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GEOREF RECORD

Effect of acid and alkali treatments on surface-charge properties of selected minerals

Grzegorz Jozefaciuk
Effect of acid and alkali treatments on surface-charge properties of selected minerals
Clays and Clay Minerals (October 2002) 50 (5): 647-656

Abstract

Bentonite, biotite, illite, kaolin, vermiculite and zeolite were treated with 0.1, 1.0 and 5.0 mol. dm (super -3) HCl or NaOH. Suspensions of Na homoionic forms of the initial and the treated minerals were back titrated with 0.1 mol. dm (super -3) NaOH. From back-titration data variable surface charge, Qv, vs. pH dependencies and apparent surface dissociation constant distribution function were estimated. Variable charge vs. pH curves were scaled against cation exchange capacity at pH 7.2 to obtain actual charge, Q (sub A) vs. pH plots. In general both treatments led to an increase of Q (sub v) , while the Q (sub A) value increased and decreased depending on the mineral and the treatment. Products of 5 mol dm (super -3) NaOH action on zeolite and of 1 and 5 mol. dm (super -3) NaOH on kaolin apparently developed a positive surface charge below pH approximately 3.7 and below approximately 4.3, respectively. The heterogeneity of charge-generating surface groups was observed in natural minerals. During acid treatment, the number of weakly-acidic surface functional groups increased while the number of groups of stronger acidic character decreased. The opposite was found for alkaline treatment: the number of surface groups of intermediate acidity increased and that of low acidity decreased.


ISSN: 0009-8604
EISSN: 1552-8367
Coden: CLCMAB
Serial Title: Clays and Clay Minerals
Serial Volume: 50
Serial Issue: 5
Title: Effect of acid and alkali treatments on surface-charge properties of selected minerals
Affiliation: Polish Academy of Sciences, Institute of Agrophysics, Lublin, Poland
Pages: 647-656
Published: 200210
Text Language: English
Publisher: Clay Minerals Society, Clarkson, NY, United States
References: 39
Accession Number: 2003-005689
Categories: Geochemistry of rocks, soils, and sedimentsSedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200302
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