全固态钢筋混凝土Cl^-选择电极的制备与性能研究

Preparation and Properties of Solid-state Chloride Ion Selective Electrode for Detecting Chloride Ions in Concrete

采用高纯银箔(99.99%)的电化学氧化法制备了全固态卷压式Ag/Ag Cl电极,并用于混凝土中的Cl-浓度检测。该Cl-选择电极具有较大的比表面积和交换电流密度,以及较低的温度系数。在模拟混凝土孔隙液中的测试表明:相比粉压式Ag/Ag Cl电极,卷压式电极具有更接近理论值的线性电压响应斜率(-58.2 m V)和电位稳定性,在230 d内电位波动不大于4 m V。混凝土中Cl-浓度测量表明:通过将电极表面包裹了一层PVA凝胶电解质薄膜,可显著提高其Cl-电位响应稳定性和抗干扰能力,且电极电位与混凝土中的lg[Cl-]之间具有良好线性度。表面分析证明,该卷压式电极不仅增加了电极的活性表面积,提高了电极的稳定性与反应活性;同时,借助于Ag Cl/Ag的多层堆叠,增强了Ag Cl颗粒与Ag基体间的附着力,提高了混凝土中Cl-的检测可靠性和电极的使用寿命。

An all solid-state and roll-shape Ag/Ag Cl electrode for detecting chloride ions in concrete was prepared by electrochemical oxidation of high purity(99.99%) silver foil. Electrochemical measurement results indicate that in comparison with the conventional powder moulding Ag/Ag Cl electrode, the novel chloride ion selective electrode has a larger exchange current density, higher specific surface area and lower temperature coefficient; by means of the electrode a better linearity is revealed of the potential response slope(-58.2 m V) versus Cl-concentration in an artificial pore solution of concrete, which is close to the theoretical value; besides, the novel electrode also exhibits a rather stable potential for a period of 230 d with fluctuations less than 4 m V. The experimental results in concrete shows that the performance of the all solid-state and roll-shape electrode, such as its linearity of potential response to lg[Cl-] and anti- interfere capability can significantly be improved by wrapping the electrode with a thin film of polyvinyl alcohol gel electrolyte. The mor-phology observation reveals that the novel Ag/Ag Cl electrode has a higher active surface area,which may be beneficial to the stability and the sensitivity of ion selection. In addition, the close stacked and layer by layer structure of the all solid-state and roll-shape Ag Cl/Ag electrode also enhances the adhesion of Ag Cl particulates to the Ag foil, which further improves its reliability on chloride detection and its service life in concrete.