Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (09): 2183-2190.doi: 10.3866/PKU.WHXB201206072

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Acid-Base Properties and Adsorption Behaviors of Heavy Metal Ions at the Surface of α-Fe2O3/SiO2Nano-Mixed System

SUN He-Yun, FAN Jia-Ni, HUANG Pei-Pei, SUN Zhong-Xi   

  1. School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, P. R. China
  • Received:2012-04-26 Revised:2012-06-06 Published:2012-08-02
  • Contact: SUN Zhong-Xi E-mail:sunzx@ujn.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (50874052, 20677022) and National Basic Research Program of China (2011CB933700).

Abstract:

α-Fe2O3and SiO2were prepared from ferric nitrate and TEOS by sol-gel method in combination with using templates. The synthetic samples were characterized by powder X-ray diffraction (XRD) and N2adsorption/desorption methods. We determined the surface acid-base properties of α-Fe2O3/SiO2nano-mixed system by potentiometric titration technique, and studied the adsorption behaviors of heavy metal ions on the solid surface of α-Fe2O3/SiO2nano-mixed system at different pH values. According to the above experimental data, we calculated the surface acid-base reaction equilibrium constants of the nano-mixed system using WinSGW software to be ≡XOH ⇔ ≡XO-+ H+(lg K = -8.19±0.15). The calculated result reveals that the single deprotonation surface of α-Fe2O3/SiO2nano-mixed system is obviously different from the surfaces of α-Fe2O3/SiO2/γ-Al2O3, α-Fe2O3/γ-Al2O3 and SiO2/γ-Al2O3nano-mixed system with surface protonation as well as deprotonation at the same time. Based on the above result, the surface complexation constants of Cu2+, Pb2+, Zn2+on the surface of α-Fe2O3/SiO2mixed systems were simulated respectively as follows:
≡XOH + M2+ ⇔ ≡XOM++ H+ [lg K =-3.1, -3.6, -3.8 (M = Cu, Pb, Zn)].

Key words: α-Fe2O3/SiO2, Surface acid-base property, Adsorption, Heavy metal ions, Speciation

MSC2000: 

  • O642