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

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 (Bi 2 O 3 /LDHs) composites were prepared based on biological template techniques, and the as-prepared composites show enhanced iodine adsorption capacity compared with LDHs fibers. The Mg Al LDHs fibers with hierarchical architectures are synthesized by directly growth of nanoscaled LDHs platelets on Al 2 O 3 fiber surfaces. The Bi 2 O 3 /LDHs composites with sponge-like structures are prepared by desorption of Bi 2 O 3 on the surfaces of LDHs fibers. The iodine adsorption behavior on Bi 2 O 3 /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 Bi 2 O 3 /LDHs composites. Since the Bi 2 O 3 /LDHs composites show near complete removal of iodine ions, the as-prepared Bi 2 O 3 /LDHs composites are expected to have practical applications as iodine adsorbent in wastewater treatment .