著者

東 保男 野上 勝憲 大島 信男

出版者

東海大学

雑誌

東海大学紀要. 工学部 (ISSN:05636787)

巻号頁・発行日

vol.33, no.1, pp.153-160, 1993

被引用文献数

1

---

The monodispered ferric oxide (ferric oxyhydrate) particles were synthesized by the hydrolysis of ferric nitrate in an aqueous nitric acid solution at high temperature. The precipitated particles were examined by TEM, XRD, TG-DTA and S_BET. The ferric nitrate solutions of different concentration dissolved in 0.01 mol/l nitric acid were aged for 24hr at 95℃, and the morphologies of the precipitated particles were observed, and it was found that the shapes of the particles precipitated from 0.5,0.2,0.005∿0.1,0.003 and 0.001 mol/l of ferric nitrate solutions were cubic, ellipsodial, fine grain, spherical and irregular, respectively. The cubic particles (by-products : ellipsodial particles) precipitated from the 0.3 mol/l ferric nitrate solution containing 0.05 mol/l nitric acid were goethite, and the ellipsodial particles from 0.03 mol/l solution were hematite. The latter particles were porous, and its specific surface area was calculated as 52∿98m^2/g. The ferric ion concentration of 0.05 mol/l ferric nitrate solution was decreased at one step with aging time, but as for 0.3 mol/l solution the ferric ion concentration was decreased at two steps, and the pH values of the solutions were shifted to acidic. ⊿G_desovl. were calculated as 115 and 135 kJ/mol by Bourne's equation. When the concentration of ferric nitrate was high, the precursors of iron aquacomplex were formed, and then goethite was precipitated by the polymerization of precursors, but in the case of low concentration of ferric nitrate, hematite was obtained immediately.