Theoretical principles for quantitative X-ray analysis in systems with high microabsorption

González, C. R.; Roque‐Malherbe, R.; Shchukin, E. D.

doi:10.1007/bf01739297

Cited by 13 publications

(6 citation statements)

References 5 publications

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“…Further, the X-ray diffraction data (Figs. 1b and 1c) allowed the calculation of the phase composition of the modified clinoptilolites by means of standards [21] by applying a previously developed methodology [56,57]. In the present case the standard was the sample NH 4 -CSW.…”

Section: Resultsmentioning

confidence: 99%

Study of the Adsorption Space of Modified Clinoptilolites

Rolando¹,

Roque-Malherbe²,

Alba³

et al. 2013

JMSE-B

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Carbon dioxide (CO 2 ) adsorption is an important adsorbent characterization method and a significant industrial process. In separation and recovery technology, the adsorption of the CO 2 is important to reduce the concentration of this gas considered as one of the greenhouse gases. Natural zeolites, particularly clinoptilolite, are widely applied as adsorbents. In this regard, in the present research, the structure, composition and morphology of modified with hexafluorosilicate (HFSi) and orthophosphoric acid (H 3 PO 4 ) clinoptilolites were investigated by characterizations and measurements made with, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDAX) and gravimetric adsorption. Additionally, the surface Chemistry of the modified clinoptilolites was analyzed by applying diffuse reflectance fourier transform infrared spectrometry (DRIFTS). Further, the interaction of CO 2 within the adsorption space of these modified clinoptilolites and a synthetic ZSM-5 zeolite was studied with the help of adsorption measurements. After all, an appropriate theoretical methodology for the analysis of the XRD and adsorption data was applied. The calculated cell parameters of the tested are similar to those reported for a typical clinoptilolite of: a = 17.662 Ǻ, b = 17.911 Ǻ, c = 7.407 Ǻ and β = 116.40 The resolution of the TGA derivative profiles indicated the presence of two steps for water release, one of them represents the loss of majority of the water present in the micropores. This was evidenced as a broad peak centered at about 50 0 C for the CSW-HFSi-0.1, but at 100 °C for the samples CSW-HFSi-0.4. The SEM micrographs corresponding to the modified clinoptilolites, was evidenced that the CSW zeolite shows secondary particles exhibiting diameters from 3 to 40 μm, formed by primary clinoptilolite crystallites showing a crystallite size, Φ = 40 nm. The EDAX elemental analysis it can be demonstrated that the exchange process replaced about 85% of the charge compensating ions. The DRIFT spectra of the modified clinoptilolites, specifically, CSW-HFSi-0.1, show a narrow band at about: 3,740 cm -l corresponding to terminal silanol groups (Si-OH) and a band 3,600-3,650 cm -1 resulting from extra-framework Al-OH. With the precision of the measured micropore volumes related to the excellent fitting of the adsorption data by the D-R isotherm equation, it can be affirm that carbon adsorption took only place in the micropore region. The isosteric heat of adsorption calculated for the modified clinoptilolites was greater than those values reported of ZSM-5 zeolite, particle packing silica, dealuminated Y zeolite (DAY) Cd, Zn and Ni-nitroprussides and Cu-nitroprusside and a Ni-MOF. With the obtained result it can be concluded that the modified clinoptilolites with HFSi showed a quality as adsorbent comparable to commercial synthetic zeolites.

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Section: Resultsmentioning

confidence: 99%

Study of the Adsorption Space of Modified Clinoptilolites

Rolando¹,

Roque-Malherbe²,

Alba³

et al. 2013

JMSE-B

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“…2003). In order to minimize the effect of microabsorption, care was taken to grind the samples thoroughly before collecting data, as microabsorption effects diminish with decreasing grain size (González et al. 1987; Pederson et al.…”

Section: Experimental Methodsmentioning

confidence: 99%

Mineralogical and spectroscopic investigation of the Tagish Lake carbonaceous chondrite by X-ray diffraction and infrared reflectance spectroscopy

Izawa

Flemming

King

et al. 2010

Meteoritics &Amp; Planetary Science

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Abstract-We have carried out a sample-correlated spectroscopic and mineralogical investigation of samples from seven different collection sites of the Tagish Lake C2 chondrite. Rietveld refinement of high-resolution powder X-ray diffraction (XRD) data was used to determine quantitative major mineral abundances. Thermal infrared (400-4500 cm )1 , 2.2-25.0 lm) spectra of the same samples were obtained using diffuse (biconical) reflectance infrared Fourier transform spectroscopy (DRIFTS). Our results are in good agreement with previous studies of the mineralogy of the Tagish Lake meteorite; we find however that Tagish Lake is more varied in major mineralogy than has previously been reported. In particular, we observed two new distinct lithologies, an inclusion-poor magnetite-and sulfide-rich lithology, and a carbonate-rich, siderite-dominated lithology in addition to the previously documented carbonate-rich and carbonate-poor lithologies. Grain density for each Tagish Lake sample was calculated from the measured mineral modal abundances and known mineral densities. For powders from three originally intact inclusion-rich samples, the calculated grain density is 2.77 ± 0.05 g cm )3 , in excellent agreement with those reported in the literature for other intact inclusion-rich Tagish Lake samples. Tagish Lake disaggregated samples have a significantly higher calculated grain density due to their lower saponite-serpentine content, likely a result of mineral separation in the meltwater holes from which they were collected; the disaggregated samples may not therefore adequately represent bulk samples of the Tagish Lake meteorite. The predominance of very fine-grained material in the Tagish Lake samples investigated in this study is expected to produce infrared spectra representative of asteroidal regolith. Gypsum and talc have been found by XRD in powders from the inclusion-rich, intact Tagish Lake samples in this study, and may have been present in the parent body; if present, these hydrous sulfates would complicate the interpretation of possible hydrated mineral features in asteroid infrared spectra.

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“…The dependence between the apparent permittivity of powdered homoionic Na-HEU, Ca-HEU Na-MOR (homoionized natural clinoptilolite and mordenite with 75 and 85 weight per cent, respectively, of zeolite phase and the remainder quartz, calcite, montmorillonite and volcanic glass [25,26], Na-PHI and Na-FAU (Phillipsite and faujasite synthesized in our laboratory (27)) and the frequency (0.04 to 100 kHz) was measured with a measuring device [1,28,29] consisting of an operational amplifier which compares the capacities of a standard and a sample capacitor. By using the relation e ( w ) = -~o x, where Cx is the capacity of the condenser full of sample and Ce is the capacity of the empty capacitor, and the relation e ( w ) = e ( oo ) + X' ( w ), it is possible to fit the experimental data with the real part of Eq.…”

Section: Methodsmentioning

confidence: 99%

Foundations of thermo-dielectrical analysis

Roque‐Malherbe

Hernández‐Vélez²

1990

Journal of Thermal Analysis

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The dielectric susceptibility of dehydrated homoionic Zeolites was calculated by using a cation hopping model consisting of classical jumps over a barrier. The calculation method was based on determination of the response function of the homoionic dehydrated zeolite under transient excitation. The dielectric susceptibility expression obtained was compared with experimental dielectric spectra at different temperatures and the activation energy for cationic diffusion in the zeolites tested was also calculated. The results were within the range of values reported for cationic migration in the solid state. Further, there is a clear difference between the activation energies of Na and Ca diffusion and this fact forms a quantitative basis for the explanation of the thermodielectric thermograms of homoionic sodium and calcium zeolites and promote the understanding of the role of cationic polarization and cationic migration in thermodielectric analysis.The study of the role of cationic polarization in thermodielectric analysis by using the dispersion spectrum of zeolites measured with a dielectric spectrometer developed in our laboratory [1] was discussed in the first paper of the present series. The approach used was essentially qualitative and the aim of the present report is to give a quantitative discussion of the role of cationic migration in zeolite polarization phenomena. Zeolite was selected as model material because of the presence in its thermodielectric thermograms of the most important polarization effects recorded by this method [3][4][5][6][7].Therefore, the object of the present paper is the calculation of the dielectric susceptibility of dehydrated homoionic zeolites based on a model of cation hopping polarization [8]. Further, we compare the experimental John W'dey & Sons, Limite~ Chichester ~ Kiad6, Budap~

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Theoretical principles for quantitative X-ray analysis in systems with high microabsorption

Cited by 13 publications

References 5 publications

Study of the Adsorption Space of Modified Clinoptilolites

Study of the Adsorption Space of Modified Clinoptilolites

Mineralogical and spectroscopic investigation of the Tagish Lake carbonaceous chondrite by X-ray diffraction and infrared reflectance spectroscopy

Foundations of thermo-dielectrical analysis

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