摘要
采用阳极氧化法电镀纯银制作Ag/AgCl氯离子选择性电极。在不同pH值的混凝土模拟液中,测试电极电位对氯离子浓度的响应关系,以及硫酸根、温度对电极电位的影响,和90 d内电极电位的波动,并结合微观SEM和EDS来观察电极的长期稳定性。结果表明:Ag/AgCl电极的电位具有良好的氯离子响应特性,pH值为13.5的模拟液中测量的氯离子临界浓度为10~(-3) mol/L,其他pH的模拟液中临界浓度为10~(-4) mol/L;高碱下Cl~-与OH~-比的阀值在有效区域内。pH值以及硫酸根对电极电位影响甚微。此外,电位与温度成线性关系。含氯或低碱无氯溶液中AgCl镀层能长期稳定存在;高碱无氯溶液中AgCl镀层转化为Ag_2O,其中Ag_2O的电位对pH敏感。
Ag/AgCl chloride ion selective electrodeis produced by plating puresilver usinganodic oxidation.The response of electrode potential to chloride concentration was tested in simulating concrete pore solutions with different pH values.The influences of sulfate ion and temperature on the electrode potentialwere also studied.The fluctuation of electrode potential was tested in 90 d,and microscopic SEM and EDS were used to see the long-term stability of the electrode.Results revealed that:Ag/AgCl electrodepotential has a good responsetochloride concentration.The critical concentration ofmeasuringchloride ions is 10~(-3)mol/L at simulating concrete pore solutions with pH of 13.5.The critical concentration is 10~(-4)mol/L at lower values.The pH and sulfate have a littleinfluence on electrode potential.In addition,there is alinear relationship between the potential and the temperature.Ag/AgCl electrode′ ssurface coating can be stable inchlorideor low-alkali chlorine-free solutionin a long time.Some of the AgClcoating has changed into Ag_2O in high alkali chlorine-free solution,andthe potential of Ag_2O electrode is sensitive to pH.
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