Enhanced degradation of refractory organics in leachate concentrates by Fe0/H2O2 coupled with microwave irradiation
ZHANG Ai-ping1, CHEN Wei-ming2, LI Qi-bin2, JIANG Guo-bin2, GU Zhe-pei1
1. Chemistry and Material Science of Sichuan Normal University, Chengdu 610068; 2. Geosciences and Environmental Engineering of Southwest Jiaotong University, Chengdu 611765
Abstract：To study the effect and mechanism of MW-Fe0/H2O2 Fenton-like process on concentrated leachate, the effects of initial pH, Fe0 dosage, H2O2 dosage, MW power and reaction time on the removal of organic substances were investigated. The phase change of Fe0 before and after reaction and its catalytic mechanism were investigated by SEM micrograph and XRD spectra. Results showed that the removal efficiencies of COD, UV254 and CN were 58.70%, 85.69% and 88.30% at initial pH of 3.0, Fe0 dosage of 0.5g/L, H2O2 dosage of 20mL/L, MW power of 400W and reaction time of 14min. Comparison of different Fenton-like process indicated that a higher removal efficiency of organic substances and a greater biodegradability were achieved after MW-Fe0/H2O2 Fenton-like process. UV-Vis spectra illustrated that both Fenton and MW-Fe0/H2O2 processes can significantly decrease the aromaticity degree, molecular weight and condensation degree of organic substances in wastewater, however, MW-Fe0/H2O2 process was the most efficient. 3D-EEM spectrum demonstrated that the fluorescence peak of concentrated leachate occurred blue-shift in MW-Fe0/H2O2 process, further indicating that condensation degree of humic substances declined and molecular weight remarkably decreased. After MW-Fe0/H2O2 process, the surface of Fe0 changed from smooth to rough and the material was corroded as Fe3O4 and FeOOH, indicating that the mechanism of MW-Fe0/H2O2 process was Fenton reaction and advanced oxidation effect of heterogeneous Fenton reaction between iron oxide and H2O2, adsorption and precipitation effects of iron based colloid on organic substances. Moreover, thermal and non-thermal effects of MW accelerated the actions mentioned above. Thereby, fast removal of organic pollutants in concentrated leachate was achieved.
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