Recovery of high purity ferric phosphate from a spent electroless nickel plating bath

Abstract

In this study, the UV-Fenton process was used to treat a spent electroless nickel plating bath, and to recover high purity ferric phosphate which could be used as a raw material in lithium ferric phosphate batteries. The effects of different parameters such as the H₂O₂ dosage, the H₂O₂ and Fe²⁺ feeding modes and the initial temperature on the treatment efficiency of the process were investigated. The results indicated that the UV-Fenton process could effectively remove the chemical oxidation demand by about 96.1%. Meanwhile, the phosphate produced from the complete oxidation of hypophosphite and phosphite was recovered as a precipitation of ferric phosphate. According to the results, about 99.9% of the phosphorus in the spent electroless nickel plating bath can be recovered. Recovered ferric phosphate particles were high in purity and nanometer-sized. This method utilizes relatively clean and economical reagents in the recovery of phosphorus resources, and does not generate hazardous substances. It will provide a new green method for the spent electroless nickel plating bath treatment.