Keiichi Miura

Atom insertion into the CoSb3 skutterudite host lattice under high pressure

Abstract CoSb3 with the skutterudite-type structure was synthesized by solid-state reaction and the atom insertion into the body-centered vacant site was attempted under high pressure and temperature conditions. Various 14-group elements were selected for atom insertion under pressure of 30 MPa to 5 GPa. It was found that various elements could be inserted in the body-centered vacant site, resulting in the formation of new filled-skutterudite phase MxCo4Sb12 (M=Si, Ge, Sn, Pb). The degree of insertion (x) increased with increasing the applied pressure. In the case of the Sn–CoSb3 system, nearly 40% of the body-centered vacant site was filled by Sn atom at 5 GPa. The crystal structure of resulting Sn0.4Co4Sb12 was refined by the Rietveld analysis of the X-ray diffraction data.

Advanced treatment of swine wastewater using an agent synthesized from amorphous silica and hydrated lime

Advanced treatment using an agent synthesized from amorphous silica and hydrated lime (M-CSH-lime) was developed and applied to swine wastewater treatment. Biologically treated wastewater and M-CSH-lime (approximately 6 w/v% slurry) were fed continuously into a column-shaped reactor from its bottom. Accumulated M-CSH-lime gradually formed a bed layer. The influent permeated this layer and contacted the M-CSH-lime, and the treatment reaction progressed. Treated liquid overflowing from the top of the reactor was neutralized with CO2 gas bubbling. The colour removal rate approximately exceeded 50% with M-CSH-lime addition rates of>0.15 w/v%. The removal rate of exceeded 80% with the addition of>0.03 w/v% of M-CSH-lime. The removal rates of coliform bacteria and Escherichia coli exceeded 99.9% with>0.1 w/v%. Accumulated M-CSH-lime in the reactor was periodically withdrawn from the upper part of the bed layer. The content of citric-acid-soluble P2O5 in the recovered matter was>15% when the weight ratio of influent to added M-CSH-lime was>0.15. This content was comparable with commercial phosphorus fertilizer. The inhibitory effect of recovered M-CSH-lime on germination and growth of leafy vegetable komatsuna (Brassica rapa var. perviridis) was evaluated by an experiment using the Neubauers pot. The recovered M-CSH-lime had no negative effect on germination and growth. These results suggest that advanced water treatment with M-CSH-lime was effective for simultaneous removal of colour, and coliform bacteria at an addition rate of 0.03–0.15 w/v%, and that the recovered M-CSH-lime would be suitable as phosphorus fertilizer.