Peter Harting

Highest Pressure Adsorption Equilibria Data: Measurement with Magnetic Suspension Balance and Analysis with a New Adsorbent/Adsorbate-Volume

Adsorption data at high pressures provide information about properties of the adsorbent material and about the structure of the adsorbed phase. In order to obtain this information adsorption processes need to be measured in a wide pressure range and require careful experimental data handling. In this paper, an experimental installation with a magnetic suspension balance for the gravimetric measurement of adsorption equilibria data at pressures still inaccessible for this experimental technique will be presented. Using this instrument the adsorption data of He, CH4, N2 and Ar on a microporous activated carbon are measured at pressures up to 50 MPa at T = 298.15 K. The resulting data allow a critical discussion of the commonly used model for the volume of the adsorbent material (i.e. the Helium-volume). As a result of this, a new model for the volume of the adsorbed phase is proposed. This volume model allows to calculate a pressure dependent density of the adsorbed phase. The model and the resulting densities of the adsorbed phase are discussed concerning their physical sensitivity.

Thermodynamic Description of Excess Isotherms in High-Pressure Adsorption of Methane, Argon and Nitrogen

In the present work the supercritical fluids argon, methane and nitrogen were picked out as examples, and the results of analysis concerning the adsorption of these fluids at activated carbon Norit R1 (Norit company, Germany) and SCS-3 (ISPE, Kiev) at different temperatures up to a pressure of 50 MPa are presented and discussed in this paper. The principle of working of the measuring device is described in this context as well.A three-parameter isothermal equation is used to represent the adsorption equilibrium. The isothermal equation is based on a physical model concept which has already been used for the modelling of adsorption processes with a pressure up to 15 MPa.

Experimental Determination and Analysis of High Pressure Adsorption Data of Pure Gases and Gas Mixtures

Adsorption data of the pure gases ethane, methane and their mixtures on zeolite 13X and the pure gases carbon dioxide, nitrogen and their mixtures on activated carbon Norit R1 were measured gravimetrically at a temperature of 298 K and pressures up to 15 MPa. From the total loads the partial loads were calculated by the modified van Ness approach. The calculated loads show a good agreement with the experimental data.

Application of surfactants to the supercritical fluid extraction of nitroaromatic compounds from sediments

Abstract Supercritical fluid extraction using supercritical carbon dioxide was applied to extract nitroaromatic compounds covering a wide range of polarity from soils having high humic organic matter content. Commercially available non-ionic, anionic and cationic surfactants were utilised as modifiers to enhance analyte solubility in the fluid. The applied surfactants turned out to have no significant beneficial impact on target analyte recoveries. On the contrary, surfactants exercise a detrimental effect on recovery by the formation of a “layer” on the soil or by “plugging” micropores, thus hampering analyte desorption. The surfactant deposition onto the soil under supercritical conditions was traced using electrospray ionisation mass spectrometry. The surfactant can be fully solubilised by adding polar methanol modifier to the fluid, but there was no synergetic effect between surfactant and modifier.

The magnetic suspension balance in high pressure measurements of pure gases

In the present work the supercritical fluids argon, methane, nitrogen, carbon dioxide, ethane, ethylene and propane were picked out as examples, and the results of analysis concerning the adsorption of these fluids at activated carbon Norit R1 (Norit Company, Germany) and SCS-3 (ISPE, Kiev) at different temperatures up to a pressure of 50 MPa are presented and discussed in this paper. The principle of working of the measuring device is described in this context as well.A three-parameter isothermal equation is used to represent the adsorption equilibrium. The isothermal equation is based on a physical model concept which has already been used for the modelling of adsorption processes with a pressure up to 15 MPa.

Contactless weighing up to high pressures for analysing adsorption and density of fluids

Adsorption of supercritical fluids methane, nitrogen and argon by active carbons was studied up to a pressure of 500 bar. A three-parameter isothermal equation was used to represent the adsorption equilibrium. This isothermal equation is based on a physical model conception which had already been used for the modelling of adsorption processes with a pressure up to 150 bar. Beside the exact knowledge of the measurable parameters pressure, temperature and fluid composition, the density of the adsorbate are essential for the evaluation of the adsorption analysis. The fluid density can be determined either via equations of state, which is normally the most practicable and fastest way, or via lift measurements of a lowering body in the fluid based on the principle of Archimedes. This work represents and discusses the question of to what extent the fluid density determined under real conditions via equations of state, using, for example, equation of Bender, corresponds to the fluid density measured under high-pressure.