| Summary: | 碩士 === 淡江大學 === 水資源及環境工程學系碩士班 === 101 === Plating wastewater containing metal ions with chelating agents to form chelated heavy metal complexes causes ineffectiveness in its treatment by conventional chemical coagulation. This study compares the treatment of wastewater with Cu-EDTA by chemical sedimentation, chemical coagulation and electrochemical coagulation. The mechanisms of the treatment of wastewater with Cu-EDTA by electrochemical coagulation are also studied. In the electrochemical coagulation comparison, different electrolytes, anode materials, operating voltage and chelating metal ratio are tester and compared. This study concludes the following findings:
1.The organic chelating agent EDTA is destructed by oxidation from both anode oxidation and NaCl electrolyte derived oxidants; hence the chelated copper ions are released into the wastewater solution for further coagulation and removal.
2.The removal efficiency of the EDTA chelated Cu2+ is decreased with the increased Cu2+ concentration and EDTA/Cu ratio.
3.Since the chelating constant between the EDTA and Fe is larger than that of EDTA and Cu, it is believed that some Cu2+ are replaced by Fe3+ to chelated with the EDTA in the electrochemical coagulation process.
4.Precipitation and/or co-precipitation occurred is one of the Cu removal mechanisms where the coagulant produced by electrolysis of metal anode absorbs the Cu2+ released from the chelating Cu-EDTA complexes and precipitated.
5.The reduction of Cu2+ on the cathode or by the Fe2+ also contribute to the Cu2+ removal.
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