Evaluation of Getter Metals in Na–Al–Si–O Aerogels and Xerogels for the Capture of Iodine Gas

In this paper, sodium aluminosilicate aerogels and xerogels were evaluated as scaffolds for a variety of different getters including Ag⁺, Cs⁺, Cu²⁺, Fe³⁺, K⁺, Li⁺, Rb⁺, Sb³⁺, Sn²⁺, and Sn⁴⁺ for the capture of gaseous iodine coming from nuclear facilities. The exchange capacities varied widely from a near complete exchange in the case of Ag⁺ to much lower exchange levels for some of the Sn compounds [i.e., colloidal SnO₂, Sn(II) acetate, and Sn(IV) acetate]. Several of the additives showed great promise at allowing for high iodine loadings in the base materials including the following: AgNO₃, colloidal SnO₂, Sn(II) acetate, Sn(IV) acetate, Cu(NO₃)₂, and CuSO₄. From the standpoint of iodine uptake as a function of getter loading, Sn⁴⁺ was the most promising with a getter utilization (mass of iodine divided by mass of Sn, in atomic %) of 8.4, a chemical uptake of 60.7 mass % (oxygen excluded), and an m_I m_s^-1 (mass of iodine per mass of sorbent) value of 0.881; these are some of the highest values reported to date for inorganic iodine sorbents.