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.
Further research into more cost-effective methods to treat toxic metal-ethylenediaminetetraacetate (Me-EDTA) complexes is required due to their high bioavailability. In this study, we compared electrodialysis (ED) with different compartment designs (2-, 3- and 4-compartment designs) and electrochemical oxidation (EO, 1-compartment design) to treat a dilute Cu(II)-EDTA solution (1 mM). After a 48-h treatment with a constant current applied at 32 mA, the Cu removal efficiencies were achieved at 49%, 87%, 79% and 96% for 1-compartment EO and 2- to 4-compartment ED, respectively, and the total organic carbon concentrations decreased from 138 mg/L to 100, 64, 57 and 39 mg/L, respectively. The energy consumptions for 1-compartment EO and 2- to 4-compartment ED were 7.7, 8.4, 13.9 and 15.4 W h, respectively. Based on all above results, the most cost-effective design was determined to be the 2-compartment ED. Moreover, the 3- and 4-compartment ED treatments have faster contaminant removal kinetics than 1-compartment EO and 2-compartment ED. This study clarified the mechanisms of the migration and the transformation of Cu-EDTA during EO and ED with different membrane combinations, which is helpful for improved selection of compartment design for metal-chelate complex removal.
Miaomiao Zhao,Zezhou Zhang,Liying Wang,Xuan Xu,You Li,Ao Liu,Degang Ma,Chunfeng Song
Stable, treatment-resistant Cu complexes in practical wastewater are frequently neglected. Positively charged lysozyme amyloid fibrils (AF), however, exhibit unexplored potential for their adsorption. This study engineered an amyloid fibril-chitosan composite (AF-CS) xerogel and evaluated its adsorption performance in three systems: free Cu 2+ , Cu-Citrate binary, and Cu-EDTA binary. The characterization confirmed successful synthesis of AF-CS, revealing a porous and amine-rich structure with a more positive surface charge than that of pure AF xerogel. Systematic evaluation demonstrated adsorption capacities of 65.37 mg/g (free Cu 2+ ), 166.14 mg/g (Cu-Citrate), and 40.31 mg/g (Cu-EDTA). MINTEQ 3.0 speciation analysis identified anionic Cu-ligand complexes as dominant species in binary systems. Further investigation revealed synergistic adsorption mechanisms in the Cu-Citrate system: electrostatic attraction coupled with decomplexation-complexation pathways liberated citrate ligands, enabling electrostatic shielding and adsorption bridging that enhanced Cu coordination. Conversely, the high stability of Cu-EDTA chelates limited adsorption primarily to mechanisms involving electrostatic attraction, resulting in suboptimal performance. These findings advance the theoretical understanding of AF-CS interactions with diverse Cu species, demonstrating AF-CS as a promising material for Cu recovery from complex wastewater and providing guidance for designing novel remediation materials.
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