Humic substances and pH effects on sodium- and calcium- montmorillonite flocculation and dispersion

J. Tarchitzky, Y. Chen, A. Banin

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79 Scopus citations

Abstract

In this study, flocculation and dispersion characteristics of homoionic montmorillonite were studied as a function of the exchangeable cation (Na+ and Ca2+), humic acid and fulvic acid concentration, and pH. Flocculation values of Na-montmorillonite increased with increasing concentrations of humic substances (HS) at all pH levels. In the presence of HS at pH values below the point of zero charge, negative HS molecules are adsorbed to positive edge sites causing edge-charge reversal. Consequently, increased electrolyte concentrations are required for flocculation relative to Na-montmorillonite suspensions without HS. The second flocculation mechanism proposed is based on a random distribution of the HS macromolecules among the montmorillonite tactoids. The FV of such a mixture is higher than the FV of montmorillonite suspensions. -from Authors

Original languageEnglish
Pages (from-to)367-372
Number of pages6
JournalSoil Science Society of America Journal
Volume57
Issue number2
DOIs
StatePublished - 1993

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