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Physicochemical Investigations of Clay‐adsorbed Organic Colloids: II
Author(s) -
Stevenson F. J.,
Van Winkle Q.,
Martin W. P.
Publication year - 1953
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1953.03615995001700010007x
Subject(s) - colloid , chemistry , diffusion , sedimentation , humic acid , partial specific volume , adsorption , mineralogy , analytical chemistry (journal) , chromatography , geology , thermodynamics , organic chemistry , sediment , paleontology , fertilizer , physics , enzyme
The purpose of this study was to determine the sedimentation velocity and free diffusion behavior of humic acid extracted from Miami clay with neutral sodium pyrophosphate solution. In addition the organic colloids extracted from several soils of the Miami catena were analyzed using the eletrophoretic technique. The electrophoresis examination indicated that the organic colloids extracted from the clay fractions of a Brookston, Crosby, and Miami soil were similar. In all cases it appeared that the extract consisted mainly of dark colored humic acid, with two additional colloids present in very small quantities. The sedimentation velocity and free diffusion study showed that the humic colloid isolated from Miami clay was polydisperse with respect to particle size. The following data were obtained for the colloid dissolved in a water solution: Sedimentation constant s 20 2.8 × 10 ‐13 cm/sec/dyne Diffusion constant D 20 3.9 × 10 ‐7 sq cm/sec Partial specific volume V 0.67 Frictional coefficient f/f 0 2.3 Weight‐average molecular weight M w 53,000