Application of Solvent Extraction Using Synergistic Effect to Electroless Nickel Plating Waste Liquor

Electroless nickel plating waste liquor contains a large amount of nickel ions, but nickel ions in waste liquor have not been recovered for technical and economic reasons. If the recovery of nickel ions is effectively carried out, nickel ions could be recycled as a nickel source for electroless plating liquor. The process to recover nickel ions from electroless plating waste liquor was investigated by using a solvent extraction method. The existence of various phosphate species and organic acids in the waste liquor causes the incomplete extraction of nickel ions with any single extractant due to the complex formation between nickel ions and them. The application of solvent extraction using a synergistic effect makes possible to separate and recover 90% or more of nickel ions in the waste liquor. The extractant mixtures of acidic extractant such as D2EHPA and PC-88A, and another extractants with electron-donating ability such as nicotinic acid dodecyl ester and iso-nicotinic acid dodecyl ester are used for this purpose.