Abstract:Coagulation and electrocoagulation methods were applied to remove multiple metal ions (Pb2+, Cd2+, Cu2+, Ni2+) from aqueous solution. Effects of pH value of solution and dosage of coagulant (PAC) on metal ions removal efficiency during coagulation process were explored. Effects of pH value of waste water and current density on metal ions removal efficiency during metal ions electrocoagulation precipitation were comprehensively discussed. The co-precipitation mechanism of multiple metal ions with coagulation and electrocoagulation methods was discovered. The results show that the optimal pH value for Pb2+, Cd2+, Cu2+, Ni2+ removal from aqueous solution with PAC-coagulation is 7.0 and PAC dosage is 600 mg/L. Removal efficiency of Pb2+ and Cu2+ is much higher than that of Cd2+ and Ni2+. While, for multiple metal ions precipitation with electrocoagulation technology, the optimal pH value is 7.0, and suitable current density is 1.2-1.8 mA/cm2. Removal efficiency of metal ions with coagulation and electrocoagulation methods has nothing to do with radius and relative molecular mass of metal ions but is directly related to solubility of metal ions. The smaller the solubility of metal ions is, the higher the removal efficiency is. Compared with coagulation, electrocoagulation has more removal efficiency of metal ions. This project may provide support and guidance for further application of coagulation and electrocoagulation technologies in metallic pollution wastewater treatment.