Excellent disinfection and fluoride removal using bifunctional nanocomposite

Bacterium (Staphylococcus aureus) and fluoride are considered as acute dental infectants. Simultaneous bacterial and fluoride decontamination for healthy teeth is therefore of high priorities. Hence, we have fabricated a Ca-Ce nanocomposite (NC) for dual decontamination of bacteria and fluoride from drinking water. The antibacterial activities were performed against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) using bacterial growth curves based on optical density and colony growth using the well diffusion method. The dose-dependent antibacterial activity showed 50% bacterial inhibition (IC50) at 31.5 and 27.0 μg mL-1 Ca-Ce NC concentrations for E. coli and S. aureus cells, respectively within 4 h of exposure. The mechanism of antibacterial action was evaluated using membrane protein leakage studies as well as dehydrogenase enzyme activity analysis of treated bacterial cells coupled with scanning electron microscopy (SEM) analysis. The fluoride adsorption mechanism was confirmed using FTIR and X-ray photoelectron spectroscopy (XPS) studies which supported the involvement of -OH groups on Ca and Ce ions where Ce-OH was the preferred adsorption site even at low Ce concentration in the nanocomposite as Ca:Ce ≈ 2:1. The prepared Ca-Ce NC proved to be very promising for water purification.