Silver-Loaded Aluminosilicate Aerogels As Iodine Sorbents

In this paper, aluminosilicate aerogels were used as scaffolds for silver nanoparticles to capture I2(g). The starting materials for these scaffolds included Na–Al–Si−O and Al–Si–O aerogels, both synthesized from metal alkoxides. The Ag0 particles were added by soaking the aerogels in aqueous AgNO3 solutions followed by drying and Ag+ reduction under H2/Ar to form Ag0 crystallites within the aerogel matrix. In some cases, aerogels were thiolated with 3-(mercaptopropyl)trimethoxysilane as an alternative method for binding Ag+. During the Ag+-impregnation steps, for the Na–Al–Si−O aerogels, Na was replaced with Ag, and for the Al–Si–O aerogels, Si was replaced with Ag. The Ag-loading of thiolated versus nonthiolated Na–Al–Si–O aerogels was comparable at ∼35 atomic %, whereas the Ag-loading in unthiolated Al–Si–O aerogels was significantly lower at ∼7 atomic % after identical treatment. Iodine loadings in both thiolated and unthiolated Ag0-functionalized Na–Al–Si–O aerogels were >0.5 mI ms–1 (denoting the mass of iodine captured per starting mass of the sorbent) showing almost complete utilization of the Ag through chemisorption to form AgI. Iodine loading in the thiolated and Ag0-functionalized Al–Si–O aerogel was 0.31 mI ms–1. The control of Ag uptake over solution residence time and [Ag] demonstrates the ability to customize the Ag-loading in the base sorbent to regulate the loading capacity of iodine.