Effects of electrode materials and current intermittence in electro-osmosis

Abstract

The effects of electrode materials and current intermittence on the coefficient of electro-osmotic permeability and the voltage loss at the soil-electrode interfaces are investigated using a marine soil. An electro-osmotic testing cell is designed and fabricated to measure the electro-osmotic induced flow under known boundary conditions. Six pairs of electrodes are tested for the voltage loss at the soil- electrode interfaces and for the coefficient of electroosmotic permeability. The losses in the applied voltage are found to be dependent on the anode material and are less in metallic anodes (steel or copper) than carbon anodes. The coefficients of electro-osmotic permeability are relatively independent of the electrode materials and are controlled by the effective electric field intensity in the soil. The application of current intermittence generates a higher electro-osmotic flow than continuous d.c. for the same applied voltage and the open electric circuit is superior to the short electric circuit configuration. The coefficient of electro-osmotic permeability is maximum using current intermittence of 2 min on/1 min off and open-circuit configuration for the soil tested. Nous étudions, en utilisant un sol marin, les effets des matériaux des électrodes et de l'intermittence de courant sur le coefficient de perméabilitéélectro-osmotique et la perte de tension aux interfaces sol-électrode. Nous avons conçu et fabriquéune cellule d'essai électro-osmotique pour mesurer le flux provoquépar électro-osmose en conditions limites connues. Nous testons six paires d'électrodes pour la perte de tension aux interfaces sol-électrodes et pour le coefficient de perméabilité électroosmotique. Nous constatons que les pertes de tension appliquée dépendent du matériau de l'anode et sont moindres avec les anodes métalliques (acier ou cuivre) qu'avec les anodes en carbone. Les coefficients de perméabilité électro-osmotique sont relativement indépendants du matériau de l'électrode et sont fonction de l'intensité du champ é lectrique effectif dans le sol. L'application d'un courant intermittent produit un flux é lectro-osmotique plus e levéque l'application d'un courant direct continu pour la même tension appliquée; et le circuit é lectrique ouvert est supérieur àla configuration de circuit é lectrique court. Le coefficient de perméabilitéé lectro-osmotique est à son maximum quand on utilise un courant intermittent activé pendant 2 minutes et désactivépendant 1 minute et une configuration à circuit ouvert pour le sol testé

Electro-kinetic dewatering of oily sludges

“…This decreased the electric resistance of the electrolyte, which in turn increased the electric current and ultimately the temperature. The biggest potential loss in the experiments was observed at the interface of sludge and the graphite anode, consistent with the findings of Mohamedelhassan and Shang [20], who attributed this to the electrochemical potential of the electrode material. Materials with low-electrochemical potential have a low-electrode/electrolyte interface voltage loss.…”

A Review Article: Electrokinetic Bioremediation Current Knowledge and New Prospects

“…That study also concluded that the combined effect of applied current intensity and duration is the crucial factor affecting living organisms rather than the current intensity alone. The effect of electrode materials in EK applications using different materials for anode and cathode including steel, copper, and carbon with different combination (anode-cathode) was [83] investigate [75]. The results show that using a particular material as anode and another as cathode or vice versa can result in considerable differences in the electrode performance (efficiency).…”

“…Intermittent current was used to avoid the adverse impact of the high temperature [86]. The use of current intermittence not only controls the increase in temperature, but also enhances the outcome of the EK application [75].…”

“…It is suggested that the fluctuation of the power generated from solar panels during the day and the diminishment of electric field during the night would stimulate the remediation process. Many studies have proven that current intermittence is beneficial to the outcome of an electrokinetic process [75] [100]. In a previous study, the authors have used solar panels to generate power for the electrokinetic remediation of clay soil contaminated with copper [67] [101].…”

Electro-Osmotic Dehydration of Hangzhou Sludge with Selected Electrode Arrangements

“…[2,[17][18][19] In addition to these studies on electrode materials, some other investigations investigated the conduction procedures of electro-osmosis, particularly with regard to polarity reversal and interrupted currents. [20][21][22][23] Furthermore, recent research has also determined that electro-osmotic consolidation can be significantly enhanced in the presence of pre-loading or vacuum loading. [1,[24][25][26] Hence, it is recommended that future applications of electro-osmosis should be coupled with other techniques.…”