Photo-Fenton degradation of carbamazepine and ibuprofen by iron-based metal-organic framework under alkaline condition.

Metal-organic frameworks have been widely used as photocatalytic materials. In this paper, a novel photocatalyst HSO-MIL-53(Fe) with acidity regulating groups was successfully synthesized by the solvothermal method and applied to remove carbamazepine (CBZ) and ibuprofen (IBP). The photodegradation efficiency of vis/HO/HSO-MIL-53(Fe) can reach 100% when the pH value is 8 or 9. The free radical capture experiment and electron paramagnetic resonance analysis proved that hole (h), hydroxide radical (·OH), singlet oxygen (O), and superoxide Radical (·O) are the main active species for pollutants degradation. In the vis/HO/HSO-MIL-53(Fe) system, the high pollutant degradation efficiency under alkaline conditions was attributed to two factors: (1) the acidity adjusting group -HSO adjusts the pH value of the whole system, which is beneficial to the photo-Fenton process. (2) The photogenerated electrons of HSO-MIL-53(Fe) can be captured by Fe (III), HO and O to accelerate the reduction of Fe (III) and generate ·OH, O, and ·O. Besides, HO can also be activated by Fe (II) and Fe (III). The above processes synergistically improved the photocatalytic efficiency. Based on liquid chromatography-mass spectrometry (LC-MS) analysis, the possible degradation pathways of the two pollutants were proposed.