NANOSTRUCTURING OF ALUMINA SPHERES WITH HYDROXYAPATITE FOR CADMIUM (II) REMOVAL IN AQUEOUS MEDIUM

Abstract

The presence of heavy metals in bodies of water represent a threat to all living organisms due to its high toxicity, non-biodegradable properties and bioaccumulation. In the present investigation, the process of synthesis, characterization, and adsorbent capacity of Cd2+ of millimetric alumina spheres coated with hydroxyapatite is described. In addition to this, obtaining an adsorbent material that is easy to handle and can be used as a candidate in adsorption processes at an industrial level was studied. The alumina and Alumina-Hydroxyapatite spheres of ~5 mm was sintered; hydroxyapatite coating improve the surface area and pore size to 0.96 m2 /g and 13.24 nm and increased the number of acid sites from 0.064 to 0.306 meq/g. Alumina-Hydroxyapatite spheres show improved adsorbent properties for a potential alternative ceramic adsorption material. The adsorption of Cd2+ on the AHAp spheres is dominated by chemical interactions where the acid sites of the hydroxyapatite with the Cd2+ at the equilibrium to form multilayers of cadmium on the surface of the material. The hydroxyapatite in an insoluble matrix allow surface for complexation instead of adsorption by dissolution precipitation. This is beneficial in adsorption processes at an industrial level because it avoids the use of additional techniques for the recovery of precipitates.