Preparation of manganese-doped cubic carbon electrode based on ZIF-8 and its capacitive deionization performance for fluoride removal

Fluoride pollution will cause serious harm to the human ecological environment. The capacitive deionization method for fluoride removal has the advantages of low cost, low energy consumption, and convenient operation. Electrode material is crucial for desalination performance. In this study, a novel manganese doped hollow cubic carbon material (MHCC) was prepared by constructing ZIF-8 with hollow cubic morphology as a precursor and carbonizing it with manganese acetate as a manganese source. Then, the derived MHCC material was characterized and tested for capacitive fluoride removal. The adsorption capacity of MHCC10 (the mass ratio of carbon material to manganese acetate tetrahydrate was 10:1) reached 6.2 mg/g and 25.5 mg/g at the initial NaF concentration of 30 mg/L and 150 mg/L respectively. It could maintain 85.5% of the initial capacity after 10 adsorption–desorption cycles. The CDI defluoridation mechanism of MHCC was analyzed. The hollow porous structure inherited from etched ZIF-8 can promote the formation of electric double layers. An appropriate amount of manganese doping has a pseudocapacitive effect, which helps to increase adsorption capacity and improve cycling performance. This work provides a new approach for the design and preparation of novel capacitive fluoride removal electrode materials.