Yoshiyuki Kudo

SEASONAL VARIATION AND THEIR CHARACTERIZATION OF SUSPENDED PARTICULATE MATTER IN THE AIR OF SUBWAY STATIONS

In order to accumulate fundamental data on the atmospheric environments in subway, the mass concentration, particle size distribution and elemental constitution of suspended particulate matter (SPM), and the concentration and constitution of polycyclic aromatic hydrocarbon (PAH), were measured and analyzed at three subway stations with different air supply systems on the same line. The mass concentration of SPM in the subway stations showed seasonal variations, and was higher in December and October than in March and June. It was also higher at the subway stations than in the aboveground throughout the seasons. The concentrations of SPM in the size range of 0.5–5.0 μm were higher in the subway stations than aboveground, suggesting this size of SPM was generated by the operation of trains. The elements that were observed at high concentrations in the subway SPM were Fe, Ba, Cu and Ca. On the other hand, the elements of which concentrations were relatively higher in the aboveground air were Cl, Na and K. Polycylic aromatic hydrocarbons collected at the subway stations showed similar concentrations and characteristics to those observed in the urban atmosphere.

Preparation of monodispersed manganese (IV) oxide particles from manganese (II) carbonate

Spherical and monoclinic-like manganese (IV) oxide particles of moderately narrow size distribution were prepared by conversion of carbonates obtained by simple mixing and aging procedures. The conversion of manganese (II) carbonates gave γ-manganese (IV) oxide particles having the composition MnO1.80–1.90 and retaining the morphology of the mother crystals under air (300–400°C) and oxygen (400°C) atmospheres. The isoelectric point and point of zero charge of the oxides thus obtained were determined as pH 3.5 and 4.0, respectively.

Preparation and reduction kinetics of uniform copper particles from copper(I) oxides with hydrogen

Abstract Uniform copper particles were prepared by reduction of copper(I) oxides with hydrogen at 69–111°C. Three types of precursor particles having average modal sizes of O.46, 0.62 and 1.26 μm, respectively were produced by reducing Fehlings solutions of different concentrations with glucose. The reduction of fine copper(I) oxide particles took place through an autocatalytic process, while the reaction rates of rather coarse oxide particles were controlled by the diffusion of gaseous species through the copper layers formed at a later stage of the process. The resulting copper particles retained the original morphology of the oxides. A moderately oxygen-rich layer about 30 A thick was detected on exposure to air by means of photoelectron surface microanalysis (XPS).

Fundamentals of Forced Hydrolysis of Indium Hydroxide

During forced hydrolysis an acidified metal salt solution with its solution complexes is placed in a sealed test tube and heated at a specific rate to a high temperature <100°C. By heating the solution equilibria are altered, the hydroxide concentration is increased, and often a metal hydroxide is precipitated from solution as a narrow particle size distribution. This paper presents a theory that links solution complexation equilibria with a population balance model for precipitation predicting the particle size distribution. This model uses classical nucleation theory and growth rates by various rate limiting steps for the growth of the crystals. This theory is compared to forced hydrolysis experiments where dilute Indium nitrate solutions, acidified with nitric acid, were placed in a water bath at 80°C for various periods of time. The experiments produced cubic particles of Indium hydroxide. The experiments were monitored for temperature, pH, turbidity, and particle size distribution, all as a function of time for comparison with this model.