CoS Nanoparticles Decorated Biomass-Derived Carbon Spheres: A Highly Efficient Peroxymonosulfate Activator for Tetracycline Degradation

The development of efficient and environmentally friendly catalysts for peroxymonosulfate (PMS) activation is critical for antibiotic wastewater remediation. Herein, a cobalt sulfide-modified biomass carbon composite (CoS/BC) was synthesized via a hydrothermal method using waste pine trunks as a sustainable carbon source. The optimized 30% CoS/BC catalyst demonstrated exceptional PMS activation performance, achieving 93% tetracycline (TC) degradation within 30 min. Systematic experiments revealed that the degradation efficiency was influenced by catalyst dosage, PMS concentration, pH, and coexisting anions, with the system maintaining high activity over a broad pH range (3-11) and in complex water matrices. Mechanistic studies through radical quenching tests and electron paramagnetic resonance (EPR) analysis confirmed that sulfate radicals (SO₄^·-), singlet oxygen (¹O₂), and superoxide radicals (O₂^·-) jointly contributed to TC degradation, with SO₄^·- playing the dominant role. The carbon support facilitated electron transfer and enhanced the Co(II)/Co(III) redox cycle, thereby promoting continuous generation of reactive species. This work not only provides a value-added strategy for converting waste biomass into high-performance catalysts but also advances the fundamental understanding of radical and nonradical pathways in PMS-based oxidation processes. The proposed catalyst demonstrates great potential for practical applications in antibiotic wastewater treatment.