Adsorption property on Pb(Ⅱ) of bentonite modified by chitosan/hydroxy-lanthanum
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Abstract:
To improve adsorption effect of Na-bentonite on Pb(Ⅱ), chitosan/hydroxy-lanthanum complex pillared bentonite (GZ-P) is prepared by hydrothermal synthesis method using Na-Bentonite modified with the mixture of chitosan and hydroxy-lanthanum cation as pillared agent. The properties of GZ-P are characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), scanning electron microscopy (SEM) and other analytical methods. And the adsorption property of Pb(Ⅱ) by GZ-P is discussed. The results show that the mixture of chitosan and hyroxy-lanthanum cation intercalates into bentonite and plays the role of pillar. The particles become fuller and denser. Surface voids and roughness increases. Removal rate and adsorption capacity of Pb(Ⅱ) by GZ-P increase first and then decrease, and increase again with the increase of PH value when the temperature is 25℃ and reaction time is 120 min. The highest removal rate reached to 98.93% and the maximum Pb2+ adsorption capacity is 33.67 mg/g when initial pH is 4. The least adsorption capacity is found when pH is 6. However, the removal rate is more than 85% even under that condition. Langmuir equation could better imitate the adsorption isothermal process of GZ-P to Pb(Ⅱ), and the adsorption process could be fitted by the pseudo-second order model, which indicates that Pb(Ⅱ) ions are adsorbed onto GZ-P by chemical interactions via monolayer.
