Surface Area Changes of a Vermiculite by Acid and Thermal Treatment

López-González, J. de D.

doi:10.1346/ccmn.1957.0060130

Cited by 4 publications

(2 citation statements)

References 9 publications

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“…After the modification using HCl 2 mol/L, at 2 hours of contact time and 60˚C, it could be visually observed that the expanded vermiculite lost color and structural features. Results produced by Lopez-Gonzalez and Barrel-Ruiz [39] corroborate these observations. These authors found a total dissolution of the vermiculite and also reported obtaining a white silicate after modification using HCl 5 mol/L, at a 30-minute contact time.…”

Section: Modification Of Expanded Vermiculitesupporting

confidence: 63%

Characterization and Modification of a Clay Mineral Used in Adsorption Tests

Dias¹,

Steiner²,

Braga

2015

JMMCE

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Clay minerals are widespread in natural systems and have been widely used for the removal of pollutants. In this study, natural expanded vermiculite was used in adsorption tests to remove ammonium nitrogen from landfill leachate. The modification of vermiculite was carried out using NaOH and HCl, and for both modifications the best concentration was 0.1 mol/L. The results produced by XRD (X-ray diffraction) showed that Al replaced K after modification of the vermiculite using HCl and that Mg and Na replaced K after modification using NaOH. It was observed that the adsorption capacity increased as the percentage in mass of K diminished. The Langmuir is the isotherm that presents the best fit of the data, and the values of RL (the Langmuir coefficient) suggest that the adsorption is linear. The thermodynamic parameters indicate that the process is spontaneous and endothermic, that there is a high affinity between the adsorbate and the adsorbent, and that physical adsorption is prevalent.

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Section: Modification Of Expanded Vermiculitesupporting

confidence: 63%

Characterization and Modification of a Clay Mineral Used in Adsorption Tests

Dias¹,

Steiner²,

Braga

2015

JMMCE

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“…In the spectra of the vermiculitic group, the 14A peak remained unchanged even after 7 days' treatment, but the 10-14A region became increasingly devoid of signals. DISCUSSION AND CONCLUSIONS Boiling with 1 M HN03 has been considered drastic treatment of micaceous soil minerals (18,23). Our results show that although it dissolves intergrades and vermiculites, it has very little effect on dioctahedral minerals with 10A interlaminar spacing.…”

Section: 76mentioning

confidence: 64%

Kinetics and structural effects of the extraction of non‐exchangeable potassium from the clay fraction of soils of Galicia (N.W. Spain)

Gil‐Sotres

Armesto

1992

Communications in Soil Science and Plant Analysis

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The kinetics of non-exchangeable K extraction by the boiling HN03 and sodium tetraphenylborate (NaTPB) methods for the clay fractions of six typical soils of Galicia (N.W. Spain), whose predominant clay minerals are illites, vermiculites and illite-vermiculite intergrades, was investigated. The progressive structural degradation of the clay minerals during extraction was studied by X-ray diffraction. For the boiling HNO 3 method, extraction rate constants were significantly smaller for predominantly illite clays than for clays in which other micaceous minerals predominated. The X-ray diffraction data showed that even 60 minutes of the boiling nitric acid treatment was unable to expand the minerals widi 10A interlayer spacing, which invalidates this method for routine work. For extraction with NaTPB, there were no significant differences among the different types of clay regarding their extraction rate constants, but the X-ray data showed that illites were progressively expanded as extraction progressed. The theoretical models best fitting the K extraction data were in all cases the Elovich, power function and parabolic difussion equations, but the data were actually best fitted by a pair of straight line segments. The nearly 24 h mean time at which the two segments met for the NaTPB method suggests that extracting for this period of time would make the results of the NaTPB method more meaningful than the usual 72 h.

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Textural variations of acid‐treated serpentine

Girgis

Mourad

1976

J. Appl. Chem.

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A natural serpentine deposit was subjected to treatment with hydrochloric acid of different concentrations, and for varying times. Changes in the texture parameters were determined from adsorption isotherms of nitrogen. In general, treatment with increasing acid concentrations (up to 25%) leads to an increase in various characteristics of serpentine, i.e. weight loss, dissolved iron oxide, “free” silica, surface area, and pore volume. Prolonged treatment results in only slight changes in such parameters. Solids of high specific surface areas (up to 300 m2/g) and of microporous character (mean pore radii ca 15–20 Å) are obtained.

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Surface Area Changes of a Vermiculite by Acid and Thermal Treatment

Cited by 4 publications

References 9 publications

Characterization and Modification of a Clay Mineral Used in Adsorption Tests

Characterization and Modification of a Clay Mineral Used in Adsorption Tests

Kinetics and structural effects of the extraction of non‐exchangeable potassium from the clay fraction of soils of Galicia (N.W. Spain)

Textural variations of acid‐treated serpentine

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