地熱水中の亜ひ酸の酸化について

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書誌事項

タイトル別名
  • Oxidation of Arsenite in Geothermal Water
  • 地熱水中の亜砒酸の酸化について
  • チネツ スイチュウ ノ アヒサン ノ サンカ ニ ツイテ

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抄録

At Kakkonda geothermal plant in Iwate Prefecture, the geothermal water after the separation of vapor is rejected underground through the rejection well because it contains arsenic (ca.3.4 mg / l). Arsenic exists mostly as arsenite (As (III)) or arsenate (As (V)) in natural water. As(III) is more toxic than As(V), and As(V) is removed more effectively than As(III). The oxidation of As (III) to As (V) is necessary to achieve effective removal of arsenic.<BR>In this study the speciation of arsenic in the geothermal water was carried out and the effects of several parameters such as pH, temperature and stirring time on the oxidation of As (III) in the geothermal water were investigated. In addition, the effect of oxidation of As(III) on the arsenic removal by the coprecipitation using Fe(III) was examined. Results obtained are summarized as follows;<BR>1) Arsenic was present as As(III) in the geothermal water after the separation from the vapor.<BR>2) As(III) concentration decreased gradually with time at 80 °C while total concentration of arsenic did not changed, indicating the oxidation of As(III) to As(V). The oxidation rate decreased with decrease in temperature down to 30 °C.<BR>3) The pH adjustment to over natural pH (8.4) enhanced the oxidation rate at 80 °C<BR>4) Prior to the coprecipitation treatment using Fe(III), adjusting pH values to more than 10 followed by the stirring for several minutes improved the removal of arsenic from the geothermal water. It was due to effective oxidation of As(III) to As(V).

収録刊行物

  • 資源と素材

    資源と素材 119 (4/5), 171-174, 2003

    一般社団法人 資源・素材学会

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