with different phase compositions has been performed. The manganese oxide sols were obtained by redox reactions of potassium permanganate with hydrogen peroxide or manganese(II) chloride in aqueous solutions. The isotherms of the low-temperature adsorption-desorption of nitrogen with manganese oxide xerogels treated at 80, 200, 400, and 600°C were measured. The samples were studied by electron microscopy and thermal and XRD analysis. The phase transformation and the changes in the adsorption and capillary-condensation properties of manganese oxide were shown to depend on the sol synthesis conditions and the temperature of the thermal treatment of the gel. The X-ray amorphous samples heated at 80°C were shown to have low values of the specific surface; at higher temperatures, the xerogel crystallized into mixed phases with various compositions and its surface area increased at 200-400°C and decreased at 600°C.

Enhanced photocatalytic activity of Fe-doped TiO2 coated on N-doped activated carbon composites for photocatalytic degradation of dyeing wastewater

NASA Astrophysics Data System (ADS)

Zhou, Jie; Zhu, Beibei; Wang, Lu; Li, Ya; Qiao, Qichen

2017-10-01

Fe-doped TiO2 coated on N-doped activated carbon (Fe-TiO2/N-AC, FTNA) composites were synthesized simply by a straightforward two-step procedure. The obtained materials were characterized by X-ray diffractometry (XRD), N2 adsorption-desorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopies. Through the degradation of dyeing wastewater, the photocatalytic activity of FTNA was investigated under ultraviolet light irradiation. The results showed that containing N functional groups were successfully introduced onto the surface of the activated carbon. Compared with Fe-TiO2/AC (FTA), FTNA with average particle size of TiO2 13.6 nm and surface area 1007.89 m2/g showed a higher photoactivity. Additionally, for the photocatalytic degradation of dyeing wastewater, the optimum N content and catalyst content were 0.8% and 5g/L, respectively. Moreover, the photoactivity and photo stability of the catalyst after many runs was also evaluated.

Humidity sensing behavior of tin-loaded 3-D cubic mesoporous silica

NASA Astrophysics Data System (ADS)

Poonia, Ekta; Dahiya, Manjeet S.; Tomer, Vijay K.; Kumar, Krishan; Kumar, Sunil; Duhan, Surender

2018-07-01

The present scientific investigation deals with template synthesis of 3D-cubic mesoporous KIT-6 with in-situ loading of SnO2 to obtain a material with enhanced number of surface active sites. The structural insights have been reported through analysis of XRD, TEM, FESEM, N2 sorption and mid-IR absorption data. X-ray diffraction confirmed 3D-cubic mesoporous structure of silica with Ia 3 bar d symmetry and existence of anatase SnO2 species. A decrease in surface area on loading of SnO2 nanoparticles is revealed via analysis of N2 adsorption-desorption isotherms. Rapid response time of 15 s and super rapid recovery time of 2 s (with response > 100) have been exhibited by sensor based on sample containing 1 wt% of SnO2. Further investigation on sensing performance of nanocomposite with 1 wt% of SnO2 confirmed its ohmic behavior (with negligible V-I hysteresis), excellent cycle stability, outstanding long term stability and very low hysteresis (1.4% at 53% RH).

Preparation and catalytic activities of LaFeO3 and Fe2O3 for HMX thermal decomposition.

PubMed

Wei, Zhi-Xian; Xu, Yan-Qing; Liu, Hai-Yan; Hu, Chang-Wen

2009-06-15

Perovskite-type LaFeO(3) and alpha-Fe(2)O(3) with high specific surface areas were directly prepared with appropriate stearic acid-nitrates ratios by a novel stearic acid solution combustion method. The obtained powders were characterized by XRD, FT-IR and XPS techniques. The catalytic activities of perovskite-type LaFeO(3) and alpha-Fe(2)O(3) for the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were investigated by TG and TG-EGA techniques. The experimental results show that the catalytic activity of perovskite-type LaFeO(3) was much higher than that of alpha-Fe(2)O(3) because of higher concentration of surface-adsorbed oxygen (O(ad)) and hydroxyl of LaFeO(3). The study points out a potential way to develop new and more active perovskite-type catalysts for the HMX thermal decomposition.

Ga[OSi(O(t)Bu)3]3·THF, a thermolytic molecular precursor for high surface area gallium-containing silica materials of controlled dispersion and stoichiometry.

PubMed

Dombrowski, James P; Johnson, Gregory R; Bell, Alexis T; Tilley, T Don

2016-07-05

The molecular precursor tris[(tri-tert-butoxy)siloxy]gallium, as the tetrahydrofuran adduct Ga[OSi(O(t)Bu)3]3·THF (), was synthesized via the salt metathesis reaction of gallium trichloride with NaOSi(O(t)Bu)3. This complex serves as a model for isolated gallium in a silica framework. Complex decomposes thermally in hydrocarbon solvent, eliminating isobutylene, water, and tert-butanol to generate high surface area gallium-containing silica at low temperatures. When thermal decomposition was performed in the presence of P-123 Pluronic as a templating agent the generated material displayed uniform vermicular pores. Textural mesoporosity was evident in untemplated material. Co-thermolysis of with HOSi(O(t)Bu)3 in the presence of P-123 Pluronic led to materials with Ga : Si ratios ranging from 1 : 3 to 1 : 50, denoted UCB1-GaSi3, UCB1-GaSi10, UCB1-GaSi20 and UCB1-GaSi50. After calcination at 500 °C these materials exhibited decreasing surface areas and broadening pore distributions with increasing silicon content, indicating a loss of template effects. The position and dispersion of the gallium in UCB1-GaSi materials was investigated using (71)Ga MAS-NMR, powder XRD, and STEM/EDS elemental mapping. The results indicate a high degree of gallium dispersion in all samples, with gallium oxide clusters or oligomers present at higher gallium content.

Insitu grown superhydrophobic Zn-Al layered double hydroxides films on magnesium alloy to improve corrosion properties

NASA Astrophysics Data System (ADS)

Zhou, Meng; Pang, Xiaolu; Wei, Liang; Gao, Kewei

2015-05-01

A hierarchical superhydrophobic zinc-aluminum layered double hydroxides (Zn-Al LDHs) film has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method following chemical modification. The characteristics of the films were investigated by X-ray diffraction (XRD), scanning electronic microscope (SEM), and energy dispersive spectroscopy (EDS). XRD patterns and SEM images showed that the micro/nanoscale hierarchical LDHs film surfaces composed of ZnO nanorods and Zn-Al LDHs nanowalls structures. The static contact angle (CA) for the prepared surfaces was observed at around 165.6°. The corrosion resistance of the superhydrophobic films was estimated by electrochemical impedance spectroscopy (EIS) and potentiondynamic polarization measurement. EIS and polarization measurements revealed that the superhydrophobic Zn-Al LDHs coated magnesium alloy had better corrosion resistance in neutral 3.5 wt.% NaCl solution.

Optimization Study of Pulsed DC Nitrogen-Hydrogen Plasma in the Presence of an Active Screen Cage

NASA Astrophysics Data System (ADS)

Saeed, A.; W. Khan, A.; F., Jan; U. Shah, H.; Abrar, M.; Zaka-Ul-Islam, M.; Khalid, M.; Zakaullah, M.

2014-05-01

A glow discharge plasma nitriding reactor in the presence of an active screen cage is optimized in terms of current density, filling pressure and hydrogen concentrations using optical emission spectroscopy (OES). The samples of AISI 304 are nitrided for different treatment times under optimum conditions. The treated samples were analyzed by X-ray diffraction (XRD) to explore the changes induced in the crystallographic structure. The XRD pattern confirmed the formation of iron and chromium nitrides arising from incorporation of nitrogen as an interstitial solid solution in the iron lattice. A Vickers microhardness tester was used to evaluate the surface hardness as a function of treatment time (h). The results showed clear evidence of improved surface hardness and a substantial amount of decrease in the treatment time compared with the previous work.

Simple sol-gel process to obtain silica-coated anatase particles with enhanced TiO2-SiO2 interfacial area.

PubMed

Resende, S F; Nunes, E H M; Houmard, M; Vasconcelos, W L

2014-11-01

In this study we prepared silica-titania composites with a low SiO2:TiO2 molar ratio. These materials were prepared using a simple sol-gel route in which a hydrothermal treatment was used to obtain mesoporous anatase particles. Pure titania was also synthetized for comparison purposes. These materials were examined by scanning and transmission electron microscopy (SEM and TEM, respectively), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and nitrogen sorption tests. A thin silica coating was formed on the anatase particles. It was observed that the presence of this coating led to samples with an enhanced thermal stability. Indeed, the composites prepared in this work showed an anatase structure and a high specific surface area (SSA), even after their calcination at 800°C. Thus, we believe that the synthetized material present an outstanding SiO2-TiO2 interfacial area associated with a high amount of anatase particles which could improve its photoactive properties. Copyright © 2014 Elsevier Inc. All rights reserved.

CTAB-assisted ultrasonic synthesis, characterization and photocatalytic properties of WO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sánchez-Martínez, D., E-mail: dansanm@gmail.com; Gomez-Solis, C.; Torres-Martinez, Leticia M.

2015-01-15

Highlights: • WO{sub 3} 2D nanostructures were synthesized by ultrasound method assisted with CTAB. • WO{sub 3} morphology was mainly of rectangular nanoplates with a thickness of ∼50 nm. • The highest surface area value of WO{sub 3} was obtained to lowest concentration of CTAB. • WO{sub 3} activity was attributed to morphology, surface area and the addition of CTAB. • WO{sub 3} nanoplates were able to causing almost complete mineralization of rhB and IC. - Abstract: WO{sub 3} 2D nanostructures have been prepared by ultrasound synthesis method assisted with CTAB using different molar ratios. The formation of monoclinic crystalmore » structure of WO{sub 3} was confirmed by X-ray powder diffraction (XRD). The characterization of the WO{sub 3} samples was complemented by analysis of scanning electron microscopy (SEM), which revealed morphology mainly of rectangular nanoplates with a thickness of around 50 nm and length of 100–500 nm. Infrared spectroscopy (FT-IR) was used to confirm the elimination of the CTAB in the synthesized samples. The specific surface area was determinate by the BET method and by means of diffuse reflectance spectroscopy (DRS) it was determinate the band-gap energy (E{sub g}) of the WO{sub 3} samples. The photocatalytic activity of the WO{sub 3} oxide was evaluated in the degradation reactions of rhodamine B (rhB) and indigo carmine (IC) under Xenon lamp irradiation. The highest photocatalytic activity was observed in the samples containing low concentration of CTAB with morphology of rectangular nanoplates and with higher surface area value than commercial WO{sub 3}. Photodegradation of rhB and IC were followed by means of UV–vis absorption spectra. The mineralization degree of organic dyes by WO{sub 3} photocatalyst was determined by total organic carbon analysis (TOC) reaching percentages of mineralization of 92% for rhB and 50% for IC after 96 h of lamp irradiation.« less

Effect of chromium substitution on the dielectric properties of mixed Ni-Zn ferrite prepared by WOWS sol–gel technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashtar, M.; Munir, A.; Anis-ur-Rehman, M.

2016-07-15

Graphical abstract: Variation of AC conductivity (σ{sub AC}) as a function of natural log of angular frequency (lnω) for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2-x}Cr{sub x}O{sub 4} nanoferrites at room temperature. - Highlights: • Cr doped mixed Ni-Zn ferrites were successfully synthesized by a newly developed WOWS sol gel technique. • The specific surface area and specific surface area to volume ratio increased with decrease in particle size. • The resonance peaks appeared in dielectric loss graphs, shifting towards low frequency with the increase in Cr concentration. • The prepared samples have the lowest values of the dielectric constant. • The dielectricmore » constant were observed to be inversely proportional to square root of the AC resistivity. - Abstract: Cr{sup +3} doped Ni-Zn nanoferrite samples with composition Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2-x}Cr{sub x}O{sub 4}(x = 0.1, 0.2, 0.3, 0.4) were synthesized With Out Water and Surfactant (WOWS) sol-gel technique. The structural, morphological and dielectric properties of the samples were investigated. The lattice constant, crystallite size, theoretical density and porosity of each sample were obtained from X-ray diffraction (XRD) data. The specific surface area and specific surface area to volume ratio increased with the decrease in the size of Cr{sup +3} doped Ni-Zn ferrite nanoparticles, as the concentration of Cr{sup +3} increased. The SEM analysis revealed that the particles were of nano size and of spherical shape. The dielectric parameters such as dielectric constant (ε′) and dielectric loss (tanδ) of all the samples as a function of frequency at room temperature were measured. The AC conductivity (σ{sub AC}) was determined from the dielectric parameters, which showed increasing trend with the rise in frequency.« less

Characterization of a Diamond Ground Y-TZP and Reversion of the Tetragonal to Monoclinic Transformation.

PubMed

Candido, L M; Fais, Lmg; Ferreira, E B; Antonio, S G; Pinelli, Lap

To characterize the surface of an yttria-stabilized zirconia (Y-TZP) ceramic after diamond grinding in terms of its crystalline phase, morphology, mean roughness (Ra), and wettability as well as to determine a thermal treatment to reverse the resulting tetragonal to monoclinic (t-m) transformation. Y-TZP specimens were distributed into different groups according to the actions (or no action) of grinding and irrigation. Grinding was accomplished using a diamond stone at a low speed. The samples were characterized by x-ray diffraction (XRD), scanning electron microscopy, goniometry, and profilometry. In situ high-temperature XRD was used to determine an annealing temperature to reverse the t-m transformation. Ra was submitted to the Kruskal-Wallis test, followed by the Dunn test (α=0.05). The volume fraction of the monoclinic phase and contact angle were submitted to one-way analysis of variance, followed by the Tukey test (α=0.05). Monoclinic zirconia was observed on the surface of samples after dry and wet grinding with a diamond stone. The volume fraction of the monoclinic phase was smaller on the dry ground samples (3.6%±0.3%) than on the wet ground samples (5.6%±0.3%). High-temperature XRD showed reversion of the t-m phase transformation, which started at 700°C and completed at 800°C in a conventional oven. Grinding with a diamond stone partially transformed the crystalline phase on the surface of a Y-TZP ceramic from tetragonal to monoclinic zirconia while simultaneously increasing the surface roughness and wettability. The t-m transformation could be reversed by heat treatment at 800°C or 900°C for 60 minutes or 1000°C for 30 minutes.

Nano-graphene oxide carboxylation for efficient bioconjugation applications: a quantitative optimization approach

NASA Astrophysics Data System (ADS)

Imani, Rana; Emami, Shahriar Hojjati; Faghihi, Shahab

2015-02-01

A method for carboxylation of graphene oxide (GO) with chloroacetic acid that precisely optimizes and controls the efficacy of the process for bioconjugation applications is proposed. Quantification of COOH groups on nano-graphene oxide sheets (NGOS) is performed by novel colorimetric methylene blue (MB) assay. The GO is synthesized and carboxylated by chloroacetic acid treatment under strong basic condition. The size and morphology of the as-prepared NGOS are characterized by scanning electron microscopy, transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effect of acid to base molar ratio on the physical, chemical, and morphological properties of NGOS is analyzed by Fourier-transformed infrared spectrometry (FTIR), UV-Vis spectroscopy, X-ray diffraction (XRD), AFM, and zeta potential. For evaluation of bioconjugation efficacy, the synthesized nano-carriers with different carboxylation ratios are functionalized by octaarginine peptide sequence (R8) as a biomolecule model containing amine groups. The quantification of attached R8 peptides to graphene nano-sheets' surface is performed with a colorimetric-based assay which includes the application of 2,4,6-Trinitrobenzene sulfonic acid (TNBS). The results show that the thickness and lateral size of nano-sheets are dramatically decreased to 0.8 nm and 50-100 nm after carboxylation process, respectively. X-ray analysis shows the nano-sheets interlaying space is affected by the alteration of chloroacetic acid to base ratio. The MB assay reveals that the COOH groups on the surface of NGOS are maximized at the acid to base ratio of 2 which is confirmed by FTIR, XRD, and zeta potential. The TNBS assay also shows that bioconjugation of the optimized carboxylated NGOS sample with octaarginine peptide is 2.5 times more efficient compared to bare NGOS. The present work provides evidence that treatment of GO by chloroacetic acid under an optimized condition would create a functionalized high surface area nano-substrate which can be used for subsequent efficient bioconjugation applications.

The structure and transformation of the nanomineral schwertmannite: a synthetic analog representative of field samples

NASA Astrophysics Data System (ADS)

French, Rebecca A.; Monsegue, Niven; Murayama, Mitsuhiro; Hochella, Michael F.

2014-04-01

The phase transformation of schwertmannite, an iron oxyhydroxide sulfate nanomineral synthesized at room temperature and at 75 °C using H2O2 to drive the precipitation of schwertmannite from ferrous sulfate (Regenspurg et al. in Geochim Cosmochim Acta 68:1185-1197, 2004), was studied using high-resolution transmission electron microscopy. The results of this study suggest that schwertmannite synthesized using this method should not be described as a single phase with a repeating unit cell, but as a polyphasic nanomineral with crystalline areas spanning less than a few nanometers in diameter, within a characteristic `pin-cushion'-like amorphous matrix. The difference in synthesis temperature affected the density of the needles on the schwertmannite surface. The needles on the higher-temperature schwertmannite displayed a dendritic morphology, whereas the needles on the room-temperature schwertmannite were more closely packed. Visible lattice fringes in the schwertmannite samples are consistent with the powder X-ray diffraction (XRD) pattern taken on the bulk schwertmannite and also matched d-spacings for goethite, indicating a close structural relationship between schwertmannite and goethite. The incomplete transformation from schwertmannite to goethite over 24 h at 75 °C was tracked using XRD and TEM. TEM images suggest that the sample collected after 24 h consists of aggregates of goethite nanocrystals. Comparing the synthetic schwertmannite in this study to a study on schwertmannite produced at 85 °C, which used ferric sulfate, reveals that synthesis conditions can result in significant differences in needle crystal structure. The bulk powder XRD patterns for the schwertmannite produced using these two samples were indistinguishable from one another. Future studies using synthetic schwertmannite should account for these differences when determining schwertmannite's structure, reactivity, and capacity to take up elements like arsenic. The schwertmannite synthesized by the Regenspurg et al. method produces a mineral that is consistent with the structure and morphology of natural schwertmannite observed in our previous study using XRD and TEM, making this an ideal synthetic method for laboratory-based mineralogical and geochemical studies that intend to be environmentally relevant.

Thermal effects on domain orientation of tetragonal piezoelectrics

NASA Astrophysics Data System (ADS)

Chang, Wonyoung

Thermal effects on electrical poling or mechanical grinding induced texture in tetragonal lead zirconate titanate (PZT) and lead titanate (PT) have been investigated using ex situ and in situ X-ray diffraction (XRD) with an area detector. According to previous results using ex situ XRD, domain configurations of poled samples after heat-treatment at or higher than the Curie temperature (TC) are similar to that of unpoled samples showing random domain distributions. The texture parameter called multiples of a random distribution (MRD) gradually decreases with increasing depoling temperature. On the other hand, using in situ XRD measurements, it was found that the MRD maximum for soft PZT initially increases with temperature up to approximately 100°C and then falls to unity at temperatures approaching the TC, whereas the MRD of hard PZT and PT initially undergoes a smaller increase or no change. Mechanical strain energy has an apparent effect on domain wall mobility. In contrast with previous results on electrical poling, mechanically-ground PT and soft PZT materials retained strong ferroelastic textures during thermal cycling, even after excursions to temperatures slightly above the TC . For the ground PT, it was found that repeated cycling above T C results in changes in both peak intensity and peak position, whereas the ground soft PZT undergoes the decrease in intensity of the (002) reflection after the first cycle of heating. Residual stresses in the surface region from grinding resulted in domain wall motion and the retention of textures in annealed samples. The research in this thesis demonstrates that the magnitude of loading applied to the sample surface, the speed used for grinding, or the grit size, can greatly affect the grinding induced damage zone and the depoling behavior of piezoelectric ceramics. Among the possible effects of grinding conditions on surface textures, one of particular interest is the effect of mechanical stresses produced during grinding on the texture intensity in the ground surface region. Inhibited depoling of ground PT materials under different loading conditions investigated by in situ texture measurements between room temperature and approximately 100°C above the Curie temperature demonstrates the effects of residual stresses. For all the ground PT and soft PZT samples, there was little or no evidence of time dependence for domain reorientation at the whole annealing temperature range. In addition, both ground PT and soft PZT materials under lower loading conditions showed a gradual depoling behavior with increasing heat treatment temperature, whereas ground materials under higher loading conditions retained relatively strong ferroelastic texture up to temperatures around their respective TC, and then underwent a drastic change in MRD at temperatures above TC. Compared to the ground soft PZT materials, all the ground PT samples still maintained high MRD values after heat treatment above TC.

Lidar-based fracture characterization: An outcrop-scale study of the Woodford Shale, McAlister Shale Pit, Oklahoma

NASA Astrophysics Data System (ADS)

Hanzel, Jason

The use of lidar (light detection and ranging), a remote sensing tool based on principles of laser optometry, in mapping complex, multi-scale fracture networks had not been rigorously tested prior to this study despite its foreseeable utility in interpreting rock fabric with imprints of complex tectonic evolution. This thesis demonstrates lidar-based characterization of the Woodford Shale where intense fracturing could be due to both tectonism and mineralogy. The study area is the McAlister Shale Pit in south-central Oklahoma where both the upper and middle sections of the Woodford Shale are exposed and can be lidar-mapped. Lidar results are validated using hand-measured strike and dips of fracture planes, thin sections and mineral chemistry of selected samples using X-ray diffraction (XRD). Complexity of the fracture patterns as well as inaccessibility of multiple locations within the shale pit makes hand-measurement prone to errors and biases; lidar provides an opportunity for less biased and more efficient field mapping. Fracture mapping with lidar is a multi-step process. The lidar data are converted from point clouds into a mesh through triangulation. User-defined parameters such as size and orientation of the individual triangular elements are then used to group similar elements into surfaces. The strike and dip attribute of the simulated surfaces are visualized in an equal area lower hemisphere projection stereonet. Three fracture sets were identified in the upper and middle sections with common orientation but substantially different spatial density. Measured surface attributes and spatial density relations from lidar were validated using their hand-measured counterparts. Thin section analysis suggests that high fracture density in the upper Woodford measured by both the lidar and the hand-measured data could be due to high quartz. A significant finding of this study is the reciprocal relation between lidar intensity and gamma-ray (GR), which is generally used to infer outcrop mineralogy. XRD analysis of representative samples along the common profiles show that both GR and lidar intensity were influenced by the same minerals in essentially opposite ways. Results strongly suggest that the lidar cannot only remotely map the geomorphology, but also the relative mineralogical variations to the first order of approximation.

Performance analysis of flexible DSSC with binder addition

NASA Astrophysics Data System (ADS)

Muliani, Lia; Hidayat, Jojo; Anggraini, Putri Nur

2016-04-01

Flexible DSSC is one of modification of DSSC based on its substrate. Operating at low temperature, flexible DSSC requires a binder to improve particles interconnection. This research was done to compare the morphology and performance of flexible DSSC that was produced with binder-added and binder-free. TiO2 powder, butanol, and HCl were mixed for preparation of TiO2 paste. Small amount of titanium isopropoxide as binder was added into the mixture. TiO2 paste was deposited on ITO-PET plastic substrate with area of 1x1 cm2 by doctor blade method. Furthermore, SEM, XRD, and BET characterization were done to analyze morphology and surface area of the TiO2 photoelectrode microstructures. Dyed TiO2 photoelectrode and platinum counter electrode were assembled and injected by electrolyte. In the last process, flexible DSSCs were illuminated by sun simulator to do J-V measurement. As a result, flexible DSSC containing binder showed higher performance with photoconversion efficiency of 0.31%.

Effect of substrate temperature in the synthesis of BN nanostructures

NASA Astrophysics Data System (ADS)

Sajjad, M.; Zhang, H. X.; Peng, X. Y.; Feng, P. X.

2011-06-01

Boron nitride (BN) nanostructures were grown on molybdenum discs at different substrate temperatures using the short-pulse laser plasma deposition technique. Large numbers of randomly oriented nanorods of fiber-like structures were obtained. The variation in the length and diameter of the nanorods as a function of the substrate temperature was systematically studied. The surface morphologies of the samples were studied using scanning electron microscopy. Energy dispersive x-ray spectroscopy confirmed that both the elements boron and nitrogen are dominant in the nanostructure. The x-ray diffraction (XRD) technique was used to analyse BN phases. The XRD peak that appeared at 26° showed the presence of hexagonal BN phase, whereas the peak at 44° was related to cubic BN content in the samples. Raman spectroscopic analysis showed vibrational modes of sp2- and sp3-type bonding in the sample. The Raman spectra agreed well with XRD results.

Structural and optical properties of CdSe nanosheets

NASA Astrophysics Data System (ADS)

Solanki, Rekha Garg; Rajaram, P.; Arora, Aman

2018-04-01

Nanosheets of CdSe have been synthesized using a solvothermal route using citric acid as an additive. It is found that the citric acid effectively controls the structural and optical properties of CdSe nanostructures. XRD studies confirm the formation of hexagonal wurtzite phase of CdSe. The FESEM micrographs show that the obtained CdSe nanocrystals are in the form of very thin sheets (nanosheets). Optical absorption studies as well as Photoluminescence spectra show that the optical gap is around 1.76 eV which is close to the reported bulk value of 1.74 eV. The prepared CdSe nanosheets because of large surface area may be useful for catalytic activities in medicine, biotechnology and environmental chemistry and in biomedical imaging for in vitro detection of a breast cancer cells.

Gd-DTPA Adsorption on Chitosan/Magnetite Nanocomposites

NASA Astrophysics Data System (ADS)

Pylypchuk, Ie. V.; Kołodyńska, D.; Kozioł, M.; Gorbyk, P. P.

2016-03-01

The synthesis of the chitosan/magnetite nanocomposites is presented. Composites were prepared by co-precipitation of iron(II) and iron(III) salts by aqueous ammonia in the 0.1 % chitosan solution. It was shown that magnetite synthesis in the chitosan medium does not affect the magnetite crystal structure. The thermal analysis data showed 4.6 % of mass concentration of chitosan in the hybrid chitosan/magnetite composite. In the concentration range of initial Gd-DTPA solution up to 0.4 mmol/L, addition of chitosan to magnetite increases the adsorption capacity and affinity to Gd-DTPA complex. The Langmuir and Freundlich adsorption models were applied to describe adsorption processes. Nanocomposites were characterized by scanning electron microscopy (SEM), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and specific surface area determination (ASAP) methods.

Iron oxide inside SBA-15 modified with amino groups as reusable adsorbent for highly efficient removal of glyphosate from water

NASA Astrophysics Data System (ADS)

Fiorilli, Sonia; Rivoira, Luca; Calì, Giada; Appendini, Marta; Bruzzoniti, Maria Concetta; Coïsson, Marco; Onida, Barbara

2017-07-01

Iron oxide clusters were incorporated into amino-functionalized SBA-15 in order to obtain a magnetically recoverable adsorbent. The physical-chemical properties of the material were characterized by FE-SEM, STEM, XRD, TGA, XPS, FT-IR and acid-base titration analysis. Iron oxide nanoparticles were uniformly dispersed into the pore of mesoporous silica and that the adsorbent is characterized high specific surface area (177 m2/g) and accessible porosity. The sorbent was successfully tested for the removal of glyphosate in real water matrices. Despite the significant content of inorganic ions, a quantitative removal of the contaminant was found. The complete regeneration of the sorbent after the adsorption process through diluted NaOH solution was also proved.

Electrochemical characterization of Pt-Ru-Pd catalysts for methanol oxidation reaction in direct methanol fuel cells.

PubMed

Choi, M; Han, C; Kim, I T; An, J C; Lee, J J; Lee, H K; Shim, J

2011-01-01

PtRuPd nanoparticles on carbon black were prepared and characterized as electrocatalysts for methanol oxidation reaction in direct methanol fuel cells. Nano-sized Pd (2-4 nm) particles were deposited on Pt/C and PtRu/C (commercial products) by a simple chemical reduction process. The structural and physical information of the PtRuPd/C were confirmed by TEM and XRD, and their electrocatalytic activities were measured by cyclic voltammetry and linear sweep voltammetry. The catalysts containing Pd showed higher electrocatalytic activity for methanol oxidation reaction than the other catalysts. This might be attributed to an increase in the electrochemical surface area of Pt, which is caused by the addition of Pd; this results in increased catalyst utilization.

Investigation on the Activity Activation and Cementitious Property of Coal Gangue with High Iron and Silica Contents

NASA Astrophysics Data System (ADS)

Wu, Hong; Li, Yu; Teng, Min; Yang, Yu

2017-11-01

The activity of coal gangue by thermal activation and composite activation technologies was investigated. The crystal composition, framework structure and morphology change were analyzed by XRD, FT-IR and SEM, respectively. The cementitious property of coal gangue was measured by strength test. The results showed that thermal activation decomposed kaolinite in coal gangue, and formed the metastable structure with a porous state, multiple internal broken bonds and large specific surface areas. Based on thermal activation, the added lime provided the alkaline environment, then this reduced the bond energy of reactant particles and the degree of crystallinity of quartz in coal gangue. The two activation methods could effectively improve the cementitious property of coal gangue based unburned bricks, and that the composite activation technology was superior performance.

Preparation of Self-assembly Mesoporous TiO2 Using Block Copolymer Pluronic PE6200 Template

NASA Astrophysics Data System (ADS)

Septina, W.; Yuliarto, B.; Nugraha

2008-03-01

In this research, nanocrystal mesoporous TiO2 powders were synthesized by sol-gel method, with TiCl4 as a precursor in methanol solution. Block copolymer Pluronic PE 6200 was used as pores template. It was found that from the XRD measurements, both at 400 °C and 450 °C calcination temperatures, resulted in nanocrystal TiO2 with anatase phase. Based on N2 adsorption characterization (BET method), TiO2 samples have surface area 108 m2/g and 88 m2/g for 400 °C and 450 °C calcination temperatures respectively. From Small-angle Neutron Scattering (SANS) patterns, it is investigated that TiO2 samples have mesoporous structure where the pore order degree depend on the calcination temperature.

Atmospheric pressure chemical vapor deposition: an alternative route to large-scale MoS2 and WS2 inorganic fullerene-like nanostructures and nanoflowers.

PubMed

Li, Xiao-Lin; Ge, Jian-Ping; Li, Ya-Dong

2004-11-19

Large-scale MoS2 and WS2 inorganic fullerene-like (IF) nanostructures (onionlike nanoparticles, nanotubes) and elegant three-dimensional nanoflowers (NF) have been selectively prepared through an atmospheric pressure chemical vapor deposition (APCVD) process with the reaction of chlorides and sulfur. The morphologies were controlled by adjusting the deposition position, the deposition temperature, and the flux of the carrier gas. All of the nanostructures have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). A reaction mechanism is proposed based on the experimental results. The surface area of MoS2 IF nanoparticles and the field-emission effect of as-prepared WS2 nanoflowers is reported.

An alternative method to remove PEO-PPO-PEO template in organic-inorganic mesoporous nanocomposites by sulfuric acid extraction

NASA Astrophysics Data System (ADS)

Zhuang, Xin; Qian, Xufang; Lv, Jiahui; Wan, Ying

2010-06-01

Sulfuric acid is used as an extraction agent to remove PEO-PPO-PEO templates in the organic-inorganic mesoporous nanocomposites from the triconstituent co-assembly which includes the low-polymerized phenolic resins, TEOS and triblock copolymer F127. The XRD and TEM results show well ordered mesostructure after extraction with sulfuric acid. As followed from the N 2 sorption isotherms the extracted composites possess high surface areas (332-367 m 2/g), large pore volumes (0.66-0.78 cm 3/g), and large pore sizes (about 10.7 nm). The FT-IR analysis reveals almost complete elimination of triblock copolymer F127, and the maintenance of organic groups. This method shows potentials in removing templates from nanocomposites containing functional moieties.

Synthesis and characterization of gold nanodogbones by the seeded mediated growth method

NASA Astrophysics Data System (ADS)

Huang, Chien-Jung; Chiu, Pin-Hsiang; Wang, Yeong-Her; Meen, Teen-Hang; Yang, Cheng-Fu

2007-10-01

Novel gold nanodogbones (GDBs) are successfully fabricated using a simple seeded mediated growth (SMG) method. The shapes of GDBs depend on the amount of added vitamin C solvent. The amount of vitamin C solvent was varied from 10 to 40 µl to investigate the influence of vitamin C solvent on the GDBs. It is found that the aspect ratios (R) of GDBs were in the range from 2.34 to 1.46, and the UV-vis absorption measurement revealed a pronounced blueshift on the longitudinal surface plasmon resonance (SPR) band from 713 to 676 nm. The GDBs were determined by x-ray diffraction (XRD) to be single-crystalline with a face-centered cubic (fcc) structure. The lattice constant calculated from this selected-area electron diffraction (SAED) pattern is 4.068 Å.

Purification of Tronoh Silica Sand via preliminary process of mechanical milling

NASA Astrophysics Data System (ADS)

H, Nazratulhuda; M, Othman

2016-02-01

The purification of Tronoh silica sand is an important step in expanding technical applications of this silica sand. However no research on purifying of Tronoh silica sand has been reported. This study is focused on ball milling technique as a preliminary technique for Tronoh silica sand purification. The objectives are to study the effect of ball milling to the purification of the silica sand and to analyze its characteristics after the ball milling process. The samples before and after milling process were analyzed by using XRF, XRD, SEM and TEM. Results showed that the purity of SiO2 was increased, the size of the particles has been reduced and the surface area has increased. The crystalline phases for the silica before and after 4 hour milling time were remained constant.

Porous carbons prepared by direct carbonization of MOFs for supercapacitors

NASA Astrophysics Data System (ADS)

Yan, Xinlong; Li, Xuejin; Yan, Zifeng; Komarneni, Sridhar

2014-07-01

Three porous carbons were prepared by direct carbonization of HKUST-1, MOF-5 and Al-PCP without additional carbon precursors. The carbon samples obtained by carbonization at 1073 K were characterized by XRD, TEM and N2 physisorption techniques followed by testing for electrochemical performance. The BET surface areas of the three carbons were in the range of 50-1103 m2/g. As electrode materials for supercapacitor, the MOF-5 and Al-PCP derived carbons displayed the ideal capacitor behavior, whereas the HKUST-1 derived carbon showed poor capacitive behavior at various sweep rates and current densities. Among those carbon samples, Al-PCP derived carbons exhibited highest specific capacitance (232.8 F/g) in 30% KOH solution at the current density of 100 mA/g.

Morphological, chemical and structural characterisation of deciduous enamel: SEM, EDS, XRD, FTIR and XPS analysis.

PubMed

Zamudio-Ortega, C M; Contreras-Bulnes, R; Scougall-Vilchis, R J; Morales-Luckie, R A; Olea-Mejía, O F; Rodríguez-Vilchis, L E

2014-09-01

The purpose of this study was to characterise the enamel surface of sound deciduous teeth in terms of morphology, chemical composition, structure and crystalline phases. The enamel of 30 human deciduous teeth was examined by: Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Chemical differences between incisors and canines were statistically evaluated using the Mann-Whitney U test (p ≤ 0.05). Three enamel patterns were observed by SEM: 'mostly smooth with some groves', 'abundant microporosities' and 'exposed prisms'. The average Ca/P molar ratios were 1.37 and 1.03 by EDS and XPS, respectively. The crystallite size determined by XRD was 210.82 ± 16.78 Å. The mean ratio between Ca bonded to phosphate and Ca bonded to hydroxyl was approximately 10:1. The enamel of sound deciduous teeth showed two main patterns: 'mostly smooth with some groves' and 'abundant microporosities'. 'Exposed prisms' was a secondary pattern. There were slight variations among the Ca/P molar ratios found by EDS and XPS, suggesting differences in the mineral content from the enamel surface to the interior. The crystalline phases found in enamel were hydroxyapatite and carbonate apatite, with major type B than type A carbonate incorporation.

Study the target effect on the structural, surface and optical properties of TiO2 thin film fabricated by RF sputtering method

NASA Astrophysics Data System (ADS)

Vyas, Sumit; Tiwary, Rohit; Shubham, Kumar; Chakrabarti, P.

2015-04-01

The effect of target (Ti metal target and TiO2 target) on Titanium Dioxide (TiO2) thin films grown on ITO coated glass substrate by RF magnetron sputtering has been investigated. A comparative study of both the films was done in respect of crystalline structure, surface morphology and optical properties by using X-ray diffractometer (XRD), Atomic Force Microscopy (AFM) studies and ellipsometric measurements. The XRD results confirmed the crystalline structure and indicated that the deposited films have the intensities of anatase phase. The surface morphology and roughness values indicated that the film using Ti metal target has a smoother surface and densely packed with grains as compared to films obtained using TiO2 target. A high transmission in the visible region, and direct band gap of 3.67 eV and 3.75 eV for films derived by using Ti metal and TiO2 target respectively and indirect bandgap of 3.39 eV for the films derived from both the targets (Ti metal and TiO2 target) were observed by the ellipsometric measurements.

Preparation of WO3/g-C3N4 composites and their application in oxidative desulfurization

NASA Astrophysics Data System (ADS)

Zhao, Rongxiang; Li, Xiuping; Su, Jianxun; Gao, Xiaohan

2017-01-01

WO3/graphitic carbon nitride (g-C3N4) composites were successfully synthesized through direct calcining of a mixture of WO3 and g-C3N4 at 400 °C for 2 h. The WO3 was prepared by calcination of phosphotungstic acid at 550 °C for 4 h, and the g-C3N4 was obtained by calcination of melamine at 520 °C for 4 h. The WO3/g-C3N4 composites were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Brunner-Emmett-Teller analysis (BET). The WO3/g-C3N4 composites exhibited stronger XRD peaks of WO3 and g-C3N4 than the WO3 and pure g-C3N4. In addition, two WO3 peaks at 25.7° and 26.6° emerged for the 36% -WO3/g-C3N4 composite. This finding indicated that WO3 was highly dispersed on the surface of the g-C3N4 nanosheets and interacted with the nanosheets, which resulted in the appearance of (012) and (022) planes of WO3. The WO3/g-C3N4 composite also exhibited a larger specific surface area and higher degree of crystallization than WO3 or pure g-C3N4, which resulted in high catalytic activity of the catalyst. Desulfurization experiments demonstrated that the desulfurization rate of dibenzothiophene (DBT) in model oil reached 91.2% under optimal conditions. Moreover, the activity of the catalyst was not significantly decreased after five recycles.

Fe(Ⅲ) ions enhanced catalytic properties of (BiO)2CO3 nanowires and mechanism study for complete degradation of xanthate.

PubMed

Guo, Yujiao; Cui, Kuixin; Hu, Mingyi; Jin, Shengming

2017-08-01

The wire-like Fe 3+ -doped (BiO) 2 CO 3 photocatalyst was synthesized by a hydrothermal method. The photocatalytic property of Fe 3+ -doped (BiO) 2 CO 3 nanowires was evaluated through degradation of sodium isopropyl xanthate under UV-visible light irradiation. The as-prepared Fe 3+ -doped (BiO) 2 CO 3 nanowires were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) in detail. The results of XRD showed that the crystallinity of (BiO) 2 CO 3 nanowires decreased when Fe 3+ ions were introduced into the solution system. XPS results illustrated that xanthate could be absorbed on the surface of Fe 3+ -doped (BiO) 2 CO 3 nanowires to produce BiS bond at the beginning of the reaction, which could broaden the visible light absorption. FTIR spectra confirmed the formation of SO 4 2- after photocatalytic decomposition of xanthate solution. The Fe 3+ -doped (BiO) 2 CO 3 nanowires showed an enhanced photocatalytic activity for decomposition of xanthate due to the narrower band gap and larger BET surface area, comparing with pure (BiO) 2 CO 3 nanowires. By the results of UV-vis spectra of the solution and FTIR spectra of recycled Fe 3+ -doped (BiO) 2 CO 3 , the xanthate was oxidized completely into CO 2 and SO 4 2- . The photocatalytic degradation process of xanthate followed a pseudo-second-order kinetics model. The mechanism of enhanced photocatalytic activity was proposed as well. Copyright © 2017 Elsevier Ltd. All rights reserved.

Surface-pattern geometry, topography, and chemical modifications during KrF excimer laser micro-drilling of p-type Si (111) wafers in ambient environment of HCl fumes in air

NASA Astrophysics Data System (ADS)

Zakria Butt, Muhammad; Saher, Sobia; Waqas Khaliq, Muhammad; Siraj, Khurram

2016-11-01

Eight mirror-like polished p-type Si (111) wafers were irradiated with 100, 200, 300, 400, 800, 1200, 1600, and 2000 KrF excimer laser pulses in ambient environment of HCl fumes in air. The laser parameters were: wavelength = 248 nm, pulse width = 20 ns, pulse energy = 20 mJ, and repetition rate = 20 Hz. For each set of laser pulses, characterization of the rectangular etched patterns formed on target surface was done by optical/scanning electron microscopy, XRD, and EDX techniques. The average etched depth increased with the increase in number of laser pulses from 100 to 2000 in accord with Sigmoidal (Boltzmann) function, whereas the average etch rate followed an exponential decay with the increase in number of laser pulses. However, the etched area, maximum etched depth, and maximum etch rate were found to increase linearly with the number of laser pulses, but the rate of increase was faster for 100-400 laser pulses (region I) than that for 800-2000 laser pulses (region II). The elemental composition for each etched-pattern determined by EDX shows that both O and Cl contents increase progressively with the increase in the number of laser shots in region I. However, in region II both O and Cl contents attain saturation values of about 39.33 wt.% and 0.14 wt.%, respectively. Perforation of Si wafers was achieved on irradiation with 1200-2000 laser pulses. XRD analysis confirmed the formation of SiO2, SiCl2 and SiCl4 phases in Si (111) wafers due to chemical reaction of silicon with both HCl fumes and oxygen in air.

Effect of the Mn oxidation state and lattice oxygen in Mn-based TiO2 catalysts on the low-temperature selective catalytic reduction of NO by NH3.

PubMed

Lee, Sang Moon; Park, Kwang Hee; Kim, Sung Su; Kwon, Dong Wook; Hong, Sung Chang

2012-09-01

TiO2-supported manganese oxide catalysts formed using different calcination temperatures were prepared by using the wet-impregnation method and were investigated for their activity in the low-temperature selective catalytic reduction (SCR) of NO by NH3 with respect to the Mn valence and lattice oxygen behavior. The surface and bulk properties of these catalysts were examined using Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), temperature-programmed reduction (TPR), and temperature-programmed desorption (TPD). Catalysts prepared using lower calcination temperatures, which contained Mn4+ displayed high SCR activity at low temperatures and possessed several acid sites and active oxygen. The TPD analysis determined that the Brönsted and Lewis acid sites in the Mn/TiO2 catalysts were important for the low-temperature SCR at 80-160 and 200-350 degrees C, respectively. In addition, the available lattice oxygen was important for attaining high NO to NO2 oxidation at low temperatures. Recently, various Mn catalysts have been evaluated as SCR catalysts. However, there have been no studies on the relationship of adsorption and desorption properties and behavior of lattice oxygen according to the valence state for manganese oxides (MnO(x)). Therefore, in this study, the catalysts were prepared by the wet-impregnation method at different calcination temperatures in order to show the difference of manganese oxidation state. These catalysts were then characterized using various physicochemical techniques, including BET, XRD, TPR, and TPD, to understand the structure, oxidation state, redox properties, and adsorption and desorption properties of the Mn/TiO2 catalysts.

Synthesis, characterization and application of Lagerstroemia speciosa embedded magnetic nanoparticle for Cr(VI) adsorption from aqueous solution.

PubMed

Srivastava, Shalini; Agrawal, Shashi Bhushan; Mondal, Monoj Kumar

2017-05-01

Lagerstroemia speciosa bark (LB) embedded magnetic nanoparticles were prepared by co-precipitation of Fe 2+ and Fe 3+ salt solution with ammonia and LB for Cr(VI) removal from aqueous solution. The native LB, magnetic nanoparticle (MNP), L. speciosa embedded magnetic nanoparticle (MNPLB) and Cr(VI) adsorbed MNPLB particles were characterized by SEM-EDX, TEM, BET-surface area, FT-IR, XRD and TGA methods. TEM analysis confirmed nearly spherical shape of MNP with an average diameter of 8.76nm and the surface modification did not result in the phase change of MNP as established by XRD analysis, while led to the formation of secondary particles of MNPLB with diameter of 18.54nm. Characterization results revealed covalent binding between the hydroxyl group of MNP and carboxyl group of LB particles and further confirmed its physico-chemical nature favorable for Cr(VI) adsorption. The Cr(VI) adsorption on to MNPLB particle as an adsorbent was tested under different contact time, initial Cr(VI) concentration, adsorbent dose, initial pH, temperature and agitation speed. The results of the equilibrium and kinetics of adsorption were well described by Langmuir isotherm and pseudo-second-order model, respectively. The thermodynamic parameters suggest spontaneous and endothermic nature of Cr(VI) adsorption onto MNPLB. The maximum adsorption capacity for MNPLB was calculated to be 434.78mg/g and these particles even after Cr(VI) adsorption were collected effortlessly from the aqueous solution by a magnet. The desorption of Cr(VI)-adsorbed MNPLB was found to be more than 93.72% with spent MNPLB depicting eleven successive adsorption-desorption cycles. Copyright © 2016. Published by Elsevier B.V.

Synthesis of ZSM-5 zeolite from coal fly ash and rice husk: characterization and application for partial oxidation of methane to methanol

NASA Astrophysics Data System (ADS)

Krisnandi, Y. K.; Yanti, F. M.; Murti, S. D. S.

2017-04-01

Indonesian fly ash (SiO2/Al2O3 mole ratio = 3.59) was used together with rice husk (SiO2 92%) as raw material for mesoporous ZSM-5 zeolite synthesis. Prior being used, coal fly ash and rice husk were subjected to pre-treatment in order to extract silicate (SiO4 4-) and aluminate (AlO4 5-) and to remove the impurities. Then the ZSM-5 zeolite were synthesized through hydrothermal treatment using two types of templates (TPAOH and PDDA). The as-synthesized ZSM-5 was characterized using FTIR, XRD, SEM-EDX, and BET. The result of FTIR showed peaks at 1250-950 cm-1 (v asymetric T-O), 820-650 cm-1 (v symetric T-O), and at 650-500 cm-1 confirming the presence of the five number ring of the pentasil structure. The result of XRD showed the appearance of certain peaks in the position 2 theta between 7-9° and 22-25° indicative of ZSM-5 structure, but also showed the pattern of low intensity magnetite and hematite. The SEM image showed the rough surface of hexagonal crystals from ZSM-5 structure, indicative of mesoporosity in the structure. EDX result showed Si/Al ratio of 20, while surface area analysis gave SA of 43.16. The ZSM-5 zeolites then was modified with cobalt oxide through impregnation method. The catalytic activity as heterogeneous catalysts in partial oxidation of methane was tested. The result showed that hence the catalytic activity of ZSM-5 and Co/ZSM-5 from fly ash and rice husk were still inferior compared to the pro-analysis sourced-counterpart, they were potential to be used as catalyst in the partial oxidation of methane to methanol.

Production of silica gel from Tunisian sands and its adsorptive properties

NASA Astrophysics Data System (ADS)

Lazaar, K.; Hajjaji, W.; Pullar, R. C.; Labrincha, J. A.; Rocha, F.; Jamoussi, F.

2017-06-01

Thanks to its highly absorbent character, silica gel is used in several applications, such as air moisture removal, as a treatment agent for effluents. In this study, silica gels were synthesised from Tunisian sands, collected from the Fortuna and Sidi Aich Formations in northern and central Tunisia. The collected quartz sand raw materials, as well as the prepared silica gels, were characterised by different techniques, such as X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy (SEM). XRD patterns of quartz sands showed quartz as main phase (86.1-98%), with lower contents of potassic feldspars, along with kaolinite and calcite. These quartz sands presented relatively small quantities of Fe2O3 (0.3%-0.5%) and TiO2 (0.1%-0.6%). The synthesised silica gels exhibited pore diameters exceeding 20 Å and surface areas up to 194 m2/g, comparable with those described in the literature and commercial silica gel. N2 adsorption isotherms showed that the silica gels prepared from Tunisian sands are mesoporous materials with high adsorption capacities. To understand better their adsorbent properties and applicability on an industrial scale, these gels were tested for methylene blue (MB) absorption. Maximum decolourisation rates (up to 96% after a contact time of 180 min) occurred with products synthesised at pH 3. The adsorption mechanism fitted better with a Langmuir model, revealing a monolayer coverage process of MB molecules over the gel surface, and the adsorption kinetics of the dye on these materials is well described by the second order model. The corresponding equilibrium adsorption capacities obtained from experimental data (Qexp = 292-214 mg/g) were close to the estimated maximum adsorption capacities (Qe = 333-250 mg/g), and to that of an industrial silica gel (250 mg/g).

Stable superhydrophilic coating on superhydrophobic porous media by functionalized nanoparticles

NASA Astrophysics Data System (ADS)

Khazaei, Masoud; Taghi Sadeghi, Mohammad; Sadat Hosseini, Marzieh

2018-01-01

In this study, the hydrophilicity property of TiO2 nano-coating was improved by zinc acetate-assisted sol-gel method. The stable superhydrophilic coating was fabricated on a superhydrophobic mineral rock surface. The wettability of surface before and after coating was characterized by contact angle measurements. The n-heptane and water droplet contact angle was 0° and 168° respectively, so the untreated rock was superhydrophobic. After nano-treatment, the n-heptane and water contact angle changed to 172° and 0° respectively, so the superhydrophilic coating was formed on the superhydrophobic surface. The thermal, mechanical and salinity stability of the fabricated coatings was investigated. The coatings had high thermal and salinity stability; they also had moderate mechanical stability that was evaluated by abrasion test. The morphology and composition of synthesized nanoparticles were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and x-ray diffraction (XRD) analyses. Characterization of the coated surfaces was conducted by SEM and XRD analyses. Applications of these nano-coatings include surfaces where cleanliness is paramount such as in hospitals as well as the protection of public monuments and building facades from weathering. Novel industrial application includes wettability alteration of oil wet carbonate rock for enhanced oil recovery.

Surface structure of coherently strained ceria ultrathin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Yezhou; Stone, Kevin H.; Guan, Zixuan

2016-11-14

Cerium oxide, or ceria, is an important material for solid oxide fuel cells and water splitting devices. Although the ceria surface is active in catalytic and electrochemical reactions, how its catalytic properties are affected by the surface structure under operating conditions is far from understood. We investigate the structure of the coherently strained CeO 2 ultrathin films on yttria-stabilized zirconia (001) single crystals by specular synchrotron x-ray diffraction (XRD) under oxidizing conditions as a first step to study the surface structure in situ. An excellent agreement between the experiment data and the model is achieved by using a “stacks andmore » islands” model that has a two-component roughness. One component is due to the tiny clusters of nanometer scale in lateral dimensions on each terrace, while the other component is due to slightly different CeO 2 thickness that span over hundreds of nanometers on neighboring terraces. We attribute the nonuniform thickness to step depairing during the thin film deposition that is supported by the surface morphology results on the microscopic level. Importantly, our model also shows that the polarity of the ceria surface is removed by a half monolayer surface coverage of oxygen. In conclusion, the successful resolution of the ceria surface structure using in situ specular synchrotron XRD paves the way to study the structural evolution of ceria as a fuel cell electrode under catalytically relevant temperatures and gas pressures.« less

In-vitro bioactivity of zirconia doped borosilicate glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samudrala, Rajkumar; Azeem, P. Abdul, E-mail: rk.satyaswaroop@gmail.com, E-mail: drazeem2002@yahoo.com

2015-06-24

Glass composition 31B{sub 2}O{sub 3}-20SiO{sub 2}-24.5Na{sub 2}O-(24.5-x) CaO-xZrO{sub 2} x=1,2,3,4,5 were prepared by melt-quenching Technique. The formation of hydroxyapatite layer on the surface of glasses after immersion in simulated body fluid (SBF) was explored through XRD, Fourier transform infrared (FTIR) and Scanning electron microscopy (SEM-EDX) analyses. In this report, we observed that hydroxyapatite formation for 5days of immersion time. Also observed that with increasing the immersion time up to 15days, higher amount of hydroxyapatite layer formation on the surface of glasses. The varying composition of zirconia in glass samples influences shown by XRD, FTIR studies. The present results indicate that,more » in-vitro bioactivity of glasses decreased with increasing zirconia incorporation.« less

Effect of deposition parameters on the structural properties of ZnO nanopowders prepared by microwave-assisted hydrothermal synthesis.

PubMed

Caglar, Yasemin; Gorgun, Kamuran; Aksoy, Seval

2015-03-05

ZnO nanopowders were synthesized via microwave-assisted hydrothermal method at different deposition (microwave irradiation) times and pH values. The effects of pH and deposition (microwave irradiation) time on the crystalline structure and orientation of the ZnO nanopowders have been investigated by X-ray diffraction (XRD) study. XRD observations showed that the crystalline quality of ZnO nanopowders increased with increasing pH value. The crystallite size and texture coefficient values of ZnO nanopowders were calculated. The structural quality of ZnO nanopowder was improved by deposition parameters. Field emission scanning electron microscope (FESEM) was used to analyze the surface morphology of the ZnO nanopowders. Microwave irradiation time and pH value showed a significant effect on the surface morphology. Copyright © 2014 Elsevier B.V. All rights reserved.

Investigations of the Failure in Boilers Economizer Tubes Used in Power Plants

NASA Astrophysics Data System (ADS)

Moakhar, Roozbeh Siavash; Mehdipour, Mehrad; Ghorbani, Mohammad; Mohebali, Milad; Koohbor, Behrad

2013-09-01

In this study, failure of a high pressure economizer tube of a boiler used in gas-Mazut combined cycle power plants was studied. Failure analysis of the tube was accomplished by taking into account visual inspection, thickness measurement, and hardness testing as well as microstructural observations using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Optical microscopy images indicate that there is no phase transformation during service, and ferrite-pearlite remained. The results of XRD also revealed Iron sulfate (FeSO4) and Iron hydroxide sulfate (FeOH(SO4)) phases formed on the steel surface. A considerable amount of Sulfur was also detected on the outer surface of the tube by EDS analysis. Dew-point corrosion was found to be the principal reason for the failure of the examined tube while it has been left out-of-service.

Evolution of microstructure and surface topography of gold thin films under thermal annealing

NASA Astrophysics Data System (ADS)

Dash, P.; Rath, H.; Dash, B. N.; Mallick, P.; Basu, T.; Som, T.; Singh, U. P.; Mishra, N. C.

2012-07-01

In the present study, we probe into evolution of microstructure and surface morphology of gold thin films of 10 to 50 nm thickness deposited on Si (100) substrate by thermal evaporation method. These films were annealed at 250°C under vacuum. The as-deposited and annealed films were characterized by glancing angle X-Ray diffraction (GAXRD) and atomic force microscopy (AFM), techniques. XRD indicated improvement of crystallinity up to 2 hours of annealing and degradation of the same thereafter. In agreement with XRD result, the grain size distribution histogram obtained from AFM indicated grain growth with annealing time up to 2 hours and saturation or decrease of grain size thereafter. The observed result is explained by the occurrence of two competing phenomena like roughening induced grain growth and smoothening induced inhibition of grain growth with increasing annealing time.

Synthesis, crystal structure, NLO and Hirshfeld surface analysis of 1,2,3-triazolyl chalcone single crystal

NASA Astrophysics Data System (ADS)

Shruthi, C.; Ravindrachary, V.; Guruswamy, B.; Lokanath, N. K.; Kumara, Karthik; Goveas, Janet

2018-05-01

Needle shaped brown coloured single crystal of the title compound was grown by slow evaporation technique using methanol as solvent. The grown crystal was characterized using FT-IR, Single crystal XRD, UV-visible and NLO studies. Crystal structure was confirmed by FT-IR study and the functional groups were identified. XRD study reveals that the crystal belongs to orthorhombic crystal system with pnaa space group and the corresponding cell parameters were calculated. UV-visible spectrum shows that the crystal is transparent in the entire visible region and absorption takes place in the UV-range. NLO efficiency of the crystal obtained 0.66 times that of urea was determined by SHG test. The intermolecular interaction and percentage contribution of each individual atom in the crystal lattice was quantized using Hirshfeld surface and 2D finger print analysis.

ASR prevention — Effect of aluminum and lithium ions on the reaction products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leemann, Andreas, E-mail: andreas.leemann@empa.ch; Bernard, Laetitia; Alahrache, Salaheddine

2015-10-15

In spite of the recent progress in the understanding of the mechanisms enabling aluminum-containing SCM like metakaolin and added LiNO{sub 3} to limit the extent of ASR in mortar and concrete, some gaps still remain. They concern mainly the effect of aluminum-containing SCM on the formed ASR products and the influence of aggregate characteristics on the effectiveness of LiNO{sub 3}. In this study, a model system, concrete and mortar were investigated by pore solution analysis, TGA, XRD, NMR, SEM combined with EDX and ToF-SIMS to address these questions. The amount of aluminum present in the pore solution of concrete andmore » mortar is only able to slow down SiO{sub 2} dissolution but not to alter morphology, structure and composition of the reaction products. LiNO{sub 3} can suppress ASR by forming dense products protecting reactive minerals from further reaction. But its effectiveness is decreasing with increasing specific surface area of the reactive minerals in aggregates. - Highlights: • Aluminum of SCM slows down SiO{sub 2} dissolution. • Aluminum of SCM does not alter morphology and structure of ASR product. • ASR suppressing effect of LiNO{sub 3} depends on specific surface area of the aggregates.« less

Nonstoichiometric Zn Ferrite and ZnFe2O4/Fe2O3 Composite Spheres: Preparation, Magnetic Properties, and Chromium Removal

NASA Astrophysics Data System (ADS)

Hang, Chun-Liang; Yang, Li-Xia; Sun, Chang-Mei; Liang, Ying

2018-03-01

Monodisperse and porous nonstoichiometric Zn ferrite can be prepared by a solvothermal method. Such non-Zn ferrite was used to be the precursor for synthesis of ZnFe2O4/Fe2O3 composite via calcination at 600°C for 3 h in air. X-ray powder diffractometer (XRD) and Energy Dispersive Spectrometer (EDS) proved the nonstoichiometry of Zn ferrite synthesized by solvothermal method and the formation of ZnFe2O4/Fe2O3 composite via calcination. TEM image showed that non-Zn ferrite spheres with wormlike nanopore structure were made of primary nanocrystals. BET surface area of non-Zn ferrite was much higher than that of ZnFe2O4/Fe2O3 composite. Saturation magnetization of non-Zn ferrites was significantly higher than that of ZnFe2O4/Fe2O3 composites. Calcination of non-Zn ferrite resulted in the formation of large amount of non-magnetic Fe2O3,which caused a low magnetization of composite. Because of higher BET surface area and higher saturation magnetization, non-Zn ferrite presented better Cr6+ adsorption property than ZnFe2O4/Fe2O3 composites.

Double-shell Fe2O3 hollow box-like structure for enhanced photo-Fenton degradation of malachite green dye

NASA Astrophysics Data System (ADS)

Jiang, De Bin; Liu, Xiaoying; Xu, Xuan; Zhang, Yu Xin

2018-01-01

In this work we demonstrate the synthesis of novel Fe2O3 nanosheets with double-shell hollow morphology by replica molding from diatomite framework. The nanostructures of Fe2O3 nanosheets were examined by focused-ion-beam scanning electron microscopy (FIB/SEM), X-ray diffraction spectroscopy (XRD), Brunauer-Emmett-Teller (BET) specific surface area measurements and Fourier transform infrared (FT-IR) spectroscopy. The results reveal that (1) Pure Fe2O3 nanosheets were successfully obtained; (2) The double-shell Fe2O3 hollow structure achieved via the NaOH etching silica method was observed; (3) Fe2O3 nanosheets possessed uniformly distributed porous nanosheets. Such structural features enlarged the specific surface area of Fe2O3 nanosheets and led to more catalytic active sites. In the heterogeneous photo-Fenton reaction, the double-shell Fe2O3 hollow morphology exhibited excellent catalytic capability for the degradation of malachite green (MG) at circumneutral pH condition. Under optimum condition, MG solution was almost completely decolorized in 60 min (99.9%). The Fe2O3 nanosheets also showed good stability and recyclability, demonstrating great potential as a promising photo-Fenton catalyst for the effective degradation of MG dye in wastewater.

Reaction Heterogeneity in LiNi 0.8 Co 0.15 Al 0.05 O 2 Induced by Surface Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grenier, Antonin; Liu, Hao; Wiaderek, Kamila M.

2017-08-15

Through operando synchrotron powder X-ray diffraction (XRD) analysis of layered transition metal oxide electrodes of composition LiNi0.8Co0.15Al0.05O2 (NCA), we decouple the intrinsic bulk reaction mechanism from surface-induced effects. For identically prepared and cycled electrodes stored in different environments, we demonstrate that the intrinsic bulk reaction for pristine NCA follows solid-solution mechanism, not a two-phase as suggested previously. By combining high resolution powder X-ray diffraction, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and surface sensitive X-ray photoelectron spectroscopy (XPS), we demonstrate that adventitious Li2CO3 forms on the electrode particle surface during exposure to air, through reaction with atmospheric CO2. This surfacemore » impedes ionic and electronic transport to the underlying electrode, with progressive erosion of this layer during cycling giving rise to different reaction states in particles with an intact vs an eroded Li2CO3 surface-coating. This reaction heterogeneity, with a bimodal distribution of reaction states, has previously been interpreted as a “two-phase” reaction mechanism for NCA, as an activation step that only occurs during the first cycle. Similar surface layers may impact the reaction mechanism observed in other electrode materials using bulk probes such as operando powder XRD.« less

Electrodeposition of Sn-Ni Alloy Coatings for Water-Splitting Application from Alkaline Medium

NASA Astrophysics Data System (ADS)

Shetty, Sandhya; Hegde, A. Chitharanjan

2017-02-01

In this work, Sn-Ni alloy coatings were developed onto the surface of copper from a newly formulated electrolytic bath by a simple and cost-effective electrodeposition technique using gelatin as an additive. The electrocatalytic behavior of coatings deposited at different current densities (c.d.'s) for water-splitting applications, in terms of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), has been researched. The experimental results showed that the electrocatalytic activity of Sn-Ni coatings has a close relationship with its composition, surface morphology, and phase structure depending on the c.d. used, supported by scanning electron microscopy (SEM-EDX) and X-ray diffraction (XRD) analyses. Cyclic voltammetry and chronopotentiometry techniques have demonstrated that Sn-Ni alloy deposited at 4.0 A dm-2 (having 37.6 wt pct Ni) and 1.0 A dm-2 (having 19.6 wt pct Ni) exhibit, respectively, the highest electrocatalytic behavior for HER and OER in 1.0-M KOH solution. Sn-Ni alloy coatings were found to be stable under working conditions of electrolysis, confirmed by electrochemical corrosion tests. High electrocatalytic activity of Sn-Ni alloy coatings for both HER and OER is specific to their composition, surface morphology, and active surface area.

The Effect of Eu Doping on Microstructure, Morphology and Methanal-Sensing Performance of Highly Ordered SnO2 Nanorods Array

PubMed Central

Zhao, Yanping; Li, Yuehua; Ren, Xingping; Gao, Fan; Zhao, Heyun

2017-01-01

Layered Eu-doped SnO2 ordered nanoarrays constructed by nanorods with 10 nm diameters and several hundred nanometers length were synthesized by a substrate-free hydrothermal route using alcohol and water mixed solvent of sodium stannate and sodium hydroxide at 200 °C. The Eu dopant acted as a crystal growth inhibitor to prevent the SnO2 nanorods growth up, resulting in tenuous SnO2 nanorods ordered arrays. The X-ray diffraction (XRD) revealed the tetragonal rutile-type structure with a systematic average size reduction and unit cell volume tumescence, while enhancing the residual strain as the Eu-doped content increases. The surface defects that were caused by the incorporation of Eu ions within the surface oxide matrix were observed by high-resolution transmission electron microscope (HRTEM). The results of the response properties of sensors based on the different levels of Eu-doped SnO2 layered nanoarrays demonstrated that the 0.5 at % Eu-doped SnO2 layered nanorods arrays exhibited an excellent sensing response to methanal at 278 °C. The reasons of the enhanced sensing performance were discussed from the complicated defect surface structure, the large specific surface area, and the excellent catalytic properties of Eu dopant. PMID:29168796

Promising SiC support for Pd catalyst in selective hydrogenation of acetylene to ethylene

NASA Astrophysics Data System (ADS)

Guo, Zhanglong; Liu, Yuefeng; Liu, Yan; Chu, Wei

2018-06-01

In this study, SiC supported Pd nanoparticles were found to be an efficient catalyst in acetylene selective hydrogenation reaction. The ethylene selectivity can be about 20% higher than that on Pd/TiO2 catalyst at the same acetylene conversion at 90%. Moreover, Pd/SiC catalyst showed a stable catalytic life at 65 °C with 80% ethylene selectivity. With the detailed characterization using temperature-programmed reduction (H2-TPR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption analysis, CO-chemisorption and thermo-gravimetric analysis (TGA), it was found that SiC owns a lower surface area (22.9 m2/g) and a broad distribution of meso-/macro-porosity (from 5 to 65 nm), which enhanced the mass transfer during the chemical process at high reaction rate and decreased the residence time of ethylene on catalyst surface. Importantly, SiC support has the high thermal conductivity, which favored the rapid temperature homogenization through the catalyst bed and inhabited the over-hydrogenation of acetylene. The surface electronic density of Pd on Pd/SiC catalyst was higher than that on Pd/TiO2, which could promote desorption of ethylene from surface of the catalyst. TGA results confirmed a much less coke deposition on Pd/SiC catalyst.

Carbon-silicon composite anode electrodes modified with MWCNT for high energy battery applications

NASA Astrophysics Data System (ADS)

Akbulut, H.; Nalci, D.; Guler, A.; Duman, S.; Guler, M. O.

2018-07-01

In this study, we comparatively study the electrochemical characteristics of Si, Si-C and vacuum-assisted filtration fabrication of a novel free-standing Si@C/Mutli Wall Carbon Nanotubes (MWCNT) nanocomposite. The surfaces of the as-received Si nanaoparticles were coated with an amorphous carbon layer and homogenously anchored onto the surfaces of as-received MWCNTs by a simple vacuum filtration method. The samples were then analyzed with field emission scanning electron microscopy and X-ray diffraction (XRD) methods. Si@C/MWCNT samples have shown a stable capacity of 1290 mA h g-1 after 200 cycles. The results have proven that MWCNT's large surface area, highly conductive network which can provide good contact between Si@C nanoparticles, tolerating large volume change sand suppressing aggregation of Si@C nanoparticles during charge/discharge processes. Such a comparison between the performances of carbon-MWCNT-metal materials is reasonably envisaged not only to be useful for understanding the individual contribution from MWCNT and metal but also to form a fundamental basis for energy storage applications. Free-standing Si-C/MWCNT nano paper has been successfully obtained by a facile vacuum filtration method.

A laboratory study of supercritical CO2 adsorption on cap rocks in the geological storage conditions

NASA Astrophysics Data System (ADS)

Jedli, Hedi; Jbara, Abdessalem; Hedfi, Hachem; Bouzgarrou, Souhail; Slimi, Khalifa

2017-04-01

In the present study, various cap rocks have been experimentally reacted in water with supercritical CO2 in geological storage conditions ( P = 8 × 106 Pa and T = 80 °C) for 25 days. To characterize the potential CO2-water-rock interactions, an experimental setup has been built to provide additional information concerning the effects of structure, thermal and surface characteristics changes due to CO2 injection with cap rocks. In addition, CO2 adsorption capacities of different materials (i.e., clay evaporate and sandstone) are measured. These samples were characterized by XRD technique. The BET specific surface area was determined by nitrogen isotherms. In addition, thermal characteristics of untreated adsorbents were analyzed via TGA method and topography surfaces are identified by Scanning Electron Microscope (SEM). Taking into account pressure and temperature, the physical as well as chemical mechanisms of CO2 retention were determined. Isotherm change profiles of samples for relative pressure range indicate clearly that CO2 was adsorbed in different quantities. In accordance with the X-ray diffraction, a crystalline phase was formed due to the carbonic acid attack and precipitation of some carbonate.

Application of zeolitic material synthesized from thermally treated sediment to the removal of trivalent chromium from wastewater.

PubMed

Guan, Qingyu; Wu, Deyi; Lin, Yan; Chen, Xuechu; Wang, Xinze; Li, Chunjie; He, Shengbing; Kong, Hainan

2009-08-15

Zeolitic materials were synthesized from thermally treated sediment by alkali treatment using different NaOH/sediment ratios. Characterization of the materials was done by XRD, FTIR, cation exchange capacity and specific surface area. Use of high NaOH/sediment ratio favored the formation of zeolite. The potential value of the zeolitic materials for the retention of trivalent chromium from water was examined. The maximum of Cr(III) sorption by the zeolitic materials, determined by a repeated batch equilibration method, ranged from 38.9 to 75.8 mg/g which was much greater than that of the thermally treated sediment (6.3 mg/g). No release of sorbed Cr(III) by 1.0M MgCl(2) at pH 7 was observed but Cr(III) desorption by ionic electrolyte increased with decreasing pH. The zeolitic materials could completely remove Cr(III) from wastewater even in the presence of Na(+) and Ca(2+) with high concentrations with a dose above 2.5 g/L. The pH-dependent desorption behavior and the high selectivity of zeolitic material for Cr(III) were explained by sorption at surface hydroxyl sites and formation of surface precipitates.

Synthesis and characterization of Ni NPs-doped silica-titania nanocomposites: structural, optical and photocatalytic properties

NASA Astrophysics Data System (ADS)

Islam, S.; Bidin, N.; Osman, S. S.; Krishnan, G.; Salim, A. A.; Riaz, S.; Suan, L. P.; Naseem, S.; Sanagi, M. M.

2017-01-01

The synthesis of Ni-doped silica-titania nanocomposite is performed by sol-gel method. The samples prior and after heat treatment at 300 °C for 1 h are characterized by analytical instrumental techniques. FE-SEM and AFM results indicate the regular morphology with low surface roughness without any cracks. EDX analysis verifies the formation of nanocomposites. XRD of the films reveals crystalline titania phases after annealing at 300 °C. The FTIR confirms the bond linkage between silica, titania and nickel molecules. High surface area 155 m2/g, pore volume of 0.2 cm3/g and pore diameter of 48.10 Å are obtained after heat treatment. The magnetic results show that the composite content is reminiscent of ferromagnetic hysteresis loop, with remanence magnetization Mr of 45.35 and 13.20 emu/g for both samples. The organic dye phenol red is used for the evaluation of photocatalytic activity of the synthesized magnetic material. The homogeneous surface morphology, crystalline nature, good solubility of magnetic nanoparticles into the silica-titania matrix show that the Ni/SiO2-TiO2 magnetic photocatalyst can be efficient and reusable.

Structural characteristics of mixed oxides MOx/SiO2 affecting photocatalytic decomposition of methylene blue

NASA Astrophysics Data System (ADS)

Gun'ko, V. M.; Blitz, J. P.; Bandaranayake, B.; Pakhlov, E. M.; Zarko, V. I.; Sulym, I. Ya.; Kulyk, K. S.; Galaburda, M. V.; Bogatyrev, V. M.; Oranska, O. I.; Borysenko, M. V.; Leboda, R.; Skubiszewska-Zięba, J.; Janush, W.

2012-06-01

A series of photocatalysts based on silica (nanoparticulate) supported titania, ceria, and ceria/zirconia were synthesized and characterized by a variety of techniques including surface area measurements, X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential, surface charge density, and photocatalytic behavior toward methylene blue decomposition. Thermal treatment at 600 °C increases the anatase content of the titania based catalysts detected by XRD. Changes in the infrared spectra before and after thermal treatment indicate that at low temperature there are more tbnd Sisbnd Osbnd Titbnd bonds than at high temperature. As these bonds break upon heating the SiO2 and TiO2 separate, allowing the TiO2 anatase phase to form. This results in an increased catalytic activity for the thermally treated samples. Nearly all titania based samples exhibit a negative surface charge density at pH 7 (initial pH of photocatalytic studies) which aids adsorption of methylene blue. The crystallinity of ceria and ceria/zirconia based catalysts are in some cases limited, and in others non-existent. Even though the energy band gap (Eg) can be lower for these catalysts than for the titania based catalysts, their photocatalytic properties are inferior.

First X-Ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest Aeolian Bedform at Gale Crater

NASA Technical Reports Server (NTRS)

Bish, D. L.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Sarrazin, P.; Morris, R. V.; Ming, D. W.; Treiman, A. H.; Downs, R. T.; Morrison, S. M.;

Anatomy of a metabentonite: nucleation and growth of illite crystals and their colescence into mixed-layer illite/smectite

USGS Publications Warehouse

Eberl, D.D.; Blum, A.E.; Serravezza, M.

2011-01-01

The illite layer content of mixed-layer illite/smectite (I/S) in a 2.5 m thick, zoned, metabentonite bed from Montana decreases regularly from the edges to the center of the bed. Traditional X-ray diffraction (XRD) pattern modeling using Markovian statistics indicated that this zonation results from a mixing in different proportions of smectite-rich R0 I/S and illite-rich R1 I/S, with each phase having a relatively constant illite layer content. However, a new method for modeling XRD patterns of I/S indicates that R0 and R1 I/S in these samples are not separate phases (in the mineralogical sense of the word), but that the samples are composed of illite crystals that have continuous distributions of crystal thicknesses, and of 1 nm thick smectite crystals. The shapes of these distributions indicate that the crystals were formed by simultaneous nucleation and growth. XRD patterns for R0 and R1 I/S arise by interparticle diffraction from a random stacking of the crystals, with swelling interlayers formed at interfaces between crystals from water or glycol that is sorbed on crystal surfaces. It is the thickness distributions of smectite and illite crystals (also termed fundamental particles, or Nadeau particles), rather than XRD patterns for mixed-layer I/S, that are the more reliable indicators of geologic history, because such distributions are composed of well-defined crystals that are not affected by differences in surface sorption and particle arrangements, and because their thickness distribution shapes conform to the predictions of crystal growth theory, which describes their genesis.

Surface topographical and structural analysis of Ag+-implanted polymethylmethacrylate

NASA Astrophysics Data System (ADS)

Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Naab, Fabian; Toader, Ovidiu; Sagheer, Riffat; Bashir, Shazia; Zia, Rehana; Siraj, Khurram; Iqbal, Saman

2016-08-01

Specimens of polymethylmethacrylate (PMMA) were implanted with 400-keV Ag+ ions at different ion fluences ranging from 1 × 1014 to 5 × 1015 ions/cm2 using a 400-kV NEC ion implanter. The surface topographical features of the implanted PMMA were investigated by a confocal microscope. Modifications in the structural properties of the implanted specimens were analyzed in comparison with pristine PMMA by X-ray diffraction (XRD) and Raman spectroscopy. UV-Visible spectroscopy was applied to determine the effects of ion implantation on optical transmittance of the implanted PMMA. The confocal microscopic images revealed the formation of hillock-like microstructures along the ion track on the implanted PMMA surface. The increase in ion fluence led to more nucleation of hillocks. The XRD pattern confirmed the amorphous nature of pristine and implanted PMMA, while the Raman studies justified the transformation of Ag+-implanted PMMA into amorphous carbon at the ion fluence of ⩾5 × 1014 ions/cm2. Moreover, the decrease in optical transmittance of PMMA is associated with the formation of hillocks and ion-induced structural modifications after implantation.

Surface modification of calcium hydroxyapatite by grafting of etidronic acid

NASA Astrophysics Data System (ADS)

Othmani, Masseoud; Aissa, Abdallah; Bac, Christophe Goze; Rachdi, Férid; Debbabi, Mongi

2013-06-01

The surface of prepared calcium hydroxyapatite CaHAp has been modified by grafting the etidronic acid (ETD). For that purpose, CaHAp powders have been suspended in an aqueous etidronate solution with different concentrations. The obtained composites CaHAp-(ETD) were characterized by TEM and AFM techniques to determinate morphological properties and were also characterized by XRD, IR, NMR and chemical and thermal analysis to determinate their physico-chemical properties and essentially the nature of the interaction between the inorganic support and the grafted organic ETD. After reaction with ETD, XRD powder analysis shows that the apatitic structure remains unchanged with slight affectation of its crystallinity. The presence of etidronate fragment bounded to hydroxyapatite was confirmed by IR and solid-state NMR spectroscopy. TEM and AFM techniques indicate that the presence of etidronate changes the morphology of the particles. Basing on the obtained results, a reactional mechanism was proposed to explain the formation of covalent Casbnd Osbnd Porg bonds on the hydroxyapatite surface between the superficial hydroxyl groups (tbnd Casbnd OH) of the apatite and phosphonate group (Psbnd OH) of etidronate.

Direct Synthesis of Anatase Films with ~100% (001) Facets and [001] Preferred Orientation.

PubMed

Ichimura, Andrew S; Mack, Brianne; Usmani, Shirin M; Mars, Diana

2012-06-26

Anatase films exhibiting ~100% (001) reactive facets at the surface were grown hydrothermally on gold substrate from a homogeneous solution of TiF(4) and NaF. In addition to NaF, it was found that TiO(2) films with very similar properties could be prepared with the fluoride salts LiF, CsF, HF, NH(4)F, and N(CH(2)CH(3))(4)F. The polycrystalline anatase films are continuous, approximately 1 μm thick, and evenly coat the substrate. The surface grain size is ~400 nm. Grazing angle XRD measurements show that the films exhibit a high degree of preferred orientation with the c-axis normal to the substrate surface. SEM images reveal that the grains span the thickness of the films. Annealing the films at 500 °C removes fluorine and causes crystallites within the grains to restructure as shown by SEM, XRD, and Raman spectroscopy. Supported anatase films grown from this one-pot method may serve as oxidative photocatalysts and electrodes for photoelectrochemical applications such as solar cells and hydrogen evolution.

Study of benzotriazole as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

NASA Astrophysics Data System (ADS)

Solehudin, Agus; Nurdin, Isdiriayani

2014-03-01

Corrosion and inhibition studies on API 5LX65 carbon steel in chloride solution containing various concentrations of benzotriazole has been conducted at temperature of 70°C using Electrochemical Impedance Spectroscopy (EIS). Corroded carbon steel surface with and without inhibitor have been observed using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The objectives of this research are to study the performance of benzotriazole as corrosion inhibitors. The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H2S at different BTAH concentrations showed that corrosion rate of carbon steel decreases with increasing of BTAH concentrations from 0 to 10 mmol/l. The inhibition efficiency of BTAH was found to be affected by its concentration. The optimum efficiency obtained of BTAH is 93% at concentration of 5 mmol/l. The result of XRD and EDS analysis reveal the iron sulfide (FeS) formation on corroded carbon steel surface without inhibitor. The EDS spectrum show the Nitrogen (N) bond on carbon steel surface inhibited by BTAH.

Magnetic ordered mesoporous Fe3O4/CeO2 composites with synergy of adsorption and Fenton catalysis

NASA Astrophysics Data System (ADS)

Li, Keyan; Zhao, Yongqin; Song, Chunshan; Guo, Xinwen

2017-12-01

Magnetic Fe3O4/CeO2 composites with highly ordered mesoporous structure and large surface area were synthesized by impregnation-calcination method, and the mesoporous CeO2 as support was synthesized via the hard template approach. The composition, morphology and physicochemical properties of the materials were characterized by XRD, SEM, TEM, XPS, Raman spectra and N2 adsorption/desorption analysis. The mesoporous Fe3O4/CeO2 composite played a dual-function role as both adsorbent and Fenton-like catalyst for removal of organic dye. The methylene blue (MB) removal efficiency of mesoporous Fe3O4/CeO2 was much higher than that of irregular porous Fe3O4/CeO2. The superior adsorption ability of mesoporous materials was attributed to the abundant oxygen vacancies on the surface of CeO2, high surface area and ordered mesoporous channels. The good oxidative degradation resulted from high Ce3+ content and the synergistic effect between Fe and Ce. The mesoporous Fe3O4/CeO2 composite presented low metal leaching (iron 0.22 mg L-1 and cerium 0.63 mg L-1), which could be ascribed to the strong metal-support interactions for dispersion and stabilization of Fe species. In addition, the composite can be easily separated from reaction solution with an external magnetic field due to its magnetic property, which is important to its practical applications.

Effect of natural Bayah zeolite particle size reduction to physico-chemical properties and absortion against potassium permanganate (KMnO4)

NASA Astrophysics Data System (ADS)

Widayanti, Siti Mariana; Syamsu, Khaswar; Warsiki, Endang; Yuliani, Sri

2016-02-01

Recently, researches on nanotechnology have been developed very rapid, as well as the utilization of nano-zeolites. Nano-sized material has several advantages which are expanding absorptive surfaces so it will enhance the material absorption and shorten the absorption time. Zeolite as a KMnO4 binder, has been widely recognized for its ability to extend the shelf life of vegetables and fruits. This study was conducted to determine zeolites physico-chemical characters from different particle size and the effect on KMnO4 absorption. Potassium permanganate (KMnO4) is a strong oxidizer for reducing the quantity of ethylene in storage process of fresh horticultural products. The treatment consisted of (1) different length of milling time (10, 20, 30, 40, and 60 minutes) and (2) the duration of chemical activation with 1 N KOH solution. Physical and chemical characters of zeolite were analyzed using BET, PSA, XRD and SEM. The research design was randomized design. The result implied that milling time was significantly affecting the zeolite particle size, material surface area, and the size of pore diameter and volume. Milling treatment for 40 minutes produced higher zeolite surface area and pore volume than other treatments. While the duration of chemical activation using 1 N KOH solution gives different effect on zeolite absorption to KMnO4 solution. Milling time for 60 minutes and activated for 48 hours has higher initial adsorption than other treatments.

Mesoporous anatase TiO{sub 2}/reduced graphene oxide nanocomposites: A simple template-free synthesis and their high photocatalytic performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Qi; Zhong, Yong-Hui; Laboratory of Nanomaterials and Environmental Detection, Hefei Institute of Physical Sciences, Chinese Academy of Sciences, Hefei 230031

2014-03-01

Graphical abstract: - Highlights: • Mesoporous TiO{sub 2} nanoparticles with anatase phase were assembled on reduced graphene oxide via a template-free one-step hydrothermal method. • The TiO{sub 2}/rGO nanocomposites have better adsorption capacity and photocatalytic degradation efficiency for dyes removal. • Improved dye adsorption and photogenerated charge separation are responsible for enhanced activity. - Abstract: Mesoporous anatase phase TiO{sub 2} was assembled on reduced graphene oxide (rGO) using a template-free one-step hydrothermal process. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Brunauer–Emmett–Teller (BET) surface area.more » Morphology of TiO{sub 2} was related to the content of graphene oxide. TiO{sub 2}/rGO nanocomposites exhibited excellent photocatalytic activity for the photo-degradation of methyl orange. The degradation rate was 4.5 times greater than that of pure TiO{sub 2} nanoparticles. This difference was attributed to the thin two-dimensional graphene sheet. The graphene sheet had a large surface area, high adsorption capacity, and acted as a good electron acceptor for the transfer of photo-generated electrons from the conduction band of TiO{sub 2}. The enhanced surface adsorption characteristics and excellent charge transport separation were independent properties of the photocatalytic degradation process.« less

In situ assembly of well-dispersed Ni nanoparticles on silica nanotubes and excellent catalytic activity in 4-nitrophenol reduction

NASA Astrophysics Data System (ADS)

Zhang, Shenghuan; Gai, Shili; He, Fei; Ding, Shujiang; Li, Lei; Yang, Piaoping

2014-09-01

The easy aggregation nature of ferromagnetic nanoparticles (NPs) prepared by conventional routes usually leads to a large particle size and low loading, which greatly limits their applications to the reduction of 4-nitrophenol (4-NP). Herein, we developed a novel in situ thermal decomposition and reduction strategy to prepare Ni nanoparticles/silica nanotubes (Ni/SNTs), which can markedly prevent the aggregation and growth of Ni NPs, resulting in an ultra-small particle size (about 6 nm), good dispersion and especially high loading of Ni NPs. It was found that Ni/SNTs, which have a high specific surface area (416 m2 g-1), exhibit ultra-high catalytic activity in the 4-NP reduction (complete reduction of 4-NP within only 60 s at room temperature), which is superior to most noble metal (Au, Pt, and Pd) supported catalysts. Ni/SNTs still showed high activity even after re-use for several cycles, suggesting good stability. In particular, the magnetic property of Ni/SNTs makes it easy to recycle for reuse.The easy aggregation nature of ferromagnetic nanoparticles (NPs) prepared by conventional routes usually leads to a large particle size and low loading, which greatly limits their applications to the reduction of 4-nitrophenol (4-NP). Herein, we developed a novel in situ thermal decomposition and reduction strategy to prepare Ni nanoparticles/silica nanotubes (Ni/SNTs), which can markedly prevent the aggregation and growth of Ni NPs, resulting in an ultra-small particle size (about 6 nm), good dispersion and especially high loading of Ni NPs. It was found that Ni/SNTs, which have a high specific surface area (416 m2 g-1), exhibit ultra-high catalytic activity in the 4-NP reduction (complete reduction of 4-NP within only 60 s at room temperature), which is superior to most noble metal (Au, Pt, and Pd) supported catalysts. Ni/SNTs still showed high activity even after re-use for several cycles, suggesting good stability. In particular, the magnetic property of Ni/SNTs makes it easy to recycle for reuse. Electronic supplementary information (ESI) available: XRD pattern and TEM image of SNTs after calcination, XRD pattern and EDS of NiSNTs, SEM images of a single SNT, NiSNTs and Ni/SNTs, enlarged HRTEM of Ni/SNTs, XRD pattern of NiO/SNTs, UV-vis spectra of the catalytic reduction of 4-NP to 4-AP over Ni/SNTs with different loading amounts, Ni/SNTs synthesized by wet impregnation and Ni/CNTs, TEM images of Ni/SNTs synthesized by wet impregnation and Ni/CNTs. See DOI: 10.1039/c4nr02096k

Applications of RIGAKU Dmax Rapid II micro-X-ray diffractometer in the analysis of archaeological metal objects

NASA Astrophysics Data System (ADS)

Mozgai, Viktória; Szabó, Máté; Bajnóczi, Bernadett; Weiszburg, Tamás G.; Fórizs, István; Mráv, Zsolt; Tóth, Mária

2017-04-01

During material analysis of archaeological metal objects, especially their inlays or corrosion products, not only microstructure and chemical composition, but mineralogical composition is necessary to be determined. X-ray powder diffraction (XRD) is a widely-used method to specify the mineralogical composition. However, when sampling is not or limitedly allowed due to e.g. the high value of the object, the conventional XRD analysis can hardly be used. Laboratory micro-XRD instruments provide good alternatives, like the RIGAKU Dmax Rapid II micro-X-ray diffractometer, which is a unique combination of a MicroMax-003 third generation microfocus, sealed tube X-ray generator and a curved 'image plate' detector. With this instrument it is possible to measure as small as 10 µm area in diameter on the object. Here we present case studies for the application of the micro-XRD technique in the study of archaeological metal objects. In the first case niello inlay of a Late Roman silver augur staff was analysed. Due to the high value of the object, since it is the only piece known from the Roman Empire, only non-destructive analyses were allowed. To reconstruct the preparation of the niello, SEM-EDX analysis was performed on the niello inlays to characterise their chemical composition and microstructure. Two types of niello are present: a homogeneous, silver sulphide niello (acanthite) and an inhomogeneous silver-copper sulphide niello (exsolution of acanthite and jalpaite or jalpaite and stromeyerite). The micro-X-ray diffractometer was used to verify the mineralogical composition of the niello, supposed on the base of SEM results. In the second case corrosion products of a Late Roman copper cauldron with uncertain provenance were examined, since they may hold clues about the burial conditions (pH, Eh, etc.) of the object. A layer by layer analysis was performed in cross sections of small metal samples by using electron microprobe and micro-X-ray diffractometer. The results show two corrosion zones: 1) the original (internal) surface zone of the metallic copper object was replaced by copper(I) oxide (cuprite), while 2) basic copper(II) carbonate (malachite) was deposited (externally) on the original surface. In our view these two minerals were formed during long-time burial, and protected the cauldron from further corrosion. Rarely copper(I) chloride (nantokite), basic copper(II) trihydroxychloride (atacamite/paratacamite) and basic copper(II) sulphate (brochantite) were also identified in the two corrosion zones. Their uneven distribution on the cauldron and their known formation conditions indicate, that these latter mineral phases may be the results of active corrosion, started possibly after excavation.

Rapid synthesis of rutile TiO2 nano-flowers by dealloying Cu60Ti30Y10 metallic glasses

NASA Astrophysics Data System (ADS)

Wang, Ning; Pan, Ye; Wu, Shikai; Zhang, Enming; Dai, Weiji

2018-01-01

The 3D nanostructure rutile TiO2 photocatalyst was rapidly synthesized by dealloying method using Cu60Ti30Y10 amorphous ribbons as precursors. The preparation period was kept down to just 3 h, which is much shorter than those of the samples by dealloying Cu60Ti30Al10, Cu70Ti30 and Cu60Ti30Sn10. The synthesized sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD and XPS reveal the successful synthesis of rutile TiO2. The SEM and TEM images show that the synthesized rutile TiO2 nano-material presents homogeneous distributed 3D nanoflowers structure, which is composed of large quantities of fine rice-like nanorods (40-150 nm in diameter and 100-250 nm in length). BET specific surface areas of the samples were investigated by N2 adsorption-desorption isotherms, the fabricated rutile TiO2 exhibits very high specific surface area (194.08 m2/g). The photocatalytic activities of the samples were evaluated by degrading rhodamine B (RhB) dye (10 mg/L) under the irradiation of both simulated visible light (λ > 420 nm) and ultraviolet (UV) light (λ = 365 nm). The results show that the photocatalytic activity of rutile TiO2 prepared by dealloying Cu60Ti30Y10 amorphous ribbons is higher than those of commercial rutile and the sample synthesized by dealloying Cu70Ti30 precursors. The advantages of both short preparation period and superior photocatalytic activity suggest that Cu60Ti30Y10 metallic glasses are really a kind of perfect titanium source for rapidly fabricating high efficient TiO2 nano-materials. In addition, the influence of chemical composition of the amorphous precursors on preparation period of the rutile TiO2 nano-material was investigated from the point of view of standard electrode potentials.

Preparation of Binary and Ternary Oxides by Molten Salt Method and its Electrochemical Properties

NASA Astrophysics Data System (ADS)

Reddy, M. V.; Theng, L. Pei; Soh, Hulbert; Beichen, Z.; Jiahuan, F.; Yu, C.; Ling, A. Yen; Andreea, L. Y.; Ng, C. H. Justin; Liang, T. J. L. Galen; Ian, M. F.; An, H. V. T.; Ramanathan, K.; Kevin, C. W. J.; Daryl, T. Y. W.; Hao, T. Yi; Loh, K. P.; Chowdari, B. V. R.

2013-07-01

We report simple binary oxides namely SnO2, TiO2, CuO, MnO2, Fe2O3, Co3O4 and ternary oxides like MnCo2O4 by molten salt method at a temperature range of 280°C to 950°C in air and discuss the effect of morphology, crystal structure and electrochemical properties of binary and ternary oxides. Materials were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area methods. XRD patterns showed all MSM prepared materials exhibited characteristic lattice parameter values. BET surface area varies depending on the nature of the material, molten salt and preparation temperature and the obtained values are in the range, 1 to 160 m2/g. Electrochemical properties were studied using cyclic voltammetry (CV) and electrochemical performance studies were carried in the voltage range, 0.005-1.0V for SnO2, 1.0-2.8V for TiO2 and Fe2O3, MCo2O4 (M = Co, Mn), MnO2 and CuO were cycled in the range, 0.005-3.0V. At a current rates of 30-100 mA/g and a scan rate of 0.058 mV/sec was used for galvanostatic cycling and cyclic voltammetry. SnO2 showed that an alloying-de-alloying reaction occurs at ˜0.2 and ˜0.5 V vs. Li. TiO2 main intercalation and de-interaction reactions at ˜1.7 and ˜1.8 V vs. Li. Co3O4, MnCo2O4, and MnO2 main discharge potentials at ˜1.2, 0.9V and 0.4V, resp. and charge potentials peak ˜2.0V and 1.5V vs. Li. CuO prepared at 750°C exhibited main anodic peak at ˜2.45V and cathodic peaks at ˜0.85V and ˜1.25V. We discussed the possible reaction mechanisms and Li-storage performance values in detail.

Ultrasonic assisted synthesis of Bikitaite zeolite: A potential material for hydrogen storage application.

PubMed

Roy, Priyanka; Das, Nandini

2017-05-01

Li containing Bikitaite zeolite has been synthesized by an ultrasound-assisted method and used as a potential material for hydrogen storage application. The Sonication energy was varied from 150W to 250W and irradiation time from 3h to 6h. The Bikitaite nanoparticles were characterized by X-ray diffraction (XRD), infrared (IR) spectral analysis, and field-emission scanning electron microscopy (FESEM) thermo-gravimetrical analysis and differential thermal analysis (TGA, DTA). XRD and IR results showed that phase pure, nano crystalline Bikitaite zeolites were started forming after 3h irradiation and 72h of aging with a sonication energy of 150W and nano crystalline Bikitaite zeolite with prominent peaks were obtained after 6h irradiation of 250W sonic energy. The Brunauer-Emmett-Teller (BET) surface area of the powder by N 2 adsorption-desorption measurements was found to be 209m 2 /g. The TEM micrograph and elemental analysis showed that desired atomic ratio of the zeolite was obtained after 6h irradiation. For comparison, sonochemical method, followed by the hydrothermal method, with same initial sol composition was studied. The effect of ultrasonic energy and irradiation time showed that with increasing sonication energy, and sonication time phase formation was almost completed. The FESEM images revealed that 50nm zeolite crystals were formed at room temperature. However, agglomerated particles having woollen ball like structure was obtained by sonochemical method followed by hydrothermal treatment at 100°C for 24h. The hydrogen adsorption capacity of Bikitaite zeolite with different Li content, has been investigated. Experimental results indicated that the hydrogen adsorption capacities were dominantly related to their surface areas as well as total pore volume of the zeolite. The hydrogen adsorption capacity of 143.2c.c/g was obtained at 77K and ambient pressure of (0.11MPa) for the Bikitaite zeolite with 100% Li, which was higher than the reported values for other zeolites. To the best of our knowledge, there is no report on the synthesis of a Bikitaite zeolite by sonochemical method for H 2 storage. Copyright © 2016. Published by Elsevier B.V.

Probing Phase Transformations and Microstructural Evolutions at the Small Scales: Synchrotron X-ray Microdiffraction for Advanced Applications in [Phase 3 Memory,] 3D IC (Integrated Circuits) and Solar PV (Photovoltaic) Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radchenko, I.; Tippabhotla, S. K.; Tamura, N.

2016-10-21

Synchrotron x-ray microdiffraction (μXRD) allows characterization of a crystalline material in small, localized volumes. Phase composition, crystal orientation and strain can all be probed in few-second time scales. Crystalline changes over a large areas can be also probed in a reasonable amount of time with submicron spatial resolution. However, despite all the listed capabilities, μXRD is mostly used to study pure materials but its application in actual device characterization is rather limited. This article will explore the recent developments of the μXRD technique illustrated with its advanced applications in microelectronic devices and solar photovoltaic systems. Application of μXRD in microelectronicsmore » will be illustrated by studying stress and microstructure evolution in Cu TSV (through silicon via) during and after annealing. Here, the approach allowing study of the microstructural evolution in the solder joint of crystalline Si solar cells due to thermal cycling will be also demonstrated.« less

Synthesis and photocatalytic properties of graphitic carbon nitride nanofibers using porous anodic alumina templates

NASA Astrophysics Data System (ADS)

Suchitra, S. M.; Udayashankar, N. K.

2017-12-01

In the present study, we describe an effective method for the synthesis of Graphitic carbon nitride (GCN) nanostructures using porous anodic alumina (AAO) membrane as template by simple thermal condensation of cyanamide. Synthesized nanostructure was fully analysed by various techniques to detect its crystalline nature, morphology, luminescent properties followed by the evaluation of its photocatalytic activity in the degradation of Methylene blue dye. Structural analysis of synthesized GCNNF was systematically carried out using x-ray powder diffraction (XRD) and scanning electron microscope (SEM), and. The results confirmed the growth of GCN inside the nanochannels of anodic alumina templates. Luminescent properties of GCNNF were studied using photoluminescence (PL) spectroscopy. PL analysis showed the presence of a strong emission peak in the wavelength range of 350-600 nm in blue region. GCNNF displays higher photocatalytic performance in the photodegradation of methylene blue compare to the bulk GCN. Highlights 1. In the present paper, we report the synthesis of graphitic carbon nitride nanofibers (GCNNF) using porous anodic aluminium oxide membranes as templates through thermal condensation of cyanamide at 500 °C. 2. The synthesis of Graphitic carbon nitride nanofibers using porous andic alumina template is the efficient approach for increasing crystallinity and surface area. 3. The high surface area of graphitic carbon nitride nanofibers has a good impact on novel optical and photocatalytic properties of the bulkGCN. 4. AAO templating of GCN is one of the versatile method to produce tailorable GCN nanostructures with higher surface area and less number of structural defects. 5. Towards photocatalytic degradation of dyes, the tuning of physical properties is very essential thing hence we are succeeded in achieving better catalytic performance of GCN nanostructures by making use of AAO templates.

Surface morphology and electrochemical studies on polyaniline/CuO nano composites

NASA Astrophysics Data System (ADS)

Ashokkumar, S. P.; Vijeth, H.; Yesappa, L.; Niranjana, M.; Vandana, M.; Basappa, M.; Devendrappa, H.

2018-05-01

An electrochemically synthesized Polyaniline (PANI) and Polyaniline/copper oxide (PCN) nano composite have studied the morphology and electrochemical properties. The composite is characterized by X-ray diffraction (XRD) and surface morphology was studied using FESEM and electrochemical behavior is studied using cyclic voltammetry (CV) technique. The CV curves shows rectangular shaped curve and they have contribution to electrical double layer capacitance (EDCL).

Catalytic oxidation of 1,2-DCBz over V2O5/TiO2-CNTs: effect of CNT diameter and surface functional groups.

PubMed

Du, Cuicui; Wang, Qiulin; Peng, Yaqi; Lu, Shengyong; Ji, Longjie; Ni, Mingjiang

2017-02-01

A series of V 2 O 5 /TiO 2 -carbon nanotube (CNT) catalysts were prepared and tested to decompose gaseous 1,2-dichlorobenzene (1,2-DCBz). Several physicochemical methods, including nitrogen adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and H 2 temperature-programmed reduction (TPR) were employed to characterise their physicochemical properties. To better understand the effect of CNT properties on the reactivity of V 2 O 5 /TiO 2 -CNT catalysts, the 1,2-DCBz residue remaining in the off-gas and on the catalyst surface were both collected and analysed. The results indicate that the outer diameter and the surface functional groups (hydroxide radical and carboxyl) of CNTs significantly influence upon the catalytic activity of CNT-containing V 2 O 5 /TiO 2 catalysts: the CNT outer diameter mainly affects the aggregation of CNTs and the π-π interaction between the benzene ring and CNTs, while the introduction of -OH and -COOH groups by acid treatment can further enlarge specific surface area (SSA) and contribute to a higher average oxidation state of vanadium (V aos ) and supplemental surface chemisorbed oxygen (O ads ). In addition, the enhanced mobility of lattice oxygen (O latt) also improves the oxidation ability of the catalysts.

Radiolytic hydrogen generation at silicon carbide-water interfaces

NASA Astrophysics Data System (ADS)

Schofield, Jennifer; Reiff, Sarah C.; Pimblott, Simon M.; LaVerne, Jay A.

2016-02-01

While many of the proposed uses of SiC in the nuclear industry involve systems that are assumed to be dry, almost all materials have dissociated chemisorbed water associated with their surface, which can undergo chemistry in radiation fields. Silicon carbide α-phase and β-phase nanoparticles with water were irradiated with γ-rays and 5 MeV 4He ions followed by the determination of the production of molecular hydrogen, H2, and characterization of changes in the particle surface. The yields of H2 from SiC-water slurries were always greater than expected from a simple mixture rule indicating that the presence of SiC was influencing the production of H2 from water, probably through an energy transfer from the solid to liquid phase. Although the increase in H2 yields was modest, a decrease in the water mass percentage led to an increase in H2 yields, especially for very low amounts of water. Surface analysis techniques included diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), nitrogen absorption with the Brunauer - Emmett - Teller (BET) methodology for surface area determination, X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Little change in the SiC surface was observed following radiolysis except for some conversion of β-phase SiC to the α-phase and the formation of SiO2 with He ion radiolysis.

The origin of high electrolyte-electrode interfacial resistances in lithium cells containing garnet type solid electrolytes.

PubMed

Cheng, Lei; Crumlin, Ethan J; Chen, Wei; Qiao, Ruimin; Hou, Huaming; Franz Lux, Simon; Zorba, Vassilia; Russo, Richard; Kostecki, Robert; Liu, Zhi; Persson, Kristin; Yang, Wanli; Cabana, Jordi; Richardson, Thomas; Chen, Guoying; Doeff, Marca

2014-09-14

Dense LLZO (Al-substituted Li7La3Zr2O12) pellets were processed in controlled atmospheres to investigate the relationships between the surface chemistry and interfacial behavior in lithium cells. Laser induced breakdown spectroscopy (LIBS), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, synchrotron X-ray photoelectron spectroscopy (XPS) and soft X-ray absorption spectroscopy (XAS) studies revealed that Li2CO3 was formed on the surface when LLZO pellets were exposed to air. The distribution and thickness of the Li2CO3 layer were estimated by a combination of bulk and surface sensitive techniques with various probing depths. First-principles thermodynamic calculations confirmed that LLZO has an energetic preference to form Li2CO3 in air. Exposure to air and the subsequent formation of Li2CO3 at the LLZO surface is the source of the high interfacial impedances observed in cells with lithium electrodes. Surface polishing can effectively remove Li2CO3 and dramatically improve the interfacial properties. Polished samples in lithium cells had an area specific resistance (ASR) of only 109 Ω cm(2) for the LLZO/Li interface, the lowest reported value for Al-substituted LLZO. Galvanostatic cycling results obtained from lithium symmetrical cells also suggest that the quality of the LLZO/lithium interface has a significant impact on the device lifetime.

A novel step towards immobilization of biocatalyst using agro waste and its application for ester synthesis.

PubMed

Tomke, Prerana D; Rathod, Virendra K

2018-05-04

This work explains the utilization of agro-waste (coconut and peanut shell) to produce mesoporous activated carbon which further utilized as a support material for lipase immobilization (Candida antarctica B, CALB). Various parameters affecting the binding of enzyme to activated carbon with high surface area (1603 m 2  g -1 ) were optimized. Maximum 200 μg g -1 CALB has been loaded at 40 °C and pH 6.8 in 12 h by using glutaraldehyde as a cross-linker. The operational parameters such as pH (5.8-8.8) and temperature (30-70 °C) were optimized for free and immobilized form of lipase. In thermal stability (50-70 °C) study, immobilization of enzyme showed 2.35 folds increased half-life with respect to free enzyme. The samples, before and after immobilization, were characterized by specific surface area, FT-IR, SEM, XRD. This immobilized lipase was successfully used for the synthesis of cinnamyl acetate by transesterification reaction producing 94% conversion in 60 min. Catalytic efficiency (58 ± 1.08) was seen to be retained for more than five consecutive cycles of chemical reaction for repeated applications. Sequential results towards activity retention were obtained upto 30 days of storability study. In the context, this process constitutes a clean route for the development of sustainable biocatalysts from agro waste, capable of applications in various area. Copyright © 2017. Published by Elsevier B.V.

Mg2+ Doped into Electro-synthesized HKUST-1 and Their Initial Hydrogen Sorption Properties

NASA Astrophysics Data System (ADS)

Lestari, W. W.; Ni'maturrohmah, D.; Arrozi, U. S. F.; Suwarno, H.

2018-01-01

The hydrogen storage materials are essentially play important roles in supporting the utilization of hydrogen as a promising alternative energy. Several innovative materials have been proposed and intensively investigated in this regard, including Metal-Organic Framework (MOFs). MOFs type HKUST-1 [Cu3(BTC)2] (BTC = benzene-tri-carboxylate) is the most explored materials in hydrogen storage. In this research, HKUST-1 was electro-synthesized under 15 volt for 1.5 h. This material was ex-situ modified with magnesium(II) ion with variation: 3, 5 and 10 wt% to add attractive sites for hydrogen to form Mg2+@HKUST-1. The final materials were characterized by XRD, FTIR, SEM-EDX, and SAA. Hydrogen sorption measurement was conducted using Sievert system at 30 and 80 °C with pressure from 0.2 to 1.5 bar in 10 minutes for each condition. According to XRD analysis, the basic structure of Mg2+@HKUST-1 was remaining stable. In contrary, SEM analysis showed that HKUST-1 morphology was changed after modification with Mg2+. In addition, the surface area of materials significantly increased from 372.112 to 757.617m2/g, based on SAA analysis. The presence of Mg2+ in the HKUST-1 increased the hydrogen sorption capacity up to 0.475 wt% at 1.4 bar at 30 °C and 0.256 wt% at 80 °C (1.4 bar).

Synthesis of ultrasmooth nanostructured diamond films by microwave plasma chemical vapor deposition using a He/H(2)/CH(4)/N(2) gas mixture.

PubMed

Chowdhury, S; Hillman, Damon A; Catledge, Shane A; Konovalov, Valery V; Vohra, Yogesh K

2006-10-01

Ultrasmooth nanostructured diamond (USND) films were synthesized on Ti-6Al-4V medical grade substrates by adding helium in H(2)/CH(4)/N(2) plasma and changing the N(2)/CH(4) gas flow from 0 to 0.6. We were able to deposit diamond films as smooth as 6 nm (root-mean-square), as measured by an atomic force microscopy (AFM) scan area of 2 μm(2). Grain size was 4-5 nm at 71% He in (H(2) + He) and N(2)/CH(4) gas flow ratio of 0.4 without deteriorating the hardness (~50-60 GPa). The characterization of the films was performed with AFM, scanning electron microscopy, x-ray diffraction (XRD), Raman spectroscopy, and nanoindentation techniques. XRD and Raman results showed the nanocrystalline nature of the diamond films. The plasma species during deposition were monitored by optical emission spectroscopy. With increasing N(2)/CH(4) feedgas ratio (CH(4) was fixed) in He/H(2)/CH(4)/N(2) plasma, a substantial increase of CN radical (normalized by Balmer H(α) line) was observed along with a drop in surface roughness up to a critical N(2)/CH(4) ratio of 0.4. The CN radical concentration in the plasma was thus correlated to the formation of ultrasmooth nanostructured diamond films.

Development of stress corrosion cracking resistant welds of 321 stainless steel by simple surface engineering

NASA Astrophysics Data System (ADS)

Mankari, Kamal; Acharyya, Swati Ghosh

2017-12-01

We hereby report a simple surface engineering technique to make AISI grade 321 stainless steel (SS) welds resistant to stress corrosion cracking (SCC) in chloride environment. Heat exchanger tubes of AISI 321 SS, welded either by (a) laser beam welding (LBW) or by (b) metal inert gas welding (MIG) were used for the study. The welds had high magnitude of tensile residual stresses and had undergone SCC in chloride environment while in service. The welds were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Subsequently, the welded surfaces were subjected to buffing operation followed by determination of residual stress distribution and surface roughness by XRD and surface profilometer measurements respectively. The susceptibility of the welds to SCC was tested in buffed and un-buffed condition as per ASTM G-36 in boiling MgCl2 for 5 h and 10 h, followed by microstructural characterization by using optical microscope and FESEM. The results showed that the buffed surfaces (both welds and base material) were resistant to SCC even after 10 h of exposure to boiling MgCl2 whereas the un-buffed surfaces underwent severe SCC for the same exposure time. Buffing imparted high magnitude of compressive stresses on the surface of stainless steel together with reduction in its surface roughness and reduction in plastic strain on the surface which made the welded surface, resistant to chloride assisted SCC. Buffing being a very simple, portable and economic technique can be easily adapted by the designers as the last step of component fabrication to make 321 stainless steel welds resistant to chloride assisted SCC.

Tuning the relative concentration ratio of bulk defects to surface defects in TiO2 nanocrystals leads to high photocatalytic efficiency.

PubMed

Kong, Ming; Li, Yuanzhi; Chen, Xiong; Tian, Tingting; Fang, Pengfei; Zheng, Feng; Zhao, Xiujian

2011-10-19

TiO(2) nanocrystals with tunable bulk/surface defects were synthesized and characterized with TEM, XRD, BET, positron annihilation, and photocurrent measurements. The effect of defects on photocatalytic activity was studied. It was found for the first time that decreasing the relative concentration ratio of bulk defects to surface defects in TiO(2) nanocrystals could significantly improve the separation efficiency of photogenerated electrons and holes, thus significantly enhancing the photocatalytic efficiency.

Sb:SnO2 thin films-synthesis and characterization

NASA Astrophysics Data System (ADS)

Bhadrapriya B., C.; Varghese, Anitta Rose; Amarendra, G.; Hussain, Shamima

2018-04-01

Transparent thin films of antimony doped SnO2 have been synthesized and characterized using optical spectroscopy, XRD, RAMAN and FESEM. The band gap of Sb doped tin oxide thin film samples were found to vary from 3.26 eV to 3.7 eV. The XRD peaks showed prominent rutile SnO2 peaks with diminished intensity due to antimony doping. A wide band in the range 550-580 cm-1 was observed in raman spectra and is a feature of nano-sized SnO2. SEM images showed flower-like structures on thin film surface, a characteristic feature of antimony.

Structural and magnetic analysis of Cu, Co substituted NiFe2O4 thin films

NASA Astrophysics Data System (ADS)

Sharma, Hakikat; Bala, Kanchan; Negi, N. S.

2016-05-01

In the present work we prepared NiFe2O4, Ni0.95Cu0.05Fe2O4 and Ni0.94Cu0.05Co0.01 Fe2O4 thin films by metallo-organic decomposition method (MOD) using spin coating technique. The thin films were analyzed by X-ray diffractometer (XRD) and Atomic force microscope (AFM) for structural studies. The XRD patterns confirmed the ferrite phase of thin films. From AFM, we analyzed surface morphology, calculated grain size (GS) and root mean square roughness (RMSR). Room temperature magnetic properties were investigated by vibrating sample magnetometer (VSM).

Operando XRD studies as a tool for determination of transport parameters of mobile ions in electrode materials

NASA Astrophysics Data System (ADS)

Kondracki, Łukasz; Kulka, Andrzej; Świerczek, Konrad; Ziąbka, Magdalena; Molenda, Janina

2017-11-01

In this work a detailed operando XRD investigations of structural properties of LixMn2O4 manganese spinel are shown to be a complementary, successful method of determination of diffusion coefficient D and surface exchange coefficient k in the working electrode. Kinetics of lithium ions transport are estimated on the basis of rate of structural changes of the cathode material during a relaxation stage after a high current charge, i.e. during structural relaxation of the material. The presented approach seems to be applicable as a complementary method of determination of transport coefficients for all intercalation-type electrode materials.

The Influence of the Interlayer Distance on the Performance of Thermally Reduced Graphene Oxide Supercapacitors.

PubMed

Lin, Jun-Hong

2018-02-08

In this paper, cationic surfactant cetyltrimethylammonium bromide (CTAB) was employed to prevent the restack of the thermally reduce graphene oxide (TRG) sheets. A facile approach was demonstrated to effectively enlarge the interlayer distance of the TRG sheets through the ionic interaction between the intercalated CTAB and ionic liquids (ILs). The morphology of the composites and the interaction between the intercalated ionic species were systematically characterized by SEM, SAXS, XRD, TGA, and FTIR. In addition, the performance of the EDLC cells based on these TRG composites was evaluated. It was found that due to the increased interlayer distance (0.41 nm to 2.51 nm) that enlarges the accessible surface area for the IL electrolyte, the energy density of the cell can be significantly improved (23.1 Wh/kg to 62.5 Wh/kg).

Synthesis and properties of ternary mixture of nickel/cobalt/tin oxides for supercapacitors

NASA Astrophysics Data System (ADS)

Ferreira, C. S.; Passos, R. R.; Pocrifka, L. A.

2014-12-01

The present study reports the synthesis and morphological, structural and electrochemical characterization of ternary oxides mixture containing nickel, cobalt and tin. The ternary oxide is synthesized by Pechini method with subsequent deposition onto a titanium substrate in a thin-film form. XRD and EDS analysis confirm the formation of ternary film with amorphous nature. SEM analysis show that cracks on the film favor the gain of the surface area that is an interesting feature for electrochemical capacitors. The ternary film is investigated in KOH electrolyte solution using cyclic voltammetry and charge-discharge study with a specific capacitance of 328 F g-1, and a capacitance retention of 86% over 600 cycles. The values of specific power and specific energy was 345.7 W kg-1 and 18.92 Wh kg-1, respectively.

Sonochemical fabrication of fluorinated mesoporous titanium dioxide microspheres

NASA Astrophysics Data System (ADS)

Yu, Changlin; Yu, Jimmy C.; Chan, Mui

2009-05-01

A sonochemical-hydrothermal method for preparing fluorinated mesoporous TiO 2 microspheres was developed. Formation of mesoporous TiO 2 and doping of fluorine was achieved by sonication and then hydrothermal treatment of a solution containing titanium isopropoxide, template, and sodium fluoride. The as-synthesized TiO 2 microspheres were characterized by X-ray diffraction (XRD), Fourier translation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, photoluminescence spectroscopy (PL), and BET surface areas. The P123 template was removed completely during the hydrothermal and washing steps, which was different from the conventional calcination treatment. The as- synthesized TiO 2 microspheres had good crystallinity and high stability. Results from the photocatalytic degradation of methylene blue (MB) showed that fluorination could remarkably improve the photocatalytic activity of titanium dioxide.

Powder properties of hydrogenated ball-milled graphite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Y., E-mail: y.zhang062012@gmail.com; Wedderburn, J.; Harris, R.

2014-12-15

Ball milling is an effective way of producing defective and nanostructured graphite. In this work, the hydrogen storage properties of graphite, ball-milled in a tungsten carbide milling pot under 3 bar hydrogen for various times (0–40 h), were investigated by TGA-Mass Spectrometry, XRD, SEM and laser diffraction particle size analysis. For the conditions used in this study, 10 h is the optimum milling time resulting in desorption of 5.5 wt% hydrogen upon heating under argon to 990 °C. After milling for 40 h, the graphite became significantly more disordered, and the amount of desorbed hydrogen decreased. After milling up tomore » 10 h, the BET surface area increased while particle size decreased; however, there is no apparent correlation between these parameters, and the hydrogen storage properties of the hydrogenated ball-milled graphite.« less

The Influence of the Interlayer Distance on the Performance of Thermally Reduced Graphene Oxide Supercapacitors

PubMed Central

Lin, Jun-Hong

2018-01-01

In this paper, cationic surfactant cetyltrimethylammonium bromide (CTAB) was employed to prevent the restack of the thermally reduce graphene oxide (TRG) sheets. A facile approach was demonstrated to effectively enlarge the interlayer distance of the TRG sheets through the ionic interaction between the intercalated CTAB and ionic liquids (ILs). The morphology of the composites and the interaction between the intercalated ionic species were systematically characterized by SEM, SAXS, XRD, TGA, and FTIR. In addition, the performance of the EDLC cells based on these TRG composites was evaluated. It was found that due to the increased interlayer distance (0.41 nm to 2.51 nm) that enlarges the accessible surface area for the IL electrolyte, the energy density of the cell can be significantly improved (23.1 Wh/kg to 62.5 Wh/kg). PMID:29419773

Microwave-assisted synthesis of Pt/CNT nanocomposite electrocatalysts for PEM fuel cells.

PubMed

Zhang, Weimin; Chen, Jun; Swiegers, Gerhard F; Ma, Zi-Feng; Wallace, Gordon G

2010-02-01

Microwave-assisted heating of functionalized, single-wall carbon nanotubes (FCNTs) in ethylene glycol solution containing H(2)PtCl(6), led to the reductive deposition of Pt nanoparticles (2.5-4 nm) over the FCNTs, yielding an active catalyst for proton-exchange membrane fuel cells (PEMFCs). In single-cell testing, the Pt/FCNT composites displayed a catalytic performance that was superior to Pt nanoparticles supported by raw (unfunctionalized) CNTs (RCNTs) or by carbon black (C), prepared under identical conditions. The supporting single-wall carbon nanotubes (SWNTs), functionalized with carboxyl groups, were studied by thermogravimetric analysis (TGA), cyclic voltammetry (CV), and Raman spectroscopy. The loading level, morphology, and crystallinity of the Pt/SWNT catalysts were determined using TGA, SEM, and XRD. The electrochemically active catalytic surface area of the Pt/FCNT catalysts was 72.9 m(2)/g-Pt.

Green synthesis of silica nanoparticles using sugarcane bagasse

NASA Astrophysics Data System (ADS)

Mohd, Nur Kamilah; Wee, Nik Nur Atiqah Nik; Azmi, Alyza A.

2017-09-01

Silica nanoparticles have been great attention as it being evaluated for used in abundant fields and applications. Due to this significance, this research was conducted to synthesis silica nanoparticles using local agricultural waste, sugarcane bagasse. We executed extraction and precipitation process as it involved low cost, less toxic and low energy process compared to other methods. The Infrared (IR) spectra showed the vibration peak of Si-O-Si, which clearly be the evidence for the silica characteristics in the sample. In this research, amorphous silica nanoparticles with spherical morphology with an average size of 30 nm, and specific surface area of 111 m2/g-1 have been successfully synthesized. The XRD patterns showed the amorphous nature of silica nanoparticles. As a comparison, the produced silica nanoparticles from sugarcane bagasse are compared with the respective nanoparticles synthesized using Stöber method.

Magnetic graphene oxide for adsorption of organic dyes from aqueous solution

NASA Astrophysics Data System (ADS)

Drashya, Lal, Shyam; Hooda, Sunita

2018-05-01

Graphene oxide (GO), a 2-D carbon nanomaterial, large surface area, oxygen-containing groups (like: hydroxyl, epoxy and carboxyl) and excellent water dispersibility due to it is good adsorbent dye removal from pollutant water1. But it's difficult to separate GO from water after adsorption. Therefore, Iron oxide was introduced in Graphene oxide by decorating method to make separation more efficient2. We present herein a one step process to prepare Magnetic Graphene oxide (MGO). The Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and Raman Spectroscopy characterized the chemical structure of the MGO composite. The adsorption of dyes onto MGO was studied in relation to initial concentration of Dyes, contact time, adsorbent dose, temperature and pH value of solution. We have studied adsorption capacity of different dyes (Methylene blue and crystal violet) by MGO.

Structural and optical properties of WTe2 single crystals synthesized by DVT technique

NASA Astrophysics Data System (ADS)

Dixit, Vijay; Vyas, Chirag; Pathak, V. M.; Soalanki, G. K.; Patel, K. D.

2018-05-01

Layered transition metal di-chalcogenide (LTMDCs) crystals have attracted much attention due to their potential in optoelectronic device applications recently due to realization of their monolayer based structures. In the present investigation we report growth of WTe2 single crystals by direct vapor transport (DVT) technique. These crystals are then characterized by energy dispersive analysis of x-rays (EDAX) to study stoichiometric composition after growth. The structural properties are studied by x-ray diffraction (XRD) and selected area electron diffraction (SAED) is used to confirm orthorhombic structure of grown WTe2 crystal. Surface morphological properties of the crystals are also studied by scanning electron microscope (SEM). The optical properties of the grown crystals are studied by UV-Visible spectroscopy which gives direct band gap of 1.44 eV for grown WTe2 single crystals.

Photocatalytic Performance of a Novel MOF/BiFeO₃ Composite.

PubMed

Si, Yunhui; Li, Yayun; Zou, Jizhao; Xiong, Xinbo; Zeng, Xierong; Zhou, Ji

2017-10-10

In this study, MOF/BiFeO₃ composite (MOF, metal-organic framework) has been synthesized successfully through a one-pot hydrothermal method. The MOF/BiFeO₃ composite samples, pure MOF samples and BiFeO₃ samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and by UV-vis spectrophotometry. The results and analysis reveal that MOF/BiFeO₃ composite has better photocatalytic behavior for methylene blue (MB) compared to pure MOF and pure BiFeO₃. The enhancement of photocatalytic performance should be due to the introduction of MOF change the surface morphology of BiFeO 3, which will increase the contact area with MB. This composing strategy of MOF/BiFeO₃ composite may bring new insight into the designing of highly efficient photocatalysts.

Synthesis and adsorption properties of flower-like layered double hydroxide by a facile one-pot reaction with an eggshell membrane as assistant

NASA Astrophysics Data System (ADS)

Li, Songnan; Zhang, Jiawei; Jamil, Saba; Cai, Qinghai; Zang, Shuying

In this paper, flower-like layered double hydroxides were synthesized with eggshell membrane assistant. The as-prepared samples were characterized by a series of techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermal gravity-differential thermal analysis and Nitrogen sorption/desorption. The resulting layered double hydroxides were composed of nanoplates with edge-to-face particle interactions. The specific surface area and total pore volume of the as-prepared flower-like layered double hydroxides were 160m2/g and 0.65m3/g, respectively. The adsorption capacity of flower-like layered double hydroxides to Congo Red was 258mg/g, which was higher than that of layered double hydroxides synthesized by the traditional method.

Silicon-on-insulator with hybrid orientations for heterogeneous integration of GaN on Si (100) substrate

NASA Astrophysics Data System (ADS)

Zhang, Runchun; Zhao, Beiji; Huang, Kai; You, Tiangui; Jia, Qi; Lin, Jiajie; Zhang, Shibin; Yan, Youquan; Yi, Ailun; Zhou, Min; Ou, Xin

2018-05-01

Heterogeneous integration of materials pave a new way for the development of the microsystem with miniaturization and complex functionalities. Two types of hybrid silicon on insulator (SOI) structures, i.e., Si (100)-on-Si (111) and Si (111)-on-Si (100), were prepared by the smart-cut technique, which is consist of ion-slicing and wafer bonding. The precise calculation of the lattice strain of the transferred films without the epitaxial matching relationship to the substrate was demonstrated based on X-ray diffraction (XRD) measurements. The XRD and Raman measurement results suggest that the transferred films possess single crystalline quality. With a chemical mechanical polishing (CMP) process, the surface roughness of the transferred thin films can be reduced from 5.57 nm to 0.30 nm. The 4-inch GaN thin film epitaxially grown on the as-prepared hybrid SOI of Si (111)-on-Si (100) by metalorganic chemical vapor deposition (MOCVD) is of improved quality with a full width at half maximum (FWHM) of 672.54 arcsec extracted from the XRD rocking curve and small surface roughness of 0.40 nm. The wafer-scale GaN on Si (111)-on-Si (100) can serve as a potential platform for the one chip integration of GaN-based high electron mobility transistors (HEMT) or photonics with the Si (100)-based complementary metal oxide semiconductor (CMOS).

Zinc-Containing Hydroxyapatite Enhances Cold-Light-Activated Tooth Bleaching Treatment In Vitro

PubMed Central

Shi, Xinchang

2017-01-01

Cold-light bleaching treatment has grown to be a popular tooth whitening procedure in recent years, but its side effect of dental enamel demineralization is a widespread problem. The aim of this study was to synthesize zinc-substituted hydroxyapatite as an effective biomaterial to inhibit demineralization or increase remineralization. We synthesized zinc-substituted hydroxyapatite containing different zinc concentrations and analysed the product using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and energy dispersive spectrometer (EDS). The biological assessment of Zn-HA was conducted by CCK-8 assay and bacterial inhibition tests. pH cycling was performed to estimate the effect of Zn-HA on the enamel surface after cold-light bleaching treatment. The XRD, FTIR, and EDS results illustrated that zinc ions and hydroxyapatite combined in two forms: (1) Zn2+ absorbed on the surface of HA crystal and (2) Zn2+ incorporated into the lattice of HA. The results indicated that 2% Zn-HA, 4% Zn-HA, and 8% Zn-HA effectively inhibited the growth of bacteria yet showed poor biocompatibility, whereas 1% Zn-HA positively affected osteoblast proliferation. The XRD and scanning electron microscopy (SEM) results showed that the use of Zn-HA in pH cycling is obviously beneficial for enamel remineralization. Zinc-substituted hydroxyapatite could be a promising biomaterial for use in cold-light bleaching to prevent enamel demineralization. PMID:29159178

Cd(II) removal on surface-modified activated carbon: equilibrium, kinetics and mechanism.

PubMed

Liang, Jianjun; Liu, Meiling; Zhang, Yufei

2016-10-01

Commercial pulverous activated carbon (AC-0) was modified through two steps: oxidize AC-0 acid firstly, impregnate it with iron using ferric chloride secondly. Orthogonal experiment was conducted then to prepare modified activated carbon with high Cd(II) adsorption capacity (ACNF). Batch adsorption experiments were undertaken to determine the adsorption characteristics of Cd(II) from aqueous solution onto AC-0 and ACNF and the effect of pH, contact time and initial Cd(II) concentration. The results indicate that: the adsorption behavior of Cd(II) on ACNF can be well fitted with Langmuir model, and the maximum adsorption capacity of ACNF was 2.3 times higher than that of AC-0, supporting a monolayer coverage of Cd(II) on the surface. The kinetics of the adsorption process can be described by pseudo-second-order rate equation very well, and the adsorption capacity increased from 0.810 mg/g to 0.960 mg/g after modification. Compared with AC-0, the kinetic parameters of ACNF showed a higher adsorption rate through the aqueous solution to the solid surface and a lower intraparticle diffusion rate. Surface modification resulted in a lower Brunauer-Emmett-Teller (BET) surface area and pore size because of the collapse and blockage of pores, according to the X-ray diffraction (XRD) analysis, while the total number of surface oxygen acid groups increased, and this was supposed to contribute to the enhanced adsorption capacity of modified activated carbon.

A contrastive study of three graphite anodes in the piperidinium based electrolytes for lithium ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Xiao-Tao; Wang, Chen-Yi; Gao, Kun, E-mail: gaokun0451@163.com

Graphical abstract: The fitting results of R{sub sei} and R{sub ct} of three graphite/Li cells. Besides three graphite/Li cells show the similar R{sub sei}, the NG198/Li cell demonstrates a higher R{sub ct} value in all test temperatures. Especially, the R{sub ct} at 333 K is even up to 355.8 Ω cm{sup 2}. Obviously, the narrow distribution of edge plane for NG198 caused this result, and then greatly restricts its cell capacity. By contrast, CMB with bigger specific surface area and more Li{sup +} insertion points shows lower resistance at room temperature, which should help to improve its capacity. - Highlights:more » • SEI film is closely related to graphite structures and formation temperature. • The graphite with bigger surface area and more Li{sup +} insertion points behaves better. • The graphite with narrow edge plane is uncompetitive for ionic liquid electrolyte. - Abstract: The electrochemical behaviors of natural graphite (NG198), artificial graphite (AG360) and carbon microbeads (CMB) in an ionic liquid based electrolyte are investigated by cyclic voltammetry (CV). The surface and structure of three graphite materials are characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) before and after cycling. It is found that solid electrolyte interface (SEI) is closely related to graphite structure. Benefiting from larger specific surface area and more dispersed Li{sup +} insertion points, CMB shows a better Li{sup +} insertion/de-insertion behavior than NG198 and AG360. Furthermore, electrochemical impedance spectra (EIS) prove that the SEI of different graphite electrodes has different intrinsic resistance and Li{sup +} penetrability. By comparison, CMB behaves better cell performances than AG360, while the narrow edge plane makes NG198 uncompetitive as a potential anode for the ionic liquids (ILs)-type Li-ion battery.« less

Mechanisms and efficiency of the simultaneous removal of metals and cyanides by using ferrate(VI): crucial roles of nanocrystalline iron(III) oxyhydroxides and metal carbonates.

PubMed

Filip, Jan; Yngard, Ria A; Siskova, Karolina; Marusak, Zdenek; Ettler, Vojtech; Sajdl, Petr; Sharma, Virender K; Zboril, Radek

2011-08-29

The reaction of potassium ferrate(VI), K(2)FeO(4), with weak-acid dissociable cyanides--namely, K(2)[Zn(CN)(4)], K(2)[Cd(CN)(4)], K(2)[Ni(CN)(4)], and K(3)[Cu(CN)(4)]--results in the formation of iron(III) oxyhydroxide nanoparticles that differ in size, crystal structure, and surface area. During cyanide oxidation and the simultaneous reduction of iron(VI), zinc(II), copper(II), and cadmium(II), metallic ions are almost completely removed from solution due to their coprecipitation with the iron(III) oxyhydroxides including 2-line ferrihydrite, 7-line ferrihydrite, and/or goethite. Based on the results of XRD, Mössbauer and IR spectroscopies, as well as TEM, X-ray photoelectron emission spectroscopy, and Brunauer-Emmett-Teller measurements, we suggest three scavenging mechanisms for the removal of metals including their incorporation into the ferrihydrite crystal structure, the formation of a separate phase, and their adsorption onto the precipitate surface. Zn and Cu are preferentially and almost completely incorporated into the crystal structure of the iron(III) oxyhydroxides; the formation of the Cd-bearing, X-ray amorphous phase, together with Cd carbonate is the principal mechanism of Cd removal. Interestingly, Ni remains predominantly in solution due to the key role of nickel(II) carbonate, which exhibits a solubility product constant several orders of magnitude higher than the carbonates of the other metals. Traces of Ni, identified in the iron(III) precipitate, are exclusively adsorbed onto the large surface area of nanoparticles. We discuss the relationship between the crystal structure of iron(III) oxyhydroxides and the mechanism of metal removal, as well as the linear relationship observed between the rate constant and the surface area of precipitates. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oriented Nucleation of both Ge-Fresnoite and Benitoite/BaGe4O9 during the Surface Crystallisation of Glass Studied by Electron Backscatter Diffraction

PubMed Central

Wisniewski, Wolfgang; Patschger, Marek; Murdzheva, Steliana; Thieme, Christian; Rüssel, Christian

2016-01-01

Two glasses of the compositions 2 BaO - TiO2 - 2.75 GeO2 and 2 BaO – TiO2 –3.67 GeO2 (also known as BTG55) are annealed at temperatures from 680 to 970 °C to induce surface crystallization. The resulting samples are analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) including electron backscatter diffraction (EBSD). Ge-Fresnoite (Ba2TiGe2O8, BTG) is observed at the immediate surface of all samples and oriented nucleation is proven in both compositions. After a very fast kinetic selection, the crystal growth of BTG into the bulk occurs via highly oriented dendrites where the c-axes are oriented perpendicular to the surface. The growth of this oriented layer is finally blocked by dendritc BTG originating from bulk nucleation. The secondary phases BaTiGe3O9 (benitoite) and BaGe4O9 are also identified near the surface by XRD and localized by EBSD which additionally indicates orientation preferences for these phases. This behaviour is in contrast with previous reports from the Ba2TiSi2O8 as well as the Sr2TiSi2O8 systems. PMID:26853738

Optimization and Surface Modification of Al-6351 Alloy Using SiC-Cu Green Compact Electrode by Electro Discharge Coating Process

NASA Astrophysics Data System (ADS)

Chakraborty, Sujoy; Kar, Siddhartha; Dey, Vidyut; Ghosh, Subrata Kumar

2017-06-01

This paper introduces the surface modification of Al-6351 alloy by green compact SiC-Cu electrode using electro-discharge coating (EDC) process. A Taguchi L-16 orthogonal array is employed to investigate the process by varying tool parameters like composition and compaction load and electro-discharge machining (EDM) parameters like pulse-on time and peak current. Material deposition rate (MDR), tool wear rate (TWR) and surface roughness (SR) are measured on the coated specimens. An optimum condition is achieved by formulating overall evaluation criteria (OEC), which combines multi-objective task into a single index. The signal-to-noise (S/N) ratio, and the analysis of variance (ANOVA) is employed to investigate the effect of relevant process parameters. A confirmation test is conducted based on optimal process parameters and experimental results are provided to illustrate the effectiveness of this approach. The modified surface is characterized by optical microscope and X-ray diffraction (XRD) analysis. XRD analysis of the deposited layer confirmed the transfer of tool materials to the work surface and formation of inter-metallic phases. The micro-hardness of the resulting composite layer is also measured which is 1.5-3 times more than work material’s one and highest layer thickness (LT) of 83.644μm has been successfully achieved.

An evaluation of controlled permeability formwork for long-term durability of structural concrete elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suryavanshi, A.K.; Swamy, R.N.

1997-07-01

The long-term performance of a concrete slab (CPF slab) exposed to chloride ingress and atmospheric carbonation from the surface generated by controlled permeability formwork (CPF) is investigated. The results are compared with a similar slab exposed to long-term chloride ingress and atmospheric carbonation from the cast face (Control slab). Techniques such as X-ray diffraction (XRD) and differential thermal analyses (DTA) were employed to determine the resistance against carbonation while, mercury porosimetry was used for investigating the pore size distribution at the surface of the slabs. Amount of acid soluble chlorides was determined by using Volhard`s method. The CPF employed atmore » the bottom of the mould was not fully effective in its intended purpose of generating a permanent and dense impermeable concrete layer adjacent to it when the design water-cement (w/c) ration of the concrete mix was 0.60. This resulted in an almost similar extent of carbonation at the surface for both CPF and control slabs as shown by XRD and DTA studies. Similarly, there were no significant differences in the amount of chlorides and their depths of penetration for both CPF and control slabs, although the former was marginally superior in chloride penetration resistance at the surface.« less

Allyl triphenyl phosphonium bromide based DES-functionalized carbon nanotubes for the removal of mercury from water.

PubMed

AlOmar, Mohamed Khalid; Alsaadi, Mohammed Abdulhakim; Hayyan, Maan; Akib, Shatirah; Ibrahim, Muhammad; Hashim, Mohd Ali

2017-01-01

Recently, deep eutectic solvents (DESs) have shown their new and interesting ability for chemistry through their involvement in variety of applications. This study introduces carbon nanotubes (CNTs) functionalized with DES as a novel adsorbent for Hg 2+ from water. Allyl triphenyl phosphonium bromide (ATPB) was combined with glycerol as the hydrogen bond donor (HBD) to form DES, which can act as a novel CNTs functionalization agent. The novel adsorbent was characterized using Raman, FTIR, XRD, FESEM, EDX, BET surface area, TGA, TEM and Zeta potential. Response surface methodology was used to optimize the removal conditions for Hg 2+ . The optimum removal conditions were found to be pH 5.5, contact time 28 min, and an adsorbent dosage of 5 mg. Freundlich isotherm model described the adsorption isotherm of the novel adsorbent, and the maximum adsorption capacity obtained from the experimental data was 186.97 mg g -1 . Pseudo-second order kinetics describes the adsorption rate order. Copyright © 2016 Elsevier Ltd. All rights reserved.

Unzipping of multi-wall carbon nanotubes with different diameter distributions: Effect on few-layer graphene oxide obtention

NASA Astrophysics Data System (ADS)

Torres, D.; Pinilla, J. L.; Suelves, I.

2017-12-01

Few-layer graphene oxide (FLGO) was obtained by chemical unzipping of multi-wall carbon nanotubes (MWCNT) of different diameter distributions. MWCNT were synthesized by catalytic decomposition of methane using Fe-Mo/MgO catalysts. The variation in the Fe/Mo ratio (1, 2 and 5) was very influential in MWCNT diameter distribution and type of MWCNT obtained, including textural, chemical, structural and morphological characteristics. MWCNT diameter distribution and surface defects content had a profound impact on the characteristics of the resulting FLGO. Thus, MWCNT obtained with the catalyst with a Fe/Mo: 5 and presenting a narrow diameter distribution centered at 8.6 ± 3.3 nm led to FLGO maintaining non-oxidized graphite stacking (according to XRD analysis), lower specific surface area and higher thermostability as compared to FLGO obtained from MWCNT showing wider diameter distributions. The presence of more oxygen-containing functionalities and structural defects in large diameter nanotubes promotes the intercalation of species towards the inner layers of the nanotube, resulting in an enhanced MWCNT oxidation and opening into FLGO, what improves both micro- and mesoporosity.

A low cost preparation of WO3 nanospheres film with improved thermal stability of gasochromic and its application in smart windows

NASA Astrophysics Data System (ADS)

Zhou, Baoyu; Feng, Wei; Gao, Guohua; Wu, Guangming; Chen, Yue; Li, Wen

2017-11-01

Porous WO3 nanospheres film was successfully synthesized by employing a low-cost and facile template-assisted sol-gel method. The effects of template agent (Pluronic F127) on structure, morphology and specific surface area were systematically studied by Fourier transform infrared (FTIR), x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and N2 physisorption. It was found that F127 played a significant role in governing the morphology of WO3 sol clusters, and the optimal post-processing for ‘naked’ WO3 nanospheres film is acetone extraction and subsequent annealing treatment at 350 °C. As anticipated, the relative fast coloring/bleaching rates of WO3 nanospheres film are believed to be the results of porous microstructure and nanocrystalline, where provides much surface active position (166 m2 g-1) and shortens the proton diffusion distance. We believe that this unique approach to synthesize nanospheres structure may has beneficial effects on applications which also are based on insertion/extraction and diffusion abilities, such as supercapacitor, batteries and gas sensors.

Thin film rechargeable electrodes based on conductive blends of nanostructured olivine LiFePO4 and sucrose derived nanocarbons for lithium ion batteries.

PubMed

Praveen, P; Jyothsna, U; Nair, Priya; Ravi, Soumya; Balakrishnan, A; Subramanian, K R V; Nair, A Sreekumaran; Nair, V Shantikumar; Sivakumar, N

2013-08-01

The present study provides the first reports of a novel approach of electrophoretic co-deposition technique by which titanium foils are coated with LiFePO4-carbon nanocomposites synthesized by sol gel route and processed into high-surface area cathodes for lithium ion batteries. The study elucidates how sucrose additions as carbon source can affect the surface morphology and the redox reaction behaviors underlying these cathodes and thereby enhance the battery performance. The phase and morphological analysis were done using XRD and XPS where the LiFePO4 formed was confirmed to be a high purity orthorhombic system. From the analysis of the relevant electrochemical parameters using cyclic voltammetry and electrochemical impedance spectroscopy, a 20% increment and 90% decrement in capacity and impedance values were observed respectively. The composite electrodes also exhibited a specific capacity of 130 mA h/g. It has been shown that cathodes based on such composite systems can allow significant room for improvement in the cycling performance at the electrode/electrolyte interface.

Acetone sensors based on microsheet-assembled hierarchical Fe2O3 with different Fe3+ concentrations

NASA Astrophysics Data System (ADS)

Wang, Han; Yan, Lei; Li, Shuo; Li, Yu; Liu, Li; Du, Liting; Duan, Haojie; Cheng, Yali

2018-02-01

Several different morphologies of microsheet-assembled Fe2O3 have been fabricated by hydrothermal method using diverse concentrations of Fe3+ precursor solutions (0.025, 0.020, 0.015, 0.010 mol/L Fe3+). The as-synthesized materials have been characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), and energy-dispersive X-ray spectrometry (EDS). The SEM images reflect that the morphologies of as-synthesized materials are affected by the concentrations of Fe3+ in precursor solutions. The less concentration of Fe3+, the more porous of Fe2O3 microflowers, and thinner of slices distributed on the surface. Furthermore, gas sensors based on these Fe2O3 microflowers manufactured and tested to various common gases. The optimum response value to 100 ppm acetone is 52 at the working temperature of 220 °C. Meanwhile, the Fe2O3 microflower sensors possess ultrafast response-recovery speed, which are 8 and 19 s, respectively. The possible sensing mechanism was mainly attributed to the high surface area, three-dimensional porous structure.

Effective visible light-active boron and europium co-doped BiVO4 synthesized by sol-gel method for photodegradion of methyl orange.

PubMed

Wang, Min; Che, Yinsheng; Niu, Chao; Dang, Mingyan; Dong, Duo

2013-11-15

Eu-B co-doped BiVO4 visible-light-driven photocatalysts have been synthesized using the sol-gel method. The resulting materials were characterized by a series of joint techniques, including XPS, XRD, SEM, BET, and UV-vis DRS analyses. Compared with BiVO4 and B-BiVO4 photocatalysts, the Eu-B-BiVO4 photocatalysts exhibited much higher photocatalytic activity for methyl orange (MO) degradation under visible light irradiation. The optimal Eu doping content is 0.8 mol%. It was revealed that boron and europium were doped into the lattice of BiVO4 and this led to more surface oxygen vacancies, high specific surface areas, small crystallite size, a narrower band gap and intense light absorbance in the visible region. The doped Eu(III) cations can help in the separation of photogenerated electrons. The synergistic effects of boron and europium in doped BiVO4 were the main reason for improving visible light photocatalytic activity. Copyright © 2013 Elsevier B.V. All rights reserved.

Estimation of Supraglacial Dust and Debris Geochemical Composition via Satellite Reflectance and Emissivity

NASA Technical Reports Server (NTRS)

Casey, Kimberly Ann; Kaab, Andreas

2012-01-01

We demonstrate spectral estimation of supraglacial dust, debris, ash and tephra geochemical composition from glaciers and ice fields in Iceland, Nepal, New Zealand and Switzerland. Surface glacier material was collected and analyzed via X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD) for geochemical composition and mineralogy. In situ data was used as ground truth for comparison with satellite derived geochemical results. Supraglacial debris spectral response patterns and emissivity-derived silica weight percent are presented. Qualitative spectral response patterns agreed well with XRF elemental abundances. Quantitative emissivity estimates of supraglacial SiO2 in continental areas were 67% (Switzerland) and 68% (Nepal), while volcanic supraglacial SiO2 averages were 58% (Iceland) and 56% (New Zealand), yielding general agreement. Ablation season supraglacial temperature variation due to differing dust and debris type and coverage was also investigated, with surface debris temperatures ranging from 5.9 to 26.6 C in the study regions. Applications of the supraglacial geochemical reflective and emissive characterization methods include glacier areal extent mapping, debris source identification, glacier kinematics and glacier energy balance considerations.

Biocompatible cephalosporin-hydroxyapatite-poly(lactic-co-glycolic acid)-coatings fabricated by MAPLE technique for the prevention of bone implant associated infections

NASA Astrophysics Data System (ADS)

Rădulescu, Dragoş; Grumezescu, Valentina; Andronescu, Ecaterina; Holban, Alina Maria; Grumezescu, Alexandru Mihai; Socol, Gabriel; Oprea, Alexandra Elena; Rădulescu, Marius; Surdu, Adrian; Trusca, Roxana; Rădulescu, Radu; Chifiriuc, Mariana Carmen; Stan, Miruna S.; Constanda, Sabrina; Dinischiotu, Anca

2016-06-01

In this study we aimed to obtain functionalized thin films based on hydroxyapatite/poly(lactic-co-glycolic acid) (HAp/PLGA) containing ceftriaxone/cefuroxime antibiotics (ATBs) deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. The prepared thin films were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-Ray diffraction (XRD), selected area electron diffraction (SAED), and infra red (IR) analysis. HAp/PLGA/ATBs thin films sustained the growth of human osteoblasts, proving their good biocompatibility. The microscopic evaluation and the culture-based quantitative assay of the E. coli biofilm development showed that the thin films inhibited the initial step of microbial attachment as well as the subsequent colonization and biofilm development on the respective surfaces. This study demonstrates that MAPLE technique could represent an appealing technique for the fabrication of antibiotics-containing polymeric implant coatings. The bioevaluation results recommend this type of surfaces for the prevention of bone implant microbial contamination and for the enhanced stimulation of the implant osseointegration process.

Comparison of characteristics of montmorillonite supported nano zero valent iron (M-nZVI) and nano zero valent iron (nZVI)

NASA Astrophysics Data System (ADS)

How, Ho Kuok; Wan Zuhairi W., Y.

2015-09-01

In this study, synthesized montmorillonite supported nano zero valent iron (M-nZVI) and nano zero valent iron (nZVI) are compared physically and chemically. The samples were prepared using chemical reduction method that includes sodium borohydride and ethanol. Due to the tendency of nZVI to aggregate, montmorillonite is used as a supporting material. TEM and FESEM images show that the M-nZVI has decreased the aggregation by dispersing the particles on the surface of montmorillonite whereas images of nZVI show chain-like particle due to aggregation. Both images also show particles synthesized are nanoparticles. With less aggregation, the surface area of the M-nZVI is greater than nZVI which is 45.46 m2/g and 10.49 m2/g respectively. XRD patterns have shown Fe0 are synthesized and small amount of iron oxides are produced. M-nZVI has the capability in reducing aggregation which might lead to the increase in reactivity of the particles thus enhancing the performance of nZVI.

Graphene oxide/MnO2 nanocomposite as destructive adsorbent of nerve-agent simulants in aqueous media

NASA Astrophysics Data System (ADS)

Šťastný, Martin; Tolasz, Jakub; Štengl, Václav; Henych, Jiří; Žižka, David

2017-08-01

Graphene oxide/MnO2 nanocomposite was prepared by thermal hydrolysis of potassium permanganate (KMnO4) and 2-chloroacetamide aqueous solutions with graphene oxide (GO) suspension. The synthesized samples were characterized by specific surface area (BET) and porosity determination (BJH), X-ray Diffraction (XRD) and high-resolution electron microscopes (HRSEM, HRTEM). These nanocomposites were used in an experimental evaluation of their adsorption activity with nerve agent simulants dimethyl methyl phosphonate (DMMP) and triethyl phosphate (TEP) in aqueous media. The nanocomposites exhibited enhanced adsorptive degradation ability compared to pure manganese oxide (MnO2) and GO. The GO amount in the nanocomposites affected their degradation activity substantially. The best adsorption efficiency was observed for samples with moderate GO amount. Three methods were used to observe the mechanism of the nerve-agent simulants deactivation: Gas chromatography with mass spectrometry (GC-MS), High-Performance Liquid Chromatography (HPLC) and in situ Infrared spectroscopy (FTIR). It was shown that the hydrolysis on the surface of prepared nanocomposites yields volatile primary alcohols (methanol and ethanol) as the main hydrolysis products.

Enhancing the photocatalytic degradation of Fe-Ti over SiO2 nanocomposite material for paraquat removal

NASA Astrophysics Data System (ADS)

Kruanetr, Senee; Wanchanthuek, Ratchaneekorn

2018-05-01

The effect of Fe and Ti loaded over SiO2 (called FeTi/SiO2) in paraquat degradation was studied for both the catalytic activity and the catalyst surface properties. Sufficient characterization techniques were used to obtain the physical and chemical properties of the FeTi/SiO2 system, such as the adsorption-desorption isotherm, surface area and porous structure, XRD diffraction, FTIR spectroscopy, UV–vis diffuse reflection spectrometry and XPS spectroscopy. The catalytic activity in paraquat degradation studies showed that the bimetallic Fe-Ti over SiO2 had higher activity than the monometallic of either Fe or Ti over SiO2 and also the order of the Fe and Ti loading was the significant parameter affecting the activity. The XPS showed that the level of Fe3+ over the catalyst was related to the obtained activity. Moreover, the optimum Fe:Ti ratio in the FeTi/SiO2 system was 1:1 (by weight). Finally, the effect of the support pretreatment (SiO2 pretreatment) was studied and showed a negative effect on the expressed activity.

Soot Combustion over Nanostructured Ceria with Different Morphologies

PubMed Central

Zhang, Wen; Niu, Xiaoyu; Chen, Liqiang; Yuan, Fulong; Zhu, Yujun

2016-01-01

In this study, nano-structure ceria with three different morphologies (nanorod, nanoparticle and flake) have been prepared by hydrothermal and solvothermal methods. The ceria samples were deeply characterized by XRD, SEM, TEM, H2-TPR, XPS and in-situ DRIFTS, and tested for soot combustion in absence/presence NO atmospheres under loose and tight contact conditions. The prepared ceria samples exhibit excellent catalytic activities, especially, the CeO2 with nanorod (Ce-R) shows the best catalytic activity, for which the peak temperature of soot combustion (Tm) is about 500 and 368 °C in loose and tight contact conditions, respectively. The catalytic activity for Ce-R is higher than that of the reported CeO2 catalysts and reaches a level that of precious metals. The characterization results reveal that the maximal amounts of adsorbed oxygen species on the surface of the nanostructure Ce-R catalyst should be the crucial role to decide the catalytic soot performance. High BET surface area may also be a positive effect on soot oxidation activity under loose contact conditions. PMID:27353143

Visible light assisted photoelectrocatalytic degradation of sugarcane factory wastewater by sprayed CZTS thin films

NASA Astrophysics Data System (ADS)

Hunge, Y. M.; Mahadik, M. A.; Patil, V. L.; Pawar, A. R.; Gadakh, S. R.; Moholkar, A. V.; Patil, P. S.; Bhosale, C. H.

2017-12-01

Highly crystalline Cu2ZnSnS4 (CZTS) thin films have been deposited onto glass and FTO coated glass substrates by simple chemical spray-pyrolysis technique. It is an important material for solar energy conversion through the both photovoltaics and photocatalysis. The effect of substrate temperatures on the physico-chemical properties of the CZTS films is studied. The XRD study shows the formation of single phase CZTS with kesterite structure. FE-SEM analysis reveals nano flakes architecture with pin-hole and crake free surface with more adherent. The film deposited at optimized substrate temperature exhibits optical band gap energy of 1.90 eV, which lies in the visible region of the solar spectrum and useful for photocatalysis application. The photoelectrocatalytic activities of the large surface area (10 × 10 cm2) deposited CZTS thin film photocatalysts were evaluated for the degradation of sugarcane factory wastewater under visible light irradiation. The results show that the CZTS thin film photocatalyst exhibited about 90% degradation of sugar cane factory wastewater. The mineralization of sugarcane factory wastewater is studied by measuring chemical oxygen demand (COD) values.

The functionalization and characterization of multi-walled carbon nanotubes (MWCNTs)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdullah, Mohd Pauzi; Center of Water Analysis and Research; Zulkepli, Siti Aminah

2015-09-25

Functionalization is the process of introducing chemical functional groups on the surface of the material. In this study, a multi-walled carbon nanotube (MWCNTs) was functionalized by oxidation treatment using concentrated nitric acid. The functionalized and pristine MWCNTs were analyzed by using Fourier Transform Infrared Spectroscopy (FT-IR) and X-Ray Diffraction (XRD). The XRD patterns exhibit the graphitic properties for all samples. Besides, the XRD results also demonstrate that the percent of crystallinity of MWCNTs increases as the duration of acid treatment increases. The percent of crystallinity increases from 66% to 80% when the pristine MWCNT treated for 12 hours with additionalmore » 12 hours reflux process with nitric acid. The IR spectrum for the 12 hours-treated MWCNTs shows the formation of carboxyl functional group. Additional 12 hours reflux process with nitric acid on the 12 hours-treated MWCNTs have shown the loss of existing carboxyl group and only hydroxyl group formed.« less

Synthesis and characterization of Ag-doped TiO2 nanotubes on Ti-6Al-4V and Ti-6Al-7Nb alloy

NASA Astrophysics Data System (ADS)

Ulfah, Ika Maria; Bachtiar, Boy M.; Murnandityas, Arnita Rut; Slamet

2018-05-01

The present paper is focused on comparative behavior of nanotubes growth on Ti-6Al-4V and Ti-6Al-7Nb alloy using electrochemical anodization method. These alloys were anodized in electrolytes solution containing glycerol, water and 0.5wt.% of NH4F. Silver-doped TiO2 nanotubes were synthesized using photo-assisted deposition (PAD) at various Ag loading concentration in 0.05 M, 0.10 M, and 0.15 M. The phase composition and morphological characteristics were investigated by XRD and FESEM/EDX, respectively. The surface wettability was measured by contact angle meter. The results showed that TiO2 nanotubes can be grown on these surface alloys. XRD profiles revealed crystal formation of anatase, rutile and Ag on these surface alloys. According to FESEM images, the average nanotube diameter of Ti-6Al-4V alloy and Ti-6Al-7Nb alloy are 134 nm and 120 nm, respectively. EDX-Mapping analysis showed that Ag desposited over surface of TiO2 nanotubes. The surface wettability indicated hydrophilicity properties on Ti-4Al-4V alloy and Ti-6Al-7Nb alloy surface. This study may contribute to the development of silver-doped TiO2 nanotubes on Ti-6Al-4V alloy and Ti-6Al-7Nb alloy can be considered in various photocatalytic applications such as biomedical devicesdue to photocatalytic mechanism and antibacterial ability.

Characterization of modified zeolite as microbial immobilization media on POME anaerobic digestion

NASA Astrophysics Data System (ADS)

Cahyono, Rochim B.; Ismiyati, Sri; Ginting, Simparmin Br; Mellyanawaty, Melly; Budhijanto, Wiratni

2018-03-01

As the world’s biggest palm oil producer, Indonesia generates also huge amount of Palm Oil Mill Effluent (POME) wastewater and causes serious problem in environment. In conventional method, POME was converted into biogas using lagoon system which required extensive land area. Anaerobic Fluidized Bed Reactor (AFBR) proposes more effective biogas producing with smaller land area. In the proposed system, a immobilization media would be main factor for enhancing productivity. This research studied on characterization of Lampung natural zeolite as immobilization media in the AFBR system for POME treatment. Various activation method such as physical and chemical were attempted to create more suitable material which has larger surface area, pore size distribution as well as excellent surface structures. The physical method was applied by heating up the material till 400°C while HCl was used on the chemical activation. Based on the result, the chemical activation increased the surface area significantly into 71 m2/g compared to physical as well as original zeolite. The strong acid material was quite effective to enforce the impurities within zeolite pore structure compared to heating up the material. According to distribution data, the Lampung zeolite owned the pore size with the range of 3 – 5 μm which was mesopore material. The pore size was appropriate for immobilization media as it was smaller than size of biogas microbial. The XRD patterns verified that chemical activation could maintain the zeolite structure as the original. Obviously, the SEM photograph showed apparent structure and pore size on the modified zeolite using chemical method. The testing of modified zeolite on the batch system was done to evaluate the characterization process. The modified zeolite using chemical process resulted fast reduction of COD and stabilized the volatile fatty acid as the intermediate product of anaerobic digestion, especially in the beginning of the process. Therefore, the chemical activation process was most suitable to produce the immobilization media from Lampung natural zeolite for POME waste treatment

Phosphorus Sorption Characteristics in Aluminum-based Water Treatment Residuals Reacted with Dairy Wastewater: 1. Isotherms, XRD, and SEM-EDS Analysis.

PubMed

Zohar, Iris; Massey, Michael S; Ippolito, James A; Litaor, M Iggy

2018-05-01

We examined P sorption characteristics in Al-based water treatment residuals (Al-WTR) generated from slightly alkaline surface water and in an organic residual composite (WW-Al/O-WTR), produced by using the Al-WTR to treat organic-rich and high P concentration dairy wastewater. Solids from both residuals were examined using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD), and exposed to P additions of 0 to 4000 mg L in a sorption experiment. The Al-WTR removed ∼97% of the added P, whereas WW-Al/O-WTR removed only 78% of the added P in the addition range of 0 to 100 mg P L. With P additions of ≥100 mg L, the removal rate declined to <38% by Al-WTR and to 16% by WW-Al/O-WTR, possibly implying a change in sorption mechanisms. Analysis by XRD indicated that the major mineral was calcite, with some silica and poorly crystalline Al hydroxides. Analysis by SEM-EDS, which used three-element overlay maps of the residual surfaces, indicated that P was sparsely sorbed on both calcic and Al (hydr)oxide surfaces, along with a few clusters, even at low P concentrations of the treated waters. Ternary clusters of P, Al, and Ca were more abundant on the WW-Al/O-WTR. Carbon distribution suggested that organic substances covered Al surfaces. Sorption of P onto WW-Al/O-WTR may be reversible due to relatively weak Ca-P and Al-P bonds induced by the slight alkaline nature and in the presence of organic moieties, enhancing the WW-Al/O-WTR potential to act as a P source, rather than a P sink, in agricultural applications. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Real-Time XRD Studies of Li-O2 Electrochemical Reaction in Nonaqueous Lithium-Oxygen Battery.

PubMed

Lim, Hyunseob; Yilmaz, Eda; Byon, Hye Ryung

2012-11-01

Understanding of electrochemical process in rechargeable Li-O2 battery has suffered from lack of proper analytical tool, especially related to the identification of chemical species and number of electrons involved in the discharge/recharge process. Here we present a simple and straightforward analytical method for simultaneously attaining chemical and quantified information of Li2O2 (discharge product) and byproducts using in situ XRD measurement. By real-time monitoring of solid-state Li2O2 peak area, the accurate efficiency of Li2O2 formation and the number of electrons can be evaluated during full discharge. Furthermore, by observation of sequential area change of Li2O2 peak during recharge, we found nonlinearity of Li2O2 decomposition rate for the first time in ether-based electrolyte.

Influence of 300°C thermal conversion of Fe-Ce hydrous oxides prepared by hydrothermal precipitation on the adsorptive performance of five anions: Insights from EXAFS/XANES, XRD and FTIR (companion paper).

PubMed

Chubar, Natalia; Gerda, Vasyl; Banerjee, Dipanjan

2017-04-01

In this work, we report atomic-scale reconstruction processes in Fe-Ce oxide-based composites (hydrothermally precipitated at Fe-to-Ce dosage ratios of 1:0, 2:1, 1:1, 1:2, and 0:1), upon treatment at 300°C. The structural changes are correlated with the adsorptive removal of arsenate, phosphate, fluoride, bromide, and bromate. The presence of the carbonate-based Ce-component and surface sulfate in precursor samples creates favorable conditions for phase transformation, resulting in the formation of novel (unknown) layered compounds of Fe and Ce. These compounds are of the layered double hydroxide type, with sulfate in the interlayer space. In spite of general awareness of the importance of surface area in adsorptive removal, the increase in surface area upon thermal treatment did not increase adsorption of the studied anions. However, EXAFS simulations and the adsorption tests provided evidence of regularities between local structures of Fe in composites obtained at 80 and 300°C and adsorption performance of most studied anions. The best adsorption of tetrahedral anions was demonstrated by samples whose simulated outer Fe shells resulted from oscillations from both O and Fe atoms. In contrast, the loss of extended x-ray absorption fine structure was correlated with the decrease of adsorptive removal. Both Fe K-edge and Ce L 3 -edge EXAFS suggested the formation of solid solutions. For the first time, the utilization of extended x-ray absorption fine structure is suggested as a methodological approach (first expressed in the companion paper) to estimate the surface reactivity of inorganic materials intended for use as anion exchange adsorbents. Copyright © 2016 Elsevier Inc. All rights reserved.

Aging of Nanocrystalline Mackinawite (FeS): Mineralogical and Physicochemical Properties

NASA Astrophysics Data System (ADS)

Jeong, H. Y.; Lee, H.

2011-12-01

Due to the extraordinary physical properties and high surface areas, nanocrystalline minerals have been widely investigated for their potential uses in treating contaminated groundwaters and surface waters. Most previous studies in this field have focused on either preparation of nanocrystalline minerals or measurement of their reactivity with environmental contaminants. Nanocrystalline minerals, due to the inherent thermodynamic instability, tend to change the physicochemical and mineralogical properties over time, usually resulting in the decreased reactivity. Thus, to better assess the long-term effectiveness of nanocrystalline minerals in field applications, such "aging" effects should be clearly delineated. In the present work, we have investigated the aging impact on nanocrystalline mackinawite (FeS), the ubiquitous Fe-bearing mineral in anoxic sulfidic sediments. Mackinawite (FeS) is known to be an effective scavenger for metal pollutants and a strong reducing reagent for chromate and chlorinated organic compounds. Our preliminary results indicate that nanocrystalline FeS ages via Ostwald ripening, particle aggregation, or mineralogical transformation. By X-ray diffraction (XRD) analysis, aging of nanocrystalline FeS via Ostwald ripening is found to be dominant at acidic pH. Cryogenic transmission electron microscopy (TEM) shows that particle aggregation is most evident at neutral pH. Transformation of nanosized FeS into a more thermodynamically stable greigite (Fe3S4) is observed in the presence of folic acid at acidic pH. The pH-dependent aging process may be linked with changes in the apparent solubility and surface charge of FeS with pH. The Ostwald ripening or particle aggregation of nanocrystalline FeS leads to the decrease surface area, thus causing the decreased reactivity. Given the less reactivity of greigite, the transformation of nanocrystalline FeS to greigite is also expected to result in the decreased reactivity.

Dependence of catalytic properties of Al/Fe2O3 thermites on morphology of Fe2O3 particles in combustion reactions

NASA Astrophysics Data System (ADS)

Zhao, Ningning; He, Cuicui; Liu, Jianbing; Gong, Hujun; An, Ting; Xu, Huixiang; Zhao, Fengqi; Hu, Rongzu; Ma, Haixia; Zhang, Jinzhong

2014-11-01

Three Fe2O3 particle samples with the same crystal structure but different morphologies were prepared by the hydrothermal method and then combined with Al nanoparticles to produce Al/Fe2O3 thermites using ultrasonic mixing. The properties of Fe2O3 and Al/Fe2O3 were studied using a combination of experimental techniques including scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The influences of the three Al/Fe2O3 thermites on the combustion properties of the AP/HTPB (ammonium perchlorate/hydroxyl-terminated polybutadiene) composite propellant were investigated in comparison to those of Fe2O3. The results show that the Al/Fe2O3 thermites are better than Fe2O3 in enhancing the combustion performance of AP/HTPB. Furthermore, the surface area, which depends on size and mophology, of Fe2O3 particles was found to play a vital role in improving the burning rate of the thermites-containing propellant formulation, with the smallest particles with the largest surface-to-volume (S/V) ratio performing the best. The enhanced catalytic property of the granular-shape Fe2O3 and the corresponding thermite is attributed to the large specific surface area of Fe2O3. The different thermal behaviors of these three superthemites were supposed to be attributed to the surface site of Fe2O3 particles. This work provides a better understanding on the catalytic properties of thermites that are important for combustion applications.

Microstructural characterization of Charpy-impact-tested nanostructured bainite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Y.T.; Chang, H.T.; Huang, B.M.

2015-09-15

In this work, a possible cause of the extraordinary low impact toughness of nanostructured bainite has been investigated. The microstructure of nanostructured bainite consisted chiefly of carbide-free bainitic ferrite with retained austenite films. X-ray diffractometry (XRD) measurement indicated that no retained austenite existed in the fractured surface of the Charpy-impact-tested specimens. Fractographs showed that cracks propagated mainly along bainitic ferrite platelet boundaries. The change in microstructure after impact loading was verified by transmission electron microscopy (TEM) observations, confirming that retained austenite was completely transformed to strain-induced martensite during the Charpy impact test. However, the zone affected by strained-induced martensite wasmore » found to be extremely shallow, only to a depth of several micrometers from the fracture surface. It is appropriately concluded that upon impact, as the crack forms and propagates, strain-induced martensitic transformation immediately occurs ahead of the advancing crack tip. The successive martensitic transformation profoundly facilitates the crack propagation, resulting in the extremely low impact toughness of nanostructured bainite. Retained austenite, in contrast to its well-known beneficial role, has a deteriorating effect on toughness during the course of Charpy impact. - Highlights: • The microstructure of nanostructured bainite consisted of nano-sized bainitic ferrite subunits with retained austenite films. • Special sample preparations for SEM, XRD and TEM were made, and the strain-affected structures have been explored. • Retained austenite films were found to transform into martensite after impact loading, as evidenced by XRD and TEM results. • The zone of strain-induced martensite was found to extend to only several micrometers from the fracture surface. • The poor Charpy impact toughness is associated with the fracture of martensite at a high strain rate during impact loading.« less

Uranium speciation as a function of depth in contaminated hanford sediments--a micro-XRF, micro-XRD, and micro- and bulk-XAFS study.

PubMed

Singer, David M; Zachara, John M; Brown, Gordon E

2009-02-01

The distribution and speciation of U and Cu in contaminated vadose zone and aquifer sediments from the U.S. DOE Hanford site (300 Area) were determined using a combination of synchrotron-based micro-X-ray fluorescence (microXRF) imaging, micro-X-ray absorption near edge structure (microXANES) spectroscopy, and micro-X-ray diffraction (microXRD) techniques combined with bulk U LIII-edge X-ray absorption fine structure (XAFS) spectroscopy. Samples were collected from within the inactive North Process Pond (NPP2) at 8 ft (2.4 m, NPP2-8) depth and 12 ft (3.7 m, NPP2-12) depth in the vadose zone, and fines were isolated from turbid groundwater just below the water Table (12-14 ft, approximately 4 m, NPP2-GW). microXRF imaging, microXRD, and microXANES spectroscopy revealed two major U occurrences within the vadose and groundwater zones: (1) low to moderate concentrations of U(VI) associated with fine-textured grain coatings that were consistently found to contain clinochlore (referred to here as chlorite) observed in all three samples, and (2) U(VI)-Cu(II) hotspots consisting of micrometer-sized particles associated with surface coatings on grains of muscovite and chlorite observed in samples NPP2-8' and NPP2-GW. In the aquifer fines (NPP2-GW), these particles were identified as cuprosklodowskite (cps: Cu[(UO2)(SiO2OH)]2 x 6H2O) and metatorbernite (mtb: Cu(UO2)2(PO4)2 x 8H2O). In contrast, the U-Cu-containing particles in the vadose zone were X-ray amorphous. Analyses of U LIII-edge XAFS spectra by linear-combination fitting indicated that U speciation consisted of (1) approximately 75% uranyl sorbed to chlorite and approximately 25% mtb-like X-ray amorphous U-Cu-phosphates (8 ft depth), (2) nearly 100% sorbed uranyl (12 ft depth), and (3) approximately 70% uranyl sorbed to chlorite and approximately 30% cps/mtb (groundwater zone). These findings suggest that dissolution of U(VI)-Cu(II)-bearing solids as well as desorption of U(VI), mainly from phyllosilicates, are important persistent sources of U(VI) to the associated uranium groundwater plume in Hanford Area 300.

X-Ray Amorphous Phases in Terrestrial Analog Volcanic Sediments: Implications for Amorphous Phases in Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Smith, R. J.; Horgan, B.; Rampe, E.; Dehouck, E.; Morris, R. V.

2017-01-01

X-ray diffraction (XRD) amorphous phases have been found as major components (approx.15-60 wt%) of all rock and soil samples measured by the CheMin XRD instrument in Gale Crater, Mars. The nature of these phases is not well understood and could be any combination of primary (e.g., glass) and secondary (e.g., allophane) phases. Amorphous phases form in abundance during surface weathering on Earth. Yet, these materials are poorly characterized, and it is not certain how properties like composition and structure change with formation environment. The presence of poorly crystalline phases can be inferred from XRD patterns by the appearance of a low angle rise (< or approx.10deg 2(theta)) or broad peaks in the background at low to moderate 2(theta) angles (amorphous humps). CheMin mineral abundances combined with bulk chemical composition measurements from the Alpha Particle X-ray Spectrometer (APXS) have been used to estimate the abundance and composition of the XRD amorphous materials in soil and rock samples on Mars. Here we apply a similar approach to a diverse suite of terrestrial samples - modern soils, glacial sediments, and paleosols - in order to determine how formation environment, climate, and diagenesis affect the abundance and composition of X-ray amorphous phases.

In situ supported MnOx-CeOx on carbon nanotubes for the low-temperature selective catalytic reduction of NO with NH3

NASA Astrophysics Data System (ADS)

Zhang, Dengsong; Zhang, Lei; Shi, Liyi; Fang, Cheng; Li, Hongrui; Gao, Ruihua; Huang, Lei; Zhang, Jianping

2013-01-01

The MnOx and CeOx were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH3. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H2-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH3-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO2-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods.The MnOx and CeOx were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH3. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H2-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH3-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO2-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods. Electronic supplementary information (ESI) available: SEM images and EDS analysis, TEM images, and XPS spectrum of samples. See DOI: 10.1039/c2nr33006g

Enhanced adsorptive and photocatalytic achievements in removal of methylene blue by incorporating tungstophosphoric acid-TiO2 into MCM-41.

PubMed

Zanjanchi, M A; Golmojdeh, H; Arvand, M

2009-09-30

The use of titania-dispersed materials in photocatalytic processes has been proposed as an alternative to the conventional bare TiO(2), in order to modify the surface area and activity of the catalyst. A homogeneously dispersed Keggin unit into TiO(2) was synthesized using tungstophosphoric acid (TPA) and titanium tetraisopropoxide. This compound was then loaded into MCM-41 by dispersing it in a suspension containing the mesoporous phase. Two other titanium-containing MCM-41 catalysts, Ti-MCM-41 and TiO(2)/MCM-41 were also prepared using isomorphous substitution synthesis method and impregnation method, respectively, for the sake of comparison. The prepared photocatalysts were characterized by X-ray diffraction (XRD), nitrogen physisorption (BET) and chemical analysis. The catalysts were used to study degradation of methylene blue (MB) in aqueous solution. XRD result shows a pure anatase crystalline phase for TPA-containing TiO(2) indicating that there is good molecular distribution of tungstophosphoric acid into TiO(2) structure. Supported TPA-TiO(2) into MCM-41 shows both TPA-TiO(2) and MCM-41 characteristic X-ray reflections in the high-angle and low-angle parts of the XRD patterns, respectively. The experimental results show that adsorption is a major constituent in the elimination of MB from the dye solutions by the TPA-containing materials. Exploitation of both adsorption and photocatalytic processes speeds up the removal of the dye using the TPA-TiO(2)-loaded MCM-41 photocatalyst. The elimination of MB is completed within 15 min for a 30 mg l(-1) MB solution containing a catalyst dose of 100mg/100ml. The efficiencies of the other photocatalysts such as commercial TiO(2), Ti-MCM-41, TiO(2)/MCM-41 and TPA-TiO(2) for adsorption and degradation of MB were also studied and compared with that of the prepared catalyst.

MUDMASTER: A Program for Calculating Crystalline Size Distributions and Strain from the Shapes of X-Ray Diffraction Peaks

USGS Publications Warehouse

Eberl, D.D.; Drits, V.A.; Środoń, Jan; Nüesch, R.

1996-01-01

Particle size may strongly influence the physical and chemical properties of a substance (e.g. its rheology, surface area, cation exchange capacity, solubility, etc.), and its measurement in rocks may yield geological information about ancient environments (sediment provenance, degree of metamorphism, degree of weathering, current directions, distance to shore, etc.). Therefore mineralogists, geologists, chemists, soil scientists, and others who deal with clay-size material would like to have a convenient method for measuring particle size distributions. Nano-size crystals generally are too fine to be measured by light microscopy. Laser scattering methods give only average particle sizes; therefore particle size can not be measured in a particular crystallographic direction. Also, the particles measured by laser techniques may be composed of several different minerals, and may be agglomerations of individual crystals. Measurement by electron and atomic force microscopy is tedious, expensive, and time consuming. It is difficult to measure more than a few hundred particles per sample by these methods. This many measurements, often taking several days of intensive effort, may yield an accurate mean size for a sample, but may be too few to determine an accurate distribution of sizes. Measurement of size distributions by X-ray diffraction (XRD) solves these shortcomings. An X-ray scan of a sample occurs automatically, taking a few minutes to a few hours. The resulting XRD peaks average diffraction effects from billions of individual nano-size crystals. The size that is measured by XRD may be related to the size of the individual crystals of the mineral in the sample, rather than to the size of particles formed from the agglomeration of these crystals. Therefore one can determine the size of a particular mineral in a mixture of minerals, and the sizes in a particular crystallographic direction of that mineral.

Effect of calcination temperature on structure and photocatalytic activity under UV and visible light of nanosheets from low-cost magnetic leucoxene mineral

NASA Astrophysics Data System (ADS)

Charerntanom, Wissanu; Pecharapa, Wisanu; Pavasupree, Suttipan; Pavasupree, Sorapong

2017-07-01

This research has experimentally synthesized the nanosheets from the naturally-mineral magnetic leucoxene under the hydrothermal synthesis condition of 105 °C for 24 h. Magnetic leucoxene was utilized as the starting material due to its high TiO2 content (70-80%) and inexpensiveness. The characterization of the synthesized nanosheets was subsequently carried out: the crystalline structure, the chemical composition, the shape, the size and the specific surface area, by the X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) specific surface area analysis. The analysis results indicated that the starting magnetic leucoxene is of rutile phase while the synthesized nanosheets are of titanate structure (H2TixO2x + 1). After calcination at the temperature range of 300 and 400 °C, the calcined samples demonstrated TiO2 (B). At 500 and 600 °C, the calcined nanosheets revealed a bi-crystalline mixture consisting of TiO2 (B) and anatase TiO2. At 700-1000 °C, the crystalline structure shows anatase and rutile phase. At 1100 °C, the prepared samples consisted of a mixture of anatase, rutile phase of TiO2, and Fe2O3 phase. The synthesized product also exhibited the flower-like morphology with 2-5 μm in diameter, and the nanosheets structure was slightly curved, with 100 nm to 2 μm in width and 1-3 nm in thickness. At 100-200 °C showed sheets-like structure. At 300-1100 °C, the calcined nanosheets became unstable and began to decompose and transform into nanoparticles. The increasing size of nanoparticle decreased the specific surface area of the nanosheets, caused by increasing calcination temperature. Furthermore, the BET specific surface area of the nanosheets was approximately 279.8 m2/g. More importantly, the synthesized nanosheets achieved the higher photocatalytic activity under UV and visible light than did the commercial TiO2 nanoparticles (JRC-01, JRC-03, ST-01 and P-25).

Hydrothermal synthesis of flower-like MoS2 nanospheres for electrochemical supercapacitors.

PubMed

Zhou, Xiaoping; Xu, Bin; Lin, Zhengfeng; Shu, Dong; Ma, Lin

2014-09-01

Flower-like MoS2 nanospheres were synthesized by a hydrothermal route. The structure and surface morphology of the as-prepared MoS2 was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The supercapacitive behavior of MoS2 in 1 M KCl electrolyte was studied by means of cyclic voltammetry (CV), constant current charge-discharge cycling (CD) and electrochemical impedance spectroscopy (EIS). The XRD results indicate that the as-prepared MoS2 has good crystallinity. SEM images show that the MoS2 nanospheres have uniform sizes with mean diameter about 300 nm. Many nanosheets growing on the surface make the MoS2 nanospheres to be a flower-like structure. The specific capacitance of MoS2 is 122 F x g(-1) at 1 A x g(-1) or 114 F x g(-1) at 2 mv s(-1). All the experimental results indicate that MoS2 is a promising electrode material for electrochemical supercapacitors.

Surface Characteristics of Machined NiTi Shape Memory Alloy: The Effects of Cryogenic Cooling and Preheating Conditions

NASA Astrophysics Data System (ADS)

Kaynak, Y.; Huang, B.; Karaca, H. E.; Jawahir, I. S.

2017-07-01

This experimental study focuses on the phase state and phase transformation response of the surface and subsurface of machined NiTi alloys. X-ray diffraction (XRD) analysis and differential scanning calorimeter techniques were utilized to measure the phase state and the transformation response of machined specimens, respectively. Specimens were machined under dry machining at ambient temperature, preheated conditions, and cryogenic cooling conditions at various cutting speeds. The findings from this research demonstrate that cryogenic machining substantially alters austenite finish temperature of martensitic NiTi alloy. Austenite finish ( A f) temperature shows more than 25 percent increase resulting from cryogenic machining compared with austenite finish temperature of as-received NiTi. Dry and preheated conditions do not substantially alter austenite finish temperature. XRD analysis shows that distinctive transformation from martensite to austenite occurs during machining process in all three conditions. Complete transformation from martensite to austenite is observed in dry cutting at all selected cutting speeds.

Study on defect properties of nanocrystalline TiO2 during phase transition by positron annihilation lifetime

NASA Astrophysics Data System (ADS)

Zheng, F.; Liu, Y.; Liu, Z.; Dai, Y.-Q.; Fang, P.-F.; Wang, S.-J.

2012-08-01

The defect properties of nanocrystalline TiO2 were investigated by positron annihilation lifetime spectroscopy (PALS) and X-ray diffraction (XRD) as a function of annealed temperature that ranged from 300 to 850 °C. Below 500 °C, the measured positron lifetimes of τ1 (200-206 ps) and τ2 (378-402 ps) revealed the existence of mono-vacancy and vacancy-clusters at grain surface and in the micro-void of intergranular region. Between 500 and 750 °C, the phase transition from anatase to rutile was probed by the variations of positron lifetime and XRD pattern. With the increasing temperature from 500 to 850 °C, the positron lifetime τ1, τ2 and its intensity I2 sharply decreased from 200 ps, 378 ps, and 60% to 135 ps, 274 ps, and 33%, respectively. The results clearly indicate that the mono-vacancy or vacancy-clusters at grain surface and micro-voids between the grains were annealed out during the phase transition.

Study of lattice strain and optical properties of nanocrystalline SnO2

NASA Astrophysics Data System (ADS)

Ahmad, Naseem; Khan, Shakeel; Bhargava, Richa; Ansari, Mohd Mohsin Nizam

2018-05-01

Nanocrystalline SnO2 has been synthesized by co-precipitation method by using two solvents (water and ethylene glycol). The structure and surface morphology were investigated using XRD and scanning electron microscope (SEM). The optical properties were studied using diffused reflectance spectroscopy (DRS). From the XRD analysis, the prepared materials are found to be pure crystalline with tetragonal rutile structure. The lattice strain and crystallite size, were calculated using Williamson-Hall method, are found to be 0.00413 & 16.3 nm in water assisted SnO2 and 0.00495 & 35.6 nm for EG assisted SnO2. Study of surface morphology of the samples was carried out using SEM. It has been seen that the solvents which are used in synthesis can also alter the optical properties of the materials. The optical band gap of the water based SnO2 and EG based SnO2 are found to be 3.92eV and 3.86eV respectively.

Metal copper films deposited on cenosphere particles by magnetron sputtering method

NASA Astrophysics Data System (ADS)

Yu, Xiaozheng; Xu, Zheng; Shen, Zhigang

2007-05-01

Metal copper films with thicknesses from several nanometres to several micrometres were deposited on the surface of cenosphere particles by the magnetron sputtering method under different working conditions. An ultrasonic vibrating generator equipped with a conventional magnetron sputtering apparatus was used to prevent the cenosphere substrates from accumulating during film growth. The surface morphology, the chemical composition, the average grain size and the crystallization of cenosphere particles were characterized by field emission scanning electron microscopy (FE-SEM), inductively coupled plasma-atom emission spectrometer, x-ray photoelectron spectroscopy and x-ray diffraction (XRD) analysis, respectively, before and after the plating process. The results indicate that the copper films were successfully deposited on cenosphere particles. It was found from the FE-SEM results that the films were well compacted and highly uniform in thickness. The XRD results show that the copper film coated on cenospheres has a face centred cubic structure and the crystallization of the film sample increases with increasing sputtering power.