Ultrasonic assisted adsorptive removal of toxic heavy metals from environmental samples using functionalized silica-coated magnetic multiwall carbon nanotubes (MagMWCNTs@SiO2)

In this approach, an amino-functionalized silica coated multiwall carbon nanotube (AminMagMWCNTs@SiO₂), for the first time, was rationally designed, prepared, and then investigated as an adsorbent for the adsorption and removal of Pb (II) and Cd (II) from environmental samples. The properties of synthesized magnetic nanoadsorbents were analyzed by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The diameter of magnetic nanoadsorbents was in the range of 60–80 nm. The effects of various parameters on the adsorption efficiency were simultaneously studied using a chemometric design. The variables of interest were the amount of nanoadsorbent, pH and ultrasonication time. The experimental parameters were optimized using a Box–Behnken design and the response surface equations were derived. The removal of magnetic nanoadsorbents from the aqueous solution was simply achieved by applying an external magnetic field following the adsorption process. The adsorption efficiencies of AminMagMWCNTs@SiO₂ nanoadsorbent for Pb (II) and Cd (II) ions were in the range of 98–104% under the optimum condition. The results demonstrated that the amino-functionalized MagMWCNTs@SiO₂ nanoadsorbent could be used as a simple, efficient, regenerable and cost-consuming material for the removal of desired heavy metal ions from environmental water and soil samples.