铌(Ⅴ)-酒石酸-2-(5′-溴-2′-吡啶偶氮)-5-二乙氨基苯酚三元配合物在汞电极上的吸附

The Adsorption of the Complex of Niobium (V) with Tartaric Acid and 2-(5'-Bromo-2'-pyridylazo)-5-diethylaminophenol at the Hanging Mercury Drop Electrode

本文用线性变势吸附伏安法研究了铌(Ⅴ)-酒石酸-2-(5′-溴-2′-吡啶偶氮)-5-二乙氨基苯酚三元配合物在汞电极上的电吸附性质,测定了表面浓度,讨论了吸附浓度的表达式及其与吸附时间、金属离子浓度、配位体浓度的关系。验证了吸附量与电极面积及还原峰电流的关系。证明了配合物在电极上的还原是一个可逆吸附的还原过程。

The adsorption characteristics of the complex of niobium (V) with tartaric acid and 2-(5'-bromo-2'-pyridylazo)-5-diethylaminophenol (5-Br-PADAP), Nb(V)AB, at the hanging mercury drop electrode (HMDE) by linear sweep adsorption voltammetry have been investigated in H_2SO_4. Nb(V)AB can be adsorbed on the surface of HMDE very well for potentials between +0.03 and -0.10V(vs. BCE). Reduction of the adsorbed complex proceeds reversibly. The surperficial concentration equations of Nb (V)AB and its product for adsorption voltammetry, corresponding to the condition of the strong adsorption, are Γ_0(t_a)=(D_0t_a)/δ·(β[β])/(1+β[β])cNb(V) and Γ_B(t_a)=(kD_0t_a)/δ·(β[β])/(1+β[β])cNb(V) where Γ_0 (t_a) and Γ_R (t_a) are the surperficial concentrations of Nb (V)AB and its product at time t_a, respectively, t_a is the preconcentration time. D_0)o is the diffusion coefficent of Nb (V)AB.β is the stability constant of Nb (V)AB. δis the diffusion layer thickness. c_(Nb)(V) and [B] are the tetal concentration of niobium and the concentration of the free 5-Br-PADAP in the solution, respectively. k is a constant less than unity. The equations have been verified experimentally.