Abstract
The electroless nickel plating is one of the important plating technologies, and high concentration of its large amount of waste solution is generated with nickel, phosphate, hypophosphite and various organic acids [1]. Electroless plating process is simple and it does not use external electric current to produce deposit. Therefore electroless nickel plating is applied to many electronics industries due to possible the uniform layer formed onto different geometry and the possibility to control the thickness [2]. Electroless nickel plating reactions are as follows [3]:
With time, nickel and phosphate ions are simultaneously reduced to form the coating and the spent plating solution is discarded to maintain plating quality. However this wastewater is a valuable source of Ni with other hazardous organic compound and phosphate. Currently, the spent baths are treated by alkaline precipitation, but this process generated a large amount of hazardous sludge [4]. In this study, the purpose of electroless nickel plating wastewater treatment was performed to effectively remove the harmful species (COD, P, N) and recover Ni metal. For Ni recovery, selective precipitation and electro-winning process were utilized and the organic species were removed by advanced oxidation process.
