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 HSO3-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/H2O2/HSO3-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 (1O2), and superoxide Radical (·O2-) are the main active species for pollutants degradation. In the vis/H2O2/HSO3-MIL-53(Fe) system, the high pollutant degradation efficiency under alkaline conditions was attributed to two factors: (1) the acidity adjusting group -HSO3 adjusts the pH value of the whole system, which is beneficial to the photo-Fenton process. (2) The photogenerated electrons of HSO3-MIL-53(Fe) can be captured by Fe (III), H2O2 and O2 to accelerate the reduction of Fe (III) and generate ·OH, 1O2, and ·O2-. Besides, H2O2 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.