Akademik Veri Yönetim Sistemi
CANADIAN GEOTECHNICAL JOURNAL, cilt.42, sa.5, ss.1280-1289, 2005 (SCI-Expanded)
Laboratory and in situ test results show that electrokinetic decontamination is a promising subsurface decontamination method. However, it has also been reported that several problems arise, such as reverse flow and pH gradient across the anode and the cathode during the electrokinetic decontamination process. Variation in pH alters the zeta (zeta) potential of soils, which is one of the factors affecting the efficiency of contaminant removal by the electrokinetic method. The magnitude of the zeta potential controls the fluid flow rate, whereas its sign controls the flow direction. However, research on how the zeta potential of soils changes under various chemical conditions is limited. In this paper, the effect of pore-fluid chemistry on the zeta potential of kaolinite, montmorillonite, and quartz powder is determined with NaCl, LiCl, CaCl(2 center dot)2H(2)O, MgCl(2 center dot)6H(2)O, CuCl2, CoCl2, ZnCl2, AlCl3, and Pb(NO3)(2). The test results reveal that the zeta potential of the minerals with alkali and alkaline-earth metals changes according to the diffuse electrical double-layer theory. The hydrolyzable metal ions produce two points of zero charge (PZCs), one of which is that of the soil; and the other, that of hydrolyzable oxide. The zeta potential of minerals with hydrolyzable metal ions becomes increasingly positive and reaches its maximum value at neutral pH. It then decreases and again reaches very negative values at alkaline pH values (pH 10), depending on ion concentration and the bulk precipitation pH of hydrolyzable metals as hydrolyzable oxides. On the basis of the results of this study, it is recommended that the zeta potential of the soils be determined before electrokinetic decontamination.