对氨基苯甲酸——铁络合物催化氢波的研究

POLAROGRAPHIC BEHAVIOUR OF P-AMINOBENZOIC ACID-IRON (Ⅱ) COMPLEX

作者研究了对氨基苯甲酸——铁络合物在生理食盐水底液中的极谱催化氢波,观察了当固定铁或络合剂浓度时改变络合剂或铁浓度催化电流的变化情况,推导了催化电流与络合剂浓度的关系式,并测定了络合物形成常数和络合物组成;通过表面活性剂、温度和循环伏安法等实验证明催化氢波主要是受扩散控制的不可逆过程。

By using of 0.45%NaCl as supporting elecrtolyte, P-aminobenzoic acid (PABA)-iron (Ⅱ) complex exhibites overlapped double peaks (P_1 and P_2) in deconvolution voltammetric curve. The peak potentials of P_1 and P_2 are -1.581±0.006 and -1.696±0.007 volts vs, Ag/AgCl, respectively. The results showed that P_1 is a hydrogen catalytic wave and P_2 is a normal hydrogen wave. When PABA concentration fixed. the peak current of P_1 is proportional to Fe(Ⅱ) concentration in the range of 3.6×10^(-5)—2.1×10^(-4)mol/L. The higher PABA concentration is, the higher the slope above relation is. The formation constant of PABA-Fe(Ⅱ) complex was determined as 3.98x10^7(n=3) by the method of equilibrium moving. Surfactants, temperature coefficient, and cyclic voltammetric curves of P_1 proved that the electrode process was controlled dominantly by diffusion and is irrevcsible. The kinetic transfer coefficient (α) and the number of electron of P_1 are 0.6 and 1.0.