【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)].更多还原

【Abstract】 α-Fe2O3and 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 α-Fe2O3/SiO2 nano-mixed system were determined by potentiometric titration,and the adsorption behaviors of heavy metal ions on the solid surface of α-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+(lgK=-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 /γ-Al2O3,α-Fe2O3/γ-Al2O3and SiO2 /γ-Al2O3nano-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 α-Fe2O3/SiO2 mixed systems were simulated respectively as follows:≡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)].更多还原