Ethylene and phenylene bridged polysilsesquioxanes functionalized by amine and thiol groups as adsorbents of volatile organic compounds

Abstract Ethylene and phenylene bridged polysilsesquioxane xerogels having amine and thiol groups attached to the surface have been obtained by the sol–gel method from 1,2-bis(triethoxysilyl)ethane or 1,4-bis(triethoxysilyl)benzene and functionalized silanes in the presence of an ammonium fluoride catalyst in an ethanol solution. The synthesized samples have a porous structure (700–850 m2/g) and a high content of functional groups (1.4–1.9 mmol/g). The obtained porous bridged polysilsesquioxanes exhibit a considerable affinity for adsorbing several organic compounds (n-hexane, n-heptane, benzene, cyclohexane, acetonitrile and triethylamine) from the gas phase. The sample with an ethylene br…

The 23rd international vacuum microbalance techniques conference

Investigation of surface properties of lunar regolith - Part IV

�berschallgeschwindigkeiten im Hochvakuum

SELF SIMILARITY IN SWELLING SYSTEMS: FRACTAL PROPERTIES OF PEAT

Sphagnum peat gives an example of a swelling system with a self-similar structure in sufficiently wide range of scales. The surface fractal dimension, dfs, has been calculated by means of thermodynamic method on the basis of water adsorption and capillary equilibrium measurements. This method makes possible the exploration of the self-similarity in the scale range over at least 4 decimal orders of magnitude from 1 nm to 10 μm. In a sample explored, two ranges of fractality have been observed: dfs ≈ 2.55 in the range 1.5–80 nm and dfs ≈ 2.42 in the range 0.25–9 µm.

Comments on surface structure analysis by water and nitrogen adsorption

Specific surface area and pore size distribution are determined usually from adsorption isotherms at low temperatures using nitrogen or noble gases. These are not absolute parameters and the measuring methods are fraught with serious difficulties. General problems of sorption measurements and recent developments are discussed. To obtain information for practical purposes these measurements need to be supplemented by investigations of the sorbate/sorbent system used in practice. Results of the measurement of nitrogen and water vapour adsorption on different materials are compared.

Planning of gravimetric investigations on mars

We propose to install a balance at the surface of Mars. In this paper we present a survey on tasks which could be accomplished by means of a balance. The determination of the specific surface area and porosity of Martian soil and other sorption experiments are discussed. Criteria for the choice of a suitable balance type are given.

The application of Jäntti's method for the fast calculation of equilibrium in case of multilayer adsorption

On the basis of a molecular model for sorption kinetics Jäntti introduced a method to calculate equilibria shortly after a change of the pressure of the sorptive gas. In the present paper we apply that method for the description of multilayer adsorption.