Simultaneously degradation of 2,4-Dichlorophenol and EDTA in aqueous solution by the bimetallic Cu-Fe/O2 system

Oxidative degradation of aqueous organic contaminants 2,4-dichlorophenol (2,4-DCP) using ethylenediaminetetraacetic acid (EDTA)-enhanced bimetallic Cu-Fe system in the presence of dissolved oxygen was investigated. The proposed process was applied for the pH range of 3 similar to 7 with the degradation efficiency of 2,4-DCP and EDTA varying within 10 %, and achieved at 100 % degradation of 40 mg L-1 2,4-DCP in 1 h, at the initial pH of 3, 25 g L-1 of bimetallic Fe-Cu powder (W-Cu/W-Fe = 0.01289) and initial EDTA of 0.57 mM. However, the removal efficiency of 2,4-DCP in control tests were 7.52 % (Cu-Fe/O-2 system) and 84.32 % (EDTA-enhanced Fe/O-2 process), respectively, after 3 h, reaction. The proposed main mechanism, involves the in situ generation of H2O2 by the electron transfer from Fe-0 to O-2 which was enhanced by ethylenediaminetetraacetic acid (EDTA), and the in situ generation of center dot OH via advanced oxidation reaction. Accordingly, 2,4-DCP was attacked by center dot OH to achieve complete dechlorination and low molecular weight organic acids, even mineralized. Systematic studies on the effects of initial EDTA and 2,4-DCP concentration, Cu-Fe dosing, Cu content, and pH revealed that these effects need to be optimized to avoid the excessive consumption of center dot OH and new EDTA and heavy metal Cu pollution.