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Calcium‐Magnesium Exchange in Aluminum Hydroxide‐Coated Montmorillonite
Author(s) -
Levy Rachel,
Tamura Tsuneo
Publication year - 1973
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.197300029
Subject(s) - chemistry , magnesium , calcium hydroxide , inorganic chemistry , calcium , aluminium , precipitation , montmorillonite , sodium hydroxide , adsorption , nuclear chemistry , organic chemistry , meteorology , physics
Aluminum hydroxide‐coated montmorillonites have been shown to exhibit exchange properties which differ from those of pure montmorillonites. The direction of change was found to depend on the coating method used and the pH at which the coating is applied. The aluminum hydroxide‐coated montmorillonites were prepared by two different methods at two pH's: (1) reacting aluminum chloride and sodium hydroxide in the presence of the clays (pH 7), and (2) titrating aluminum‐saturated clays with calcium hydroxide to an alkaline pH (∼10). The resulting clay systems were equilibrated with calcium‐magnesium solutions. The first system showed preferential adsorption of calcium over magnesium because the clays contained exchangeable sodium due to the precipitation of aluminum hydroxide in the presence of the clay. The second system showed no preference either for calcium or for magnesium. A distribution coefficient of unity resulted from compensation of exchangeable calcium by magnesium released from the aluminum hydroxide.