非平衡态-恒电位配位滴定法同时测定铁和铝

Simultaneous Determination of Iron and Aluminum with Constant Potential Complexometric Titration under Non-equilibrium State

以氟离子溶液作滴定剂,氟离子选择性电极作指示电极,在氟-铝反应没有达到平衡条件下通过恒电位配位滴定法同时测定了铁和铝。控制溶液的pH值为1.5,温度为25℃,硝酸钠离子强度调节剂浓度为0.1mol/L,反应时间为60 s。在氟-铁反应达到平衡,但在氟-铝反应没有达到平衡的条件下,采集滴定数据。根据非平衡条件下,响应值的重现性,利用最小二乘法求出常数kFe、kA l及k0,进而计算出铁和铝的浓度。

The simultaneous determination of iron and aluminum with constant potential complexometric titration under non-equilibrium state in which the complex formation reaction between fluoride and aluminum hadn＇ t yet reached its equilibrium was researched. In this determination, the fluoride ion solution was taken as titrant and the fluoride ion selective electrode was taken as indicating electrode. The pH of titration reaction was 1.5; the temperature of experiment was 25℃ ; the concentration of ionic strength adjustment buffer （NaNO3） was 0.1 mol/L; and the time of collecting titration data was 60s after titrant had been added. When titration data was collected, the reaction between fluoride and iron had reached its equilibrium but the reaction between fluoride and aluminum hadn＇t yet reached its equilibrium. According to the repeatability of response curves of non-equilibrium state, the constants of kFe, kAl, k0 and the concentration of CFe and CAl can be calculated by least squares method. The feasibility of using the method of constant potential titration under nonequilibrium state was also studied and discussed.