T. Tominaga

Adsorption of europium(III) and americium(III) on kaolinite and montmorillonite in the presence of humic acid

Distribution of trace amount of Eu(III), or Am(III), in the aqueous/solid system containing humic acid and kaolinite, or montmorillonite, was studied by batch experiments. Humic acid was also adsorbed on the clay minerals and its adsorption isotherm can be regarded as a Langmuir type. It is shown that Eu(III), or Am(III), exists as humate complex either in the aqueous or on solid phase in the system including kaolinite, or montmorillonite. These results suggest that the organic-inorganic complex like clay minerals coated with humic substances is important as metal reservoir in the environment.

Ionic strength and pH dependence of binding constants of Am(III)- and Eu(III)-humates

Binding constants of Eu(III)- and Am(III)-complexes with soil-derived humic acid were determined by solvent extraction at various pH and ionic strength. Based on the dependence of binding constants on pH and ionic strength, stabilities of the humate complexes in land water and seawater were estimated. Speciation calculation based on the binding constants indicated that Am(III) could combine with humic substances in natural water system.

Characterization of silica supported Rh-Fe catalysts by Mössbauer technique

Silica supported Rh−Fe catalysts were characterized by means of in situ57Fe Mössbauer spectroscopy. The Mössbauer spectra indicated that iron on the silica support existed either as Fe/O/ in the Rh−Fe alloy or as Fe3+ in Rh−Fe metal cluster compounds. The (Fe3+/Fe/O/) ratio and Mössbauer parameters were found to depend on the (Fe/Rh) atomic ratio in the catalysts. Such dependence corresponded to the change of catalytic properties of the supported Rh−Fe catalyst with the varying (Fe/Rh) ratio.

MULTITRACER STUDY ON THE EFFECT OF HUMATE FORMATION ON THE ADSORPTION BEHAVIOR OF METAL IONS ON KAOLINITE AND SILICA GEL

The multitracer technique was applied to elucidate of influence of humate formation on adsorption behavior of ultratrace elements. Dissolved fractions of Co, As, Rb, Sr, Y, Zr, Ba, Ce, Eu, Gd, Tb, Yb, Lu, Hf, Re and Pt in contact with kaolinite or silica gel were determined simultaneously either in the presence or absence of humic acid, which was partly adsorbed on the solid. Percentage of dissolved fraction of rare earth elements was identical to that of humic acid, indicating high stability of the rare earth-humate complex. Hydrolysis was the most important factor controlling the behavior of Zr and Hf. Both hydrolysis and humate complexation influenced the adsorption of Co, Sr, Ba and Pt, whereas neither affected the distribution of As, Rb and Re.

Mössbauer studies on photoaggregation and photoreduction of tris/β-diketonato/ iron/III/ complexes isolated in low temperature matrices

The state of dispersion and photochemical behaviour of tris/β-diketonato/ iron/III/ complexes isolated in low temperature matrices were characterized by means of57Fe Mössbauer spectroscopy. Tris/acetylacetonato/iron/III/ iron/III/ molecules isolated in a nitrogen matrix were aggregated by photoexcitation. Photoreduction of tris/hexafluoroacetylacetonato/-iron/III/ in solid ethanol was also monitored by the Mössbauer technique.

Mössbauer study on the photolysis of pentacarbonyliron isolated in low temperature nitrogen matrix

The UV photolysis of pentacarbonyliron isolated in low temperature nitrogen matrix was studied by the Mössbauer Technique. Besides stable compounds /Fe2/CO/9 and Fe3/CO/12/ unstable species such as Fe/Co/4 and Fe2/CO/8 were produced by UV irradiation. Furthermore, the unstable species were found to react with nitrogen matrix, leading to the formation of Fe/CO/4N2. Mössbauer parameters of the products were obtained.

Positive muons in spin-crossover complex [Fe(NCS)2(phen)2]

Diamagnetic muon species in a spin-crossover complex diisothiocyanatobisphenanthrolineiron(II) were investigated: two species with different spin relaxation functions and rates were observed over the range from 21 to 293 K. The sum of their yields changed at about the spin transition temperature of the complex, where the spin state of the complex changes from paramagnetic to diamagnetic when it is cooled down across the temperature. The results suggest that paramagnetic muon species could exhibit diamagnetic muon-like μSR signals in paramagnetic environment.

MOSSBAUER STUDY ON THE PHOTOLYSIS OF PENTACARBONYLIRON ISOLATED IN LOW TEMPERATURE NITROGEN MATRIX BY CONTINUOUS OR PULSED DEPOSITION

The UV photolysis of pentacarbonyliron isolated in low temperature nitrogen matrix by continuous or pulsed deposition was studied by means of Mössbauer technique. Unstable species such as Fe/CO/n /n=2–4/ were produced by UV irradiation and their Mössbauer parameters were measured. The yields of unstable species were found to be influenced by the deposition method of nitrogen matrix.

Synthesis of 13N-labelled amines by reduction of 13N-labelled amides

Abstract 13 N-β-phenethylamine and 13 N-n-octylamine were synthesized by LialH 4 reduction of 13 N-phenylacetamide and 13 N-octamide prepared by 13 N-ammonolysis in ether. The reaction produced a fairly good yield even in a non-carrier-added state. Both 13 N-amines were isolated by extraction, and organ distribution in mice was studied preliminarily. After i.v. administration of both 13 N-amines, high accumulation was observed in the brain, lung, and heart. Long-term retention of the radioactivity was observed in the brain and the heart.

Mössbauer spectroscopic study of phthalocyanineiron/II/ in NaY zeolite

Phthalocyanineiron/II/ in NaY zeolite was synthesized via various processes from an iron carbonyl compound into NaY zeolite in gaseous phase. Mössbauer spectra of the final product /phthalocyanineiron/II// and the precursor species /iron oxide and [phthalocyaninato/2-/]bis/pyridine/iron/II// in NaY zeolite were measured to characterize the chemical and physical states of the iron species.