Porous Ceramic Tablet Embedded with Silver Nanopatches for Low-Cost Point-of-Use Water Purification

Porous Ceramic Tablet Embedded with Silver Nanopatches for Low-Cost Point-of-Use Water Purification. Environ. Sci. Technol., November 11, 2014

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Beeta Ehdaie , Carly Krause , and James A. Smith *

Department of Civil and Environmental Engineering, University of Virginia, Charlottesville, Virginia 22904,

Email: *J. A. Smith. E-mail: jas9e@virginia.edu.

This work describes a novel method to embed silver in ceramic porous media in the form of metallic silver nanopatches. This method has been applied to develop a new POU technology, a silver-infused ceramic tablet that provides long-term water disinfection. The tablet is fabricated using clay, water, sawdust, and silver nitrate. When dropped into a household water storage container, the ceramic tablet releases silver ions at a controlled rate that in turn disinfect microbial pathogens. Characterization of the silver-embedded ceramic media was performed using transmission electron microscopy. Spherical-shaped patches of metallic silver were observed at 1–6 nm diameters and confirmed to be silver with energy dispersive spectroscopy. Disinfection experiments in a 10 L water volume demonstrated a 3 log reduction of Escherichia coli within 8 h while silver levels remained below the World Health Organization drinking water standard (0.1 mg/L). Silver release rate varied with clay mineralogy, sawdust particle size, and initial silver mass. Silver release was repeatable for daily 10 L volumes for 154 days. Results suggest the ceramic tablet can be used to treat a range of water volumes. This technology shows great potential to be a low-cost, simple-to-use water treatment method to provide microbiologically safe drinking water at the household level.