Numerical Analysis of Capacitive Deionization Process Using Activated Carbon Electrodes

The discharge of untreated high-salinity mine water will cause harm to the environment, such as the increase of salt content in river water. Capacitive deionization technology has the advantages of low cost, high efficiency, and no pollution. It is an effective means to treat highly mineralized water in the oil field. This paper establishes a simplified mathematical model based on the Nernst Planck equation, combined with porous media flow theory and Langmuir isotherm theory. The capacitive deionization process of NaCl solution by finite element method is simulated. The results show that the convection mass transfer effect of ions in the activated carbon electrodes is weak. When the initial solution ion concentration is equal, the activated carbon cathode can absorb more Cl-. In the solution with an initial concentration of 1.7 mol/m(3), when the electrode adsorption reaches saturation, the concentration of Cl- is 0.1 mm lower than that of Na+. In the capacitive deionization process using activated carbon electrodes, the desalting efficiency of ions is almost proportional to the voltage and inversely proportional to the liquid flow rate. In a relatively low concentration solution, the desalination effect of using activated carbon as electrodes is better.