Mo2C/C catalyst as efficient peroxymonosulfate activator for carbamazepine degradation.

Compared with generally reported Mo4+/Mo6+ redox cycle, the exposed Mo2+ active sites of Mo-based materials may have a superior potential to effectively activate PMS. However, Mo2+-involved materials as efficient catalysts in sulfate radical-based advanced oxidation processes (SR-AOPs) has rarely been researched. In this work, a spherical Mo2C-loaded carbon material, Mo2C/C, was prepared for the first time by hydrothermal-calcination method directly used as peroxymonosulfate (PMS) activator towards carbamazepine (CBZ) degradation. The results showed that the Mo2C/C could effectively remove nearly 100% CBZ (5 mg·L-1) in the presence of 0.75 mM PMS within 75 min under the optimal conditions. It was attributed to the reductive Mo2+, as active sites, benefits to absorb PMS on the surface to trigger electron transmission, and the defective carbon structures accelerate the activation of PMS. Consequently, the efficient Mo2+/Mo4+/Mo6+ electron transfer was achieved, resulting in excellent catalysis. A series of reactive species including SO4-, OH and 1O2 species participated in CBZ oxidation degradation. Derived from the superior stability and reusability of Mo2C/C, the removal rate of CBZ still maintained above 80% even after five consecutive cycles, which is expected to be applied in the wastewater treatment including pharmaceuticals in the future.