Streaming potential method for characterizing the overlapping of diffuse layers of the electrical double layers between oppositely charged particles

Interaction of the electrical double layers (EDLs) between negatively charged quartz grains and positively charged iron (Fe)/aluminum (Al) oxide colloids was investigated in this work by comparing the difference in zeta potentials between the single quartz in electrolyte and quartz with Fe/Al oxide suspensions. The Fe/Al oxides used were alpha-Fe2O3, amorphous Fe hydroxide, gibbsite and amorphous Al hydroxide. The zeta potential of quartz was measured using a self-made streaming potential apparatus. Our results indicated that the overlapping degree of diffuse layers of the EDLs between quartz and Fe/Al oxides increased with increased concentration of Fe/Al oxides and decreased with the decrease in negative surface charge on quartz due to ferric coating. The overlapping degree of diffuse layers of the EDLs between quartz and Fe/Al oxides decreased with increased ionic strength due to the decreased thickness of the diffuse layers. The results should provide a useful reference for using the streaming potential method to investigate the effect of the colloidal transport process on the properties of bulk soil in situ. (C) 2015 Elsevier B.V. All rights reserved.