Tadao Kanzaki

Boron isotopic composition of fumarolic condensates from some volcanoes in Japanese island arcs

Boron samples from 40 fumarolic condensates from volcanoes in the Ryukyu arc (Satsuma Iwo-jima and Shiratori Iwo-yama) and the North-east Japan arc (Usu-shinzan, Showa-shinzan, Esan and Issaikyo-yama) all have 11B10B ratios close to 4.07. Higher values, from 4.09 to 4.13, were only observed in condensates from volcanoes in the southernmost end of the North-east Japan arc (Nasu-dake), the northern part of the Izu-Bonin arc (Hakone), and the North Mariana arc (Ogasawara Iwo-jima). These higher values suggest geological interaction of the magmas with sea-water enriched in 11B.

Boron isotopic composition of fumarolic condensates and sassolites from Satsuma Iwo-jima, Japan

11B/10B ratios of the high temperature fumarolic gases (>465°C) of this island were found to be constant within the limits of experimental error (11B/10B = 4.066). This value may represent the 11B/10B ratio of boron in the andesite magma. 11B/10B ratios of the low temperature fumarolic gases (<235°C) were found to vary from 4.053 to 4.077. 11B/10B ratios of some sassolites were approximately equal to that of the fumarolic condensates and the other ones were slightly enriched in 10B compared to the fumarolic condensates.

Fundamental Studies on the Ion Exchange Separation of Isotopes, (V)

The breakthrough experiments have been done through a cation exchange resin column of 100 cm height and 1 cm diameter with 0.6N and 2N hydrochloric acid solutions containing greater part of uranous ions together with smaller uranyl ions. For each experiment the largest depletion of 235U was found at the front of uranous breakthrough, while minor depletion was also observed at the front of uranyl fraction. A equation giving the approximate value for the separation factor S235238 from the breakthrough results was derived:S235238=1+D/Q·1/R0where D is total depletion of 235U in eluates, Q is total amount of uranium adsorbed on the column and R0 is the mole fraction of 235U in the original sample solution. The values 1.000281.00048 were obtained for S235238 from the equation.

Mössbauer spectra at 77 K of products formed during transformation of Fe(OH)2 to Fe3O4 in aqueous suspension by air oxidation

Mossbauer spectra at 77 K of the products formed during the aerial oxidation of aqueous iron(II) hydroxide suspensions, combined with X-ray powder diffraction and electron micrograph data have suggested that at pH 9.0, Fe(OH)2 and Fe3O4 are formed. [During the initial stage, iron(III) hydroxide oxide, γ-FeO(OH), is also formed.] It has been also suggested that at pH 7.0, only ‘green rust II’ is formed in the second stage, followed by the formation of Fe3O4, while the content of Fe2+ ion in the supernatant gradually decreases. The Mossbauer data suggest that the FeII : FeIII mol ratio in green rust II is 2 : 1.

Formation of molybdenum-bearing ferrites, Fe3 –xMoxO4(x= 0.04–0.19), in aqueous suspension by air oxidation

Molybdenum-bearing ferrites (Mo : Fetot., mol ratios 0.015–0.069 : 1) have been formed by air oxidation of iron(II) hydroxide suspensions, which were prepared in the presence of MoIII ions, at Mo : Fetot. mol ratios of 0.032–0.326 : 1 in the initial suspensions, at pH 9.0 and 65 °C. Lattice constants of the Mo-bearing ferrites, Fe3 –xMoxO4, were found to increase linearly with increasing values of x. This relationship agrees with that of stoicheiometric Mo-bearing ferrites.

Formation of oxidized molybdenum-bearing ferrites, Fe2.95 –xMoxO4(x = 0.03–0.30) in aqueous suspensions by air oxidation, and valence state of molybdenum

Oxidized molybdenum-bearing ferrites (MO : Fetot. mol ratios 0.012–0.114 : 1) have been formed by air oxidation of iron hydroxide suspensions, which were prepared in the presence of molybdenum(VI) ions at initial MO: Fetot. mol ratios of 0.015–0.300 : 1, at pH 9.0, and 65°C. The molybdenum content in the centre part of the ferrite particles was found to be very low. X-Ray photoelectron spectra of the MO 3d5/2 electrons (229.7–230.0 eV) from the molybdenum-bearing ferrites have suggested that MO is in the valence state of +4 in a lattice of the spinel type.

X-Ray photoelectron and mössbauer spectroscopy studies on molybdenum-bearing ferrite

Abstract The X-ray photoelectron spectra of Mo 3 d electrons (232.4–232.9 and 229.4–229.6 eV) for Mo-bearing ferrites have suggested that molybdenum ions are in the 4+ valence state on the lattice points in the spinel structure. The XPS data for Mo 3 d and Fe 2 p electrons combined with the Mossbauer data at room temperature suggest that Fe 2 MoO 4 takes a valence state (Fe 2+ ) tet [Fe 2+ Mo 4+ ] oct O 4 .

Formation of aluminium-bearing ferrite in aqueous suspension by air oxidation

Aluminium-bearing ferrites and Al-bearing goethites are formed by air oxidation of Fe[OH]2 suspensions containing aluminium(III) ions, with the mol ratio, AIIII: Fetotal(rAl), in the range 0.03–0.40 : 1 at pH 10.5 and 65 °C. The amount of Al-bearing ferrites in the products decreases with increasing rAl, whereas that of the Al-bearing goethites increases. At rAl= 0.60 : 1 only the Al-bearing goethite, Fe0.71Al0.29O(OH), is formed. The chemical composition of the Al-bearing ferrite formed at rAl= 0.03 : 1 is that of the stoicheiometric ferrite (Fe2.95Al0.05O4.00). The values of rAl in the Al-bearing ferrites are approximately half of those in the Al-bearing goethites.