α-Fe_2O_3、γ-Al_2O_3、SiO_2混合体系的表面配位反应  

Surface Complexation Reactions in a Mixed α-Fe_2O_3,γ-Al_2O_3 and SiO_2 Suspension

作　　者：刘嘉[1] 张卫民[1] 黄佩佩[1] 樊佳妮[1] 孙仁贵[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》2011年第1期186-192,共7页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20677022;50874052)资助项目~~

摘　　要：运用自动电位滴定技术分别研究了纳米α-Fe2O3、γ-Al2O3、SiO2单一体系及三组分混合体系中氧化物表面的酸碱性质和对重金属离子Cu2+、Pb2+、Zn2+的吸附行为.依据表面配位理论恒电容模式(CCM),计算了相应的表面酸碱配位常数.结果表明:α-Fe2O3/γ-Al2O3/SiO2三组分混合体系的表面化学反应并非是单一体系的简单叠加,而是存在着不同矿物表面间复杂的交互作用.三组分表面酸碱反应平衡式和相应的酸碱反应平衡常数分别为:≡XOH2+≡XOH+H+(lgKa1=-4.23),≡XOH≡XO-+H+(lgKa2=-8.41).根据重金属离子Cu2+、Pb2+、Zn2+在α-Fe2O3/γ-Al2O3/SiO2混合体系表面的吸附行为,计算得到Cu2+、Pb2+、Zn2+在混合体系表面配位反应及其平衡常数如下:≡XOH+M2+≡XOM++H+;lgK=-2.20,-1.90,-3.20(M=Cu,Pb,Zn).We systematically studied the surface acid-base properites and complexation behavior of heavy metal ions in aqueous suspensions of α-Fe2O3,γ-Al2O3,SiO2 of mixed oxides and the α-Fe2O3/γ-Al2O3/SiO2 mixed systems using potentiometric titrations in combination with computer-based calculations using the constant capacitance model（CCM）.The experimental and calculated results reveal that the surface chemical reactions in the mixed system are quite different from the sum of the individual single systems.A complicated mutual interaction exists among these mineral surfaces.The surface chemical reaction models and relevant equilibrium constants in the mixed system are：≡XOH2＋≡XOH＋H＋（lgKa1 =-4.23）,≡XOH≡XO-＋H＋（lgKa2 =-8.41）.The surface complexation model and related equilibrium constants for Cu2＋,Pb2＋,and Zn2＋ in the mixed system can be described by following reaction：≡XOH＋M2＋≡XOM＋ ＋H＋,with lgK of-2.20,-1.90,-3.20 for Cu2＋,Pb2＋,Zn2＋,respectively.

关 键 词：FE2O3 AL2O3 SIO2 混合体系 表面配位 表面酸碱性 

分 类 号：O641.4[理学—物理化学]