Research on treatment processes for chelated copper desmear wastewater

During the processing and production of semiconductors, a large amount of copper-containing desmear wastewater with strong chelating properties is generated. The effects of four different treatment processes, namely the Na2S precipitation method, the sodium hypochlorite oxidation method, the ferrous precipitation method, and the ferrous-potassium persulfate oxidation method, were compared. The Na2S precipitation method was selected as the best treatment method due to its significant advantages of good copper removal effect and low treatment cost. The effects of the n(Na2S)∶n(Cu) molar ratio, reaction pH, and reaction time on the removal of chelated copper were investigated, and the process conditions were optimized by the response surface method. The results showed that the order of contribution to the removal efficiency of chelated copper was n(Na2S)∶n(Cu)>reaction pH>reaction time. Under the optimal process parameters of n(Na2S)∶n(Cu) of 14:1, reaction pH of 10.5,and reaction time of 60 min, the copper content in the effluent was less than 0.146 mg/L, and the copper removal rate reached 98.8%.