A synergistic strategy for the removal and secondary utilization of Cu(II) organic complexes in wastewater for the efficient degradation of tetracycline

Abstract

Heavy metals in industries such as electroplating plants and semiconductor industries usually exist in the form of heavy metal organic complexes, and the removal of heavy metal organic complexes is troubled by the difficulty of decomplexation as well as the complexity of the treatment process of the free heavy metal ions after decomplexation. In this study, we proposed a synergistic strategy for the removal and secondary utilization of Cu(II) organic complexes (Cu-EDTA) in wastewater through mixed pyrolysis of carbon nitride precursor and Cu-EDTA, and the resulted product was used for the efficient degradation of tetracycline (TC). The unique electronic structure of carbon nitride and abundant surface defects anchor Cu during pyrolysis, which effectively realizes the removal of Cu-EDTA from wastewater. In addition, the Cu and O co-doped carbon nitride (Cu/O-CN) catalyst constructed by this strategy was proved to be effective in peroxydisulfate activation TC degradation, with a removal efficiency of 91.5% in 20 min, a degradation rate of 0.1643 min−1, and a TOC removal efficiency of 53%. X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculation revealed Cu+ active center constructed by the strong metal support interaction between Cu and carbon nitride in Cu/O-CN and the 1O2 dominated nonradical degradation pathways of TC. This study demonstrated a synergistic strategy for the efficient removal and secondary utilization of Cu-EDTA in wastewater, providing new insights into the use of environmentally friendly and cost-effective methods for the removal and recovery of heavy metal organic complexes from wastewater.