Yoshiteru Itagaki

Heat generation properties in AC magnetic field for composite powder material of the Y3Fe5O12–nSiC system prepared by reverse coprecipitation method

Composite powder material of the Y3Fe5O12–nSiC system was synthesized by a reverse coprecipitation method to study its heat generation property in an AC magnetic field. For Y3Fe5O12 (n = 0), the maximum heat generation ability of 0.45 W·g−1 in an AC magnetic field (370 kHz, 1.77 kA·m−1) was obtained for the sample calcined at 1100 °C. The SiC addition helped to suppress the particle growth for Y3Fe5O12 at the calcination temperature. The heat generation ability was improved by the addition of the SiC powder, and the maximum value of 0.93 W·g−1 was obtained for the n = 0.3 sample calcined at 1250 °C. The heat generation ability and the hysteresis loss value were proportional to the cube of the magnetic field (H3). The heat generation ability (W·g−1) of the Y3Fe5O12–0.3SiC sample calcined at 1250 °C could be expressed by the equation 4.5×10−4 · f · H3 using the frequency f (kHz) and the magnetic field H (kA·m−1).

Cs+ decontamination properties of mordenites and composite materials synthesized from coal fly ash and rice husk ash

ABSTRACT Mordenites were synthesized using the natural resource such as coal fly ash and rice husk ash. The Cs+ adsorption rate (100 ppm Cs+, 100 mL) in seawater for the prepared mordenite (1.0 g) was 83.2%. The Cs+ adsorption rate for these mordenites almost depended on the calculated Cs+ exchangeable value (mmol) using the cation exchange capacity (CEC) values. Composite powder materials consisting of mordenite and nanosized magnetite (Fe3O4) (10, 20, 30 wt%) were also synthesized from coal fly ash and rice husk ash. The total Cs+ decontamination rates using the magnetic collection after the Cs+ adsorption in water and seawater were ca. 90% and ca. 70% for the examined 20 wt% magnetite-containing composite material, respectively. Although the elution ratio of the Cs+ ion was ca. 8% from all of the adsorbed Cs+ by the dissolution test in slowly shaken deionized water for 14 days in the case of the Cs+ adsorbed composite material (20wt% magnetite), the Cs+ ion did not elute when the sample was heated at 1000°C and higher temperature due to the Cs+ containment in the glassy phase.