Synthesis, characterization, and application of nickel oxide/CNT nanocomposites to remove Pb2+ from aqueous solution

In this study, the efficiency of nickel oxide/carbon nanotube (NiO/CNT) nanocomposite to remove Pb2+ from aqueous solution is investigated. NiO/CNT nanocomposite was prepared using the direct coprecipitation method in an aqueous media in the presence of CNTs. Samples were characterized using simultaneous thermal analysis (STA), X-ray diffraction (XRD), filed emission scanning electron microscopy (FESEM), and Brunauer– Emmett–Teller (BET). To optimize the adsorption of Pb2+ ions on NiO/CNT nanocomposite, the effects of different parameters including pH, contact time, initial concentration of Pb2+, and adsorbent mass—were also investigated. The optimum Pb2+ removal efficiency on NiO/CNT nanocomposite is achieved under experimental conditions of pH 7, contact time of 10 min, initial Pb2+ concentration of 20 ppm, and adsorbent mass of 0.1 g. The experimental data showed that the Pb2+ ions adsorption of NiO/CNT nanocomposite was through a Freundlich isotherm model rather than a Langmuir model. The kinetic data of adsorption of Pb2+ ions on the adsorbent was perfectly shown by a pseudo-second-order equation, to indicate their chemical adsorption. Thermodynamic parameters such as DGo, DHo, and DSo were also measured; the obtained values showed that the adsorption was basically spontaneous and endothermic.