Snail Based Carbonated-Hydroxyapatite Material as Adsorbents for Water Iron (II)

Carbonated hydroxyapatite (CHAp) adsorbent material was prepared from Achatina achatina snail shells and phosphate-containing solution using a wet chemical deposition method. The CHAp adsorbent material was investigated to adsorb aqua Fe(II) complex; [Fe(H₂O)₆]²⁺ from simulated iron contaminated water for potential iron remediation application. The CHAp was characterized before and after adsorption using infrared (IR) and Raman spectroscopy. The IR and the Raman data revealed that the carbonate functional groups of the CHAp adsorbent material through asymmetric orientation in water bonded strongly to the aqua Fe(II) complex adsorbate. The adsorption behaviour of the adsorbate onto the CHAp adsorbent correlated well to pseudo-second-order kinetics model, non-linear Langmuir and Freundlich model at room temperature of a concentration (20–100 mg L⁻¹) and contact time of 180 min. The Langmuir model estimated the maximum adsorption capacity to be 45.87 mg g⁻¹ whereas Freundlich model indicated an S-type isotherm curvature which supported the spectroscopy revelation.