| 摘要 |
<p>PURPOSE:To practically completely decomposedly remove heavy metal cyanocomplex salts, by adding the specified amount of NaCl or KCl to a waste plating solution containing a cyanocomplex salt, electrolyzing said waste solution under a specified condition and further electrolyzing it at a pH of 4-7 under a specified condition. CONSTITUTION:Potassium or sodium chloride is added to a waste plating solution containing a cyanocomplex salt, in a manner such that the ratio of Cl<->/CN in said waste water is adjusted to 4-1. The waste water is then electrolyzed at a pH of 10.5-12.0 with DK below 5A/dm<2> at an ordinary temp. using a stainless steel plate as a cathode, until oxidation-reduction potential becomes to 300- 350mV. Thereafter, the obtd. aqueous solution is adjusted to a pH of 4-7 by adding sulfuric acid to it and further electrolyzed with DK below 5A/dm<2> at an ordinary temp., until oxidation-reduction potential becomes to 600-1,000mV. By this method, CN in the treated liquid can be reduced to 0.5ppm or less.</p> |
