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Electric Charges on Sesquioxidic Soil Clays
Author(s) -
Fey M. V.,
Roux J.
Publication year - 1976
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/sssaj1976.03615995004000030017x
Subject(s) - cation exchange capacity , titration , salt (chemistry) , electrolyte , chemistry , ion exchange , pyrophosphate , bicarbonate , inorganic chemistry , potentiometric titration , oxalate , mineralogy , soil water , ion , geology , soil science , organic chemistry , electrode , enzyme
The effects of pH, phosphate, oxalate, pyrophosphate, citratedithionite‐bicarbonate and Na 2 CO 3 pretreatments on the positive and negative exchange charges of sesquioxidic clays from soils of South Africa, Australia, Brazil, Japan, and New Zealand were measured using 0.05 N KCl as index electrolyte according to a method which obviates a washing step for removal of excess salt prior to replacement of the index ions, Behavior of clays rich in allophane was compared to that of three synthetic amorphous, aluminosilica gels. Hysteretic, pH‐dependent net negative exchange charge appears to arise from positive exchange charge hysteresis only, CEC being fully reversible by titration with strong acid. The methodology of cation and anion exchange capacity determinations is discussed with special reference to the problem of surface charge density variations encountered in different materials.