| 摘要 |
PURPOSE:To surely regenerate chromate treatment liquid without depositing unnecessary metal by introducing the chromate treatment liquid to be regenerated into an anodic chamber partitioned with a cation exchange membrane and introducing a mineral acid aq. soln. having proper concn. into a cathodic chamber and conducting DC current. CONSTITUTION:A tank is partitioned into an anodic chamber and a cathodic chamber with a cation exchange membrane, and an anode made of a metallic electrode coated with noble metal such as Pt and Ir and a cathode made of Fe and Ni or the like are arranged respectively. Chromate treatment liquid to be regenerated which contains metallic ions such as Zn, Ni and Fe is introduced into the anodic chamber. On the other hand, an aq. soln. contg. at least 5wt% preferably 5-50% mineral acid is introduced into the cathodic chamber. Then DC current preferably high current and low current are alternately conducted between both electrodes. In this case, it is effective that the high current is conducted at 10-50A/dm<2> for 10-300min and the low current is conducted at 0.1-4A/dm<2> for 1-60min. Thereby the regeneration of the above- mentioned chromate treatment liquid is surely performed without depositing unnecessary metal on the cathode. |
