Calcite buffer effects in electrokinetic remediation of clopyralid-polluted soils

Abstract

This work presents a study of the dissolution-precipitation processes of calcite in soil undergoing electrokineticremediation processes. For this purpose, a numerical inspection of one of these processes in a calcareous soil(10% calcite content) contaminated with an of the organochlorine acid herbicide (3,6-dichloro-2-pyr-idinecarboxylic acid) was carried out. The numerical tool used to perform this analysis was the Multiphysics for EKR (M4EKR), a module programmed by the authors in the COMSOL Multiphysics platform. A detailed analysisof the pH, the distribution of species that have a significant influence on soil buffering capacity (carbonates andcalcite), as well as the pollutant, has been performed. In this way, the kinetics of the calcite dissolution-pre-cipitation processes have been analysed in order to determine the pH of the water in the pores and, therefore,how it directly affects the effectiveness of the treatment. Additionally, a sensitivity analysis of the selected EKRprocess has been carried out at different values of the rate of calcite dissolution due to the uncertainty associatedwith the reactive surface area parameter.