Electrokinetic filtration

Yukawa H et al (1976) Analysis of batch electrokinetic filtration. J Chem Eng Japan 9 396-401... 

The use of centrifugation to separate the liquid from solid phases in traditional batch or tube techniques has several disadvantages. Centrifugation could create electrokinetic effects close to soil constituent surfaces that would alter the ion distribution (van Olphen, 1977). Additionally, unless filtration is used, centrifugation may require up to 5 min to separate the solid from the liquid phases. Many reactions on soil constituents are complete by this time or less (Harter and Lehmann, 1983 Jardine and Sparks, 1984 Sparks, 1985). For example, many ion exchange reactions on organic matter and clay minerals are complete after a few minutes, or even seconds (Sparks, 1986). Moreover, some reactions involving metal adsorption on oxides are too rapid to be observed with any batch or, for that matter, flow technique. For these reactions, one must employ one of the rapid kinetic techniques discussed in Chapter 4. 

Plastic microdevices for high-throughput screening with MS detection were also prepared for detection of aflatoxins and barbiturates. These devices incorporated concentration techniques interfaced with electrospray ionization MS (ESI-MS) through capillaries [2], The microfluidic device for aflatoxin detection employed an affinity dialysis technique, in which a poly (vinylidene fluoride) (PVDF) membrane was incorporated in the microchip between two channels. Small molecules were dialyzed from the aflatoxin/antibody complexes, which were then analyzed by MS. A similar device was used for concentrating barbiturate/antibody complexes using an affinity ultrafiltration technique. A barbiturate solution was mixed with antibodies and then flowed into the device, where uncomplexed barbiturates were removed by filtration. The antibody complex was then dissociated and electrokinetically mobilized for MS analysis. In each case, the affinity preconcentration improved the sensitivity by at least one to two orders of magnitude over previously reported detection limits. 

The experiments consisted of three parts. In the first part, the characterization of minerals was explained by using x-ray diffractometer and electron microscope studies. Also, it was performed electrokinetic s studies of suspension. The effect of particle shape and size on the vacuum and pressure filtration of minerals has been investigated in the second part of the study. At the last part, the comparison of the particle shape and size effect on shear strength of the mineral filter cakes was performed. 

Closely related to this is the general problem in the whole chemical industry of the separation of solids from liquids. The processes of thickening, flocculation, dewatering, and filtration are all intimately controlled by the forces and structures arising in colloidal systems. The improvements brought about by the use of electroseparation processes depend on the exploitation of the electrokinetic effects discussed in Chapter 6. 

Therefore, the problem of effective remediation of soils of radioactive nuclides is very relevant. Most technologies of soil decontamination that are currently developed are based on flushing soils with various chemicals and include processes of chemical leaching and selective extraction of radioactive nuclides (Prozorov et flZ., 2000 Shevtsova, 2003). The electrokinetic technique is a new and perspective method of soil remediation, whose main advantage consists in its applicability to decontaminating soils with low filtration ability directly at the site of its local pollution (e.g. in a rock mass) (Pamukcu and Wittle, 1992 Acar et al, 1993, 2001 Janosy and Piot, 1998 Korolev, 2001, 2006 Korolev, Barkhatova, and Shevtsova, 2007). 

The common approach to maintain minimal polarization is to operate at high shear rates [103] however, this can be harmful to biocatalysts. To decrease gel-layer formation in the surface of the membrane, Hakoda and co-workers [178] applied an electric field of 50 and 100 V to a ceramic membrane module used in the lipolysis of triolein in a reversed micellar system. These authors reported a slight increase in the filtration flux (about 15%), without deleterious effects on enzyme stability for an operation time length of 12 h. The electrokinetic phenomena leading to the observations occurred even in apolar media, since small amounts of water or surfactant were present in such media [178]. 

Church C, Zhu J, Wang G, Tzeng TJ, Xuan X (2009) Electrokinetic focusing and filtration of cells in a serpentine microchannel. Biomicrofluidics 3 044109... 

Our objective is to identify the effect of gate potential in selective electrokinetic transport of ions and to realize its potential for filtration of biological fluids. Similar but more extensive work for diffusion-Umited patterning has been done recently by Kamik et al. [7]. 

The potential development of electrokinetic geotextUes offers an opportunity to increase the redevelopment of derelict land as a means of reducing the pressure for construction within the natural environment. This electrically conductive material enhances the filtration and drainage functionalities by electro-osmosis and ion migration. Various types of conductive component can be incorporated in the geotextile structure to achieve this effect, but the possible use of activated carbon fibre or similar additives with pollution sorptive surface properties can aid land recovery of poUuted areas. 

Uniform and non-uniform DC electric fields with field gradients less than 100 V cm can be combined with more conventional filtration and deliquoring apparatus to improve separation rates and reduce overall operating costs (see Figure 1.58). Electrokinetic phenomena such as electrophoresis (movement... 

Electrokinetic phenomena are sometimes hindered in practical applications such as filtration processes or separation by ion exchanging membranes [5] [6],... 

The combination of the effect of inertial impaction, diffusion, interception, and electrokinetic attraction on the cell particle capture and retention to a fibre is called direct adhesion, and the most important mechanism of leucocyte depletion filtration... 

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