Showing papers by "Ray L. Frost published in 2010"
TL;DR: In this article, the authors synthesize cobalt hydroxide, cobalt oxyhydroxide and cobalt oxide nanomaterials through simple soft chemistry, and characterisation of these cobalt-based materials is fully developed, including X-ray diffraction, transmission electron microscopy combined with selected area electron diffraction.
Abstract: Cobalt hydroxide, cobalt oxyhydroxide, and cobalt oxide nanomaterials were synthesized through simple soft chemistry. The cobalt hydroxide displays hexagonal morphology with clear edges 20 nm long. This morphology and nanosize is retained through to cobalt oxide Co3O4 through a topotactical relationship. Cobalt oxyhydroxide and cobalt oxide nanomaterials were synthesized through oxidation and low-temperature calcination from the as-prepared cobalt hydroxide. Characterization of these cobalt-based nanomaterials was fully developed, including X-ray diffraction, transmission electron microscopy combined with selected area electron diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and thermal gravimetric analysis. Bonding of the divalent cobalt hydroxide from the oxyhydroxide and oxides by studying their high-resolution XPS spectra for Co 2p3/2 and O 1s. Raman spectroscopy of the as-prepared Co(OH)2, CoO(OH), and Co3O4 nanomaterials characterized each material. T...
1,249 citations
TL;DR: The presence of zero-valent iron reactive species on the palygorskite surface strongly increases the decolourization capacity for methylene blue, and it is significant for providing novel modified clay catalyst materials for the removal of organic contaminants from waste water.
188 citations
TL;DR: In this paper, the phase transition from trititanate to hexatitanate is a step-by-step slipping process of the TiO6 octahedral slabs with the loss of sodium cations, and a new phase with formula Na1.5H 0.5Ti3O7 has been discovered as an intermediate phase to interlink Na2Ti 3O7 and Na2Ni6O13.
Abstract: Ti – O bond was observed to become stronger with the increase in temperature, indicating that there is no terminal oxygen atom in the crystal structure of Na2Ti6O13 and that all the oxygen atoms become linearly coordinated by two titanium atoms. Furthermore, the TiO6 octahedron in Na2Ti6O13 are more regular because the very long (2.2 A) or very short (1.7 A) Ti – O bonds disappear. It is revealed that the phase transition from trititanate to hexatitanate is a step-by-step slipping process of the TiO6 octahedral slabs with the loss of sodium cations, and a new phase with formula Na1.5H0.5Ti3O7 has been discovered as an intermediate phase to interlink Na2Ti3O7 and Na2Ti6O13 .C opyrightc � 2010 John Wiley & Sons, Ltd.
88 citations
TL;DR: Wang et al. as discussed by the authors investigated the spatial and temporal changes of contamination of As, Cd, Co, Cr, Cu, Ni, Pb and Zn in sediment and suspended solid during dry and flood seasons.
85 citations
TL;DR: The infrared emission spectra of halloysite were found to be considerably different to that of kaolinite at lower temperatures, attributed to the fundamental difference in the structure of the two minerals.
76 citations
TL;DR: In this article, the most recent achievements in the study of kaolinite organo-complexes obtained with the most common intercalating compounds such as urea, potassium acetate, dimethyl sulphoxide, formamide, and hydrazine using vibrational...
Abstract: The industrial application of kaolinite is closely related to its reactivity and surface properties. The reactivity of kaolinite can be tested by intercalation; that is, via the insertion of low-molecular-weight organic compounds between the kaolinite layers resulting in the formation of a nano-layered organo-complex. Although intercalation of kaolinite is an old and ongoing research topic, there is limited knowledge available on the reactivity of different kaolinites and the mechanism of complex formation, as well as on the structure of the complexes formed. Grafting and incorporation of exfoliated kaolinite in polymer matrices and other potential applications can open new horizons in the study of kaolinite intercalation. This article attempts to summarize (without completion) the most recent achievements in the study of kaolinite organo-complexes obtained with the most common intercalating compounds such as urea, potassium acetate, dimethyl sulphoxide, formamide, and hydrazine using vibrational...
76 citations
TL;DR: The reproducibility of measurement, signal to noise ratio and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for mineral analysis.
74 citations
TL;DR: The wet ball-milling kaolinite after intercalation did not change the structural order, and the particulates have high aspect ratio according SEM images.
71 citations
TL;DR: In this paper, a series of kaolinite-potassium acetate intercalation composite was prepared and the thermal behavior and decomposition of these composites were investigated by simultaneous differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), X-ray diffraction (XRD) and Fourier-transformation infrared (FT-IR).
63 citations
TL;DR: In this paper, an immersion method for preparing the kaolinite-potassium acetate intercalation complexes was presented, and the results showed that the intercalization of the mixture by potassium acetate is strongly related to the crystallinity of the kolinite, concentration of intercalating agent solution, aging time and pH.
58 citations
TL;DR: Thermally activated seawater neutralised red mud removes at least twice the concentration of anionic species than thermally activated red mud alone, due to the formation of 40-60% Bayer hydrotalcite during the neutralisation process.
TL;DR: In this article, the thermal decomposition of halloysite-potassium acetate intercalation compound was investigated by thermogravimetric analysis and infrared emission spectroscopy.
TL;DR: In this article, the effects of alkaline concentration, hydrothermal temperature, and precursor phase and crystallite size on the resultant nanostructure formation have been studied through X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and nitrogen adsorption.
Abstract: A systematic study of four parameters within the alkaline hydrothermal treatment of three commercial titania powders—anatase, rutile, and Degussa P25—was made. These powders were treated with 5, 7.5, 9, and 10 M NaOH between 100 and 220 °C for 20 h. The effects of alkaline concentration, hydrothermal temperature, and precursor phase and crystallite size on the resultant nanostructure formation have been studied through X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and nitrogen adsorption. Through the correlation of these data, morphological phase diagrams were constructed for each commercial powder. Interpretation of the resultant morphological phase diagrams indicates that alkaline concentration and hydrothermal temperature affect nanostructure formation independently, where nanoribbon formation is significantly influenced by temperature for initial formation. The phase and crystallite size of the precursor also significantly influenced nanostructure formation, with rutile displaying a slower rate of precursor consumption compared with anatase. Small crystallite titania precursors formed nanostructures at reduced hydrothermal temperatures.
TL;DR: In this paper, the authors used thermogravimetric analysis-mass spectrometry, X-ray diffraction and scanning electron microscopy (SEM) to characterize eight kaolinite samples from China.
TL;DR: In this article, two kinds of coal-bearing kaolinite from China were analyzed by X-ray diffraction (XRD), Thermogravimetric analysis-mass spectrometry (TG-MS), infrared emission spectroscopy.
01 Jan 2010
TL;DR: In this paper, the effects of alkaline concentration, hydrothermal temperature, and precursor phase and crystallite size on the resultant nanostructure formation have been studied through X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and nitrogen adsorption.
Abstract: A systematic study of four parameters within the alkaline hydrothermal treatment of three commercial titania powders—anatase, rutile, and Degussa P25—was made. These powders were treated with 5, 7.5, 9, and 10 M NaOH between 100 and 220 °C for 20 h. The effects of alkaline concentration, hydrothermal temperature, and precursor phase and crystallite size on the resultant nanostructure formation have been studied through X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and nitrogen adsorption. Through the correlation of these data, morphological phase diagrams were constructed for each commercial powder. Interpretation of the resultant morphological phase diagrams indicates that alkaline concentration and hydrothermal temperature affect nanostructure formation independently, where nanoribbon formation is significantly influenced by temperature for initial formation. The phase and crystallite size of the precursor also significantly influenced nanostructure formation, with rutile displaying a slower rate of precursor consumption compared with anatase. Small crystallite titania precursors formed nanostructures at reduced hydrothermal temperatures.
TL;DR: In this paper, the authors used coprecipitation and thermal activation to identify vanadate and arsenate specie intercalated into the hydrotalcite structure.
Abstract: The removal of toxic anions has been achieved using hydrotalcite via two methods: (1) coprecipitation and (2) thermal activation. Hydrotalcite formed via the coprecipitation method, using solutions containing arsenate and vanadate up to pH 10, are able to remove more than 95% of the toxic anions (0.2 M) from solution. The removal of toxic anions in solutions with a pH of >10 reduces the removal uptake percentage to 75%. Raman spectroscopy observed multiple A1 stretching modes of V−O and As−O at 930 and 810 cm−1, assigned to vanadate and arsenate, respectively. Analysis of the intensity and position of the A1 stretching modes helped to identify the vanadate and arsenate specie intercalated into the hydrotalcite structure. It has been determined that 3:1 hydrotalcite structure predominantly intercalate anions into the interlayer region, while the 2:1 and 4:1 hydrotalcite structures shows a large portion of anions being removed from solution by adsorption processes. Treatment of carbonate solutions (0.2 M) containing arsenate and vanadate (0.2 M) three times with thermally activated hydrotalcite has been shown to remove 76% and 81% of the toxic anions, respectively. Thermally activated hydrotalcite with a Mg:Al ratio of 2:1, 3:1, and 4:1 have all been shown to remove 95% of arsenate and vanadate (25 ppm). At increased concentrations of arsenate and vanadate, the removal uptake percentage decreased significantly, except for the 4:1 thermally activated hydrotalcite. Thermally activated Bayer hydrotalcite has also been shown to be highly effective in the removal of arsenate and vanadate. The thermal activation of the solid residue component (red mud) removes 30% of anions from solution (100 ppm of both anions), while seawater-neutralized red mud removes 70%. The formation of hydrotalcite during the seawater neutralization process removes anions via two mechanisms, rather than one observed for thermally activated red mud.
TL;DR: In this paper, the authors focus on the vibrational spectroscopy of the compounds and minerals containing the arsenite, antimonite and antimonate anions and collect and correlate the published data.
Abstract: This review focuses on the vibrational spectroscopy of the compounds and minerals containing the arsenite, antimonite and antimonate anions. The review collects and correlates the published data.
TL;DR: In this paper, the transition of cubic indium hydroxide (In(OH)3) to In2O3 was studied by thermogravimetric analysis complimented with hot-stage Raman spectroscopy.
Abstract: The transition of cubic indium hydroxide to cubic indium oxide has been studied by thermogravimetric analysis complimented with hot-stage Raman spectroscopy. Thermal analysis shows the transition of In(OH)3 to In2O3 occurs at 219 °C. The structure and morphology of In(OH)3 synthesised using a soft chemical route at low temperatures was confirmed by X-ray diffraction and scanning electron microscopy. A topotactical relationship exists between the micro/nano-cubes of In(OH)3 and In2O3. The Raman spectrum of In(OH)3 is characterised by an intense sharp band at 309 cm−1 attributed to ν1 In–O symmetric stretching mode, bands at 1137 and 1155 cm−1 attributed to In-OH δ deformation modes, bands at 3083, 3215, 3123 and 3262 cm−1 assigned to the OH stretching vibrations. Upon thermal treatment of In(OH)3, new Raman bands are observed at 125, 295, 488 and 615 cm−1 attributed to In2O3. Changes in the structure of In(OH)3 with thermal treatment is readily followed by hot-stage Raman spectroscopy.
TL;DR: In this article, coal fly ash was used as a precursor and sodium hydroxide and solid sodium silicate powder as alkaline activators to produce a binder with similar properties as Portland cement but without the drawback linked to greenhouse gas emissions.
Abstract: The alkali activation of waste materials can produce a binder with similar properties as Portland cement but without the drawback linked to greenhouse gas emissions. Geopolymer pastes were made using coal fly ash as precursor and sodium hydroxide and solid sodium silicate powder as alkaline activators. One sample was activated with sodium silicate only while the second sample used a 50:50 mass% mixture of sodium silicate and 8 M NaOH solution. Fresh geopolymer paste was immediately placed in the Environmental SEM chamber for microstructure observation using the ESEM mode. The sodium silicate activator dissolves rapidly and begins to bond fly ash particles. Open porosity can be observed and is rapidly filled with gel as soon as the liquid phase is able to reach the ash particle. The liquid phase is important as a fluid transport medium permitting the activator to reach and react with the fly ash particles. During this ESEM experiment, the reaction was limited to the surface of the fly ash particles. The reaction products examined had a gel like morphology and no crystallized phase was observed. The effect of the activator on the gel composition was investigated by quantitative microanalysis. The gel analyzed in the sample activated with the mixture of sodium silicate and NaOH solution is enriched in Na and Al. In that sample, the fly ash reaction rate is more advanced considering that the gel is richer in Al and that this element results from the fly ash. In fly ash-based geopolymers, the aluminum content of the aluminosilicate gel is an indicator of the fly ash reactivity.
TL;DR: In this article, a comparison of the Raman spectrum of leiteite with the arsenite minerals reinerite and cafarsite is made with the As2O42- bending mode.
Abstract: The selected arsenite minerals leiteite, reinerite and cafarsite have been studied by Raman spectroscopy. DFT calculations enabled the position of AsO22- symmetric stretching mode at 839 cm-1, the antisymmetric stretching mode at 813 cm-1, and the deformation mode at 449 cm-1 to be calculated. The Raman spectrum of leiteite shows bands at 804 and 763 cm-1 assigned to the As2O42- symmetric and antisymmetric stretching modes. The most intense Raman band of leiteite is the band at 457 cm-1 and is assigned to the ν2 As2O42- bending mode. A comparison of the Raman spectrum of leiteite is made with the arsenite minerals reinerite and cafarsite.
TL;DR: Silylated layered double hydroxides (LDHs) were synthesized through a surfactant-free method involving an in situ condensation of silane with the surface hydroxyl group of LDHs during its reconstruction in carbonate solution and show high thermal stability by maintained Si related bands even when the temperature was increased to 1000 degrees C.
Abstract: Silylated layered double hydroxides (LDHs) were synthesized through a surfactant-free method involving an in situ condensation of silane with the surface hydroxyl group of LDHs during its reconstruction in carbonate solution. X-ray diffraction (XRD) patterns showed the silylation reaction occurred on the external surfaces of LDHs layers. The successful silylation was evidenced by 29Si cross-polarization magic-angle spinning nuclear magnetic resonance (29Si CP/MAS NMR) spectroscopy, attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy, and infrared emission spectroscopy (IES). The ribbon shaped crystallites with a “rodlike” aggregation were observed through transmission electron microscopy (TEM) images. The aggregation was explained by the T2 and T3 types of linkage between adjacent silane molecules as indicated in the 29Si NMR spectrum. In addition, the silylated products show high thermal stability by maintained Si related bands even when the temperature was increased to 1000 °C...
TL;DR: In this paper, the influence of particle concentration in suspension, suspension pH and particle size on the clay platelet orientation was investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods.
TL;DR: In this article, a combination of Raman spectroscopy and infrared spectroscopic analysis of reevesite has been used to identify water bending modes at positions greater than 1620 cm−1, indicating that water is strongly hydrogen bonded to both the interlayer anions and the hydrotalcite surface.
Abstract: Raman spectroscopy, complemented with infrared spectroscopy of compounds equivalent to reevesite, formula (Ni,Co)6Fe2(OH)16(CO3)·4H2O, with the ratio of Ni/Co ranging from 0 to 1, have been synthesised and characterised based on the molecular structure of the synthesised mineral. The combination of Raman spectroscopy with infrared spectroscopy enables an assessment of bands attributable to water stretching and brucite-like surface hydroxyl units to be obtained. Raman spectroscopy shows a reduction in the symmetry of the carbonate anion, leading to the conclusion that the carbonate anion is bonded to the brucite-like hydroxyl surface and to the water in the interlayer. Variation in the position of the carbonate anion stretching vibrations occurs and is dependent on the Ni/Co ratio. Water bending modes are identified in both the Raman and infrared spectra at positions greater than 1620 cm−1, indicating that water is strongly hydrogen bonded to both the interlayer anions and the hydrotalcite surface. Copyright © 2009 John Wiley & Sons, Ltd.
TL;DR: In this paper, the antisymmetric and symmetric stretching vibrations of the SiOSi bridges, δ siOSi and δ OSiO bending vibrations, ν (SiOterminal)− stretching vibrations, and ν OH stretching vibrations were attributed to the observed bands.
Abstract: The kaolinite-like phyllosilicate minerals bismutoferrite BiFe3+2Si2O8(OH) and chapmanite SbFe3+2Si2O8(OH) have been studied by Raman spectroscopy and complemented with infrared spectra. Tentatively interpreted spectra were related to their molecular structure. The antisymmetric and symmetric stretching vibrations of the SiOSi bridges, δ SiOSi and δ OSiO bending vibrations, ν (SiOterminal)− stretching vibrations, ν OH stretching vibrations of hydroxyl ions, and δ OH bending vibrations were attributed to the observed bands. Infrared bands in the range 3289–3470 cm−1 and Raman bands in the range 1590–1667 cm−1 were assigned to adsorbed water. OH···O hydrogen-bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.
TL;DR: A detailed study on the structural deformation of trititanate nanofibers after the adsorption of divalent strontium (Sr) and barium (Ba) cations was conducted by using Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM).
Abstract: A detailed study on the structural deformation of trititanate nanofibers after the adsorption of divalent strontium (Sr) and barium (Ba) cations was conducted by using Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the Raman bands at 309 cm−1 corresponding to very long TiO bonds (2.2 A) and at 883 cm−1 corresponding to the very short TiO bonds (1.7 A) decreased in intensity after the adsorption of Ba2+ and Sr2+ cations. Additionally, the band at 922 cm−1 corresponding to an intermediate length TiO bond was observed to weaken with the adsorption of divalent cations, indicating that the TiO6 octahedra in Na2Ti3O7 are more regular. These results suggest that the active sodium (Na+) cations in Na2Ti3O7 should be located at the corner of the TiO6 octahedral slabs, i.e. the plane (003). This was further confirmed by a large decrease of diffraction intensity of the plane (003) observed in the XRD pattern. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this article, Raman spectroscopy complemented with IR spectrograms was used to study the molecular structure of the mineral euchroite, a mineral involved in a complex set of equilibria between the copper hydroxy arsenates.
Abstract: Raman spectroscopy complemented with infrared spectroscopy was used to study the molecular structure of the mineral euchroite, a mineral involved in a complex set of equilibria between the copper hydroxy arsenates: euchroite Cu2(AsO4)(OH)·3H2O olivenite Cu2(AsO4)(OH) strashimirite Cu8(AsO4)4(OH)4·5H2O arhbarite Cu2Mg(AsO4)(OH)3. The Raman bands observed at 848 and 768 cm−1 are assigned to the ν1 and ν3 (AsO4)3− stretching vibrations. Two Raman bands at 358 and 385 cm−1 are attributed to the ν2 (AsO4)3− bending mode and two Raman bands at 441 and 474 cm−1 to the ν4 AsO43− bending modes. Two sharp Raman bands are observed at 3470 and 3537 cm−1 and are attributed to the stretching vibrations of hydroxyl units. A comparison of the Raman spectrum of euchroite is made with the other copper hydroxy arsenate minerals including strashimirite, olivenite, cornubite, and cornwallite. Copyright © 2009 John Wiley & Sons, Ltd.
TL;DR: In this article, a methodology for the synthesis of chromium oxyhydroxide nanoplates was developed for the analysis of high resolution XPS spectra for Cr 2p3/2 and O 1s.
Abstract: Chromium oxyhydroxide nanomaterials were synthesised through a simple soft chemical hydrothermal method. The chromium oxyhydroxide materials display platelet morphology with clear edges, ~11 nm in diameter. CrO(OH) nanomaterials synthesised under different conditions were fully characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM) combined with selected area electron diffraction (SAED), scanning electron microscopy (SEM), BET specific surface area analysis, X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). Bonding of the trivalent chromium from the oxyhydroxide nanomaterials was defined through the analysis of their high resolution XPS spectra for Cr 2p3/2 and O 1s. The thermal stability of the nanomaterials CrO(OH) was established. This research has developed methodology for the synthesis of chromium oxyhydroxide nanoplates.
TL;DR: Raman spectroscopy has been used to study the arsenate minerals haidingerite Ca (AsO3OH)•H2O and brassite Mg(AsO 3 OH)•4 H2O as discussed by the authors.
Abstract: Raman spectroscopy has been used to study the arsenate minerals haidingerite Ca(AsO3OH)•H2O and brassite Mg(AsO3OH)•4H2O. Intense Raman bands in haidingerite spectrum observed at 745 and 855 cm-1 are assigned to the (AsO3OH)2- ν3 antisymmetric stretching and ν1 symmetric stretching vibrational modes. For brassite two similarly assigned intense bands are found at 809 and 862 cm-1. The observation of multiple Raman bands in the (AsO3OH)2- stretching and bending regions suggests that the arsenate tetrahedrons in the crystal structures of both minerals studied are strongly distorted. Broad Raman bands observed at 2842 cm-1 for haidingerite and 3035 cm-1 for brassite indicate strong hydrogen bonding of water molecules in the structure of these minerals. OH…O hydrogen bond lengths were calculated from the Raman spectra based on empiric relations.
TL;DR: In this article, the thermal stability of the gallium containing hydrotalcite was determined using thermogravimetric analysis using four mass loss steps at 77, 263, 280, 485 and 828 °C with mass losses of 10.23, 21.55, 5.20 and 7.58% are attributed to dehydration, dehydroxylation and decarbonation.
Abstract: Hydrotalcites based upon gallium as a replacement for aluminium in hydrotalcite over a Mg/Al ratio of 2:1 to 4:1 were synthesised. The d(003) spacing varied from 7.83 A for the 2:1 hydrotalcite to 8.15 A for the 3:1 gallium containing hydrotalcite. A comparison is made with the Mg/Al hydrotalcite in which the d(003) spacing for the Mg/Al hydrotalcite varied from 7.62 A for the 2:1 Mg hydrotalcite to 7.98 A for the 4:1 hydrotalcite. The thermal stability of the gallium containing hydrotalcite was determined using thermogravimetric analysis. Four mass loss steps at 77, 263–280, 485 and 828 °C with mass losses of 10.23, 21.55, 5.20 and 7.58% are attributed to dehydration, dehydroxylation and decarbonation. The thermal stability of the gallium containing hydrotalcite is slightly less than the aluminium hydrotalcite.