Abstract: Cobalt-based catalysts were regarded as highly effective for pollutant degradation through peroxymonosulfate activation. Nevertheless, conventional synthesis methods for cobalt-based catalysts were associated with issues of cobalt ion leakage, which posed a risk of secondary environmental contamination. Addressing this issue, a novel cobalt-based catalyst, CoS nanoparticles, was biosynthesized by Shewanella algae and designated as SA@CoS. SA@CoS, a nanoflower coated with proteins/peptides, contained a significant number of sulfur vacancies. Compared to chemically synthesized CoS, SA@CoS exhibited lower cobalt ion release (0.13 mg/L) and higher catalytic activity. Based on this, SA@CoS was employed to degrade Rhodamine B (RhB) and tetracycline (TC) by activating peroxymonosulfate. The results indicated that the degradation efficiencies of RhB and TC could reach 99.9 % and 90.5 % within 10 min, respectively. Further analyses revealed that both radical (·O₂^-, ·OH and SO₄^•-) and non-radical (¹O₂) pathways were involved in the degradation of RhB and TC, with the non-radical pathway dominating the degradation process. This work not only offered a facile approach for the biosynthesis of stable cobalt-based catalysts, but also underscored the immense potential of biogenic nano-catalysts in the realm of environmental remediation.

Key words: Biosynthesis, Cobalt-based catalyst, Rhodamine B, Tetracycline, Peroxymonosulfate activation