Optimizing
the Design and Synthesis of Supported Silver
Nanoparticles for Low Cost Water Disinfection
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Abstract
Silver
nanoparticles (AgNPs) were successfully synthesized and
impregnated on silica using chemical reduction methods. XPS and Ag <i>K</i>-edge XANES analysis revealed that the impregnation of
AgNPs onto silica using a chitosan + sodium borohydride (NaBH<sub>4</sub>) method results in higher silver loading and Ag(0)/Ag(I)
ratio compared to that obtained using NH<sub>3</sub> + NaBH<sub>4</sub>/glucose methods. The effects of the dosage of chitosan on silver
loading, Ag(I) release, and bactericidal activities of AgNP-impregnated
silica were investigated, with results showing that, at high dosages
of chitosan, Ag(I) released from AgNP-impregnated silica plays an
important role in disinfection, while AgNP-mediated bactericidal action
dominates at low dosages of chitosan. To further decrease the manufacturing
cost, partially oxidized “black rice husk ash” containing
substantial residual carbon was applied as AgNP support and found
to lead to a greater degree of silver impregnation and to exhibit
a longer disinfection lifetime than that of lower carbon content silica
supports. On the basis of these findings, it is clear that considerable
scope exists for careful optimization in the design and production
of AgNP-based bactericidal materials for water treatment purposes