We have proposed a synthesis of calcium phosphate hydrogel as a new way of reusing fly ash from the waste incineration. However, the hydrogel obtained from the waste-incinerated fly ash have an electric conductivity lower than that synthesized from CaCO₃ reagent. In order to improve the electric conductivity, the waste incinerated fly ash was pretreated with various methods. As a result, it was found that pretreatment of washing with distilled water and CO₂ gas can reduce the content of K in the fly ash, and also increase the content of Ca. This pretreated ash comprises mainly CaCO₃ in the crystalline phase. For these reasons, both the crystallinity degree and the electric conductivity of the crystallized calcium phosphate hydrogel can be enhanced by this pretreatment. Furthermore, the performance of the fuel cell containing a MEA fabricated with calcium phosphate hydrogel synthesized from pretreated ash is almost equal to the fuel cell containing a MEA obtained from pure reagent at the measured temperatures.

View full abstract

Removal of single particles adhering on a flat plate by a high-speed air jet has been investigated experimentally. Although jet nozzle or removal target is scanned in an industrial application of the air jet removal, almost all previous fundamental investigations for the air jet removal were carried out with a fixed nozzle and a fixed target. Therefore, we aimed at elucidating how the scanning speed of target flat plate affects the removal efficiency.
Experimental results showed that the removal efficiencies at a constant air pressure of the nozzle decreased with an increase in the scanning speed of the target plate. With an increase in the scanning speed, the residence time of adhered particles in the effective jet exposure area is decreased. Therefore, the decrease in the removal efficiency with an increase of the scanning speed is caused mainly by a decrease in the residence time in the impinging air jet. It was also found that the effective area can be estimated by the equation of stable removal region on a fixed target.

View full abstract

Magnetic particles such as barium ferrite particles, with finer size, higher magnetic properties and higher dispersibility are required to produce excellent magnetic recording media.
Nano-sized Barium ferrite particles, which were synthesized with hydro-thermal method, were able to be coated by carbon black layer. Carbon-coated barium ferrite particles were easily dispersed into primary particles achieving small surface roughness (Ra) on a magnetic tape. The stacking condition between particles seemed to be eased in order to achieve lower switching field distribution (SFD) and higher orientation performances. The electric resistance of magnetic tape was sufficiently reduced. As a result, suitable magnetic recording media with higher performances were derived by using carboncoated barium ferrite particles.

View full abstract

Dry dispersion of fine particles is discussed as a simultaneous process with particle dispersion and agglomeration. Various problems on the dry dispersion are summarized based mainly on our works and key terms are reviewed such as partial dispersion efficiency to analyze the dispersion mechanism, and powder characteristic value for the evaluation of easiness of dispersion for any kind of powder. Improvement of disperser is also suggested based on the analysis of dispersion process.
Electrostatic charging, especially contact electrification between particle and its surface layer, seems to give further improvements on the dry dispersion of fine powder containing sub-micron particles.

View full abstract

The Geo- Environmental Protection Center (GEPC) has estimated that as many as 44, 000 work-places and former factory sites throughout Japan require a survey on contaminated soil. Up to the present, various physical and chemical methods have been used to remedy the soil quality. However, there is a growing use of bioremediation method to purify soil since this method is believed to be capable of decomposing and rendering the contaminants harmless at a low cost. Bioremediation is defined as a technology to remedy contaminated soil or groundwater using biological function. In Japan, this technology is commonly used to treat contaminated soil with the maximum volume of less than 100, 000 m³.
Bioremediation is a practical technology for the treatment of fuel oil contaminated soil, where microbes in soil degrade the oil into harmless compounds such as carbon dioxide and water.

View full abstract