Recovery of Phosphorus from Waste Solution of Electroless Nickel-Phosphorus Plating

Abstract

We attempted to recover phosphorus species from a waste plating solution of electroless nickel-phosphorus plating. With the aim of increasing the recovery yield by oxidizing phosphite to phosphate efficiently, we examined ozonation of a model plating solution by supplying ozonecontaining oxygen gas to the solution employing an aerated mixing vessel. As a result of the measurements of the transient changes in the concentrations of the phosphorus species and dissolved ozone in the solution, we confirmed the effect of the organic additives contained in the plating solution on the ozonation efficiency. Calcium chloride was subsequently added to the ozone-treated solution to precipitate the phosphate as calcium hydrogen phosphate, which was poorly soluble to water. At this moment, the recovery yield of the phosphorus from the model waste plating solution was greater than 86%.