Characterization of Ag/AgCl electrode manufactured by immersion in sodium hypochloride acid for monitoring chloride content in concrete

In order to improve product efficiency and reduce the manufacturing cost, the chloride ion (Cl−) selective electrode was prepared through immersing silver wire in the sodium hypochloride acid (SHA) solution. The performances, such as reversibility and responding time, sensitivity and limit of detection, long-term stability and reliability, of this electrode were investigated in simulating concrete pore solutions as well as concrete. Results revealed that the electrode potential exhibited good Nernst response to Cl− content. Besides, the detection limit at pH 13.5 and lower pH values was ca. 10−3 and 10−4 mol L−1, respectively. The electrode coating indicated well stability over an immersion period of three months in solutions with Cl−. Furthermore, the electrode was capable to provide reliable and sustained real-time information by which the total Cl− content could be calculated. Therefore, the Cl− selective electrode is a promising tool because the electrode fabricated by the SHA technique enables us to get low-cost, miniaturized and reliable long-term sensors for Cl− monitoring.