Preparation of Fe(III)-Salen-grafted Fe3O4 magnetic composites and their degradation of 2,4,6-trichlorophenol via Fenton-like reaction under visible light

Ethylenediamine (EDA)-functionalized nano-Fe 3 O 4 magnetic particle (EDA@nFe 3 O 4 ) was first synthesized by solvothermal method, followed by condensation with 3 kinds of salicylaldehydes, and coordinated with Fe(III) ion to obtain 3 kinds of Fe(III)-Salen (salicylaldehydoethylenediamine)-grafted Fe 3 O 4 magnetic composites (nFe 3 O 4 @Fe(III)Salen). The nFe 3 O 4 @Fe(III)Salen composites were characterized by elementary analyzer, X-ray diffractometer, FTIR, ultraviolet Vis DRS, XPS, transmission electron microscopy, and vibrating sample magnetometer. The results showed that the nFe 3 O 4 @ Fe(III)Salen composites had an average size of ~200 nm, with the saturation magnetization intensity of 20.3–24.8 emu/g. The nFe 3 O 4 @Fe(III)Salen can be used as heterogeneous catalyst for the degradation of 2,4,6-trichlorophenol (2,4,6-TCP) via Fenton-like reaction under visible light. Radical-trapping experimental results indicated that the • OH radicals were the dominant active oxidizing species in the photoreaction process. The results showed that the highest degradation efficiency to 2,4,6- TCP was found when the nonsubstituted Fe(III)-Salen-grafted composite, nFe 3 O 4 @Fe(III)Salen, was used as catalyst. Further degradation studies indicated that at pH 4.0–7.0, with the usage amount of nFe 3 O 4 @Fe(III)Salen above 0.8 g/L and hydrogen peroxide (H 2 O 2 ) concentration at 8.16–40.8 mmol/L, the degradation of 2,4,6-TCP with initial concentration less than 50.0 mg/L (253.2 mg/L) can reach almost 100% under the nFe 3 O 4 @Fe(III)Salen/H 2 O 2 /vis system within 5 min, which showed a wider pH range than that of normal Fenton system. nFe 3 O 4 @Fe(III)Salencan be reused after regeneration for at least 5 times (with degradation percentage of 2,4,6-TCP over 95%). It is a potential effective and reusable material for catalytic degradation of 2,4,6-TCP.