Silver-embedded granular activated carbon as an antibacterial medium for water purification
2008
Bandyopadhyaya, Rajdip | Sivaiah, M Venkata | Shankar, P.A.
Silver (Ag) particle embedded granular activated carbon (GAC) was made for the first time to assess its ability in inhibiting the growth of Escherichia coli (E. coli), a water-borne bacterial pathogen. Ag-GAC was made by impregnating GAC with AgNO₃ and then reducing it to metallic Ag. Plate assay showed slight inhibition of E. coli, even with Ag-GAC prepared from 0.005 mol L⁻¹ AgNO₃, but this and shake flask tests showed a conspicuous effect only for higher concentrations of 0.1-1 mol L⁻¹ AgNO₃. Flow tests further indicated that Ag-GAC made from 1.0 mol L⁻¹ AgNO₃ caused a desirable three orders of reduction in E. coli number concentration in less than 30 s. An optimum of 9-10.5 wt% of embedded Ag in the final Ag-GAC product was necessary for the requisite complete inhibition of E. coli, killing bacteria in the contact-mode for up to 350 L of flowing water. These results prove that Ag-GAC possesses antibacterial properties and can be used for disinfection to produce potable quality water.
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