Synthesis of Co-doped Fe metal–organic framework MIL-101(Fe,Co) and efficient degradation of organic dyes in water

In order to further improve the catalytic performance of MIL-101, cobalt-doped MIL-101(Fe,Co) was synthesized by solvothermal method. By adjusting the ratio of cobalt doping, the MIL-101(Fe,Co20%) with the best catalytic activity was obtained. The activation performance of MIL-101(Fe,Co20%) for peroxymonosulfate (PMS) was studied using Rhodamine B (RhB) as a pollutant model. The experimental results proved MIL-101(Fe,Co20%) with much better catalytic performance than MIL-101(Fe), which can degrade more than 99% of RhB within 15 min. The effects of initial solution pH and coexisting anions in water on the degradation of RhB were further discussed. The results showed that MIL-101(Fe,Co20%) was with excellent stability and degradation efficiency can still keep above 90% after five cycles. The free radical quenching experiments were further studied to explore the degradation mechanism. It can be concluded that SO4-· was the main active free radical for the degradation of RhB. The possible intermediate products in the degradation process of RhB were analyzed by LC-MS. Combined with the comparison of XPS before and after the reaction, the possible reaction mechanism of RhB degradation process was inferred.