Showing papers by "Ray L. Frost published in 2011"
TL;DR: This paper reviews the adsorption of organics on organoclay based upon organoclays for water purification from recalcitrant organic chemicals.
182 citations
TL;DR: The results of IR and IES supports the concept that the formula of nesquehonite is better defined as Mg(OH)(HCO(3))·2H(2)O, which is supported by thermoanalytical results.
106 citations
TL;DR: The collected data from various techniques enable an understanding of the changes in structure and surface properties of montmorillonite and organoclays, and the confirmation of intercalated surfactant was investigated.
93 citations
TL;DR: In this paper, the authors examined the correlation between heavy metals and geochemical indices, including Fe2O3, Al2O 3, total organic carbon (TOC) and black carbon (BC), as well as magnetic susceptibility (MS) using principal component analysis (PCA).
Abstract: Heavy metal contamination of bottom sediments of the Changjiang River is widely reported, however, the potential source and methods of transportation of these heavy metals in the contaminated sediments is poorly defined. This paper examines the correlation between heavy metals and geochemical indices, including Fe2O3, Al2O3, total organic carbon (TOC) and black carbon (BC), as well as magnetic susceptibility (MS). Using these indices we investigate the contamination characteristics of heavy metals in the sediments by with Principal Component Analysis (PCA). Results from 83 sediment samples collected in the lower reach of Changjiang River (from Nanjing to Shanghai) show that the first principal component accounts for 52.23% of the total variance, corresponding to the heavy metals, Co, Cr, Cu, Ni and Zn, and conservative components of Fe2O3, Al2O3 and TOC. This result indicates that heavy metal distributions are controlled by the transportation and sedimentation of fine particles which is also confirmed by particle size analysis. The second principal component explains 24.81% of the variance and is dominated by Cd, Pb and MS, which, collectively, result chiefly from industrial and transportation activities and, for MS, fly ash production. The third principal component accounts for 7.91% of the variance and corresponds solely to Hg. Principal component analysis/multiple linear regression (PCA/MLR) was used to estimate the contribution of the three principal components to each heavy metal. PCA/MLR results suggest that more than 50% of Co, Cr, Cu, Ni and Zn were influenced by the particle size effect. Particle size effect and fly ash account for 37.1% and 27.7% of As. Cd and Pb were mainly explained by fly ash. 98.9% of Hg was related to PC3, which represented black carbon (BC). Our study indicates that the combination of geochemical and multivariable statistical methods clearly characterizes the geochemistry of heavy metals in sediment of the lower reaches of the Changjiang River and suggests that power plants are the main source of heavy metal pollution.
87 citations
TL;DR: In an attempt to make nanofibres based upon cobalt oxides, a novel compound hydrated cobalt hydroxy carbonate was formed that was characterised by vibrational spectroscopy and the spectra related to minerals of the rosasite mineral group.
74 citations
TL;DR: In this paper, a palygorskite/carbon sorbent was synthesized by hydrothermal carbonization of glucose onto palygskite using ammonium ferrous iron (Fe 2+ ) sulphate hexahydrate as catalyst under mild conditions.
68 citations
TL;DR: The Raman spectrum of volborthite is characterized by the strong band at 888 cm−1, assigned to the ν1 (VO3) symmetric stretching vibrations.
Abstract: Raman spectroscopy has been used to study vanadates in the solid state. The molecular structure of the vanadate minerals vesignieite [BaCu3(VO4)2(OH)2] and volborthite [Cu3V2O7(OH)2·2H2O] have been studied by Raman spectroscopy and infrared spectroscopy. The spectra are related to the structure of the two minerals. The Raman spectrum of vesignieite is characterized by two intense bands at 821 and 856 cm−1 assigned to ν1 (VO4)3− symmetric stretching modes. A series of infrared bands at 755, 787 and 899 cm−1 are assigned to the ν3 (VO4)3− antisymmetric stretching vibrational mode. Raman bands at 307 and 332 cm−1 and at 466 and 511 cm−1 are assigned to the ν2 and ν4 (VO4)3− bending modes. The Raman spectrum of volborthite is characterized by the strong band at 888 cm−1, assigned to the ν1 (VO3) symmetric stretching vibrations. Raman bands at 858 and 749 cm−1 are assigned to the ν3 (VO3) antisymmetric stretching vibrations; those at 814 cm−1 to the ν3 (VOV) antisymmetric vibrations; that at 508 cm−1 to the ν1 (VOV) symmetric stretching vibration and those at 442 and 476 cm−1 and 347 and 308 cm−1 to the ν4 (VO3) and ν2 (VO3) bending vibrations, respectively. The spectra of vesignieite and volborthite are similar, especially in the region of skeletal vibrations, even though their crystal structures differ.
52 citations
TL;DR: In this article, a comparison between halloysite and Halloysite-potassium acetate intercalation complex in all spectral ranges was made. But, the results showed that the reproducibility of measurement and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for molecular structural analysis.
52 citations
TL;DR: In this article, a combination of Raman and infrared spectroscopy has been used to study the mineral hydromagnesite, which is important for understanding the concept of geosequestration.
Abstract: Magnesium minerals are important for understanding the concept of geosequestration. One method of studying the hydrated hydroxy magnesium carbonate minerals is through vibrational spectroscopy. A combination of Raman and infrared spectroscopy has been used to study the mineral hydromagnesite. An intense band is observed at 1121 cm−1, attributed to the CO32−ν1 symmetric stretching mode. A series of infrared bands at 1387, 1413 and 1474 cm−1 are assigned to the CO32−ν3 antisymmetric stretching modes. The CO32−ν3 antisymmetric stretching vibrations are extremely weak in the Raman spectrum and are observed at 1404, 1451, 1490 and 1520 cm−1. A series of Raman bands at 708, 716, 728 and 758 cm−1 are assigned to the CO32−ν2 in-plane bending mode. The Raman spectrum in the OH stretching region is characterized by bands at 3416, 3516 and 3447 cm−1. In the infrared spectrum, a broad band is found at 2940 cm−1, which is assigned to water stretching vibrations. Infrared bands at 3430, 3446, 3511, 2648 and 3685 cm−1 are attributed to MgOH stretching modes. Copyright © 2011 John Wiley & Sons, Ltd.
50 citations
TL;DR: In this paper, four Chinese palygorskites clay minerals have been analyzed by thermogravimetric analysis-mass spectrometry and X-ray diffraction, and the results show that the dehydration occurs in four main steps: (a) elimination of interparticle water and partial zeolitic water at below 110°C, (b) release of the rest part of zerosolic water from the structural layer of paly gorskite at about 160 ǫ c, (c) dehydration of one part of bound water at about 340
49 citations
TL;DR: The bands of water stretching vibrations and -OH groups shifted to higher wavenumbers when CaAl-LDH-Cl was intercalated by SDBS, and their intensity of MIR and NIR spectra became lower in intensity.
TL;DR: In this paper, a mechanism for the formation of brushite on calcite surfaces is proposed, and this mechanism has relevance to the formation in urinary tracts, and the mechanism has been shown to be useful in the formation brushite in calcite.
TL;DR: In this paper, the transition of disc-like chromium hydroxide nanomaterials to Cr2O3 has been studied by hot-stage Raman spectroscopy.
Abstract: The transition of disc-like chromium hydroxide nanomaterials to chromium oxide nanomaterials has been studied by hot-stage Raman spectroscopy. The structure and morphology of α-CrO(OH) synthesised using hydrothermal treatment were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The Raman spectrum of α-CrO(OH) is characterised by two intense bands at 823 and 630 cm−1 attributed to ν1 CrIIIO symmetric stretching mode and the band at 1179 cm−1 attributed to CrIIIOH δ deformation modes. No bands are observed above 3000 cm−1. The absence of characteristic OH stretching vibrations may be due to short hydrogen bonds in the α-CrO(OH) structure. Upon thermal treatment of α-CrO(OH), new Raman bands are observed at 599, 542, 513, 396, 344 and 304 cm−1, which are attributed to Cr2O3. This hot-stage Raman study shows that the transition of α-CrO(OH) to Cr2O3 occurs before 350 °C. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, the Raman spectra of a series of related minerals of the pinakiolite group have been collected and the spectra related to the mineral structure are assigned to the ν1 BO33− symmetric stretching mode.
Abstract: The Raman spectra of a series of related minerals of the pinakiolite group have been collected and the spectra related to the mineral structure. These minerals are based upon an isolated BO33− ion. The site symmetry is reduced from D3h to C1. Intense Raman bands are observed for the minerals takeuchiite, pinakiolite, fredrikssonite and azoproite at 1084, 1086, 1086 and 1086 cm−1. These bands are assigned to the ν1 BO33− symmetric stretching mode. Low-intensity Raman bands are observed for the minerals at 1345, 1748; 1435, 1748; 1435, 1750; and 1436, 1749 cm−1, respectively. One probable assignment is to ν3 BO33− antisymmetric stretching mode. Intense Raman bands of the studied minerals at 712 cm−1 are attributed to the ν2 out-of-plane bending mode. Importantly, through the comparison of the Raman spectra, the molecular structure of borate minerals with ill-defined structures can be obtained. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this article, the effect of thermal treatment on pore structure and surface acid-alkali properties of Pg through the adsorption-desorption of NH3 and SO2 was investigated.
TL;DR: In this paper, the molecular structure of the mineral beudantite using vibrational spectroscopy was determined by a combination of Raman and infrared spectroscopic techniques, and the approximate range of O−H⋯O hydrogen bond lengths was inferred from the Raman spectra.
TL;DR: In this paper, a series of layered double hydroxides (LDHs) based composites were synthesized by using an induced hydrolysis silylation (IHS) method, surfactant precursor method, in situcoprecipitation method, and direct Silylation method.
Abstract: A series of layered double hydroxides (LDHs) based composites were synthesized by using an induced hydrolysis silylation (IHS) method, surfactant precursor method, in situcoprecipitation method, and direct silylation method. Their structures, morphologies, bonding modes and thermal stabilities can be readily adjusted by changing the parameters during preparation and drying processing of the LDHs. The characterization results show that the direct silylation reaction cannot occur between the dried LDHs and 3-aminopropyltriethoxysilane (APS) in an ethanol medium. However, the condensation reaction can proceed with a heating process between the adsorbed APS and LDHs plates. While using wet state substrates with and without surfactant and ethanol as the solvent, the silylation process can be induced by the hydrolysis of APS on the surface of the LDHs plates. Surfactants improve the hydrophobicity of the LDHs during the process of nucleation and crystallization, resulting in fluffy shaped crystals; meanwhile, they occupy the surface –OH positions and leave less “free –OH” available for the silylation reaction, favoring the formation of silylated products with a higher population in the hydrolyzed bidentate (T2) and tridentate (T3) bonding forms. These bonding characteristics lead to spherical aggregates and tightly bonded particles. All silylated products show higher thermal stability than those of pristine LDHs.
TL;DR: The Raman spectrum of atelestite Bi2O(OH)(AsO4), a hydroxy-arsenate mineral containing bismuth, has been studied in terms of spectra-structure relations and a weak band at 1082 cm(-1) is assigned to δ(BiOH) vibration.
TL;DR: Estimates of the hydrogen-bond distances have been made from the position of the OH stretching vibrations and show a wide range in both strong and weak bonds.
Journal Article•
TL;DR: In this article, the removal of sulfate anion from water using synthetic hydrotalcite (Mg/Al LDH) was investigated using powder x-ray diffraction and thermogravimetric analysis.
Abstract: The removal of the sulfate anion from water using synthetic hydrotalcite (Mg/Al LDH) was investigated using powder x-ray diffraction (XRD) and thermogravimetric analysis (TG). Synthetic hydrotalcite Mg6Al2(OH)16(CO3)∙4H2O was prepared by the co-precipitation method from aluminum and magnesium chloride salts. The synthetic hydrotalcite was thermally activated to a maximum temperature of 380°C. Samples of thermally activated hydrotalcite where then treated with aliquots of 1000ppm sulfate solution. The resulting products where dried and characterized by XRD and TG. Powder XRD revealed that hydrotalcite had been successfully prepared and that the product obtained after treatment with sulfate solution also conformed well to the reference pattern of hydrotalcite. The d(003) spacing of all samples was found to be within the acceptable region for a LDH structure. TG revealed all products underwent a similar decomposition to that of hydrotalcite. It was possible to propose a reasonable mechanism for the thermal decomposition of a sulfate containing Mg/Al LDH. The similarities in the results may indicate that the reformed hydrotalcite may contain carbonate anion as well as sulfate. Further investigation is required to confirm this.
TL;DR: In this study, the surfaces of thin alumina (γ-Al(2)O(3)) nanofibres were modified by the grafting either of two organosilane agents, 3-chloro-propyl-triethoxysilane (CPTES) and octyl- triethoxisilanes (OTES) to be used as absorbents for the removal of two herbicides, alachlor and imazaquin from water.
TL;DR: The infrared emission spectra clearly show the structural changes and dehydroxylation of the palygorskites when the temperature is raised, and is an effective method to determine the stability of the mineral.
TL;DR: The thermal behavior and decomposition of a kaolinite-potassium acetate intercalation complex was investigated through a combination of thermogravimetric analysis and infrared emission spectroscopy as mentioned in this paper.
Abstract: The thermal behavior and decomposition of kaolinite–potassium acetate intercalation complex was investigated through a combination of thermogravimetric analysis and infrared emission spectroscopy. Three main changes were observed at 48, 280, 323, and 460 °C which were attributed to (a) the loss of adsorbed water, (b) loss of the water coordinated to acetate ion in the layer of kaolinite, (c) loss of potassium acetate in the complex, and (d) water through dehydroxylation. It is proposed that the potassium acetate intercalation complex is stability except heating at above 300 °C. The infrared emission spectra clearly show the decomposition and dehydroxylation of the kaolinite intercalation complex when the temperature is raised. The dehydration of the intercalation complex is followed by the loss of intensity of the stretching vibration bands at region 3600–3200 cm−1. Dehydroxylation is followed by the decrease in intensity in the bands between 3695 and 3620 cm−1. Dehydration is completed by 400 °C and partial dehydroxylation by 650 °C. The inner hydroxyl group remained until around 700 °C.
TL;DR: In this paper, a two-step method to remove nonionic alachlor and anionic imazaquin herbicides from water was proposed, where layered beidellite clay, a member of smectite family, was treated with acid in hydrothermal process, and common silane coupling agents, 3-chloro-propyl trimethoxysilane or triethoxy silane, were grafted on the acid treated samples to prepare adsorbent materials.
TL;DR: In this article, Czech dussertite has been studied by Raman coupled with infrared spectroscopy and four bands are observed in the 800 to 950 cm-1 region.
Abstract: The mineral dussertite, a hydroxy-arsenate mineral of formula BaFe3+3(AsO4)2(OH)5, has been studied by Raman complimented with infrared spectroscopy. The spectra of three minerals from different origins were investigated and proved quite similar, although some minor differences were observed. In the Raman spectra of Czech dussertite, four bands are observed in the 800 to 950 cm-1 region. The bands are assigned as follows: the band at 902 cm-1 is assigned to the (AsO4)3- ν3 antisymmetric stretching mode, at 870 cm-1 to the (AsO4)3- ν1 symmetric stretching mode, and both at 859 cm-1 and 825 cm-1 to the As-OM2+/3+ stretching modes/and or hydroxyls bending modes. Raman bands at 372 and 409 cm-1 are attributed to the ν2 (AsO4)3- bending mode and the two bands at 429 and 474 cm-1 are assigned to the ν4 (AsO4)3- bending mode. An intense band at 3446 cm-1 in the infrared spectrum and a complex set of bands centred upon 3453 cm-1 in the Raman spectrum are attributed to the stretching vibrations of the hydrogen bonded (OH)- units and/or water units in the mineral structure. The broad infrared band at 3223 cm-1 is assigned to the vibrations of hydrogen bonded water molecules. Raman spectroscopy identified Raman bands attributable to (AsO4)3- and (AsO3OH)2- units.
TL;DR: In this paper, the ability of hydrotalcites to remove vanadate and arsenate from solution has been determined by inductively coupled optical emission spectroscopy, which was used to monitor changes in the anionic species for hydrolcites synthesized at different pH values.
Abstract: Hydrotalcites have been synthesised using solutions of three different pH values to assess the effect of pH on the uptake of arsenate and vanadate. The ability of these hydrotalcites to remove vanadate and arsenate from solution has been determined by inductively coupled optical emission spectroscopy. Raman spectroscopy was used to monitor changes in the anionic species for hydrotalcites synthesised at different pH values. The results show a reduction in the concentration of arsenate and vanadate anions that are removed in extremely alkaline solutions. Hydrotalcites containing arsenate and vanadate are stable in solutions up to pH 10. Exposure of these hydrotalcites to higher pH values results in the removal of large percentages of arsenate and vanadate from the hydrotalcite interlayer. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, the Raman spectra of the klebelsbergite Sb4O4(OH)2(SO4) were studied and related to the structure of the mineral.
Abstract: Many minerals based upon antimonite and antimonate anions remain to be studied. Most of the bands occur in the low wavenumber region, making the use of infrared spectroscopy difficult. This problem can be overcome by using Raman spectroscopy. The Raman spectra of the mineral klebelsbergite Sb4O4(OH)2(SO4) were studied and related to the structure of the mineral. The Raman band observed at 971 cm−1 and a series of overlapping bands are observed at 1029, 1074, 1089, 1139 and 1142 cm−1 are assigned to the SO42−ν1 symmetric and ν3 antisymmetric stretching modes, respectively. Two Raman bands are observed at 662 and 723 cm−1, which are assigned to the SbO ν3 antisymmetric and ν1 symmetric stretching modes, respectively. The intense Raman bands at 581, 604 and 611 cm−1 are assigned to the ν4 SO42− bending modes. Two overlapping bands at 481 and 489 cm−1 are assigned to the ν2 SO42− bending mode. Low-intensity bands at 410, 435 and 446 cm−1 may be attributed to OSbO bending modes. The Raman band at 3435 cm−1 is attributed to the OH stretching vibration of the OH units. Multiple Raman bands for both SO42− and SbO stretching vibrations support the concept of the non-equivalence of these units in the klebelsbergite structure. It is proposed that the two sulfate anions are distorted to different extents in the klebelsbergite structure. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: The mineral corkite Pb Fe 3 3 + (PO4,SO4)2(OH)6 is a hydroxy phosphate mineral belonging to the beudantite subgroup of alunites as discussed by the authors.
TL;DR: In this article, a combination of X-ray diffraction (XRD) as well as infrared and Raman spectroscopies was used to synthesize hydrotalcites (Ca-HTs) containing calcium.
Abstract: We have successfully synthesised hydrotalcites (HTs) containing calcium, which are naturally occurring minerals. Insight into the unique structure of HTs has been obtained using a combination of X-ray diffraction (XRD) as well as infrared and Raman spectroscopies. Calcium-containing hydrotalcites (Ca-HTs) of the formula Ca4Al2(CO3)(OH)12·4H2O (2:1 Ca-HT) to Ca8Al2(CO3)(OH)20· 4H2O (4:1 Ca-HT) have been successfully synthesised and characterised by XRD and Raman spectroscopy. XRD has shown that 3:1 calcium HTs have the largest interlayer distance. Raman spectroscopy complemented with selected infrared data has been used to characterise the synthesised Ca-HTs. The Raman bands observed at around 1086 and 1077 cm−1 were attributed to the ν1 symmetric stretching modes of the (CO32−) units of calcite and carbonate intercalated into the HT interlayer. The corresponding ν3 CO32− antisymmetric stretching modes are found at around 1410 and 1475 cm−1. Copyright © 2010 John Wiley & Sons, Ltd.
TL;DR: In this paper, a comparative study explored the dissolution kinetics for the case of commercial titania powders, one composed of predominantly anatase and the other rutile phase (>93%), were hydrothermally reacted in 9 mol L−1 NaOH at 160 °C over a range of reaction times of between 2 and 32 h.
Abstract: In this study, the mechanism of precursor dissolution and the influence of kinetics of dissolution on titanate nanotube formation were investigated. This comparative study explored the dissolution kinetics for the case of commercial titania powders, one composed of predominantly anatase (>95%) and the other rutile phase (>93%). These nanoparticle precursors were hydrothermally reacted in 9 mol L−1 NaOH at 160 °C over a range of reaction times of between 2 and 32 h. The high surface area nanotube-form product was confirmed using X-ray diffraction, FT-Raman spectroscopy, and transmission electron microscopy. The concentration of nanotubes produced from the different precursors was established using Rietveld analysis with internal and external corundum standardization to calibrate the absolute concentrations of the samples. Interpretation of the dissolution process of the precursor materials indicated that the dissolution of anatase proceeds via a zero-order kinetic process, whereas rutile dissolution is through a second-order process. The TiO2 nanostructure formation process and mechanism of TiO2 precursor dissolution was confirmed by non-invasive dynamic light scattering measurements. Significant observations are that nanotube formation occurred over a broad range of hydrothermal treatment conditions and was strongly influenced by the order of precursor dissolution.