Modelling of electrokinetic phenomena in soils

Modelling of electrokinetic phenomena in soils

The aim of this work was to develop theoretical methods for the prediction of remediation time and the electrical energy requirements for the remediation of soil
contaminated with sodium chloride. Laboratory scale experiments were specially designed and performed on sand and clay samples at field capacity moisture content
to identify the key features of electrokinetic processes in soil. The experiments confirmed the existence of a prominent ionic concentration or conductivity front
travelling away from the cathode. The dissertation offers a novel theoretical explanation that links this front to the electronegative charge bound onto soil particles. A mathematical model of electromigration in soil is developed based on that theory. The model is essentially a set of partial differential equations (PDEs) with some coefficients behaving non-linearly. An algorithm for numerical solution of the PDEs is developed using a finite difference time domain approach. Reasonable agreement was found between laboratory test results and prediction of
the corresponding numerical models. In addition, approximate analytical solutions to the PDEs allow remediation time and remediation energy requirements to be
evaluated. The results of this work may be generalised to soils with ionic contamination other than sodium chloride.