Characterization of Schiff Base Modified MCM-41 Molecular Sieve for Adsorption of Lead Ions from Aqueous Solution

t A new Schiff base modified MCM-41 molecular sieve (N-MCM-41) was synthesized via post-grafting method with 2-pyridine formaldehyde for efficient removal of lead ions (Pb2+) from aqueous solution. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the structure, morphology, surface functional groups and chemical states of N-MCM-41. Moreover, the adsorption behavior of Pb2+ by N-MCM-41 was systematically studied. Batch adsorption studies revealed that N-MCM-41 showed the maximal adsorption capacity of 101.3 mg/g at 45 celcius and pH=5.5 under the initial Pb2+ concentration of 80 mg/L after 180 min adsorption. The adsorption process conformed to the Langmuir isotherm model and the pseudo-second-order kinetics model. The adsorption of Pb2+ by N-MCM-41 was a spontaneous and endothermic process. Adsorption mechanism analyses suggested that functional groups on N-MCM-41 had strong coordination ability with Pb2+ to improve the adsorption capacity. The synthesized N-MCM-41 adsorbent exhibited excellent reusability in five regeneration cycles. Overall, this study showed that the N-MCM-41 had good application prospect to remove Pb2+ from aqueous solution.