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Anoxic iron electrocoagulation automatically modulates dissolved oxygen and pH for fast reductive decomplexation and precipitation of Cu(II)-EDTA: The critical role of dissolved Fe(II) TEXT SIZE: A A A

Fe-based replacement and precipitation are promising methods for removal of copper ethylenediaminetetraacetic acid (Cu(II)-EDTA) but are limited by the necessity of controlling pH and dissolved oxygen. The details of the decomplexation mechanism also remain unclear. The present work investigated an anoxic iron electro-coagulation process capable of automatically modulating anoxic conditions and solution pH during exposure to air and thus promoting the rapid and thorough decomplexation of Cu(II)-EDTA. Dissolved Fe (II), rather than Fe (II)-bearing minerals, was found to be primarily responsible for the reduction of Cu(II)-EDTA to Cu(I)-EDTA and for the subsequent replacement reaction to generate free Cu(I) ions within the initial pH range of 2-7. The Cu(I) was primarily precipitated as Cu2O on the surface of green rust and magnetite as the pH was increased. The aeration of these Fe-containing precipitates released free Cu(I) ions instead of chelated Cu into solution, allowing for recycling of the Cu. This release of Cu(I) was likely induced by the pH decrease during aeration. This study provides important insights regarding the reductive decomplexation of chelated Cu(II) and the recovery of Cu via anoxic iron electrocoagulation, which is a promising green approach to recycling Cu from wastewater.

Publication name

 Journal Of Hazardous Materials, Volume 442, Article Number 130069, DOI 10.1016/j.jhazmat.2022.130069, Published JAN 15 2023


 Xie, Shiwei; Li, Chang; Zhan, Hui; Shao, Wei; Zhao, Yuanxin; Liu, Peng; Liao, Peng

Corresponding author(s) 

 Liao, Peng
 Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550081, Peoples R China

Author(s) from IGCAS   Liao, Peng; Zhao, Yuanxin

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