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to 1.2 MPa. A new volumetric apparatus has since been developed and characterized using both helium adsorption and desorption measurements, so that the void volume that is not occupied by the adsorbent can be measured with a high precision. The data

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performances in a Mediterranean climate. Aristov et al. [ 18 ] have proposed and tested a new methodology of studying the kinetics of water vapor sorption/desorption on pellets of composite sorbent SWS-1L (CaCl 2 in silica KSK) placed on a metal plate. Many

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understanding of soils [ 2 – 4 ]. Equally important is to understand the adsorption-desorption phenomena [ 5 – 7 ]. If acids such as benzoic acid and stearic acid adsorb on soil containing clays then fundamentally natural organoclays are formed

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Abstract  

Thermal analysis and differential thermal analysis offers a novel means of studying the desorption of acids such as stearic acid from clay surfaces. Both adsorption and chemisorption can be distinguished through the differences in the temperature of mass losses. Increased adsorption is achievable by adsorbing onto a surfactant adsorbed montmorillonite. Stearic acid sublimes at 179 °C but when adsorbed upon montmorillonite sublimes at 207 and 248 °C. These mass loss steps are ascribed to the desorption of the stearic acid on the external surfaces of the organoclays and from the de-chemisorption from the surfactant held in the interlayer of the montmorillonite.

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Abstract  

The adsorption of Eu(III) on multiwalled carbon nanotubes (MWCNTs) as a function of pH, ionic strength and solid contents are studied by batch technique. The results indicate that the adsorption of Eu(III) on MWCNTs is strongly dependent on pH values, dependent on ionic strength at low pH values and independent of ionic strength at high pH values. Strong surface complexation and ion exchange contribute to the adsorption of Eu(III) on MWCNTs at low pH values, whereas surface complexation and surface precipitation are the main adsorption mechanism of Eu(III) on MWCNTs. The desorption of adsorbed Eu(III) from MWCNTs by adding HCl is also studied and the recycling use of MWCNTs in the removal of Eu(III) is investigated after the desorption of Eu(III) at low pH values. The results indicate that adsorbed Eu(III) can be easily desorbed from MWCNTs at low pH values, and MWCNTs can be repeatedly used to remove Eu(III) from aqueous solutions. MWCNTs are suitable material in the preconcentration and solidification of radionuclides from large volumes of aqueous solutions in nuclear waste management.

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Abstract  

In this work, Na-montmorillonite was used as a novel adsorbent for the sorption of Ni(II) from aqueous solutions. The sorption and desorption of Ni(II) on Na-montmorillonite was investigated as the function of pH, ionic strength, Ni(II) concentrations and temperature. The results indicated that the sorption of Ni(II) on Na-montmorillonite was strongly dependent on pH, ionic strength and temperature. The sorption of Ni(II) increases slowly from 22.1 to 51.4% at pH range 2–6.5, abruptly at pH 6.5–9, and at last maintains high level with increasing pH at pH > 9 in 0.1 mol/L NaNO3 solutions. The Ni(II) kinetic sorption on Na-montmorillonite was fitted by the pseudo-second-order model better than by the pseudo-first-order model and the experimental data implies that Ni(II) sorption on montmorillonite were mainly controlled by the film diffusion mechanism. The Langmuir, Freundlich and D–R models were used to simulate the sorption data at three different temperatures (298.15, 318.15 and 338.15 K) and the results indicated that Langmuir model simulates the experimental data better than Freundlich and D–R models. The sorption–desorption isotherm of Ni(II) on montmorillonite suggested that the sorption is irreversible. The irreversible sorption of Ni(II) on montmorillonite indicates that montmorillonite can be used to pre-concentration and solidification of Ni(II) from large volumes of solution and to storage Ni(II) ions stably.

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talajok nitrogén gazdálkodásában. Növénytermelés. 36. 269–278. Stefanovits, P. & Füleky, Gy., 2000. Zn- and Cu-adsorption and desorption in the soils after treatment with hydrogen peroxide. Agrokémia és Talajtan

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Thermal desorption analysis:

DSC curves of H2O desorption from silicate glass in the multilayer coverage range

Journal of Thermal Analysis and Calorimetry
Authors: H. Wittkopf, H. -J. Flammersheim, and L. Herlitze

Experiments on water desorption from silicate glass powders of different chemical compositions were carried out by means of DSC. In order to establish the desorption energy distributions, a model of the heterogeneous surface was applied to the thermoanalytical desorption curves, and the results are discussed together with contact angle measurements on flat polished glass samples.

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isotherms are used as tool for measuring the water adsorption of the bulk coating agent and thus assess the relationship between water content, temperature and humidity. The effect of temperature on the adsorption–desorption isotherm of Pharmacoat

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Temperature programmed desorption is a typical non-isothermal method and therefore it needs a careful experimentation and a careful evaluation of the experimental data, in order to obtain meaningful kinetic parameters.

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