Preconcentration of Pb2+ from aqueous solution using poly(acrylamide) and poly(N,N-dimethylacrylamide) grafted multiwalled carbon nanotubes

Multiwalled carbon nanotubes (MWCNTs) were grafted with poly(acrylamide) (PAAM) and with poly(N,N-dimethylacrylamide) (PDMA) at same grafting percentage by using N2 plasma technique. The PAAM grafted MWCNTs (MWCNT-g-PAAM) and PDMA grafted MWCNTs (MWCNT-g-PDMA) were characterized by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermo gravimetric analysis-differential thermal analysis (TGA–DTA), scanning electron microscopy (SEM), and potentiometric titration. The results indicated that the grafting processes occurred on the surfaces of MWCNTs without destroying the framework of MWCNTs. The application of MWCNTs, MWCNT-g-PAAM, and MWCNT-g-PDMA in the removal of Pb2+ from aqueous solution was investigated under ambient conditions. The grafted PAAM and PDMA improved MWCNT adsorption capacity in the removal of Pb2+ from large volumes of aqueous solutions. MWCNT-g-PAAM had much higher adsorption capacity than MWCNT-g-PDMA, which was attributed to higher amide group content in acrylamide than that in N,N-dimethylacrylamide.