Removal of Cd2+ from Aqueous Solution by Nickel Oxide/CNT Nanocomposites

Abstract

<em>The present work investigates the efficiency of the nickel oxide/carbon nanotube (NiO/CNT) nanocomposite for the removal of Cd²⁺ metal ions from an aqueous. The NiO/CNT nanocomposite was synthesized by the direct co-precipitation method in an aqueous media </em><em>in the presence of CNTs. The resulting materials were characterized by FT-IR, XRD, SEM, N2 adsorption-desorption</em><em> analysis. </em><em>In order to optimize the adsorption of Cd²⁺ ions on NiO/CNT</em><em> nanocomposite, the effects of the different parameters—namely pH, contact time, initial concentration of Cd²⁺, and adsorbent dosage—were also studied. </em><em>Experimental data revealed that the Cd²⁺ ions adsorption of the NiO/CNT nanocomposite was through Langmuir and Temkin isotherm models rather than </em><em>the Freundlich model. The kinetic data of adsorption of Cd²⁺ ions on the adsorbent was best described</em><em> by a pseudo-second-order equation, indicating their chemical adsorption. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were calculated</em><em>.</em><em> The obtained values showed that the adsorption was spontaneous and exothermic in nature.</em> <em>The reusability test showed that the Cd²⁺could be easily removed from the surface site of NiO/CNT nanocomposite by a 0.1 M nitric acid solution as the adsorption capacity was maintained after 5 cycles of the adsorption/desorption process. This suggests that NiO/CNT nanocomposite can be reused through many cycles of water treatment and regeneration.</em>