Preparation of an Ag-loaded Cu-MOF nanocomposite with excellent activity for photocatalytic degradation of tetracycline and enhanced antibacterial activity

Abstract

Combining metal–organic frameworks (MOFs) with active agents is considered an effective procedure to increase the removal efficiency of pristine MOFs. In this work, Cu-MOF/X-Ag nanocomposites with different Ag contents were prepared by a sequential deposition-reduction method. The physicochemical characteristics of the as-prepared samples were evaluated using XRD, FT-IR spectroscopy, FE-SEM, EDS, elemental mapping, TEM, EIS, and PL spectroscopy. Then, the photocatalytic activity of the samples for the removal of tetracycline (TC) as a model pollutant was investigated. Among the nanocomposites, Cu-MOF/12%Ag exhibited the highest photodegradation efficiency under visible light irradiation. 0.5 g L⁻¹ of this photocatalyst degraded 95.5% of 20 mg L⁻¹ TC within 60 min. To study the kinetics of the TC degradation process, the first-order kinetic model was used, and the results exhibited that the rate constant of Cu-MOF/12%Ag was higher than that of Cu-MOF, Cu-MOF/6%Ag, Cu-MOF/8%Ag, Cu-MOF/10%Ag, and Cu-MOF/14%Ag. Furthermore, the Cu-MOF/12%Ag nanocomposite displayed excellent recyclability after six cycles. The radical quenching experiments revealed that ˙OH and ˙O₂⁻ played vital roles in the TC photodegradation process. The antibacterial properties of Cu-MOF and Cu-MOF/12%Ag were evaluated against standard bacterial strains, including Staphylococcus aureus (PTCC 1112), Escherichia coli (PTCC 1330), and methicillin-resistant Staphylococcus aureus (MRSA), using the agar well diffusion method. Results demonstrated that Cu-MOF/12%Ag exhibited remarkable antibacterial efficacy, with the largest inhibition zone (2.6 mm) observed against MRSA.