Decomplexation of Cu(II)/Ni(II)-EDTA by ozone-oxidation process

Area of Science:

• Environmental Chemistry
• Oxidation Processes
• Wastewater Treatment

Background:

• Chemical plating industry generates wastewater containing metal-EDTA complexes, such as Cu(II)/Ni(II)-EDTA.
• Effective treatment technologies are needed to remove these persistent pollutants and prevent environmental contamination.

Purpose of the Study:

• To investigate the efficacy of ozone oxidation for the decomplexation and removal of Cu(II)/Ni(II)-EDTA from synthetic plating solutions.
• To determine the influence of operational parameters on the removal efficiency of Cu(II) and Ni(II).

Main Methods:

• Ozone oxidation was employed to treat synthetic Cu(II)/Ni(II)-EDTA solutions.
• Experiments were conducted to evaluate the effects of solution pH, initial metal-EDTA concentration, EDTA to metal molar ratio, and metal coexistence.
• Removal efficiencies and degradation kinetics were analyzed.

Main Results:

• Ozone oxidation, primarily through hydroxyl radical (OH) oxidation, effectively degrades EDTA-Cu(II) and EDTA-Ni(II) complexes.
• Optimal pH for Cu(II) and Ni(II) removal was found to be 7-9, with over 90% removal achieved even at acidic pH (3-5).
• Increased EDTA to metal molar ratio significantly decreased metal ion removal rates, while a synergistic removal effect was observed in the blended Cu(II)/Ni(II) system.

Conclusions:

• Ozone oxidation is a highly effective technology for the complete decomplexation of Cu(II)/Ni(II)-EDTA in chemical plating wastewater.
• The process demonstrates robustness across a range of pH conditions and highlights the importance of controlling the EDTA to metal ratio.
• The findings support the application of ozone oxidation for sustainable wastewater management in the plating industry.