Oxidative Treatment of Ethylene Diamine Tetra Acetic Acid Aqueous Solution by Bimetallic Fe0 Al0/O2 System

Abstract:

Fe0 Al0/O2 green advanced oxidation process in which reactive oxygen species (ROS) of H2O2 and ·OH is generated by the O2 spontaneous reduction at normal temperature and pressure was developed. Ethylene diamine tetra acetic acid (EDTA) simulated wastewater as the research object, effects including the initial pH, the mass ratio of Fe0 and Al0 and the initial EDTA concentration were investigated. The in situ generation of H2O2 and ·OH, as well as the oxidative degradation mechanism of EDTA degradation were confirmed by the determine methods of N,N diethyl p phenylene diamine horseradish peroxidase（DPD POD）, benzoic capturing, oxygen stripping, total oxygen carbon (TOC) changes and EDTA degradation products. The results show that EDTA degradation efficiency by the Fe0 Al0/O2 system decreases with the initial pH increasing, but it is still high at the pH range of 3~9. With the mass ratio of Al0 and Fe0 increasing and the initial concentration of EDTA reducing the removal rate of EDTA increases. Under the conditions that the initial pH is 9, initial EDTA concentration is 0.5 mmol·L-1 and mass ratio of Fe0∶Al0 is 1∶1, the EDTA removal efficiency reached at 90% above. EDTA is removed mainly through advanced oxidation. The intermediates include iminodiacetic acid, formic acid and acetic acid which are eventually mineralized to CO2 and H2O. The TOC removal efficiency reaches 72.5% after 3 h. The studies indicate that Fe0 Al0/O2 system for the EDTA degradation shows many advantages, such as no external H2O2 adding, running cost saving and wide range of pH for application.