Asahi Kasei Kogyo Kabushiki Kaisha

Hideaki Imai

Yuzuru Ishibashi

Junji Nomura

Tadahiko Hirai

Takahiko Iriyama

Kurima Kobayashi

Kunio Miyata

Tokuzo Konishi

Nitride based semiconductor device and manufacture thereof

Magentic materials represented by the formula

Magnetic materials containing rare earth element iron nitrogen and

Fluorine or fluorine compounds dissolved at low concentrations in water are efficiently separated by use of hydrated rare earth oxides or insoluble hydrated rare earth salts, particularly hydrous rare earth fluorides or hydrous rare earth phosphates, as the adsorbent. By bringing fluorine dissolved water of pH 2-7 into contact with said adsorbent, fluorine is adsorbed on the adsorbent, and the adsorbed fluorine can be desorbed by contact with an alkali solution of pH 10 to 14 to regenrate said adsorbent. Also, by addition of a precipitating agent for fluorine to the desorbed solution, fluorine compounds can be separated by precipitation and the filtrate can be reused as the regenerating solution for the adsorbent.

Process for adsorption treatment of dissolved fluorine

Growing community of inventors

Fuji, Japan

Hideaki Imai