Removal of refractory organic compounds in DDNP industrial wastewater by MW activated PS coupling coagulation process
HOU Xian-yu1, CHEN Wei-ming2, LI Qi-bin2, GU Zhe-pei1, ZHANG Ai-ping1
1. College of Chemistry and Material Science, Sichuan Normal University, Chengdu 610068, China;
2. Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong Univeristy, Chengdu 611765, China
MW activated PS coupling coagulation process was applied to treat the dinitrodiazophenol (DDNP) industrial wastewater in this study. The effects of PS dosage, n(Fe2+/PS), initial pH and MW power on organic compounds removal efficiency of DDNP wastewater were investigated. The effect and synergistic mechanism of DDNP wastewater degradation were compared by using control experiments, and the structural transformation of organics by oxidation of MW-Fe2+/PS system was characterized by UV-Vis and FTIR spectra. The reactive oxidative species (ROS) were identified by adding radical scavengers. The results indicated that under optimum condition of PS dosage of 8g/L, initial pH of 3, MW power of 600W, n(Fe2+/PS) ratio of 0.04, and reaction time of 8min, the COD and CN removal efficiency were 70.79% and 94.53%, respectively. Meanwhile, the COD removal rate of the effluent after coagulation increased, but the removal rate of CN decreased slightly. In addition, MW, PS and Fe2+ had the synergetic effect. The increase of B/C from 0.05 to 0.56 indicated that the biodegradability of the wastewater was significantly improved. Moreover, ·SO4- and ·OH are the most critical ROS in the system, which can destroy benzene ring, nitro (-NO2) and azo group (-N=N-) and form by-products containing N-H and C-O-H.
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