Electrochemical removal of chlorides: Modelling of the extraction, resulting profiles and determination of the efficient time of treatment

Abstract

Due to the increase in the hydroxyl ion concentration generated as a consequence of the cathodic reaction of water electrolysis, the diffusion coefficient of chloride ions decreases during chloride extraction experiments. In a previous work carried out by the authors, an empirical equation to model this decrease in the diffusion coefficient as the treatment proceeds was given. Based on this equation, mathematical modelling of the extraction is carried out in this paper. This modelling allows the calculation of the time needed to achieve a particular percentage of chloride extraction as a function of the electrical charge passed, as well as the remaining chloride profile in the concrete. Numerical examples applied to the case in which chlorides were homogeneously distributed in the specimens are given to illustrate the modelling. These are also applied to experimental results previously published by other authors, finding a good accordance.