| 摘要 |
PURPOSE:To simply regenerate a spent aqueous phosphoric acid soln. contg. iron ions by adding an oxidizing agent to the soln. to convert the ions into ferric phosphate with low solubility. CONSTITUTION:When the pickling of steel products by dipping in an aqueous phosphoric acid soln. is repeated, iron ions are accumulated in the soln., and the rust removing power is deteriorated gradually. By adding an oxidizing agent to such an aqueous phosphoric acid soln., ions existing in the form of ferrous phosphate are easily oxidized to ferric phosphate, and most of the ferric phosphate is deposited. The usable oxidizing agent is restricted to H2O2 and/or ozone in practical application so as to reuse the phosphoric acid soln. as a pickling soln. after purification. |
