Double Z-scheme Co3O4/Bi4O7/Bi2O3 composite activated peroxymonosulfate to efficiently degrade tetracycline under visible light

Co3O4/Bi4O7/Bi2O3 (CBB) composites were prepared, in which Co3O4 was synthesized from Co-MOF as precursor. The peroxymonosulfate (PMS) activated by CBB catalyst under visible light was used to degrade tetracycline (TC). Owing to the synergistic effect of photocatalysis and PMS activation, 98.4% of TC was removed within 60 min. The optimal loading of Co3O4 was determined, and the influence of PMS dosage, initial pH, and disturbing anions on the degradation effect were investigated. The CBB + Vis + PMS system showed good reusability, and the degradation was only reduced by 1.7% after 5 cycles. This system also had a good degradation of other five pollutants. The quenching experiment showed that holes (h(+)), superoxide radicals (center dot O-2(-)), and singlet oxygen (O-1(2)) were the main active species. The degradation products of TC were determined by liquid chromatography-mass spectrometry, and the degradation pathway was proposed. Finally, a double Z-scheme degradation mechanism was proposed in the CBB + Vis + PMS system. The peroxymonosulfate activated by CBB under visible light to degrade organic pollutants has widespread application prospects in environmental remediation.

Automated summary

Co3O4/Bi4O7/Bi2O3 (CBB) composites were prepared and used as catalysts for the degradation of tetracycline (TC) activated by peroxymonosulfate (PMS) under visible light. The system showed high efficiency in degrading TC and had good reusability. The study also revealed the active species and proposed a double Z-scheme degradation mechanism.