engleski

Antibacterial activity of metal-containing clinoptilolite in natural seawater

Antibacterial activity of a natural zeolite, clinoptilolite (Z), enriched with about 0.4–0.5 mmol of Ag (Ag–Z), Cu (Cu–Z) or Zn (Zn–Z) was tested toward two strains of Gram-negative bacteria – Escherichia coli and Acinetobacter baumannii – in natural seawater from Adriatic Sea (Croatia). The Ag–Z and Cu–Z exhibited bactericidal activity toward E. coli and A. baumannii after 3 and 6 h of exposure, respectively. The Zn–Z showed antibacterial activity toward both strains, but lacking the bactericidal effect even after 24 h of exposure. All studied samples released metal cations in seawater. Concentration of Ag and Zn leached from Ag–Z and Zn–Z was higher than maximum allowable concentrations (MAC) for drinking water, whereas concentration of Cu was below MAC. Due to high concentration of Na+ in seawater (about 1.2 g Na+ dm–3) an ion-exchange process can be responsible for the leaching of the studied cations. The lowest extent of leaching from Cu–Z was ascribed to different position and geometry of sites occupied by Cu(II) in the clinoptilolite lattice. The antibacterial activity of M–Z was attributed to the metal cations leached from the zeolite lattice into seawater. The obtained results indicate that Cu–Z can be considered as a promising disinfectant for treatment of seawater.

Escherichia coli ; Acinetobacter baumannii ; Natural zeolite ; Silver ; Copper ; Zinc ; Bactericidal activity

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