The interfacial charge change enhanced by Pr0.6Sm0.4Co0·8Mn0·2O3 activated peroxymonosulfate was used for the efficient degradation of tetracycline under the nanoscale domain limiting and distance effect

Abstract

In this work, an improved sol-gel method was used to prepare a series of Co-infused PrSmMnO₃ perovskites (Pr_0.6Sm_0.4Co_1-XMn_XO₃, PSCM) to rapidly activate peroxymonosulfate (PMS) for efficient degradation of tetracycline (TC). The experimental results showed that the degradation efficiency of the PSCM-82/PMS system for TC in the pH 2–11 range was close to 100%. The nanoscale domain-limiting and distance effect of PSCM under different activators were discussed, and the catalytic mechanism of the non-radical electron transfer pathway in the PSCM-82/PMS system was proposed. After the optimization of the DFT calculation, it can be seen that the d_Co-Mn-Co range of the PSCM-82 material is 9.8–9.9 Å. The molecular size of PMS is 9.9 Å, which precisely matches the d_Co-Mn-Co range of the material. Moreover, the distance between molecular sizes was relatively minimal, and the interface charge transfer was enhanced by both the confinement and distance effects. This promotes a fast catalytic reaction and an optimal degradation rate. During this process, PMS molecules were adsorbed by the active metal sites on the surface of PSCM-82, resulting in a large amount of interfacial charge transfer. This allows a strong coupling between the PMS and the catalyst, resulting in a reaction surface with high redox potential. According to the results of density functional theory (DFT) calculation, quenching experiment, electron paramagnetic resonance (EPR) experiment and electrochemical research, it can be concluded that the main degradation pathway of TC is realized through the direct electron transfer process.