Functionalized halloysite nanotubes for enhanced removal of lead(II) ions from aqueous solutions

In this study, environmental friendly halloysite nanotubes and their amino derivatives were used as adsorbent materials for lead(II) ions. The adsorption ability of both nanomaterials towards Pb2+ ions has been studied in NaClaq, at I = 0.1 mol L-1, in the pH range 3-6. Moreover, the effect of ionic strength on the adsorption process was evaluated at the pH of maximum efficiency of the adsorbent materials. Kinetic and equilibrium experiments were carried out by using the Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique to check the metal ion concentration in solution after contact with the two adsorbents. Different isotherm and kinetic equations were used to fit the experimental data. The speciation of metal ion and the characterization of the adsorbents with different techniques were considered in order to establish the suitable experimental conditions for the metal ion removal. The collected data showed that the functionalization of halloysite enhances the adsorption ability of the clay mineral and it makes the nanoclay a good candidate for metal removal from aqueous solutions.