Experimental and Computational Studies of the Adsorption of Furan, Pyrrole, and Thiophene on Hydroxyapatites in a Single and Ternary Component

Non-doped (Hap) and doped hydroxyapatites with Cu2+ and Fe2+ were synthesized and used to study the adsorption of furan (Fur), pyrrole (Pyr), and thiophene (Thi) in single and ternary component systems. Spectroscopic data and N2 isotherms indicated there were no structural alterations in Hap with the incorporation of Cu2+ and Fe2+. For both single and ternary components, the incorporation of the metal ions resulted in an adsorption increment consistent with the hard-soft acid-base concept. When comparing the systems, there is an inversion with Thi (5.41 mg g-1) and Fur (5.51 mg g-1) being the most adsorbed species in the single and ternary components, respectively. Monte Carlo simulations helped explain the observed experimental trends. While the electrostatic effect seems to prevail in the single system, in the ternary one the mass transport phenomenon is also operative implying greater availability of Fur on surface leading to its higher adsorption efficiency.