高岭石负载无定形零价铁去除水中 Pb(Ⅱ)

Nanozero-valent iron (NZVI) was limited in widespread applications due to factors such as easy agglomeration, high reactivity, and the formation of a passivation layer upon oxidation in the environment. Kaolinite as a natural clay mineral with green, non-polluting and abundant reactive sites, can effectively promote chemical reactions. In this study, kaolinite-supported amorphous zero-valent iron (KAZVI) was employed for the removal of Pb(Ⅱ) from water. Various characterization methods, including scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were utilized to analyze the material structure and its adsorption properties for Pb(Ⅱ). The results indicate that the mechanisms involves in the removal of Pb(Ⅱ) by KAZVI including electrostatic adsorption, redox reactions, ion exchange and synergistic effect of coprecipitation. By optimizing the reaction conditions, the optimal removal conditions are identified as: M_Fe/K=1.5, M_EDA/Fe=3, pH=5, 0.10 g/L of dosage, ρ₀=10 mg/L and reaction temperature of 25 ℃, under which the equilibrium adsorption capacity (q_e) of KAZVI reaches 70.41 mg/g. The Pb(Ⅱ) adsorption by KAZVI accords with the pseudo-second-order kinetic model, which show that the adsorption process is mainly chemical adsorption. Furthermore, KAZVI demonstrates good recyclability with removal rate of 85.51% after five adsorption cycles, confirming its potential for practical applications.