钼－棓酸配位吸附波的研究

STUDY ON THE ADSORPTIVE COMPLEX WAVE OF MOLYBDENUM(Ⅵ) WITH GALLIC ACID

在ｐＨ４．５的ＮａＡｃ－Ｈ２ＳＯ４缓冲溶液中，用单扫描示波极谱法可得到钼－棓酸配位化合物吸附波，峰电位为－０．８０Ｖ（ｖｓ．ＳＣＥ），二次导数波高与钼浓度在４．０×１０－８～８．０×１０－６ｍｏｌ／Ｌ范围内呈线性关系，最低检出限达１．０×１０－８ｍｏｌ／Ｌ．方法已应用于水样、金属样和食用植物中微量钼的测定，结果满意．利用线性扫描伏安法等对配位化物的伏安行为进行了较系统研究．

in a buffer solution of H2SO4--NaAc(pH4. 5), a sensitive polarographic adsorptive wave of Mo(Ⅵ)-gallic acid(GA) complex have been abserved by using single-sweep polarography. The peak potential of the wave appears at-0. 80V(vs. SCE). The peak current is linearly proportional to the concentration of Mo(Ⅵ) in the range of 4×10-8～8×10-6 mol/L. It can be used to determine microamount Mo(Ⅵ) in Water, alloy steel and food plant with satisfactory results. In this paper, a study of the Voltammetry behaviour of the Mo(Ⅵ)-GA complex is made systematically. On the surface of HMDE, the adsorption of the complex abeys frumkin adsorption isotherm. The adsorption coefficient. the attractive factor. maximum amount of adsorption and adsorption free energy have been determined.The electrochemical reduction reaction of the adsorptive complex on HMDE is a irreversible surface process. The number of transferred electrons in the rate determination step transfer coefficient and so on. have been determined. The machanism of complex formation and electrochemical reaction have been discussed simply.