ION EXCHANGE IN CLAYS AND OTHER MINERALS (1959)

Research Article| June 01, 1959 ION EXCHANGE IN CLAYS AND OTHER MINERALS DOROTHY CARROLL DOROTHY CARROLL U. S. GEOLOGICAL SURVEY, WASHINGTON, D. C. Search for other works by this author on: GSW Google Scholar Author and Article Information DOROTHY CARROLL U. S. GEOLOGICAL SURVEY, WASHINGTON, D. C. Publisher: Geological Society of America Received: 20 Jan 1959 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1959, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1959) 70 (6): 749–779. https://doi.org/10.1130/0016-7606(1959)70[749:IEICAO]2.0.CO;2 Article history Received: 20 Jan 1959 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation DOROTHY CARROLL; ION EXCHANGE IN CLAYS AND OTHER MINERALS. GSA Bulletin 1959;; 70 (6): 749–779. doi: https://doi.org/10.1130/0016-7606(1959)70[749:IEICAO]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Ion exchange in clays and other minerals is dependent on the crystalline structure of the mineral and on the chemical composition of any solution in contact with the mineral. The structures of clay minerals and zeolites are briefly described to provide a background for the discussion of their ion-exchange reactions. Ion exchange in these minerals is a reversible chemical reaction that takes place between ions held near a mineral surface by unbalanced electrical charges within the mineral framework and ions in a solution in contact with the mineral. Generally the excess charge on the mineral is negative, and it attracts cations from the solution to neutralize this charge. The chemical reactions in ion exchange follow the law of mass action, but the reactions are restricted by the number of exchange sites on the mineral and by the strength of the bonding of the exchangeable cations to the mineral surface. Titration of H-clays with bases shows that montmorillonites and “illites” behave like a mixture of two or three different acids, whereas kaolinite, with an indefinite number of exchange sites, behaves like an indefinite number of acids.Ion-exchange capacity is measured in chemical equivalents of base adsorbed at pH 7. Each clay mineral has a range of exchange capacities because of differences in structure and in chemical composition. The ranges (in milliequivalents per 100 grams) are kaolinite, 3–15; halloysite (2H2O), 5–10; halloysite (4H2O), 40–50; montmorillonite, 70–100; “illite,” 10–40; vermiculite, 100–150; glauconite, 11–20; attapulgite, 20–30; and allophane, 70. The common metallic cations found in exchange positions in clay minerals are Ca+2, Mg+2, Na+, and K+. At low pH values H+ replaces other cations. The order of replaceability of the common cations has been found to be: Bivalent cations enter the exchange sites preferentially to univalent cations. The common exchangeable cation in most clay minerals in soils is Ca+2. Other exchange phenomena discussed are anion exchange, fixation of cations and anions by clay minerals, effect of environment on cation exchange, and the exchange capacity of zeolites, of rocks, of other minerals, of organic matter and organic complexes, and of amorphous mineral material. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.