The aim of this study was to develop a new pulsed switching peroxi-coagulation system to control hydroxyl radical (∙OH) production and to enhance 2,4-Dichlorophenoxyacetic acid (2,4-D) degradation. The system was constructed with a sacrifice iron anode, a Pt anode, and a gas diffusion cathode. Production of H2O2 and Fe2+ was controlled separately by time delayers with different pulsed switching frequencies. Under current densities of 5.0 mA/cm2 (H2O2) and 0.5 mA/cm2 (Fe2+), the ∙OH production was optimized with the pulsed switching frequency of 1.0 s (H2O2):0.3 s (Fe2+) and the ratio of H2O2 to Fe2+ molar concentrations of 6.6. Under the optimal condition, 2,4-D with an initial concentration of 500 mg/L was completely removed in the system within 240 min. The energy consumption for the 2,4-D removal in the system was much lower than that in the electro-Fenton process (68±6 vs. 136±10 kWh/kg TOC) The iron consumption in the system was ∼20 times as low as that in the peroxi-coagulation process (196±20 vs. 3940±400 mg/L) within 240 min. The system should be a promising peroxi-coagulation method for organic pollutants removal in wastewater.
Pulsed switching peroxi-coagulation system Energy consumption Hydroxyl radical production 2,4-Dichlorophenoxyacetic acid
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This work was partly supported by grants from the National Key Scientific Instrument and Equipment Development Project (No. 2012YQ03011108), research fund program of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (No. 2016K0013), the National Natural Science Foundation of China (Grant Nos. 51608547, 51278500 and 51308557) and the Fundamental Research Funds for the Central Universities (No. 16lgjc65).
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