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 ^[rad]OH 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.