Abstract:A ligand-to-metal charge-transfer synergistic and Fenton-like gathered reaction (LFGR) was developed to effectively decompose Ni-EDTA, a typical strong complex in near-neutral wastewater. Based on the removal efficiency of Ni(Ⅱ) and other systems, the complex broken characteristics of Ni-EDTA under near-neutral conditions were analyzed. The effects of Fe(Ⅲ) and H2O2 dosage, pH, turbidity, common organic acids and conventional inorganic salts on the complex broken characteristics of LFGR were investigated. The main reactive oxygen species in the LFGR system were identified in combination with the observation of H2O2 consumption, free radical quenching experiment, free radical signal detection and degradation product analysis, and the complex broken process and dominant mechanism of Ni-EDTA were further analyzed. The removal properties of heavy metal EDTA complexes (M-EDTA) by LFGR and other UV activated oxidation technologies were quantitatively compared, and the operating cost advantages of LFGR were further clarified. For the near-neutral simulated wastewater with 1.0 mmol/L complex concentration, the optimal reaction conditions of LFGR are as follows: Fe(Ⅲ) salt dosage = 0.1 mmol/L, H2O2 dosage = 50 mmol/L, and UV illumination time is 20 min. Under the above reaction conditions, the EDTA can be completely transformed and the Ni(Ⅱ) removal rate of Ni-EDTA can reach 99.40% after alkali precipitation; LFGR shows good anti-interference to common organic acids and conventional inorganic salts in water. H2O2 is consumed by Fenton-like reaction with Fe(Ⅱ) produced by ligand-to-metal charge-transfer. The main process of LFGR is that Fe(Ⅲ) replaces Ni(Ⅱ), stimulates the ligand-to-metal charge-transfer reaction and promotes the photolysis of EDTA, UV further drives Fe(Ⅲ) reduction and accelerates Fe species cycling, and further coordinates with Fenton-like reactive oxygen species (mainly ·OH and ·O2-) to enhance the complex decomposition. LFGR can achieve a variety of M-EDTA good breaking effect under near-neutral conditions, the total cost of treatment of each ton of water is 4.21 Yuan, with good technical economy.