TY - JOUR
T1 - Humic substances and pH effects on sodium- and calcium- montmorillonite flocculation and dispersion
AU - Tarchitzky, J.
AU - Chen, Y.
AU - Banin, A.
PY - 1993
Y1 - 1993
N2 - 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
AB - 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
UR - http://www.scopus.com/inward/record.url?scp=0027865929&partnerID=8YFLogxK
U2 - 10.2136/sssaj1993.03615995005700020014x
DO - 10.2136/sssaj1993.03615995005700020014x
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AN - SCOPUS:0027865929
SN - 0361-5995
VL - 57
SP - 367
EP - 372
JO - Soil Science Society of America Journal
JF - Soil Science Society of America Journal
IS - 2
ER -