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 mIms-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.