Analysis of batch electrokinetic filtration.

Abstract

Filtration under constant D. C. electric field with constant hydraulic pressure, what is termed electrokinetic filtration, was discussed in this paper. Under these conditions it is considered that electrophoresis occurs in the slurry and causes less cake formation, and that electroosmosis occurs at the same time in the filter cake. Therefore, the flow rate of electrokinetic filtration is increased in comparison to filtration at the same hydraulic pressure. An equation taking account of both effects is presented. Experimental investigation of the characteristics of electrokinetic filtration is performed according to the theoretical equation. As a result, the flow rate of filtration is significantly increased for calcium carbonate slurry and [white clay slurry. For instance, at the electric field of 30 volt/cm under hydraulic pressure of 163.2 G/cm2, Ruth's filtration coefficient for calcium carbonate slurry was about 9.4 times as large as that of the filtration at the samehydraulic pressure, and Ruth's coefficient for white clay slurry was about 15 times at 12volt/ cmand 163.2 G/cm2. It is confirmed that the equation of electrokinetic filtration proposed in this paper is practically available.

Current state of fine mineral tailings treatment: A critical review on theory and practice

“…In electrofiltration the cathode and anode are immersed in the feed material in such a way that the particle electrophoresis is directed away from the filter media. In such a configuration, according to Yukawa, et al (1976), the resultant motion of particles would fully oppose the hydraulic transport of particles towards the filter media when a critical electric field is established. This phenomenon would certainly be beneficial to treating negatively-charged fine solids suspensions as the electroosmotic flow of cation-rich water is countercurrent to the electrophoresis of solids, as presented by Mahmoud, et al (2010) in Figure 6.…”

Electroosmotic dewatering of cellulose nanocrystals

“…Particles with a negative surface charge experience an electrophoretic force in the direction of the anode. The electric field also induces a movement of the fluid in the direction of the cathode, thereby providing a driving force for separation (Kobayashi et al 1979;Yukawa et al 1971Yukawa et al , 1976. The electroosmotic flow rate during the electrofiltration experiments can be described by the Helmholtz-Smoluchowski equation (Hiemenz and Rajagopalan 1997) thus:…”

Pressure electroosmotic dewatering with continuous removal of electrolysis products

“…Emergent technologies have been implemented based on the application of an external electric field (Moulik, 1971) complemented or not by acoustic fields (Tarleton, 1990;Wakeman and Tarleton, 1991). The processes investigated utilising an electric field include electrosedimentation to enhance sedimentation (Shirato et al, 1979); electrofiltration to enhance filtration or to reduce membrane fouling in crossflow filtration (Yukawa et al, 1976;Visvanathan and Ben Aïm, 1989;Wakeman and Sabri, 1995;Akay and Wakeman, 1997;Wakeman, 1998;Weber and Stahl, 2002a), and more recently electrowashing to remove specific solutes in porous media (Ghirisan et al, 2002;Tarleton et al, 2003). However, most research has concentrated on pressurised electroosmotic dewatering (PED), that is, the application of a DC electric field during the expression of formed cakes or porous media (Sprute and Kelsh, 1980;Lockhart, 1983;Iwata et al, 1991;Barton et al, 1999;Weber and Stahl, 2002b).…”