Acid-Base Properties and Adsorption Behaviors of Heavy Metal Ions at the Surface of alpha-Fe2O3/SiO2 Nano-Mixed System

作者：Sun He Yun; Fan Jia Ni; Huang Pei Pei; Sun Zhong Xi^*

来源：Acta Physico - Chimica Sinica, 2012, 28(9): 2183-2190.

DOI：10.3866/PKU.WHXB201206072

• alpha-Fe2O3/SiO2
• Surface acid-base property
• Adsorption
• Heavy metal ion
• Speciation distribution

alpha-Fe2O3 and SiO2 were prepared from ferric nitrate and tetraethyl orthosilicate (TEOS) using a sol-gel method and templates. The samples were characterized by powder X-ray diffraction (XRD) and N-2 adsorption-desorption methods. The surface acid-base properties of alpha-Fe2O3/SiO2 nano-mixed system were determined by potentiometric titration, and the adsorption behaviors of heavy metal ions on the solid surface of alpha-Fe2O3/SiO2 nano-mixed system were studied at different pH values. The surface acid-base reaction equilibrium constants of the nano-mixed system were calculated from the results using WinSGW software to be X reversible arrow XO-+H-center dot (IgK=-8.20 +/- 0.15). The calculated result reveals that the deprotonation surface of the alpha-Fe2O3/SiO2 nano-mixed system is different from the surfaces of alpha-Fe2O3/SiO2/gamma-Al2O3, alpha-Fe2O3/gamma-Al2O3 and SiO2/gamma-Al2O3 nano-mixed systems where surface protonation and deprotonation occur at the same time. Based on this result, the surface complexation constants of Cu2+, Pb2+, Zn2+ on the surface of alpha-Fe2O3/SiO2 mixed systems were simulated respectively as follows: XOH + M2+ reversible arrow XOM++H+, [IgK=-3.1, 3.6, 3.8 (M=Cu, Pb, Zn)]; XOH+M2++H2O reversible arrow XOMOH+2H(+), [IgK=-8.8, -8.0, -10.5 (M=Cu, Pb, Zn)].

• 出版日期2012-9
• 单位济南大学