脉冲电流对电化学除氯的影响

Effect of Pulse Current on Electrochemical Dechlorination

目的探究不同电流密度下,直流和脉冲2种电流模式对钢筋混凝土电化学除氯的影响,降低钢筋渗氢量,减小通电后阴极产生的氢气使钢筋发生氢脆的风险,提高除氯效率,改善电化学除氯效率的均匀性。方法通过在电流密度为2、3、4A/m2的条件下,对混凝土进行直流和脉冲电流电化学修复,测定处理后的钢筋的释氢电流,计算释氢总电量,来表示钢筋渗氢量,对比处理后强电流区和弱电流区混凝土的氯离子含量,分析2种方式除氯效率的均匀性,同时用扫描电子显微镜观察电化学除氯前后混凝土的微观结构。结果计算得到不同通电电流密度下钢筋的释氢总电量和除氯效率,脉冲电流的释氢总电量比直流电流低约20%,而除氯效率提高了约10%。结论增加电流密度可以提高除氯效率,但是会增加钢筋发生氢脆的风险。相较于直流电流,脉冲电流电化学修复可以降低钢筋渗氢量,显著提高弱电流区的除氯效率,从而改善除氯效率的均匀性。

The work aims to explore the influence of direct current and pulse current on the electrochemical dechlorination of reinforced concrete at different current densities,reduce the hydrogen permeation amount and hydrogen embrittlement risks of steel bars,so as to improve the efficiency of dechlorination and the uniformity of electrochemical dechlorination efficiency.The current densities of 2,3 and 4A/m2 were selected,and the concrete was electrochemically repaired by direct current and pulse current.The hydrogen release current of the treated steel bar was measured,and the total hydrogen release electricity was calculated to represent the hydrogen permeation amount of the steel bar.The chloride ion content of concrete in the solid current area and weak current area after treatment was compared,and the uniformity of dechlorination efficiency of the two methods was analyzed.At the same time,the microstructure of concrete before and after electrochemical dechlorination was observed by scanning electron microscope.The total hydrogen release amount and chlorine removal efficiency of steel bars with different current densities were calculated.Compared with direct current,the total amount of hydrogen released with pulse current is reduced about 20%,while the chlorine removal efficiency is improved about 10%.The results show that increasing the current density can improve the dechlorination efficiency but increase the risk of hydrogen embrittlement of steel bars.Compared with direct current,the hydrogen permeation of the steel bar is reduced by electrochemical repair with a pulse current,and the dechlorination efficiency in the weak current region is significantly improved.Thus,the uniformity of dechlorination efficiency is improved.