The degradation of EDTA by the bimetallic Fe-Cu/O2 system

The bimetallic Fe-Cu/O-2 process exhibited significantly higher reactivity than did the Fe/O-2 process for the degradation of ethylenediaminetetraacetic acid (EDTA). With the analysis of the soluble Cu2+ in the solution and decomposition of H2O2 catalyzed by Cu-0, possible enhanced-pathways at different pHs were suggested. The degradation efficiency of EDTA increased with decreasing initial pH ranging 3-9, however, the reactions proceeded at a weakly-basic to basic condition in most of the reaction time. POD inhibition test showed that in situ generation of H2O2 played a pivotal role in the EDTA degradation, however, the instant concentration analyzed by DPD-POD method was less than 4.5 uM due to rapid subsequent Fenton reaction. Furthermore, DMPO-ESR spectroscopy and BA-trapping experiments detected the in situ generation of OH. The mechanism of EDTA oxidative degraded by the bimetallic Fe-Cu/O-2 process was verified using control experiments of absorption, stripping, and coagulation sedimentation of EDTA in the system, analysis of solid residue, oxidation of O-2 and H2O2, as well as detection of H2O2 and OH. (C) 2014 Elsevier B.V. All rights reserved.