Photocatalytic activation of PMS over magnetic heterojunction photocatalyst SrTiO3/BaFe12O19 for tetracycline ultrafast degradation

The photocatalytic activation peroxymonosulfate (PMS) could boost the oxidation capacity of the photocatalytic system by generating multiple active species and improving the separation efficiency of photogenerated charges via PMS electron trapping. Here, SrTiO3/BaFe12O19 heterojunction was first synthesized and theoretically constructed. PMS was activated by photocatalysis of heterojunction for the tetracycline (TC) degradation, and the degradation efficiency reached 96.1% within 60 s with a reaction kinetic constant of 0.241 s−1. This degradation efficiency and reaction kinetics were 1.39 and 1.83 times higher than those of the SrTiO3/PMS/Vis catalytic system, respectively. Experimental and theoretical calculations identified the active sites for PMS activation and corresponding activation pathways. The energy band structure of the Z-scheme heterojunction and the transfer path of photogenerated charges were constructed by combining the UV-DRS, UPS tests and theoretical calculations. Then, the degradation pathway of TC was proposed based on the molecular orbits structure of TC and dominant active species for TC degradation. The toxicity evaluation indicated that the catalytic system could greatly reduce the TC toxicity. This easily recoverable, highly stable heterojunction is expected to be used in other organic wastewater degradation and practical applications.