Ferrocene-modified iron-based metal-organic frameworks as an enhanced catalyst for activating oxone to degrade pollutants in water

Ferrocene (Fc) has been regarded as a useful catalyst for activating Oxone to generate sulfate radicals (SR) in degradation of organic pollutants. Nevertheless, direct usage of Fc molecules in aqueous solutions may lead to difficult recovery and aggregation. While a few attempts have immobilized Fc on several substrates, these substrates exhibit very low surface areas/porosities and, especially, do not offer significantly additional contributions to catalytic activities. In this study, a Fe-containing metal organic frameworks (MOFs), MIL-101, is particularly selected for the first time as a support to immobilize Fc chemically. Through the Schiff base reaction, ferrocenecarboxaldehyde can react with amine-functionalized MIL-101 (namely, MIL-101-NH2) to form Fc-modified MIL-101 (Fc-MIL). As Fc-MIL consists of both Fe from MIL-101 and Fc and also exhibits high surface areas, it appears as a promising catalyst for activating Oxone. Catalytic activities for Oxone activation by Fc-MIL are studied using batch-type experiments of amaranth dye degradation. Fc-MIL shows higher catalytic activities than its precursor MIL-101-NH2 owing to the modification of Fc, which equips with MIL-101 with more catalytic sites for activating Oxone. Besides, Fc-MIL also outperforms the benchmark catalyst of Oxone activation, Co3O4, to degrade amaranth. In comparison to the other reported catalysts, Fc-MIL shows the much smaller activation energy for amaranth degradation, proving its advantage over other catalysts. The synthesis technique proposed here can be also employed to develop other Fc-modified MOFs for other environmental catalysis applications.