Enhanced sodium butyl xanthate removal and antibacterial activity by amorphous hollow CoS_x and its possible practical application

Co-based metal-organic frameworks (MOFs) have gained significant attention in wastewater treatment owing to their exceptional catalytic and antibacterial properties. In this work, CoSₓ were successfullysynthesized via the sulfurization of ZIF-67 using a solvothermal method. Among the synthesized materials, CoS-0.25 and CoS-1.00 exhibited outstanding performance in the removal of sodium butyl xanthate (SBX) and the inhibition of Escherichia coli (E.coli), respectively. CoS-0.25 activated peroxymonosulfate (PMS) to remove 89% of SBX within 1 minute and maintained high removal efficiency over a broad pH range (3-11). Furthermore, the CoS-0.25/PMS system sustained an SBX removal rate of over 80% for 10 consecutive hours, achieving up to 90% removal in actual water bodies. Meanwhile, CoS-1.00 demonstrated antibacterial performance superior to that of ZIF-67, achieving a 98% antibacterial rate against E.coli within 120 minutes, with a minimum inhibitory concentration of 31.30 μg/mL. The enhanced hydrophilicity of CoS-0.25 and CoS-1.00 promoted interfacial contact with SBX and bacterial cells, respectively, and also facilitated the generation of reactive oxygen species (ROS). Mechanistic investigations revealed that the superoxide radical(·O₂⁻) was the primary ROS responsible for SBX removal, and S species accelerated the Co³⁺/Co²⁺redox cycle, thereby promoting PMS activation. In addition, ROS contributed to bacterial inactivation by disrupting the cell wall, resulting in potent antibacterial performance.