Silver, zinc, and copper exchange in a Na-clinoptilolite and resulting effect on antibacterial activity

Ag+-Na+, Zn2+-Na+, and Cu2+-Na+ equilibria for clinoptilolite-rich mineral from Gordes (Western Anatolia) were investigated at 25 degreesC and 0.1 N total solution normality. While silver exchange was favorable over the whole concentration range, zinc and copper were partially exchanged and preferred only at low concentrations. The standard free energies of exchanges for Ag+-Na+, Zn2+-Na+, and Cu2+-Na+ pairs were found as - 6.0, 2.03, and 3.09 kJ/equiv., respectively. From these values, selectivity sequence was determined as Ag+ >Na+ >Zn2+ >Cu2+. Antibacterial activities of the exchanged samples were measured as a function of exchange level against Pseudomonas aeruginosa and Escherichia coli. Considering the selectivity sequence of the clinoptilolite and antibacterial activity results, Ag-clinoptilolite seemed to be promising antibacterial material. (C) 2003 Elsevier B.V. All rights reserved.