Chemistry September 2004 Vol 53/3 []

CONTENTS & ABSTRACTS

InEnglish. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.

Chemistry



Volume 53 No. 3September 2004



Xylidine-polluted groundwaterpurification. Ozonation and catalytic wet oxidation; 97–115

Janek Reinik and Juha Kallas

Abstract. This paper discusses theremoval of xylidines from polluted waters by means of chemical oxidationmethods. Xylidines, persistent compounds of rocket fuel, have been detected inhigh concentrations in groundwater in the areas of former Soviet missile bases.To treat such groundwater, two chemical processes, ozonation and catalytic wetoxidation, were studied. The kinetics of degradation of 2,4-xylidine byozonation was investigated in a wetted-wall column. A laboratory-scaleozone–water contact column was designed and a steady-state wetted wall reactormodel was developed. The ozonation model with the estimated parameters showedgood agreement between predicted and experimental data. The estimated reactionrate coefficients could be used for the design of a bubble ozonation column forxylidine-polluted groundwater treatment. The developed model and experimentalset-up can be used in the future to estimate the kinetic parameters ofozonation reactions involving other similar compounds. Catalytic wet oxidationwas carried out in a stirred batch autoclave in the presence of granulatedactivated carbon. 2,4-Xylidine was concentrated on the surface of thegranulated activated carbon and then oxidized at different temperatures(140–170 °C) and oxygen partial pressures (4–10 atm). The GAC typecatalyst was active enough for 2,4-xylidine oxidation, but not for theoxidation of the formed organic acids. Degradation of organic acids needsseverer conditions. Both chemical oxidation processes could be used as apre-treatment before biological treatment. The results of this paper can beused to design two chemical processes for purification of xylidine pollutedwater.

Key words: 2,4-xylidine,ozonation, wetted wall column, catalytic wet oxidation, mathematical modelling,reaction kinetics.

Kinetics of [ 3H]WAY100635 binding to5-HT1A receptors in rat hippocampal membranes; 116–124

Sven Parkel and Ago Rinken

Abstract. The binding of [ 3H]-N-[ 2-[ 4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)­cyclo­hexane­carboxamide([ 3H]WAY100635) to 5‑HT1A receptors in rathippocampal membranes was studied. Saturation experiments showed that [ 3H]WAY100635binds to a single class of binding sites with very high affinity (KD = 87 ± 4 pM, Bmax = 15.1 ± 0.2 fmol/mg protein). The binding of [ 3H]WAY100635was reversible, but slow. The dissociation of [ 3H]WAY100635 from itscomplex with 5-HT1A receptors was characterized with the koff = (7.8 ± 1.1) × 10–3 min–1, which meansthat at low concentrations of the radioligand equilibrium cannot be achievedbefore 7 h incubation at 25 °C. The obtained dataindicate that [ 3H]WAY100635 is a valuable toolfor the determination of the number of 5-HT1A receptor bindingsites, but the determination of its affinity is complicated as it hardlyreaches equilibrium at concentrations close to its KD.

Key words: [ 3H]WAY100635, 5-HT1A receptor,equilibrium, kinetics, affinity, rat hippocampus.

Gottfried Wilhelm Osann and ruthenium;125–144

Helvi Hödrejärv

Abstract. Gottfried Wilhelm Osann (1797, Weimar – 1866,Würzburg) was chemistry professor at Tartu University (Universitas Dorpatensis)in 1823–1828. In that period he analysed the crude platinum received from theUral Mountains and discovered a new platinum metal. He named this metalruthenium after the medieval name of Russia in Latin. As the quantity of thenew element he had was small he could not isolate the metal. This was doneseveral years later and published in 1844 by Carl Claus in Kazan, Russia. Clausis often mentioned as the discoverer of ruthenium and G. W. Osann isforgotten.

Key words: G. W. Osann, ruthenium,discovery of chemical element.

Instructionsto authors; 145–148

CopyrightTransfer Agreement; 149