| 摘要 |
PURPOSE:To restore the etching capacity of an acidic etching soln. when the etching performance of the etching soln. contg. a ferric salt as the principal component is deteriorated, by subjecting the etching soln. to oxidation with ozone in the presence of coal-base granular activated carbon as a catalyst and to restore the catalytic function of the catalyst having deteriorated function by exposing the catalyst to air. CONSTITUTION:An acidic soln. contg. ferric hydrochloride, sulfate or nitrate as the principal component and an acid contg. the same anion as the ferric salt as a pH adjusting agent or further contg. other mineral acid is used as an etching soln. to etch steel or the like in an etching rank 3. Coal-base granular activated carbon as a catalyst is put in the 1st and the 2nd reaction tanks 1, 2 by 1-200g/l. When the etching performance of the etching soln. is deteriorated, the etching soln. is poured into the tank 2 and subjected to oxidation by jetting gaseous ozone from a bottom aerator 4 to restore the etching capacity. At the same time, an etching soln. regenerated in the tank 1 is discharged and air is blown on the activated carbon having deteriorated catalytic function from an aerator 4 to restore the function. Continuous regeneration can be carried out by alternately using the tanks 1, 2.
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