α-Fe_2O_3/SiO_2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  

Acid-Base Properties and Adsorption Behaviors of Heavy Metal Ions at the Surface of α-Fe_2O_3/SiO_2 Nano-Mixed System

作　　者：孙和云[1] 樊佳妮[1] 黄佩佩[1] 孙中溪[1] 

机构地区：[1]济南大学化学化工学院,济南250022

出　　处：《物理化学学报》2012年第9期2183-2190,共8页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(50874052;20677022);国家重点基础研究发展规划项目(2011CB933700)资助~~

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值下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+(lgK=-8.20±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+的表面络合反应及平衡常数分别为:≡XOH+M2+≡XOM++H+,[lgK=-3.1,-3.6,-3.8(M=Cu,Pb,Zn)];≡XOH+M2++H2O≡XOMOH+2H+,[lgK=-8.8,-8.0,-10.5(M=Cu,Pb,Zn)].α-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 N2 adsorption-desorption methods. The surface acid-base properties of a-Fe2O/SiO2 nano-mixed system were determined by potentiometric titration, and the adsorption behaviors of heavy metal ions on the solid surface of a-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 -XOH =--XO-＋ H＋ （IGK=-8.20＋0.15）. The calculated result reveals that the deprotonation surface of the α-Fe2O3/SiO2 nano-mixed system is different from the surfaces of α-Fe2O3/SiO2-Al2O3, α-Fe2O3/SiO2 and SiO2/γ-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 a-Fe2O3/SiO2 mixed systems were simulated respectively as follows： -XOH ＋ M2＋ -XOM ＋＋ H ＊, [IgK=-3.1, -3.6, -3.8 （M=Cu, Pb, Zn）]; -XOH＋M2＊＋H2O--XOMOH＋2H3 [IgK=-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 

分 类 号：O647.3[理学—物理化学]