Dithionite-zerovalent iron coupling drives Cu(II)/Cu(I) redox cycling for persulfate activation and PAH degradation in carbonate-rich water.

Authors

Maolin Wang, Haoyang Fu, Yanchun Fan, Gang Zhao, Tianwen Liu, Yi Liu, Qingqing Wu, Ying Huang

Published in

Journal of environmental management. Volume 413. Pages 130414. Jul 05, 2026. Epub Jul 05, 2026.

Abstract

Persulfate (PS)-based advanced oxidation of polycyclic aromatic hydrocarbons (PAHs) in carbonate-rich water is severely constrained by radical scavenging and surface passivation of iron-based activators. Here, a dithionite-zerovalent iron-copper (DTN-ZVI-Cu) ternary system was developed to promote persulfate activation toward predominantly non-radical oxidation under bicarbonate-rich conditions. DTN and ZVI accelerated Cu(II)-to-Cu(I) reduction while simultaneously regenerating the ZVI surface, thereby sustaining Cu-centered redox turnover and facilitating the formation of Cu(III)-like oxidizing species. In parallel, DTN promoted sulfur-centered conversion pathways that favored ¹O₂ generation. These non-radical oxidizing pathways are generally less susceptible to inorganic-anion scavenging than conventional sulfate and hydroxyl radicals. Under standard conditions, the system achieved 91% acenaphthene removal within 60 min (k_obs = 0.039 min^-1), an 8.7-fold kinetic enhancement over ZVI/PS alone. Moderate bicarbonate further promoted degradation, with k_obs reaching 0.13 min^-1 at 250 mg/L HCO₃^-, which is consistent with a plausible role of copper-carbonate complexation in stabilizing Cu redox cycling and favoring non-radical oxidation pathways. XPS analysis suggested that DTN-ZVI coupling elevated the reactive copper pool (Cu(I) + Cu(III)) to 57% of total surface copper. Applied to synthetic wastewaters, the system maintained 90-96% PAH removal at optimal dosages, indicating strong performance across complex saline matrices. This work demonstrates the feasibility of using coexisting Cu(II) as a catalytic resource for non-radical persulfate activation in carbonate-rich water.

PMID:
42402235
Bibliographic data and abstract were imported from PubMed on 06 Jul 2026.

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