APPLICATION OF SOLVENT EXTRACTION AND SOLVENT-IMPREGNATED SUPPORT TO THE TREATMENT OF EFFLUENTS FROM ELECTROLESS NICKEL PLATING PROCESSES

摘要

This paper outlines our attempt to establish a recycle process of nickel in the spent baths and waste rinse water of electroless nickel plating plants using solvent extraction and solvent-impregnated support. Solvent extraction studies of nickel from actual spent baths revealed that (ⅰ) nickel is efficiently extracted by a hydroxyoxime extractant such as LIX84I at a pH greater than 6 and is readily stripped with sulfuric acid, and (ⅱ) the mixtures of LIX63 and acidic organophosphorus extractants (D2EHPA, PC88A, and Cyanex 272) enhance the nickel extraction efficiency to a sufficient degree without pH adjustment, but at the same time, reduce the stripping efficiency. The application of acidic organophosphorus extractants to selectively remove impurity metal ions (iron and zinc) from a real spent bath before extracting nickel lead to the finding that PC88A and Cyanex 272 effectively remove iron and zinc without pH adjustment leaving nickel in the raffinate. The removal of nickel from the waste rinse water was also studied. Solvent-impregnated supports with a macroporous resin and oil sorbents made of natural kapok fiber and synthetic fiber as supports were applied using D2EHPA and LIX860 as the extractants. During the batch operation, nickel is removed with a high efficiency without pH adjustment. During the column operation, however, the effective removal is hindered by (ⅰ) the dissolution of the nickel-D2EHPA complex into the aqueous phase in the high loading region, and (ⅱ) the slow removal rate of the LIX860-impregnated support.