Adsorption of Cu(II), Pb(II), and Cd(II) Ions from\nAcidic Aqueous Solutions by Diethylenetriaminepentaacetic Acid-Modified\nMagnetic Graphene Oxide

Abstract

In\nthis study, diethylenetriaminepentaacetic acid (DTPA)-modified\nmagnetic graphene oxide (MGO) was synthesized for removal of Cu­(II),\nPb­(II), and Cd­(II) ions from acidic aqueous solutions. The prepared\nDTPA/MGO composites were characterized by scanning electron microscopy,\nX-ray diffraction, Fourier transform infrared and X-ray photoelectron\nspectroscopies, and zeta potential. The results showed that DTPA successfully\nfunctionalized MGO. Adsorption experiments indicated that DTPA/MGO\ncomposites exhibited excellent adsorption property in acidic aqueous\nsolutions. The adsorption processes were applicable for the Langmuir\nadsorption isotherm and the pseudo-second-order model. The maximum\nadsorption capacities at pH 3.0 for Cu­(II), Pb­(II), and Cd­(II) ions\nwere 131.4, 387.6, and 286.5 mg/g, respectively. The thermodynamic\nstudies demonstrated that adsorption processes were endothermic and\nspontaneous. Moreover, the DTPA/MGO composites could selectively adsorb\nPb­(II) from multimetal mixed systems. Adsorption–desorption\nresults showed that the DTPA/MGO composites exhibited excellent reusability.\nThese results suggested that DTPA/MGO composites have great potential\nin removing heavy metals from acidic wastewater, especially for Pb­(II).