Ordered Mesoporous Silicas with 2,5-Dimercapto-1,3,4-Thiadiazole Ligand: High Capacity Adsorbents for Mercury Ions |
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Authors: | Oksana Olkhovyk Mietek Jaroniec |
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Institution: | (1) Department of Chemistry, Kent State University, Kent, Ohio 44242, USA |
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Abstract: | This work reports two-step synthesis of novel ordered mesoporous silicas (OMS), which contain mercury-specific multifunctional
ligand and have high surface area and well-developed porosity. One pot co-condensation synthesis was employed to introduce
chloropropyl functionality on the mesopore walls of hexagonally ordered silica. In the next step, 2,5-dimercapto-1,3,4-thiadiazole
was reacted with chloropropyl groups during template-displacement process, which resulted in high affinity adsorbent towards
mercury ions. The maximum adsorption capacity of this adsorbent for mercury ions from aqueous solutions was as high as 1.7
g/g, which is about three times higher than the concentration of surface ligand. This study shows that the surface properties
of OMS can be tailored by proper choice of chemical modification method, which affects the ligand bonding density and determines
the adsorbent capacity and affinity towards heavy metal ions. Three methods, one-pot synthesis, template-displacement and
post-synthesis modification, were used for the introduction of surface ligands into MCM41 and SBA15 mesostructures to prepare
mercury-specific adsorbents. In addition, adsorption properties of these adsorbents as well as their effectiveness for mercury
removal from aqueous solutions were comparatively studied. |
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Keywords: | MCM-41 SBA-15 mercury ion adsorption 2 5-Dimercapto-1 3 4-Thiadiazole ligand co-condensation synthesis of organosilicas template displacement synthesis post-synthesis modification of mesoporous silicas |
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