Silicic acid as a dispersibility enhancer in a Fe-oxide-rich kaolinitic soil clay

Title: Silicic acid as a dispersibility enhancer in a Fe-oxide-rich kaolinitic soil clay
Authors: Nguyen, Minh N.
Picardal, Flynn
Dultz, Stefan
Nguyen Anh V.
Nguyen Khai M.
Keywords: Silicic acid;Kaolinitic soil;Dispersion;Light scattering;Zeta potential
Issue Date: 2017
Abstract: Insoils, dispersion is a crucial steppreceding the loss of clay-sizedparticles by surface run-off and leaching,which in turn results in soil degradation. Despite the fact that silicic acid is common in soil solutions, its effect on aggre-gation stability offine sized particles in soils has not been detailed. Here we examined the effect of silicic acid on dispersion of a kaolinitic soil clay fraction rich in Fe-oxides (8.5%) at different pH values by combining dynamic light scattering for particle sizing and test tube experiments for examination of particles in suspension. Adsorp-tion of silicic acid on the clay fraction was characterized by batch adsorption experiments and effects on surface chargeby zeta potential (ζ)measurements over a pH range from2 to 11.We found that silicic acidadsorbedonto clay and co-existing Fe oxides, madeζmore negative, and thereby counteracted aggregation of the clay fraction. Silicic acid showed its most effectivity for maintaining dispersion at a pH range of 4 to 6. Beyond this pH range, dispersion was either strongly favored or prevented, and the effect of silicic acid on dispersion was obscured. Given the ubiquitous presence of silicic acid in soils, ourfindings regarding its impact on aggregation stability have important implication for conservation of acidic soils.
Description: TNS07005 ; GEODERMA Volume: 286 Pages: 8-14 Published: JAN 15 2017
ISSN: 0016-7061
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