γ-Al_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 γ-Al_2O_3/SiO_2 Nano-Mixed System

运用电位滴定技术研究了γ-Al2O3/SiO2纳米颗粒混合体系的表面酸碱性质;依据滴定数据及表面配位理论恒电容模式,利用WinSGW软件计算得出了γ-Al2O3/SiO2纳米颗粒混合体系表面的酸碱反应平衡常数:≡XOH+H+≡XOH2+(lgK1=5.06±0.05);≡XOH≡XO-+H+(lgK2=-8.45±0.10);在此基础上研究了不同pH条件下重金属离子Cu2+,Pb2+,Zn2+在γ-Al2O3/SiO2纳米颗粒混合体系表面的吸附行为,并用WinSGW软件模拟得出了Cu2+,Pb2+,Zn2+在该混合悬浮液体系中的表面配位常数:≡XOH+M2+≡XOM++H+[lgK=-2.20,-1.72,-2.90(M=Cu,Pb,Zn)].

The surface acid-base properties of a γ-Al2O3 /SiO 2 nano-mixed system were studied by potentiometric titration technique.Based on experimental data complemented by surface complexation theory of Constant Capacitance Model,the relevant equilibrium constants of surface acid-base reactions in the nano-mixed system were calculated using the WinSGW program as：≡XOH＋H ＋ ≡XOH ＋ 2（lgK 1 =5.06± 0.05）;≡XOH ≡XO ＋H ＋（lgK 2 =-8.45±0.10）.Furthermore,the adsorption of heavy metal ions（Cu2＋,Pb2＋,Zn2＋） at the surface of the γ-Al2O3 /SiO 2 nano-mixed system was studied as a function of pH.Again using WinSGW software,the surface complexation constants of Cu 2＋,Pb 2＋ and Zn 2＋ ions in aqueous suspensions of γ-Al2O3 /SiO 2 mixed systems were established respectively as：≡XOH＋M 2＋ ≡XOM ＋ ＋H ＋ [lgK=-2.20,-1.72,-2.90（M=Cu,Pb,Zn）]