TY - JOUR

T1 - Aquatic photochemistry of Cu(II) in the presence of As(III): Mechanistic insights from Cu(III) production and As(III) oxidation under neutral pH conditions

AU - Wu, Yi

AU - Guo, Juntao

AU - Zhang, Yihui

AU - Xu, Jing

AU - Pozdnyakov, Ivan P.

AU - Li, Jinjun

AU - Wu, Feng

N1 - Funding Information: This work was financially supported by National Natural Science Foundation of China (No. 21777125 and 22061132001 ), and Russian Science Foundation (Grant RSF-NSFC No. 21-43-00004 ). The author appreciates helpful comments from the editors and reviewers. Publisher Copyright: © 2022 Elsevier Ltd

PY - 2022/12/1

Y1 - 2022/12/1

N2 - Surface complexation between arsenite (As(III)) and colloidal metal hydroxides plays an important role not only in the immobilization and oxidation of As(III) but also in the cycle of the metal and the fate of their ligands. However, the photochemical processes between Cu(II) and As(III) are not sufficiently understood. In this work, the photooxidation of As(III) in the presence of Cu(II) under neutral pH conditions was investigated in water containing 200 μM Cu(II) and 5 μM As(III) under simulated solar irradiation consisting of UVB light. The results confirmed the complexation between As(III) and Cu(II) hydroxides, and the photooxidation of As(III) is attributed to the ligand-to-metal charge transfer (LMCT) process and Cu(III) oxidation. The light-induced LMCT process results in simultaneous As(III) oxidation and Cu(II) reduction, then produced Cu(I) undergoes autooxidation with O2 to produce O2•⁻ and H2O2, and further the Cu(I)-Fenton reaction produces Cu(III) that can oxidize As(III) efficiently (kCu(III)+As(III) = 1.02 × 109 M–1 s–1). The contributions from each pathway (ρrCu(II)-As(III)+hv = 0.62, ρrCu(III)+As(III) = 0.38) were obtained using kinetic analysis and simulation. Sunlight experiments showed that the pH range of As(III) oxidation could be extended to weak acidic conditions in downstream water from acid mine drainage (AMD). This work helps to understand the environmental chemistry of Cu(II) and As(III) regarding their interaction and photo-induced redox reactions.

AB - Surface complexation between arsenite (As(III)) and colloidal metal hydroxides plays an important role not only in the immobilization and oxidation of As(III) but also in the cycle of the metal and the fate of their ligands. However, the photochemical processes between Cu(II) and As(III) are not sufficiently understood. In this work, the photooxidation of As(III) in the presence of Cu(II) under neutral pH conditions was investigated in water containing 200 μM Cu(II) and 5 μM As(III) under simulated solar irradiation consisting of UVB light. The results confirmed the complexation between As(III) and Cu(II) hydroxides, and the photooxidation of As(III) is attributed to the ligand-to-metal charge transfer (LMCT) process and Cu(III) oxidation. The light-induced LMCT process results in simultaneous As(III) oxidation and Cu(II) reduction, then produced Cu(I) undergoes autooxidation with O2 to produce O2•⁻ and H2O2, and further the Cu(I)-Fenton reaction produces Cu(III) that can oxidize As(III) efficiently (kCu(III)+As(III) = 1.02 × 109 M–1 s–1). The contributions from each pathway (ρrCu(II)-As(III)+hv = 0.62, ρrCu(III)+As(III) = 0.38) were obtained using kinetic analysis and simulation. Sunlight experiments showed that the pH range of As(III) oxidation could be extended to weak acidic conditions in downstream water from acid mine drainage (AMD). This work helps to understand the environmental chemistry of Cu(II) and As(III) regarding their interaction and photo-induced redox reactions.

KW - Arsenic species

KW - Copper hydroxide colloid

KW - Direct electron transfer

KW - Kinetic simulation

KW - Trivalent copper

KW - Water

KW - Oxidation-Reduction

KW - Hydrogen Peroxide

KW - Metals

KW - Kinetics

KW - Hydrogen-Ion Concentration

UR - http://www.scopus.com/inward/record.url?scp=85141942562&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/8e235935-05e4-34c7-9773-5bb659b34eb8/

U2 - 10.1016/j.watres.2022.119344

DO - 10.1016/j.watres.2022.119344

M3 - Article

C2 - 36402098

AN - SCOPUS:85141942562

VL - 227

JO - Water Research

JF - Water Research

SN - 0043-1354

M1 - 119344

ER -