Palygorskite Supporting Homogeneously Dispersed Ag Nanoparticles: Molten Salt Method and Enhanced Antibacterial Performance

Abstract

AbstractSupported silver nanoparticles (Ag NPs) have been used extensively as antibacterial agents in biomedicine, biotechnology, and environmental remediation. However, a facile and scalable method for preparing Ag NPs dispersed homogeneously on supports remains a challenge. In this study, a novel molten salt method was developed successfully to synthesize the supported, homogeneously dispersed Ag NPs on palygorskite. Abundant pores and ample surface hydroxyl groups of palygorskite served as anchoring sites, preventing the rapid growth, aggregation, and sintering of Ag NPs. Typically, palygorskite was mixed with AgNO3 (as a precursor) and NaNO3 (as a dispersant), and then the mixture was heated slowly. During the heating process, the AgNO3 decomposed gradually into Ag NPs and the molten NaNO3 with a high concentration of ions dispersed the newly formed Ag NPs. The Ag NPs were dispersed homogeneously on the palygorskite and had very small particle sizes (~5.8 nm) even for a significant loading amount (~9 wt.%). As antibacterial agents, the Ag/palygorskite nanocomposites showed enhanced antibacterial activity, compared with those synthesized without the introduction of molten NaNO3. In addition, the key effect of the surface hydroxyl groups of palygorskite on the characteristics of the loaded Ag and the corresponding antibacterial activity were also elucidated. As such, the present work provided a novel and facile strategy for the synthesis, without a chemical reductant or surfactant, of supported, highly dispersed Ag NPs on clay minerals and this could have potential in the scalable production and practical application of Ag-based antibacterial materials.