A mathematical approach based on the Nernst-Planck equation for the total electric voltage demanded by the electrocoagulation process: Effects of a time-dependent electrical conductivity

• Published in: Chemical engineering science Vol. 220; p. 115626
• Main Authors: Espinoza-Quiñones, Fernando Rodolfo, Romani, Maurício, Borba, Carlos Eduardo, Módenes, Aparecido Nivaldo, Utzig, Camila Fernanda, Dall'Oglio, Isabella Cristina
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20.07.2020
• Subjects: Activation voltage; Desorption-diffusion equation; Electrical conductivity; Electro-migration voltage; Electrocoagulation electric voltage; non-steady Nernst-Planck equation; Activation voltage; non-steady Nernst-Planck equation; Electrical conductivity; Electrocoagulation electric voltage; Electro-migration voltage; Desorption-diffusion equation
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2020.115626

[Display omitted] •A set of phenomena involved in the EC process were theoretically modelled.•A theoretical representation of the electrical conductivity was proposed.•Voltages of diffusion, electro-migration and activation were assessed.•The anode activation is responsible for the transient voltage in EC processes.•Electrical conductivity has two essential roles on the total electric voltage. In this work, an innovative mathematical approach for the total electric voltage in the electrocoagulation process (EC) was proposed. Contributions of electrodes activation and ions species transfer were modeled by analytical solving the non-steady Nernst-Planck equation. The electrical conductivity was adequately represented in terms of available positive ions species. A time-dependent equation that resembles a desorption-diffusion process was found to represent the electrode activation voltage. An Al electrode-based EC reactor was used to perform EC tests for assessing each electric phenomenon voltage. The data of electrical conductivity were well fitted by its proposed model, highlighting its effects on the total voltage. The anode activation voltage was responsible for the starting transient stage and modulating the total voltage profile. Finally, it could state that the time-dependent electrical conductivity has influenced the total voltage profile and drove the pollutant removal performance, acting on both activation and electric migration voltages intrinsically.