SBA-15 templating synthesis of mesoporous bismuth oxide for selective removal of iodide

Mesoporous δ-Bi₂O₃ samples with high surface area and small crystallite sizes were prepared by using different SBA-15 silicas as hard templates. The latter were synthesized hydrothermally using tetraethylorthosilicate (TEOS), sodium metasilicate (SMS), and water glass (WG) as silica sources. The resulting SBA-15 silicas showed high surface area and pore volume. Among SBA-15 samples studied, the WG-generated SBA-15 exhibited the thinnest pore walls and lowest percentage of complementary pores. Interestingly, SBA-15 obtained from WG gave δ-Bi₂O₃ with the highest surface area and pore volume. This mesoporous δ-Bi₂O₃ was applied for the removal of iodide from aqueous solutions and was able to adsorb 2.87mmol/g of iodide at ambient conditions. In addition, mesoporous δ-Bi₂O₃ displayed high selectivity for iodide removal in the presence of chloride. Due to the high toxicity of the radioactive isotopes of iodine, this substance is required to be immobilized before its release to environment. This work presents a promising sorbent for selective capture of iodide from aqueous solutions.