Efficient removal of EDTA-chelated Cu(II) by zero-valent iron and peroxydisulfate: Mutual activation process

Metal complexes pose a significant challenge to remediate heavy metal-laden wastewater by classical techniques due to their stable chelating structure. The application of zero-valent iron (ZVI) to activate peroxidized sulphate (PDS) has been synergistically (ZVI/PDS) proposed for effective removal of EDTA-chelated Cu from aqueous media. In contrast to ZVI alone, ZVI/PDS process improved the EDTA-chelated Cu or total organic carbon (TOC) removal rate by 6.2 or 7.8 fold, respectively. Factors including Cu/EDTA molar ratio, initial pH, ZVI dosage, and PDS dosage affect the removal efficiency of complexed copper. The formation of Fe ions and sulfate radicals in the solution strengthens the removal effect of zero-valent iron on EDTA complexed Cu. After the reaction, ZVI EDS, XRD, and XPS analyses revealed that Cu was eventually reduced to Cu0 and immobilized on the ZVI surface. A possible decomposition mechanism followed by a Cu reduction was also proposed. In conclusion, this study presents new perspectives for the removal of complex heavy metals from contaminated water.

Automated summary

This study investigates the use of zero-valent iron activated peroxidized sulphate (ZVI/PDS) synergistic action for the effective removal of EDTA-chelated copper. The results show that the ZVI/PDS process significantly improves the removal efficiency of complexed copper and total organic carbon compared to ZVI alone. Factors such as the molar ratio, initial pH, ZVI dosage, and PDS dosage influence the removal efficiency of complexed copper. Analysis indicates that the method can reduce chelated copper and immobilize it on the ZVI surface.