The effect of pulse current on energy saving during Electrochemical Chloride Extraction (ECE) in concrete

Energy consumption is a factor influencing the cost of Electrochemical Chloride Extraction (ECE) in concrete. The aims of this work were to investigate the possibility for energy saving when using a pulsed electric field during ECE and the effect of the pulsed current on removal of chloride. Four experiments with artificially polluted concrete under same charge transfer were conducted. Results showed that the energy consumption was decreased 15% by pulse current in experiments with 0.2 mA/cm2 current density, which was higher than that of 0.1 mA/cm2 experiments with a decrease of 9.6%. When comparing the voltage drop at different parts of the experimental cells, it was found that the voltage drop of the area across the concrete was the major contributor to energy consumption, and results indicated that the pulse current could decrease the voltage drop of this part by re-distribution of ions in pore fluid during the relaxation period. However, probably due to the observed re-adsorption of chloride by concrete in pulse current, there was no significant difference between constant and pulse current experiments in relation to removal of chloride. Use of an anion exchange membrane impeded the H+ ions from the anodic reaction entering the concrete, and the pulse current also demonstrated a positive effect on the energy consumption across the membrane by diminishing the concentration polarization.