Application of Alumina Nanofibers as Adsorbents for the Removal of Mercury (II) and Lead (II) from Aqueous Solutions

This study aims to design novel amine-functionalized alumina nanofibers for the removal of lead (II) and mercury (II) ions from aqueous solutions. The ?-Al2O3 nanofibers were prepared by calcination of boehmite, and then functionalization with 3-(2-aminoethylamino) propyl trimethoxy silane. The characterization of the nanofibers was carried out using TEM, EDS, elemental mapping, XRD, and XPS. The effects of initial concentration, pH, contact time, and selectivity were studied. The results revealed that the nanofibers can remove 98% of Hg2+ ions and 90% of Pb2+ ions from aqueous solution at concentrations of 40 mg/L and 35 mg/L, respectively. Additionally, the optimal pH conditions for mercury and lead ion adsorption were established to be 6. It was also observed that for concentrations of 100 mg/L and 250 mg/L, the majority of ion contaminants were removed by the nanofibers within the first hour. The adsorption capacities were found to be 129 mg/g and 165 mg/g for Hg2+ and 72.3 mg/g and 111 mg/g for Pb2+ at 100 mg/L and 250 mg/L concentrations, respectively. The ion-adsorption kinetic data was best fitted to a pseudo-second-order model. High sorption capacities were also demonstrated when employed to selectively adsorb mercury (II) and lead (II) ions from aqueous solutions containing Zn2+, Mg2+, Cu4+, Sn4+, and Ni4+. Desorption tests were performed to explore the stability of the heavy metals on the nanofiber.