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Updated: Jul 16, 2026

Combined Size and Density Fractionation of Soils for Investigations of Organo-Mineral Interactions
Published on: February 15, 2019
Interaction between electrical double layers of soil colloids and Fe/Al oxides in suspensions
Tao Hou1, Renkou Xu, Diwakar Tiwari
1State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing, China.
Abstract:
Phyllosilicates with net negative surface charge and Fe/Al oxides with net positive surface charge coexist in variable-charge soils, and the interaction between these oppositely charged particles affects the stability of mixed colloids, aggregation, and even the surface chemical properties of variable-charge soils. The interaction of the diffuse layers of electrical double layers between the negatively charged soil colloidal particles and the positively charged particles of goethite or gamma-Al(2)O(3) was investigated in this article through the comparison of zeta potentials between single-soil colloidal systems and binary systems containing soil colloids and Fe/Al oxides. The results showed that the presence of goethite and gamma-Al(2)O(3) increased the zeta potential of the binary system containing soil colloids and Fe/Al oxides, which clearly suggests the overlapping of the diffuse layers in soil colloids and Fe/Al oxides. The overlapping of the diffuse layers leads to a decrease in the effective negative charge density on soil colloid and thus causes a shift of pH-zeta potential curves toward the more positive-value side. The interaction of the electrical double layers is also related to the charge characteristics on the Fe/Al oxides: the higher the positive charge density on Fe/Al oxides, the stronger the interaction of the electrical double layers between the soil colloid particles and the Fe/Al oxides.
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