| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 45384 | Applied Catalysis B: Environmental | 2014 | 8 Pages |
•Decomplexation of Ni-EDTA at anode complied with Ni recovery at cathode.•Cleavage of amine group at Ni-EDTA leaded to generation of Ni-NTA and Ni-IDA.•Small molecular acids were indentified.•Nitrogen-containing products were ammonium and nitrate.•Liberated nickel was deposited at cathode with zero value.
Ethylenediaminetetraacetic acid (EDTA) forms stable complexes with toxic metals such as nickel. A combined photocatalytic-electrochemical system using TiO2/Ti plate as anode and stainless steel as cathode achieves the simultaneous decomplexation of Ni-EDTA and recovery of nickel. Ni-EDTA was efficiently destroyed in photoelectrocatalytic process in comparison with individual photocatalytic and electro-oxidation process. At 60 min, removal efficiencies of Ni-EDTA were 75%, 12%, and 5%, respectively. At 180 min, the removal efficiency of Ni-EDTA in the photocatalysis and electrolysis processes is only 21% and 18%, respectively. By contrast, nearly 90% Ni-EDTA is removed in the photoelectrocatalytic process. The recovery percentage of nickel was determined to be 45%, 21%, and 5% in the photoelectrocatalysis, electrolysis, and photocatalysis process, respectively. The deposition of nickel ions at the cathode was confirmed by scanning electron microscopy analysis and the nickel species were identified via X-ray photoelectron spectra as nickel with zero value. The removal of Ni-EDTA and recovery of nickel ions increased with the current density and favored at acid conditions. Intermediates detected using a capillary electrophoresis and a high performance liquid chromatography includes Ni-NTA, glycine, maleic acid, glycolic acid, formic acid, acetic acid, oxalic acid, and oxamic acid were identified. The decomplexation pathway of Ni-EDTA was proposed.
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