Charges on the surfaces of two chlorites

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Authors:Jones, A. A.
Author Affiliations:Primary:
Univ. Reading, Dep. Soil Sci., Reading, Berks. RG1 5AQ, United Kingdom
Volume Title:Clay Minerals
Source:Clay Minerals, 16(4), p.347-359. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0009-8558
Publication Date:1981
Note:In English with French and German summaries. 2 p. refs.; illus. incl. table
Summary:Two chlorites, sheridanite and clinochlore, have been examined to determine their surface charge characteristics. In order to increase their surface area and to produce a measurable surface charge, the chlorites were treated with 10-3 m, 10-2 m, and 10-1 m HCl in 10-2 m MgCl2 solutions. These treatments are shown not to alter the crystallinity of the chlorites and to produce a small pH-dependent negative charge which is not directly related to the total surface area. The clinochlore, (Si6.13Al1.84)(Al1.53FeIII0.53FeII0.18Mg9.52)O20(OH)16, is more readily attacked by the acids than the sheridanite, (Si5.43Al2.55)(Al2.90FeII0.05Mg8.86)O20(OH)16, and also produces material with greater surface area and pH-dependent, negative, surface charge. It is concluded that: (i) isomorphous substitutions in the lattice are not reflected in a permanent surface charge; (ii) the observed surface charge arises not only at the edges of the particles but also at points where the chlorite is predisposed to attack by acids; (iii) in the chlorite-acid system used, anions-probably mainly silicate-block positively charged sites. [P.Br.]
Subjects:Chlorite group; Clay mineralogy; Clinochlore; Mineral data; Minerals; Sheet silicates; Silicates; Specific surface; Acid treatments; Sheridanite; Surface charge
Abstract Numbers:82M/2332
Record ID:1983035387
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique, Vandoeuvre-les-Nancy, France
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