Amino-functionalized iron-based MOFs for Rhodamine B degradation in heterogeneous photo-Fenton system

Amino-functionalized iron-based MOFs were successfully synthesized and used for the photo-Fenton-catalyzed degradation of Rhodamine B (RhB). The degradation efficiency of NH2-MIL-53(Fe) towards RhB (95.0%) exceeded that of NH2-MIL-88B(Fe) (87.0%) and NH2-MIL-101(Fe) (88.0%), which might be mainly because that NH2-MIL-53(Fe) had the most suitable specific surface area and pore volume, and the best light absorption properties. Additionally, NH2-MIL-53(Fe) exhibited higher degradation efficiency than MIL-53(Fe) (84.0%), possibly owing to the incorporation of amino functional groups that inhibited the recombination of photogenerated electron-hole pairs and enhanced visible light responsiveness. Remarkably, NH2-MIL-53(Fe) had a good degradation effect on RhB in a wide range of pH (3.0–7.0), and the degradation rate was still as high as 90.0% after 5 consecutive degradation experiments. The degradation process was predominantly influenced by the involvement of ·OH and 1O2, as evidenced by the outcomes of free radical capture experiments. Possible degradation pathways of RhB were proposed by mass spectrometry.