Selective solid-phase extraction and analysis of trace-level Cr(III), Fe(III), Pb(II), and Mn(II) Ions in wastewater using diethylenetriamine-functionalized carbon nanotubes dispersed in graphene oxide colloids

Abstract

Multi-walled carbon nanotubes (MCNTs) were dispersed in graphene oxide (GO) colloids to be further functionalized with diethylenetriamine (DETA), resulting in GO–MCNTs–DETA nanocomposites for the solid-phase extraction and analysis of Cr(III), Fe(III), Pb(II), and Mn(II) ions at the trace levels in wastewater. Inductively coupled plasma optical emission spectrometry (ICP–OES) indicates that this new solid-phase sorbent could facilitate the maximum static adsorption capacities of 5.4, 13.8, 6.6 and 9.5mgg−1 for Cr(III), Fe(III), Pb(II), and Mn(II) ions, respectively, showing the adsorption capacity up to 95% within about 30min. Moreover, the detection limits of the GO–MCNTs–DETA-based analysis method were found to be 0.16, 0.50, 0.24 and 0.38ngmL−1 for Cr(III), Fe(III), Pb(II), and Mn(II) ions, respectively, with the relative standard deviation of lower than 3.0% (n=5). Importantly, common coexisting ions showed no significant interference on the separation and pre-concentration of these heavy metal ions at pH 4.0. Subsequently, the GO–MCNTs–DETA sorbent was successfully employed for the separation and analysis of trace-level Cr(III), Fe(III), Pb(II), and Mn(II) ions in wastewater samples yielding 75-folds concentration factors.