Electrokinetic phenomena in porous media applied to soil decontamination

Electroosmosis in homogeneously charged micro- and nanoscale random porous media

“…Electroosmotic flows (EOFs) in porous media have been studied for nearly two hundred years due to their important applications in soil, petroleum and chemical engineering [1][2][3][4][5][6] since the electrokinetic effects were first observed by Reuss in 1809 in an experimental investigation on porous clay [7]. In the few past decades, there are considerable and reawakening interests in the EOF in porous media because of the conspicuous applications in biological-chemical-medical analysis [8][9][10][11] and new techniques in energy and geophysical engineering [12][13][14][15], especially in micro-and nano-scales [16][17][18].…”

Streaming Potential and Electro-osmosis Measurements to Characterize Porous Materials

“…The height difference as a function of time carried out for sample TS10 at possible maximum applied voltage of 6 V is shown in Figure 11. The graph has an exponential curve as expected from (8). By using the exponential part of the graph, the response time in (6) was obtained (see Figure 12).…”

“…For a conductive liquid such as distilled water, the Debye length is about 2 nm [8], and a typical pore radius of our samples (see below) is around 3 m in this case; the ratio 1 ( / )/ 0 ( / ) can be neglected [19]. Under these conditions, (5) may be simplified as…”

“…However, the method used in [8] did not work for porous media with very small pores such as Bentonite clay soils or tight-gas sandstones (the pore radius is smaller than 1 m) that are relevant for application in the oil and gas industry. In oil exploration and production, the typical pore sizes in rocks are necessary information for considering the location of oil and fluid flow through the rocks.…”

“…Li et al [7] used two reciprocal electrokinetic phenomena known as streaming potential and electro-osmosis by Ac measurement to determine the effective pore size and permeability of porous media. In [8], the authors used image analysis to determine the number of pores per cross-sectional area of porous samples (see Figure 1 for the schematic of the porous medium with different length scales). This parameter is especially important in processes of contaminant removal from low-permeability porous media under a Dc electric field [8], and in building electro-osmosis micropumps [9].…”