Title:
TREATMENT OF HYPOPHOSPHORIC ACID ION IN AGED PLATING LIQUID
Document Type and Number:
Japanese Patent JP2603895
Kind Code:
B2
Abstract:
PURPOSE: To eliminate the harmfulness of hypophosphoric acid ions as phosphoric acid ions or calcium phosphate by subjecting an aged electroless plating liquid contg. a large amt. of the hypophosphoric acid ions to an oxidation treatment.
CONSTITUTION: The aged liquid of the electroless plating liquid, such as electroless Ni plating liquid, contains the hypophosphoric acid ions of a high concn. and is inadequate as waste water in terms of eutrophication and chemical oxygen consumption and, therefore, the powder of TiO2 deposited with a noble metal, such as Pt, is added as a photocatalyst to this aged liquid in the state of maintaining the liquid at a pH 1 to 4 range at a ratio of, for example, 8g/l. While air or oxygen is blown into the liquid, the liquid is irradiated with UV rays by a high-voltage mercury lamp, by which the hypophosphoric acid ions are oxidized to the phosphoric acid ions or a Ca salt is added thereto to form the calcium phosphate. Such liquid is maintained at pH 1 to 3 and is filtered, by which the TiO2 catalyst deposited with the noble metal is recovered. The remaining liquid is reused after the phosphoric acid ions are removed. The remaining liquid is otherwise easily drained as the calcium phosphate-contg. liquid.
Inventors:
Kunihiko Higashi
Kenji Otsuka
Kenji Otsuka
Application Number:
JP31290592A
Publication Date:
April 23, 1997
Filing Date:
October 28, 1992
Export Citation:
Assignee:
Tokyo
International Classes:
C02F1/58; C02F1/72; C02F1/74; C23C18/16; C23C18/31; C23C18/36; (IPC1-7): C23C18/16; C02F1/58; C02F1/72; C02F1/74
Domestic Patent References:
| JP53133962A |