Bactericidal properties of bentonite treated with Ag+ and acid

Minerals of bentonite are much used in ion capture system and in the manufacture of cosmetics and nanocomposites. The incorporation of special properties, such as antimicrobial property in bentonite, allows its application as a special additive and extends its scope. This paper evaluates the possibility of incorporating antibacterial properties in bentonite minerals by applying the ion exchange process. The natural bentonite was characterized and treated with acidic solutions of sulfuric acid and hydrochloric acid. After treatment in acidic solution the bentonite was subjected to ion exchange processes in media containing different concentrations of silver nitrate and 430 °C temperature and subjected to microbiological characterization. The microbiological tests were carried out with Standard Agar-Diffusion microbiological tests and Inhibitory Concentration Minimum (ICM). The bacteria used in the microbiologic tests were Escherichia coli (gram positive) and Staphylococcus aureus (gram negative). The microbiological results showed that it is possible to incorporate the active bactericide properties into bentonite, and that the resulting bactericidal effect is dependent on the acid solution employed in the treatment.