Possible ways of nanostructure development in soil gels

Effect of structural transition in the humic gel matrix on some properties of soils

“…More recent studies per formed by electron, atomic force, and tunnel micro scopy [8] imply that the humic matrix in soil gels (hereafter referred to as the humic gel matrix) consists of fractal clusters having sizes of 100-200 nm, which are built of primary particles of humic substances (hereafter, referred to as humic particles) having sizes of 2-12 nm.…”

“…As a result of this and due to the mosaic surfaces of humic particles, the repulsion of ionic atmospheres around the polar regions of humic particles, and the interactions among hydrophobic regions, primary humic particles give rise to fractal species, i.e., fractal clusters. As the concen tration of fractal clusters increases, these clusters interpenetrate each other because of the low degree of filling of their volumes with humic particles (these clusters have many voids), interacting with each other through the hydrophobic regions which remained on the surfaces of humic particles so as to render this pro cess thermodynamically favorable [8,11].…”

Fractal clusters of supermolecules of humus substances in soils

“…Experimental studies of native soil gels that cover and bind soil particles [1][2][3] and provide functioning of soils as unified systems showed that they are based on clusters of supermolecules of humus substances (HSs) [4][5][6].…”

“…First, it was established [4] that the size of primary HS particles is several nanometers. Second, a study of the silt fraction (less than 2 µm) isolated from the Bra zilian oxisol (sandy soil with a 68% content of the sand fraction, 26% of clay, 6% of silt, and 1.1% of HSs, with kaolin being the predominant clayey mineral) using an atomic power microscope showed [12] that the over whelming majority of clayey particles in the silt frac tion are 150-200 nm in length and width and 15-20 nm in thickness.…”

“…A comparison of the number and sizes of mineral particles in soils with the amount and sizes of primary HS particles [4,12] allowed us to calculate specific sur faces of the clayey material and HSs (S clayey part. ~ 2.5 m 2 /g of soil, S HS ~ 20 m 2 /g of soil).…”