Abstract:In order to break the complex bonds and treat the organic wastewater containing heavy metal, such as Cu−EDTA solution, a novel process of Fe−C micro-electrolysis was proposed. Based on the principle of iron−carbon micro-electrolysis reaction, •OH radicals which were generated under the acidic aerobic condition during the micro-electrolysis process attacked to the organic groups of coordination compounds, which resulted in complex bonds breaking. Therefore copper (II) ions were removed via nascent gelatinous ferric hydroxide and ferrous hydroxide, and EDTA was degraded by •OH radicals. Effects of pH value, temperature, electrolysis time and mass ratio of Fe to C on residual concentrations of total organic carbon (TOC) and Cu(II) were studied. The mechanism of Fe−C micro-electrolysis was investigated and verified by analyzing micrographs of scanning electron microscopy (SEM), energy dispersive analysis (EDS) and Fourier transform infrared spectrometry (FTIR).The removal efficiency is optimal at pH value of 2.0, temperature of 25 °C, the mass ratio Fe to C of 0.02, and reaction time of 60 min. Under above conditions, the concentration of TOC decreases from 200 mg/L to 40.66 mg/L and the residual concentration of Cu(II) decreases from initial 60 mg/L to 1.718 mg/L.

Key words: micro-electrolysis; •OH radical; EDTA; wastewater