Synthesis and characterization of Ag-containing hydrophobic aluminosilicate aerogels for I2 capture

Abstract Ag-containing 1 hydrophobic aluminosilicate aerogels capable of capturing I2 were prepared by sol-gelation from Na, Al, and Si alkoxides using co-solvent exchange, Ag/Na ion exchange, solvent exchange, silylation-induced surface hydrophobization, and ambient-pressure drying. The Ag contents, Brunauer-Emmett-Teller (BET) surface areas, and pore size distributions of aerogels depended on the solvent of the co-solvent exchange step, with isopropanol affording higher Ag contents and lower BET surface areas than water. This behavior was ascribed to the reaction of isopropanol-insoluble NaOH in gel pores during Ag/Na exchange with aqueous AgNO3 to form water-insoluble Ag2O. The Ag-containing hydrophobic aluminosilicate aerogel modified with hexamethyldisilazane contained meso- and macropores and exhibited a maximum iodine capture capacity of 0.555 g-I/g-sorbent, a BET surface area of 172 m2/g, a specific pore volume of 1.29 cm3/g, and an average pore size of 23.4 nm.