FUNCTIONALIZED MESOPOROUS SILICA: AN EFFECTIVE ADSORBENT FOR THE UPTAKE OF GOLD THIOSULFATE
Abstract
Thiosulfate is recognized as a promising alternative lixiviant to cyanide for the extraction of gold from ore bodies. Gold
thiosulfate ([Au(S2O3)2]3-), however, is not well-adsorbed by activated charcoal, making industrial scale use of thiosulfate
for gold leaching impractical at present. Because of their high specific surface areas (500-1000 m2g-1) and uniform openframework
nanoporosity (pore channel diameters in the range 3-10 nm), functionalized mesoporous silicas are widely
recognized as highly effective materials for the selective, rapid and high capacity uptake of mercury, gold and platinum
group ions. In the present work, the efficient and rapid adsorption of gold thiosulfate by thiol-functionalized mesoporous
silica (hereafter designated MP-HMS) is demonstrated, whereby the thiol groups in the materials bind with the gold
complexes by ligand displacement. The adsorbed gold could be leached out using cyanide, regenerating the adsorbent for
further uptake cycles. Functionalized mesoporous silica is thus a promising candidate for the preconcentration of gold
from thiosulfate leachate solutions.
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