Supercritical carbon dioxide behaviour in porous silica aerogel. Erratum

Ciccariello, S.; Melnichenko, Yuri B.; He, Lilin

doi:10.1107/s0021889811035631

Cited by 2 publications

(25 citation statements)

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“…The Porod plots shown in Figure are quite similar to those reported in Figures 3 and 4 of paper I . Thus, as already anticipated and similarly to paper I, the sample is idealized as made up of three homogeneous phases, namely the silica (phase 1), the confined fluid (phase 2), and the liquid film fluid (phase 3).…”

Section: Theoretical Model and Numerical Resultssupporting

confidence: 82%

“…The existence of these parallel interfaces implies that the Porod plots of the observed intensities show an oscillatory behavior around the horizontal asymptote. The “frequency” and the amplitude of the oscillations determine δ and the scattering densities of the involved phases. , As already anticipated, this analysis was successfully applied to analyze the SANS intensities relevant to supercritical CO 2 within a silica aerogel, as a function of pressure at constant temperature, in ref , hereafter referred to as paper I.…”

Section: Introductionmentioning

confidence: 89%

“…SAXS and SANS studies of a fluid within a porous sample were already made either to better characterize the adsorption process − or to study the changes in the critical behavior of the fluid . More recently it has been possible to determine ,− the discrete value approximation of the density profile of the fluid adsorbed by a porous support by a more thorough analysis of the collected SANS or SAXS intensities. To this aim, the authors of refs , , and chose as adsorbing medium a mesoporous silica with cylindrical pores having a two-dimensional hexagonal packing.…”

Section: Introductionmentioning

confidence: 99%

“…This structure is responsible for the presence of Bragg peaks within the scattering vector ( q ) range explored in small angle scattering (SAS) experiments, and the analysis of these peaks made the determination of the scattering density profile possible. By contrast, the authors of ref choose as adsorbing medium a silica aerogel with porosity around 92% and curvature radii larger than 50 Å so as to make Porod’s law , observable in the explored outer q -range. In this case the theoretical tool that allows one to determine the discrete value approximation of the fluid density is the analysis of the oscillations present in the Porod plots of the observed SANS intensities.…”

Section: Introductionmentioning

confidence: 99%

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Phase Behavior of Carbon Dioxide Confined in Silica Aerogel in the Vicinity of the Bulk Critical Point

Ciccariello

Melnichenko

2011

J. Phys. Chem. C

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The small angle neutron scattering intensities from silica aerogel filled with carbon dioxide at different loading densities of the bulk fluid (0.3–0.65 g/cm3) were measured at fixed volume condition as a function of decreasing temperature, from 35 to 25 °C, to characterize the phase behavior of the confined CO2 about the critical point of the bulk CO2. The data present no evidence of a bulklike phase transition of the confined CO2 in the explored parameter region. They show that the confined CO2 may be approximated as a two phase system. The first phase (liquid film) is formed by CO2 molecules at the silica surface, and the second phase (confined fluid) fills up the rest of the pore volume. The thickness δ of the liquid film as well as the scattering-length densities of the two phases were obtained by analyzing the Porod invariants and the oscillations observed in the Porod plots at each loading density and temperature. The resulting δ values vary in the range 25–45 Å depending on the temperature and loading density. The density of the liquid film is 1.5–2 times larger than that of the confined fluid, which in its turn exceeds the density of bulk CO2 at similar temperature and pressure. At the lowest temperature (25 °C), the densities of the liquid film and confined fluid respectively approach 1.25 g/cm3 and 0.8 g/cm3 independently of the loading conditions.

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Section: Theoretical Model and Numerical Resultssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Phase Behavior of Carbon Dioxide Confined in Silica Aerogel in the Vicinity of the Bulk Critical Point

Ciccariello

Melnichenko

2011

J. Phys. Chem. C

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“…We also have applied the threephase model to the SANS intensities of CO 2 absorbed in a silica aerogel in two recent papers. 14,15 The aerogel is a statistically isotropic system so that its intensity shows no peaks in the explored scattering vector (q) range, aside from that set at the origin of reciprocal space. We used the property that the existence of a phase of constant thickness, i.e., the liquid film, is responsible for the presence of an oscillatory contribution 16,17 (see eq 1) in the leading asymptotic term of the scattering intensity.…”

Section: Introductionmentioning

confidence: 99%

Small-Angle Neutron Scattering Study of Deuterated Propane Adsorption in Silica Aerogel

Melnichenko

Ciccariello

2012

J. Phys. Chem. C

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The small angle neutron scattering intensities from fully deuterated propane (C3D8) absorbed in a silica aerogel were measured at two fixed temperatures (102 and 147 °C) and different pressures (P) increasing up to 16 MPa as well as at two different bulk loading densities (0.428 and 0.483 g/cm3) and temperatures (T) decreasing from 102 to 40 °C. They are numerically analyzed assuming that samples behave as made up of three homogeneous phases. The first phase is formed by the silica scaffold, the second phase (liquid film) by the C3D8 molecules at the silica surface, and the third one (confined fluid) by the C3D8 molecules filling up the remaining pore volume. Thus, the absorbed fluid is split into a liquid film and a confined fluid. The thickness δ of the liquid film as well as the scattering-length densities of the two fluid phases are obtained analyzing the Porod invariants and the oscillations observed in the Porod plots of the observed intensities. The resulting δ's vary in the range 25–45 Å. The density of the liquid film is about 0.3 g/cm3 and is nearly insensitive to P and T in contrast to the density of the confined fluid that, however, never exceeds 0.2 g/cm3. The excess densities are evaluated and compared to those of carbon dioxide absorbed in the same aerogel. They satisfactorily agree with the available values obtained by isotherm adsorption measurements.

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Supercritical carbon dioxide behaviour in porous silica aerogel. Erratum

Abstract: Errors in the paper by Ciccariello, Melnichenko & He [J. Appl. Cryst.(2011),44, 43–51] are corrected.

Cited by 2 publications

References 1 publication

Phase Behavior of Carbon Dioxide Confined in Silica Aerogel in the Vicinity of the Bulk Critical Point

Phase Behavior of Carbon Dioxide Confined in Silica Aerogel in the Vicinity of the Bulk Critical Point

Small-Angle Neutron Scattering Study of Deuterated Propane Adsorption in Silica Aerogel

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