Optimization of Silver Ion Release from Silver-Ceramic Porous Media for Household Level Water Purification

Abstract

A novel method has been developed to produce zerovalent silver nanopatches in a porous ceramic tablet using only clay, sawdust, water, and silver nitrate as precursors. When placed in 10 L of water, the silver nanopatches (2 to 3 nm diameter per patch) are gradually oxidized to produce silver ions, which diffuse out of the tablet into the bulk solution. The objective of this work is to optimize the silver-ceramic design to increase the rate of silver ion release from the tablet to further improve disinfection kinetics. To meet this objective, ceramic tablets were fabricated in different ways and tested for silver ion release into water over 8 to 24 h periods. Silver addition had an approximately linear effect on silver ion. Grinding the tablet into different particle sizes (4–60 mesh) had the most significant effect on silver release. However, if this ground fraction is compartmentalized into a fabric bag, silver levels produced in the water drop back to levels comparable to the single tablet form. Based on these results, 1 and 2 cm ceramic cubes were manufactured and represented a reasonable compromise between silver release and usability. Disinfection experiments on these silver-ceramic cubes resulted in effective disinfection of E. coli in laboratory experiments.

Effect of Chloride Ions on the Point-of-Use Drinking Water Disinfection Performance of Porous Ceramic Media Embedded with Metallic Silver and Copper

“…The biggest size of Ag cluster was 18 nm. Similar nanopatches were also reported by Singh et al [13]. We tried extensively to image copper nano patches, but we have been unsuccessful in doing so.…”

“…Therefore, there is practical evidence that the silver ceramic technology described here can be commercially viable. Moreover, silver is currently used in a variety of commercial point-of-use water treatment products, including pot-shaped ceramic water filters promoted by nonprofit organizations, such as Potters for Peace, Pure Madi, and Wine to Water [13]. The current study was a laboratory experimental effort to understand the hypothesis that chloride ions interfere with the disinfection process.…”

“…Silver has been known to have strong biocidal activity against bacteria, viruses, and protozoa [10,11]. Porous ceramic media embedded with silver has widely been used in recent decades for point-of-use water treatment, particularly in developing countries [3,8,12,13]. In aquatic environments, the release of silver from embedded ceramic is dependent on the rate of silver oxidation to produce silver ions, the primary species responsible for the disinfection [6].…”

Synthesis of Bactericidal Microfiltration Ceramic Membranes

“…In the paper (Singh, Rento, Son, Turner, & Smith, 2019), ceramic tablets were made in different ways by changing the pressure in the mold, temperature and sintering rates, sawdust composition, mixing protocols of starting materials and granulation. The prepared ceramic samples were investigated for the release of silver ions into water for periods of 8 to 24 hours.…”

COVID 19: The safety profile of common disinfectants used for sanitization

“…Metal ion, particularly silver ion is a potent disinfectant with a wide spectrum of antimicrobial properties against protozoa, bacteria and viruses [13,14,15,44,45] . Due to its broad coverage of antimicrobial activities, silver ions are used to disinfect medical equipment and in wound therapy [16,46,47] .…”