Sorption of metal elements by single-walled carbon nanotubes and x-ray absorption spectroscopy analysis

Abstract

Single-walled carbon nanotubes (SWCNTs) were used for the sorption of monovalent K(I), divalent Pb(II), Zn(II), and Cd(II) in addition to hexavalent Cr(VI) metal elements from aqueous solutions. X-ray absorption spectroscopy (XAS) was employed for the preliminary characterization of the metals sorbed SWCNTs materials. The adsorption capacities of the investigated metals are associated with the functional groups involved in the sorption mechanism. The sorption and XAS results revealed that hexavalent Cr(VI) was highly adsorbed by SWCNTs. The sorption mechanism of Cr(VI) is associated with the reduction of Cr(VI) to trivalent Cr(III). XAS also suggested that in the environment nearest to the sorbed metals Cr, Pb, Zn, and K, the existing binding interactions are Cr–O, Pb–O, Zn–O, and K–O respectively.