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Sulphate sorption by variable charge soils
Author(s) -
GUADALIX M. E.,
PARDO M. T.
Publication year - 1991
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1991.tb00107.x
Subject(s) - sorption , chemistry , phosphate , adsorption , soil water , electrolyte , inorganic chemistry , silicate , ion , ion exchange , organic chemistry , geology , soil science , electrode
SUMMARY The sorption of sulphate (SO 2− 4 ) by three variable charge soils from the Canary Islands (Spain) was studied. Sulphate sorption decreased with increasing pH. Only negligible amounts of SO 2− 4 were sorbed above pH 6.5. When the soils were washed with an indifferent electrolyte (0.01 M KCl), more SO 2− 4 was recovered than had been sorbed. This indicated a release of native SO 2− 4 Sulphate replaced hydroxyl ions (OH) and co‐ordinated H 2 O molecules, as well as very small amounts of silicate (Si). No measurable amount of phosphate (P) was released. On average hydroxyl release accounted for 50% of SO 2− 4 sorbed, the rest being accounted for by the increase in negative charge as measured by K + adsorption. The results presented here are consistent with the sorption of SO 2− 4 through a ligand exchange mechanism, but in a different plane of sorption to that of phosphate.