Kinetic and thermodynamic investigation into the lead adsorption process from wastewater through magnetic nanocomposite Fe3O4/CNT

In this study, magnetic nanocomposite Fe3O4/CNT was synthesized through chemical precipitation and was used for uptake of lead from wastewater. The nanocomposite was characterized by XRD, TEM, and FTIR spectroscopy. Batch adsorption experiments were performed to investigate the effects of such various parameters as the pH of solution, the contact time, and the adsorbent dosage on the adsorption efficiency of Fe3O4/CNT. The maximum lead adsorption was observed in pH = 3, 0.16 g of nanosorbent, the contact time of 40 min, and the temperature of 30°C. The maximum removal percentage of Pb ions in optimal conditions by Fe3O4/CNT was 95.5%. Despite the fact that the optimum pH = 3, the bath adsorption experiments were performed at pH = 6 ± 0.5. For water with high alkalinity, a problem related to microbiologically induced corrosion may occur. However, high acidic water can accelerate the corrosion rate by increasing the reaction rates or causing physical damage to the pipes. The pseudo-first order and pseudo-second order were used to evaluate the kinetic models and the mechanism of the adsorption. The results indicated that the pseudo-second-order kinetic model resulted in a satisfactory fit for the experimental data (R 2 = 0.99). The adsorption isotherms were analyzed using Langmuir and Freundlich models. The Freundlich isotherm proved to have a little better correlation compared with that of the Langmuir isotherm. The thermodynamic parameters indicate that there was a spontaneous endothermic reaction. The process was successfully applied in the treatment of battery wastewater where the presence of organic compounds, copper, lead, zinc, nickel, and cadmium is hardly influenced the removal efficiency of lead ions even after five successive cycles. The results also show that the nanocomposite has a high efficiency of lead removal from wastewater resources.