Abstract: A series of NaP zeolites doped with cobalt were synthesized by hydrothermal synthesis method using the sodium silicate and the sodium meta-aluminate as raw material. The crystal phase, morphology and pore structures of NaP zeolite samples were characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM), and N₂ adsorption-desorption methods. Moreover, the adsorption performance of NaP zeolite doped with cobalt for Pb(II) was evaluated. The results show that the NaP zeolite doped with cobalt at n(Al₂O₃)∶n(Co(NO₃)₂)=8∶1 has a specific surface area of 162.490 m²/g, which is 5 times more than the undoped NaP zeolite (from 26.767 m²/g to 162.49 m²/g), and a pore volume of 0.104 cm³/g, which is 2.5 times more than the undoped NaP zeolite (from 0.029 cm³/g to 0.104 cm³/g). When the adsorption time is 120 min, the adsorption temperature is 25 ℃, and the initial concentration of Pb(II) is 100 mg/L, Co-NaP zeolite has a removal rate of 98.8% for Pb(II). Employing the EDTA-2Na as the regeneration regent, the adsorbed NaP zeolite is regenerated completely at 30 ℃ for 30 min. After three adsorption-regeneration cycles, Co-NaP zeolite has a better adsorption property for Pb(II), and the removal rate of Pb(II) keeps over for 97%.

Key words: NaP zeolite, Co doping, hydrothermal synthesis method, synthesis regulation, Pb(II) adsorption, regeneration