Interaction between electric double layers of kaolinite and Fe/Al oxides in suspensions

Interaction of the diffuse layers of electric double layer between negatively charged kaolinite particle and positively charged particles of goethite, gibbsite, hematite or γ-Al2O3 is investigated in this article through the comparison of zeta potential between single kaolinite system and the binary-system containing kaolinite and Fe/Al oxides. The overlapping of the diffuse layers on kaolinite and Fe/Al oxides decreases the effective negative charge density on kaolinite and thus increases the zeta potential of the binary-system containing kaolinite and Fe/Al oxides. The interaction of the diffuse layers increases with the increase in the ratio of kaolinite to Fe/Al oxides and decreases with the rise of system pH. The interaction also relates to the charge characteristics on the Fe/Al oxides. Gibbsite which posses comparative maximum positive charge density leads to the strongest interaction of the diffuse layers between the oxide and kaolinite as followed by goethite, and hematite, and the γ-Al2O3 with the least positive charge density results in the weakest interaction of the diffuse layers. The outcome of the present investigation is likely to be useful reference for the interpretation of the interaction of the diffuse layers in authentic variable charge soils.