A new sorbent based on MWCNTs modification for separation/preconcentration of trace amounts of Cd(II), Cr(III), Cu(II), Ni(II), and Pb(II) and their determination by flame atomic absorption spectrometry

Abstract

Background: A new solid phase extraction (SPE) method has been developed for the separation/preconcentration and determination of lead, cadmium, chromium, nickel, and copper ions using a new sorbent. Methods: The method is based on the application of multiwalled carbon nanotubes modified with ethylenediamine-N,N-diacetic acid (MWCNTs-EDDA) as a selective sorbent in SPE for the separation and preconcentration of Pb(II), Ni(II), Cd(II), Cu(II), and Cr(III). The determination of these heavy metals was followed by flame atomic absorption spectrometry (FAAS). Results: All quantitative determinations were performed by FAAS, and surface modification of synthesized adsorbents has been confirmed on the basis of characterization with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The parameters such as pH, amount of adsorbent, shaking time, eluent type and its concentration, and matrix effect have been investigated and optimized. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 51.7, 67.6, 49.9, 57.8, and 62.3 mg g-1 for Cd(II), Cr(III), Cu(II), Ni(II), and Pb(II), respectively. Conclusions: In the presented study, MWCNTs were functionalized by EDDA and it was applied as an adsorbent for the separation and preconcentration of trace level of Pb, Ni, Cd, Cu, and Cr ions. This method is effective, selective, rapid, and simple for the determination of trace amounts of Pb, Ni, Cd, Cu, and Cr ions and can be successfully applied to analyze the trace amounts of mentioned ions in wastewater and herbal samples without evident interference from the complex matrix. Furthermore, the sorption has high capacity, and the precision and accuracy of the method are also satisfactory.