Magnetic Sorbent Based on Magnetite and Modified Carbon Nanotubes for Extraction of Some Toxic Elements

Abstract

Magnetic sorbent MNP@CNT was synthesized on the basis of magnetic nanoparticles of magnetite (MNPs) and carbon nanotubes (CNTs). The sorbent was studied in extraction of toxic elements from aqueous media and its synthesis conditions were optimized. Isotherms of sorption of the metal ions under study from aqueous solutions were plotted in relation to their concentrations and solution pH values. The optimal conditions for extraction of Pb(II), Cr(III), and Bi(III) at pH 6 and Cd(II) at pH 4.5–5.0 were found. It was shown that the sorption capacity of the MNP@CNT sorbent for the elements under study is comparable with the capacity of carbon nanotubes, being 4.0, 3.8, 3.5, and 3.5 mg g^–1 for Bi(III), Pb(II), Ct(III), and Cd(II), respectively. An important advantage of the magnetic composite sorbent over carbon nanotubes is the simple separation of the liquid and solid phases, compared with the conventional column variation of the solid-phase extraction. The resulting composite magnetic sorbent can be used both for analytical purposes, to preliminarily concentrate impurities, and for purification of various technological media and water basins in the environment to remove toxic elements.