Hierarchical Spheres Of Mg-Al Ldh For The Removal Of Phosphate Ions: Effect Of Alumina Polymorph As Precursor

In order to tailor the morphology of the layered double hydroxide (LDHs) particles, we focused on a synthesis method that involves the use of Al2O3 as a precursor, employing Al2O3 with different crystal structures (e.g., alpha-Al2O3, theta-Al2O3, and gamma-Al2O3) as well as amorphous Al2O3. A three-dimensional network of plate-shaped LDH particles was formed when theta-Al2O3 and gamma-Al2O3 were used, even though alpha-Al2O3 barely reacts to form the LDH phase. Finally, adsorption tests involving HPO42- ions confirmed that the fabricated LDH particles exhibited high ion-removal rates. The LDH particles prepared with theta-Al2O3 and gamma-Al2O3 could remove the hydrogen phosphate ions (HPO42-) in a concentration of 0.40 mmol g(-1) completely within 10 min; this is approximately 20 times shorter than the time taken by the LDH particles prepared from amorphous Al2O3.