Competitive adsorption behavior of typical heavy metal ions from acid mine drainage by multigroup-functionalization...

In response to Cd, Pb, and Cu pollution in acid mine drainage (AMD), a multigroup cellulose material (TCIS) containing thiol (-SH), carboxyl (-COOH), and imine (-C = N) groups was prepared through oxidation and grafting reactions. At pH 5, the maximum Cd(II), Pb(II), and Cu(II) adsorption performances of TCIS were 53.60, 120.6, and 36.01 mg/g, respectively. In the binary system, the interaction between metal ions was mainly inhibited by competitive adsorption. Cu(II) exhibited the most fierce inhibitory effect and had a relatively stable adsorption performance. In the ternary system, the adsorption order was Cu(II) > Cd(II) > Pb(II). In density functional theory (DFT) calculations, we combined the molecular electrostatic potentials, binding energies, differential charges, and total potentials to illustrate the competitive behavior of metal ions at different binding sites. Moreover, X-ray photoelectron spectroscopy (XPS) and DFT analysis revealed that the adsorption process of TCIS was dominated by the above functional groups, which caused competitive adsorption among Cd(II), Pb(II), and Cu(II).