Design and preparation of core-shell structured magnetic graphene oxide@MIL-101(Fe): Photocatalysis under shell to remove diazinon and atrazine pesticides

A magnetically separable support with core-shell morphology comprising amine-functionalized Fe3O4 wrapped with graphene oxide (AFG) was successfully prepared and used to support MIL-101(Fe). The ternary AFG@MIL-101(Fe) composite was investigated as a photo-Fenton catalyst for the degradation of recalcitrant diazinon (DIZ) and atrazine (ATZ) pesticides. After 105 min visible light irradiation, the AFG@30MIL-101(Fe) photocatalyst achieved 100 +/- 1% and 81 +/- 1% photocatalytic degradation efficiency for DIZ and ATZ pollutants, respectively. The recorded data indicated superior photocatalytic ability of the nanocomposite as compared to AF@30MIL-101 (Fe) and MIL-101(Fe) photocatalysts for the removal of both pollutants. Total Organic Carbon (TOC) analysis revealed 84 +/- 0.5% and 62 +/- 0.5% mineralization for DIZ and ATZ, respectively. The obtained results of characterization and also photocatalytic behavior suggest enhanced conversion between Fe2+/Fe3+ as well as fast electron transfer through interlayers of graphene oxide in this unique core-shell structure. After assaying the adsorption performance of photocatalyst, it was found that ATZ adsorption was more pronounced than DIZ. Furthermore, radical quenching tests revealed (OH)-O-center dot radicals were the main oxidizing players in this process even though the contribution of other species cannot be ruled out. It is noteworthy that magnetic stability was well preserved after 4 consecutive photocatalytic cycles, suggesting that this work can be a guideline to prepare efficient and stable magnetic Fenton systems.