Experimental Study on Effect of Soil Salinity on Electro-Osmosis in Montmorillonite Clay

In order to investigate the permeability of montmorillonite clay with different salt content under an electric field, a laboratory device was designed to capture the drainage, current intensity, voltage, and water content during electro-osmotic drainage tests at four different salinities in montmorillonite. The results show that the permeability increased significantly during electro-osmotic drainage in the electric field. Under 40 V voltage the drainage rate in electro-osmosis was as large as 1 000 times that in normal drainage tests. The electric permeability coefficient increased first and then decreased with an increase in the salt content because of the effect of montmorillonite molecular structure and electrolyte concentration. When the salt content was near 0.5%, the drainage reached a maximum. With the salt content increasing, the effective potential of the soil decreased but the current and the potential drop between cathode and anode increased, reflecting that the energy consumption at the interface increased with the increase of salinity. In addition, a short-circuit connection between the cathode and anode electrodes resulted in a charge redistribution in the process of electro-osmosis. After the electro-osmosis, the potential distribution was found not uniform: the potential of the middle region was the lowest, and the direction of current was different in the soil.