On the Formation of Supramolecular Systems in the Adsorption of Aromatic Compounds at Porous Adsorbents

N. A. Eltekova and Yu. A. Eltekov

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

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Received June 10, 2007

PACS numbers: 68.43.-h

Gas Adsorption at the Components of the GaAs-CdS System

I. A. Kirovskaya

Omsk State Technical University, Omsk, Russia

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Received June 13, 2007

Abstract — Adsorption properties of the GaAs–CdS-system solid solutions and binary compounds are studied with respect to CO and NH₃ by the piezoelectric quartz microweighing, programmed thermal desorption, and IR-spectroscopy. Based on the experimental dependences (_p = f(T), _T = f(P), _T = f(t)), thermodynamic and kinetic characteristics of adsorption, analysis of the surface chemical composition, the adsorbents’ acid-base and other physicochemical characteristics. With due allowance for electron structure of the adsorbate’s molecules, the mechanism and specifity of adsorption processes are determined as functions of the operation conditions and system composition. By comparing the adsorption properties of the binary compounds (GaAs and CdS) with those of the solid solutions (GaAs)_x(CdS)_{1 x}, their similarities, as well as the specificity of the solid solutions as multicomponent systems, were revealed. Optimal adsorbent compositions to be used in primary transducers in the medicine- and environment-orientated sensors are found.

PACS numbers: 68.43.-h

Sorption Properties of Fullerene-Modified Activated Carbon  with Respect to Metal Ions

V. V. Samonin¹, V. Yu. Nikonova¹, and M. L. Podvyaznikov^1,2

¹ St. Petersburg State Technological University, Moskovskii pr. 26, St. Petersburg, 190013 Russia

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² OAO Zavod Radiotekhnicheskogo Oborudovaniya

Received May 28, 2007

Abstract — The prospects of modying of the activated carbon with microamounts of fullerenes, which can enhance its adsorption capacity with respect to metal cations by a factor of 2.5–5, are illustrated. The analysis of experimental data makes it possible to assume that silver ions are reduced on the carbon sorbent surface to metal silver, lead cations are sorbed due to the donor-acceptor interaction, and the copper ion sorption may lead to both the cation reduction to metal copper and the formation of complexes with different ligands preferentially with those containing an amino group.

PACS numbers: 68.43.h

Sorption of Hg²⁺, Nd³⁺, Dy³⁺, and U Ions at Polysiloxane Xerogels Functionalized with Phosphonic Acid Derivatives

O. A. Dudarko¹, V. P. Goncharik¹, V. Ya. Semenii², and Yu. L. Zub¹

¹ Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine,

² Institute of Organic Chemistry, National Academy of Sciences of Ukraine, ul. Murmanskaya 5, Kiev, 02094 Ukraine

Received June 14, 2007

Abstract — The sorption properties of silicas with mono- and bifunctional surface layers containing the complexing fragment Si(CH₂)₃NHP(S)(OC₂H₅)₂ were studied. It was found that xerogels synthesized by the solgel method (like mesoporous silicas obtained by the template method) can extract mercury(II) ions from acid-ified solutions (SSC up to 450 mg/g). In a nonporous xerogel with a bifunctional surface layer (P=S/SH), thiol groups proved to be primary sorption sites for Hg²⁺ ions; part of the ligand groups were inaccessible to metal ions. Xerogels containing the phosphonic acid residues Si(CH₂)₂P(O)(OH)₂ sorbed uranyl and lanthanide ions from their nitrate solutions. The resulting surface complexes contained two (for the U ion) or three innersphere ligand groups (for the Nd³⁺ and Dy³⁺ ions). The maximum SSCs were 340 mg/g for the uranyl ion and 120 mg/g for the lanthanide ions.

PACS numbers: 68.43.-h

Interaction of Freon-22 with Aluminum and Magnesium Oxides

T. S. Minakova¹, E. B. Daibova¹, L. A. Savel’eva¹, and V. S. Zakharenko²

¹ Tomsk State University, pr. Lenina 36, Tomsk, 634050 Russia

² Boreskov Institute of Catalysis, pr. Akad. Lavrent’eva 5, Novosibirsk 90, Russia

Received June 14, 2007

Abstract — It is known that Freons can be destructively adsorbed by magnesium and calcium oxides under the effect of mild ultraviolet radiation. Insofar as these oxides along with the silicon, aluminum, and iron oxides are typical components of solid tropospheric aerosols, photo- and dark adsorption processes may represent an efficient channel of the Freon removal from the atmosphere. In this work, dark adsorption of Freon-22 on alu-minum and magnesium oxides, which were treated in a vacuum at room temperature, is studied. Experiments with the specimens that have been exposed to air for a long time are especially important in estimating the probable adsorption of a Freon on aluminum or magnesium oxide under conditions close to the tropospheric ones.

PACS numbers: 68.43.-h

Structure and Properties of the Crystalline-Silicon-Dioxide-based Macroporous Ceramics

A. I. Rat’ko, A. I. Ivanets, T. A. Azarova, and S. M. Azarov

Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus,
ul. Surganova 9/1, Minsk, 220072 Belarus

Received June 15, 2007

Abstract — Samples of macroporous ceramics based on crystalline silicon dioxide-(the pore diameter >50 m) with superficial membrane layers (the pore diameter 10–20 m) are obtained. They meet the demands to porous materials for filtering. The samples based on the polydisperse powder of crystalline silicon dioxide with granulometric composition 100–315 m, containing 11 wt % of silica-alumina binder, were formed under a pressure of 30 MPa; they demonstrated an optimal combination of porosity and mechanical strength. After thermal treatment the samples’ porosity came to 30%; the ultimate stress (compression) limit, to 35 MPa. It is shown that multilayer elements for filtering, with membrane layers formed of the silicon dioxide powder suspension, provide the water purification from iron impurity (from 1–2 mg/l and down to 0.3 mg/l, a sanitary standard). The elements for filtering with doubly deposited crystalline silica-based membrane layer (the particle size 10–50 m) showed optimal combination of operation characteristics and the purity of water from iron.

PACS numbers: 81.05.Je, Mh