聚吡咯-二甲基亚甲蓝复合纳米棒修饰电极及电化学阻抗法测定聚阴离子阻垢剂

Quantification of Polyanions on the Polypyrrole/DMMB Nanorod Modified-Electrode via Electrochemical Impedance Method

本文采用一步电聚合法,在玻碳电极上制备了聚吡咯-二甲基亚甲蓝(PPYDMMB)纳米棒薄膜,并利用电化学阻抗谱测定冷却水中的聚阴离子阻垢剂(PCA)。扫描电镜分析表明PPY-DMMB复合膜以三维纳米棒结构存在,而原PPY膜为花椰菜状结构。循环伏安扫描初步证明该复合物膜与PCA之间的相互作用。实验以[Fe(CN)_6]^(3-/4-)为电化学探针,在20mmol/L磷酸盐缓冲溶液中,采用电化学阻抗法测试不同浓度PCA对电极表面电荷转移电阻(Rct)响应。结果表明,随着PCA浓度升高,[Fe(CN)6]3-/4-在电极表面的Rct逐渐增加。在2.0×10^(-3)~3.5×10^(-2) g/L的浓度范围内呈良好的线性关系。检测限(S/N>3)为5.0×10^(-4) g/L。Ca^(2+)、Mg^(2+)离子浓度和PCA响应成负相关性,证明PCA溶液中所测信号主要来自活性PCA。该复合物修饰电极有望用于冷却水系统中PCA的检测。

In this work,a simple electrochemical method for monitoring the concentration of polyanions in aqueous solution by electrochemical impedance spectroscopy （EIS） is described. The glassy carbon electrode was modified by electrochemically polymerized PPY film hybridized with phenothiazine dye dimethyl methyl blue（DMMB）. PPY-DMMB composite is composed of the uniform nanorods pendicular to the electrode surface, which was characterized by scanning electric microscopy （SEM）. Due to the synergetic effect of PPY and DMMB, a strong interaction of the PPY-DMMB with the anionic polymer PCA was found by cyclic voltammetry and EIS. The PPY-DMMB composite film shows good responses to PCA with [Fe（CN）6]3-/4-as the electroactive marker. The sensitive response is attributed to the nanorod configuration of the PPY-DMMA composite film. The linear range is 2.0×10^（-3）-3. 5 × 10^（-2） g/L, with a limit of detection down to 5.0×10^（-4） g/L（S/N=3）. This method is very promising for monitoring the anionic-charged polymer in the industrial water system.