Adsorptive removal of lead (II) ion from water and wastewater media using carbon-based nanomaterials as unique sorbents: A review

Carbon-based nanomaterials and its derivatives such as carbon nanotubes, graphene, reduced graphene oxide, and graphene oxide have been widely used as unique sorbents for removal of both organic and inorganic contaminants due to unique physical and chemical properties. In the review, application of the carbon-based nanomaterials or nanocomposites is considered with particular focus on the lead(II) removal from water and wastewater samples. Moreover, various procedures of synthesis and functionalization of each class of carbon-based nanomaterials were reviewed. A critical review has been given to the adsorption behavior of these nanomaterials and interaction type between the sorbent and lead(II) ion s due to changes in their surface structure and functional group modification for the removal of lead(II)ions. The adsorption capacity, the sorbent selectivity and structure, and the adsorption mechanism for lead(II) ion adsorption with these sorbents were studied and compared. Specific consideration is devoted to effecting of pH of samples as a critical factor in the adsorption of lead(II)ions on each class of carbon-based nanomaterials. Also, the advantages and disadvantages of the nanomaterials or nanocomposites for the adsorption of lead(II) ion were evaluated in detail. In this way, the paper will contribute to presenting suggestions for the preparation of new sorbents to researchers for future study, as well as the remaining research challenges in this field.