Antibacterial zeolite with a high silver-loading content and excellent antibacterial performance

Abstract

The thermodynamic conditions of the AgOH precipitation–dissolution equilibrium were investigated by the solubility product principle and the Van't Hoff isobaric equation, and a mathematical expression was obtained about the influence of concentration, temperature and pH on the balance of AgOH precipitation–dissolution in the ion-exchange process. It was shown that the silver-loading process of zeolite had a theoretical equilibrium pH value under a certain concentration and temperature, and the optimal preparation conditions of silver-loaded antibacterial zeolite (Ag–Z) were 323.15 K, 0.50 mol L⁻¹, 6.20, 4.00 h for temperature, concentration, pH and time, respectively. And the silver-loading content of Ag–Z was as high as 365.73 mg g⁻¹. The minimum inhibition concentrations (MICs) of the as prepared Ag–Z to Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were as little as 1.00 μg ml⁻¹ and 3.50 μg ml⁻¹, respectively, and the minimum bactericidal concentrations (MBCs) were as little as 3.50 μg ml⁻¹ and 5.00 μg ml⁻¹, respectively. The antibacterial mechanisms were analyzed based on the quantity of released Ag⁺ and Na⁺.