Functionalization of multiwalled carbon nanotubes using Isocyanate groups for Lead adsorption

Heavy metal ions are highly toxic even at low concentrations and can accumulate in living organisms, causing several disorders and diseases. Unlike organic pollutants, heavy metals are nondegradable. Once in the food chain, they are able to accumulate in living organisms and cause extremely high toxicity. There are many conventional methods that are being used to remove the metal ions including oxidation, reduction, precipitation, membrane filtration, ion exchange and adsorption. Among the above methods, the promising process for the removal of metal ions from water and wastewater is adsorption, because the employed adsorbent can be regenerated by suitable desorption process and it is highly effective and economical. Several adsorbents which have been studied for adsorption of metal ions [1,2]. In current years, carbon nanotubes have been applied as a novel adsorbent to remove the heavy metal ions and various contaminants from an aqueous solution [3,4]. In this study, multiwalled carbon nanotubes (MWCNTs) were modified by strong oxidizing agents and were functionalized with Isocyanate groups. These MWCNTs were used for adsorption of lead ions from aqueous solution. The pristine and functionalized MWCNTs were characterized by Fourier transform infrared, transmission electron microscopy, scanning electron microscopy and X-ray diffraction. In other to study lead adsorption behaviors, the optimal conditions of experimental such as pH, amount of adsorbent and contact time were investigated. The adsorption capacity was evaluated using both the Langmuir and Freundlich adsorption isotherm models. The results showed that functionalized MWCNTs have a greater potential for adsorption of lead from aqueous solution.