Bismuth-impregnated aluminum/copper oxide-pillared montmorillonite for efficient vapor iodine sorption

AlCu-oxides pillared Montmorillonite (MMN) was synthesized by the ion-exchange reaction and then impregnated by bismuth (Bi) to produce single-phase material (Bi@AlCu-PILC) aiming at vapor iodine (I2) capture. The resulting Bi@AlCu-PILC mesoporous material demonstrated high capture capacity and thermal stability. The displayed capture capacity, 485 +/- 54 mg-I/g-sorbent, was benefited from the strong affinity of Bi to iodine and the pores of the material. The gaseous I2 was captured chemically by Bi@AlCu-PILC via Bi-O-I and BiI3 formation in the inner surface of the AlCu-PILC and pillars, respectively. In addition to the chemisorption, molecular I2 was captured physically in the pores of the material. The stability of the iodine-containing material was investigated by a leaching experiment before and after Bi2O3 treatment of the material. Without Bi2O3 treatment, Bi@AlCuPILC-I showed 22.12 mass% iodine losses after exposure to hot aqueous media for 7 days. On the other hand, after the post-sorption treatment at 500 C, the iodine loss was only 0.75 mass% under similar conditions, indicating the material is stabilized significantly after the treatment. Post-sorption treatment of Bi@AlCu-PILC-I by Bi2O3 at high temperature transformed BiI3 into a more thermally durable form (Bi-O-I). These results indicate that Bi@AlCu-PILC is a promising material for vapor iodine capture and subsequent final disposal.

Automated summary

Bi@AlCu-PILC is a mesoporous material with high iodine capture capacity and thermal stability, absorbing I2 through chemical bonding and physical adsorption. The stability of iodine-containing material significantly improves after Bi2O3 treatment, indicating the potential application of Bi@AlCu-PILC in vapor iodine capture and final disposal.