铌的吸附伏安法

ON ADSORPTION VOLTAMMETRY OF NIOBIUM

本文用线性扫描吸附伏安法研究了H_2SO_4中Nb(V)-酒石酸-2-(5＇-溴-2＇-吡啶偶氮)-5-二乙氨基苯酚三元络合物吸附还原峰形成的最佳条件;峰电流与电极面积、吸附富集时间、扫描速度、吸附量、溶液中Nb(V)浓度的关系。讨论了反应机理。提出的吸附伏安法的检测下限为5×10^(-11)mol/L。并用此法测定了矿石中的痕量铌。

The optimal conditions of reduction of the niobium(V) complex with tartaric acid and 2-(5'-bromo-2'-pyridylazo)-5-diethylaminophenol in H_2SO_4 have been investigated by linear sweep adsorption voltammetry. The dependence of the peak current (i_p) on the elect- rode area (A), the preconcentration time(t_a), the scan rate (v) and the bulk concentration of Nb (c) conforms to the following equation i_p=kn^2F^2β[B]/4RT(1+β[B])Avt-ac where, β=stability constant of the complex, n=number of electrons, and [B]=free concentration of 2-(5'-bromo-2'-pyridylazo)-5-diethylaminophenol. The reaction mechanism has been discussed. The detection limit of the method is 5×10^(-11)mol/L. The method has been applied to the determination of Nb in minerals.