High-Efficiency Broad-Spectrum Antibacterial Activity of Chitosan/Zinc Ion/Polyoxometalate Composite Films for Water Treatment

The development of multifunctional films with rapidly killing microorganisms and adsorbing residual antibiotics in wastewater remains a challenging endeavor. In this work, the chitosan/zinc ion/polyoxometalate (CS/Zn²⁺/POM) multifunctional films were prepared by the freeze-drying method using chitosan, ZnO, and POM. Notably, the CS/Zn²⁺/POM films exhibited excellent bactericidal properties against Gram-positive/negative bacterial strains including <i>Staphylococcus aureus</i> (<i>S. aureus</i>, 99.80%), <i>Escherichia coli</i> (<i>E. coli</i>, 99.82%), and drug-resistant <i>E. coli</i> bacterial strains (kanamycin-resistant <i>E. coli</i>, 87.76% and ampicillin-resistant <i>E. coli</i>, 99.71%). This may be due to the chelation of Zn²⁺ with CS disrupting the cell membrane and bringing POM into direct contact with bacteria, leading to bacterial death. In addition, the CS/Zn²⁺/POM films showed good adsorption performance to a tetracycline (TC) solution (adsorption rate 75.2%). Further studies showed that the main process of tetracycline removal by CS/Zn²⁺/POM films was controlled by a physical adsorption. This POM-based film material has an important potential for the synthesis of broad-spectrum antimicrobial materials for the removal of residual antibiotics from water pollutants such as tetracycline.