Electroosmotic Phenomena in Organic Soils

Afshin Asadi,Thamer A Mohamed,M.M Hassim,Bujang B.K Huat,Nader Shariatmad,M.M Hanafi

doi:10.3844/ajessp.2009.310.314

Abstract

Organic soils or peat represent an accumulation of disintegrated plant remains which have been preserved under condition of incomplete aeration and high water content. In order to develop a fundamental understanding of electroosmotic phenomena in peat, initially microelectrophoresis studies were carried out to conceptualize the electrokinetic phenomena. Then electroosmosis experiments were conducted on rigid cube samples containing 0.0001 M NaCl-water saturated peat. The open-anode and open-cathode systems were employed to the soil samples. Distilled Water (DW) were used as anolyte and catholyte. The experiments were carried out via applications of diffrent DC electrical potentials. The results of microelectrophoresis study showed changes of zeta potential due to the effect of HCl and NaOH. The correlations between zeta potential and pH were found. The negative charge of peat is high pH dependent and the surface charge was dropped to zero at pH around 3. The high degree of decomposition resulted in the higher zeta potential in peat. It was also experimentally found that the electroosmotic flow in peat is feasible. The direction of electroosmotic flows were from the anode to cathode.

Highlights

In 1809, Reuss, a researcher from Russia, was the first to observe water flow in soils as a result of a direct electric current passing through it
Variations in ζ with pH is probably related to the nature of electrical energy field in organic soils, the negative charge of humus is generally believed to be due to the dissociation of H+ from functional groups
Electroosmosis experiments: The cumulative electroosmotic flows in the tested organic soils were toward the cathode Fig. 5

Summary

INTRODUCTION

In 1809, Reuss, a researcher from Russia, was the first to observe water flow in soils as a result of a direct electric current passing through it. The ion concentration is equal to that of the free pore water. Applying an electrical potential to the saturated soil causes the hydrated positive ions to move toward the negative electrode (the cathode), dragging free water with them. The movement is primarily generated in the diffuse double layer, called soil moisture film, where the cations dominate. Where: ke = The electro osmotic permeability of the soil V/L = The electrical potential gradient A = The cross-sectional area of the soil sample across which the potential difference is applied. As such this is analogous to Darcy's Law of hydraulic flow. It is believed that study of electroosmosis phenomena in organic soils is crucial to extend its applications in geotechnical aspects

MATERIALS AND METHODS

RESULTS AND DISCUSSION

CONCLUSION