物理化学学报 >> 2012, Vol. 28 >> Issue (09): 2183-2190.doi: 10.3866/PKU.WHXB201206072

催化和表面科学 上一篇    下一篇

α-Fe2O3/SiO2纳米颗粒混合体系表面的酸碱性质及其对重金属离子的吸附行为

孙和云, 樊佳妮, 黄佩佩, 孙中溪   

  1. 济南大学化学化工学院,济南 250022
  • 收稿日期:2012-04-26 修回日期:2012-06-06 发布日期:2012-08-02
  • 通讯作者: 孙中溪 E-mail:sunzx@ujn.edu.cn
  • 基金资助:

    国家自然科学基金(50874052, 20677022)和国家重大科学研究计划(2011CB933700)资助项目

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).

摘要:

以Fe(NO3)3·9H2O和正硅酸乙酯(TEOS)为原料, 通过溶胶-凝胶法和辅助模板法分别制备了纳米α-Fe2O3和SiO2, 并对所合成样品进行了粉末X射线衍射(XRD)和BET表征. 使用自动电位滴定仪测定了α-Fe2O3/SiO2纳米颗粒混合体系的表面酸碱性质. 研究了在不同pH下α-Fe2O3/SiO2混合体系对Cu2+、Pb2+、Zn2+离子的吸附行为. 基于上述实验数据, 用WinSGW软件计算了α-Fe2O3/SiO2混合体系表面酸碱配位常数, 并得出结论: α-Fe2O3/SiO2混合体系表面反应为单一脱质子反应≡XOH ⇔ ≡XO-+ H+(lg K = -8.19±0.15), 明显区别于同时具有加质子和脱质子反应的α-Fe2O3/SiO2/γ-Al2O3, α-Fe2O3/γ-Al2O3和SiO2/γ-Al2O3等纳米颗粒混合体系. 在此基础上拟合得到α-Fe2O3/SiO2混合体系吸附重金属离子Cu2+、Pb2+、Zn2+的表面络合反应平衡常数分别为:
≡XOH + M2+ ⇔ ≡XOM++ H+ [lg K = -3.1, -3.6, -3.8 (M = Cu, Pb, Zn)].
≡XOH+M2++H2O ⇔≡XOMOH+2H+[lg K = -8.8, -8.0, -10.5 (M = Cu, Pb, Zn)]

关键词: α-Fe2O3/SiO2, 表面酸碱性质, 吸附, 重金属离子, 组分分布

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