Electrofiltration
Electrofiltration is a method that combines membrane filtration and electrophoresis in a dead-end process.
Electrofiltration is a technique for separation and concentration of colloidal substances – for instance biopolymers.
The principle of electrofiltration is based on overlaying electric field on a standard dead-end filtration.
In comparison to cross-flow filtration electrofiltration exhibits not only increased permeate flow but also guarantees reduced shear force stress which qualifies it as particularly mild technique for separation of biopolymers that are usually unstable.
The promising application in purification of biotechnological products is based on the fact that biopolymers are difficult for filtration but on the other hand they are usually charged as a result of the presence of amino and carboxyl groups.
The electrophoresis of the particles and the electro-osmosis become essential when the filtration process is overlaid with electric field.
When the electrophoretic force FE, oppositely directed to flow, overruns the hydrodynamic resistance force FW, the charged particles migrate from the filter medium, thus reducing significantly the thickness of the filter cake on the membrane.
When the solid particles, subject to separation, are negatively charged they migrate towards the anode (positive pole) and deposit on the filter cloth situated there.
Figure 1 presents schematic description of electrofiltration chamber with flushing electrodes.
Modifying the Darcy’s basic equation, describing filter cake formation, with electro-kinetic effects by integration under assumption of using the constants of electro-osmotic pressure Pe, the critical electric field Ekrit and the electric field E results: Previous scientific works conducted in the Dept.
