Zn2+-exchange kinetics and antimicrobial properties of synthetic zirconium umbite (K2ZrSi3O9·H2O)
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Zirconium umbite, K2ZrSi3O9·H2O, is a microporous framework ion exchanger whose potential as a carrier for Zn2+ ions in antimicrobial formulations has not yet been investigated. Accordingly, batch Zn2+-exchange kinetics of synthetic zirconium umbite (K-UM) and the subsequent antimicrobial action of the zinc-bearing phase (Zn-UM) against Staphylococcus aureus and Escherichia coli are reported. Nonstoicheiometric over-exchange of Zn2+ for K+ was observed and attributed to hydrolysis and complexation reactions of Zn2+ within the umbite framework. The exchange process, which was described by a simple pseudo-first-order model (k 1 = 2.69 × 10−4 min−1, R 2 = 0.992), did not achieve equilibrium within 120 h at 25 °C, by which time the uptake of zinc was found to be 1.04 mmol g−1. The minimal bactericidal concentrations of Zn-UM for E. coli and S. aureus were found to be >10 g cm3 and <1.0 g cm3, respectively.
KeywordsFramework zirconium silicate Umbite Ion-exchange Pseudo-first-order kinetics Zinc Antimicrobial
NJC acknowledges, with gratitude, financial support for this research from The Royal Society and from the Royal Society of Chemistry. The authors also wish to acknowledge the use of the Chemical Database Service at Daresbury.
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