Qingping Zhang,Yang Xu,Haiqing Hao,Zhongxiang Guan,Meng Wang,Zongyu Feng,Xiaowei Huang,Guang Yang,Chunmei Wang
Conventional advanced oxidation processes (AOPs) face technological bottlenecks in the stepwise treatment of heavy metal complexes (HMCs), and single-step removal strategies have attracted increasing attention. Herein, we pioneered a waste-derived strategy using NdFeB waste (NFBW) to activate H 2 O 2 for establishing a heterogeneous Fenton-like system, achieving concurrent Cu-EDTA decomplexation and Cu capture. Remarkably, 99.10 % Cu-EDTA decomplexation and 96.84 % total Cu capture were synchronously achieved within 30 min. This one-step technology is effective over a wide pH range (2.0–9.5). Notably, this system demonstrated practical efficacy in treating rare-earth purification wastewater, achieving synchronous removal of heavy metals (Cu, Zn) and rare-earth elements (Yb, Ce) as mixed organic complexes with effluent meeting industrial discharge standards. Mechanistic investigations revealed that Cu-EDTA decomplexation originated from Fe(Ⅲ)-induced ligand substitution coupled with reactive oxygen species (·OH and ·O 2 - ) attack. The ≡Fe(Ⅱ)/≡Fe(Ⅲ)-mediated heterogeneous Fenton reaction synergized with homogeneous Fe(Ⅱ)/Fe(Ⅲ) cycling to generate ROSs, where the B-B bonds and Fe 0 in NFBW facilitated electron transfer for enhanced redox cycling. Possible pathways for the decomplexation of Cu-EDTA in this system are proposed. The 90.10 % TOC removal verified EDTA mineralization through stepwise degradation pathways. Liberated Cu(Ⅱ) was captured via multiple routes: surface reduction (Cu 0 ), precipitation (Cu(OH) 2 , Cu 2 (OH) 2 CO 3 ), and Fe(OH) 3 adsorption-flocculation. This work not only opens new avenues for Fenton-like treatment of HMC wastewater through a “waste-treats-waste” strategy but also provides new ideas for synergistic activation of H 2 O 2 by multivalent iron materials.
Tianxin Gu,Songwen He,Jianxin Yi,Qianwei Liang,Hanjin Luo
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 1 O 2 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.
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