Preparation of NiO/MWCNTs nanocomposite for the removal of cadmium ions

Abstract

In this work, a portable nanocomposite film made from nickel oxide nanoparticles (NiO NPs), multi-walled carbon nanotubes (MWCNTs), and polyvinyl alcohol (PVA) was prepared and investigated for the removal of Cd (II) from an aqueous solution. The preparation was carried out by eco-friendly pulsed laser ablation in liquid environmental technique to synthesize NiO NPs and to decorate MWCNTs to form NiO NPs/MWCNTs nanocomposites, followed by the formation of a portable nanocomposite film from the interaction between PVA and NiO NPs/MWCNTs nanocomposite. After that, the physicochemical properties of the prepared samples were investigated by XRD, SEM, EDX, TGA, and FT-IR. From structural analysis, the matrix nanocomposite film showed the presence of the hexagonal structure plane of NiO, PVA, and graphite, and its elemental analysis has just C, O, and Ni, which represent the constituent elements of the PVA matrix, MWCNTs, and NiO NPs. From morphological analysis, NiO NPs were loaded on the outer surface of the tubular structure of MWCNTs in a spherical shape. From optical analysis, the typical transmittance peaks of Ni–O–C and Ni–O were appeared. Also, the peaks related to the main functional groups of MWCNTs were shifted due to the interactions between MWCNTs and NiOs by non-covalent bonds. From thermal analysis, the thermal degradation is similar to that of pure PVA, but with higher percentage of decomposition due to presence of MWCNTs and NiO NPs. Furthermore, the effects of several parameters, such as pH, initial Cd (II) concentration, and adsorbent dosage, were studied in order to reach their maximum adsorption, representing the optimal conditions for the removal of Cd (II) from an aqueous solution. From these results, the adsorption of these heavy metal ions increased with pH and peaked at about pH 7–8. Also, their percentages of adsorption increased as the weight of the adsorbent dosage was raised. Based on these findings, it can be inferred that the produced nanocomposite might be an effective adsorbent for metal ions in aqueous solutions. So, these results showed the capability of using NiO NPs/MWCNTs/PVA nanocomposite film in a water treatment process and that it might be utilized to purify water before it is released into the natural environment.