Antibacterial property of cancrinite-type zeolites exchanged with silver and copper cations.

Abstract

Ag+, Cu2+ or Ag+-Cu2+ ion-exchanged nitrate-sodium cancrinite-type zeolites were tested as bactericidal agents against Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa). Nitrated-sodium cancrinite was synthesized using solutions of NaOH and NaNO3, and using zeolite X as Al and Si sources under hydrothermal conditions at 80 ºC and autogenous pressure during 40 h. Solids were characterized by powder X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and chemical analysis. Then, different masses of these ion-exchanged zeolites were mixed with the microorganisms. Results showed that E. coli was more sensitive than P. aeruginosa, and 2.5 mg of Ag+ or Cu2+-Ag+ cancrinites were enough to inhibit the E. coli growth, while for P. aeruginosa larger amounts of Ag+ (5 mg) and Ag+-Cu2+ (20 mg) of the cancrinites were necessary. Cu-zeolites did not show bactericidal activity. Different treatments times between these microorganisms and the modified zeolites were also investigated. A 20 min treatment was enough to inhibit totally the bacterial growth. As a reference system zeolite A exchanged with these metals was used.

Keywords

• nitrate cancrinite
• silver
• antibacterial
• E. coli
• P. aeruginosa.