To provide a production method of ferric hydroxide-based adsorbent favorably used for treatment of wastewater containing hexavalent chromate ions, and a cleaning method of the water containing chromate ion using the same.
In the production method of the adsorbent, super-saturated slurry of slaked lime is added to a solution containing ferric ions in which ferric chloride containing foreign substances is dissolved, up to the point where the pH becomes 3.8 to 5.5. After the addition, it is left for the prescribed period of time, preferably for 12 hours or longer. After that, super-saturated slurry of slaked lime is added for neutralization up to the point where the pH becomes 6.5 to 7.5. Then, the ferric hydroxide-based precipitates in which the calcium obtained after the neutralization remains is dried.
NOAI HIROAKI
FUKUDA NAOKI
