Research Of Recovery Technology Of Cu And Ni From Electroplating Wastewater

There are various valuable metal ions in electroplating wastewater, such as copper, nickel, iron, chromium, and so on. If the electroplating wastewater discharges directly, it will cause serious pollution to environment. Electroplating wastewater was treated by the chemical precipitation method and resin adsorption method, and the recovery of the copper and nickel from electroplating wastewater was explored.Calcium oxide, sodium sulfide and new precipitation agent DA was adopted to treat electroplating wastewater. The effect of the precipitation agent type, dosage and pH value was examined. The recovery of Cu and Ni reached97.91%and96.74%by using calcium oxide as precipitation agent, and when pH at about10. pH was increased with the increase of precipitation agent dosage. DA was better than sodium sulfide as precipitation agent in electroplating wastewater, and when pH at7, the recovery of Cu and Ni both reached100%, copper and nickel content in the deposition were9.62%and5.45%, respectively. The fractional precipitation method was adopted, when pH approximately at3, copper and nickel content in the deposition were16.87%and0.66%, respectively. The recovery of Cu reached96.20%, and the loss of Ni was only6.63%. Then when pH reached7, the recovery of Ni reached100%and the nickel content in the deposition was about14.33%, and the copper and nickel could be recovered separately.Chelating resin CR was selected in electroplating wastewater treatment, the adsorption time, initial concentration of solution, temperature and acidity for adsorption of Cu2+and Ni2+by CR resin was examined by static method. The results showed that, the time of equilibrium adsorption of Cu2+and Ni2+were150min and180min, respectively. The adsorption capacity of CR resin increased with the increasing of initial concentration of solution and temperature. The adsorption capacity was largely effected by pH, the optimized adsorption pH of Cu2+and Ni2+were3.0and4.0, respectively.The kinetic model and isothermal adsorption model of CR resin were researched, and the adsorption mechanism of Cu2+and Ni2+was investigated. It was found that the two metal ion diffusion process obeyed liquid film diffusion process.At the same temperature, the adsorption of Cu2+and Ni2+were well fitted by the Langmuir isothermal adsorption model, which illustrated that two kinds of metal ions adsorption process was a single molecular layer adsorption.The dynamic adsorption test indicated that, the flow velocity of solution4mL·min-1, the initial concentration of solution200mg·L-1, the adsorption rate of Cu2+and Ni2+reached100%and99.85%, respectively. The dynamic desorption test indicated that, the flow velocity of eluent4mL·min-1, the concentration of eluent0.8mol·L-1, the desorption rate of Cu2+and Ni2+reached98.75%and98.32%, respectively.