Decomplexation and subsequent reductive removal of EDTA-chelated CuII by zero-valent iron coupled with a weak magnetic field: Performances and mechanisms

Abstract The feasibility of EDTA-chelated Cu II (Cu II -EDTA) removal by zero-valent iron (Fe 0 ) in the presence of a weak magnetic field (WMF) and the involved mechanisms were systematically investigated. Fe 0 combined with WMF (Fe 0 /WMF) was very effective for removing Cu II -EDTA at pH 4.0–6.0 with the rate constants ranging from 0.1190 min −1 to 0.0704 min −1 . Little passivation of Fe 0 was observed during Cu II -EDTA removal by Fe 0 /WMF in 8 consecutive runs when 10.0 mg L −1 Cu II -EDTA was dosed before the initiation of each run. The evidences presented in this study verified that Cu II -EDTA was removed by decomplexation followed by reduction/adsorption. In brief, Fe II released from Fe 0 corrosion was rapidly oxidized by oxygen to Fe III to chelate with EDTA and release free Cu II , and the detached Cu II ions were subsequently reduced/removed by Fe 0 /Fe II and co-precipitated by the generated iron (hydr)-oxides. To advance the application of Fe 0 /WMF technology in real practice, a magnetic propeller agitator was designed to offer WMF inside the reactor, which could greatly improve Cu II -EDTA removal by Fe 0 and be easily amplified.