Hierarchically porous bismuth oxide/layered double hydroxide composites: Preparation, characterization and iodine adsorption

Abstract

The discharge of iodine-containing wastewater into environment will lead to the water pollution due to the toxicity and radioactivity of iodine and iodine isotopes. A versatile adsorbent which can effectively adsorb the iodine is in high demanded for this issue. In this work, the hierarchically porous bismuth oxide/layered double hydroxide (Bi2O3/LDHs) composites were prepared based on biological template techniques, and the as-prepared composites show enhanced iodine adsorption capacity compared with LDHs fibers. The MgAl LDHs fibers with hierarchical architectures are synthesized by directly growth of nanoscaled LDHs platelets on Al2O3 fiber surfaces. The Bi2O3/LDHs composites with sponge-like structures are prepared by desorption of Bi2O3 on the surfaces of LDHs fibers. The iodine adsorption behavior on Bi2O3/LDHs composites was examined in sodium iodine aqueous solutions. The appropriate iodine adsorption was obtained at a neutral pH with maximum adsorption capacity of 101.9 mg/g. The Langmuir model successfully describes the iodine adsorption isotherms, while the pseudo-second-order kinetic model is better at describing the iodine adsorption kinetics onto the Bi2O3/LDHs composites. Since the Bi2O3/LDHs composites show near complete removal of iodine ions, the as-prepared Bi2O3/LDHs composites are expected to have practical applications as iodine adsorbent in wastewater treatment.