FIXATION OF MANGANESE BY CLAY MINERALS

Abstract
Samples of bentonite, illite, and kaolinite clays were studied for their Mn fixation properties under various pH levels, alternate wetting and drying conditions, and incubation at moisture saturation. Bentonite and illite fixed significant quantities of Mn under wetting and drying. Fixation was directly related to pH and the amount of Mn added. Incubation of treated samples at moisture saturation resulted in considerably less than half the amount of Mn fixed as when subjected to repeated wetting and drying. Kaolinite fixed relatively small amounts of Mn as compared to bentonite and illite regardless of treatment.Since x-ray did not reveal a mineralogical change, it was concluded that Mn was fixed as a result of precipitation, physical entrapment in clay lattice wedge zones, or because it was oxidized to higher valence oxides and/or strongly adsorbed at the exchange sites. Cation exchange capacity (CEC) values were inversely related to Mn fixation. Samples of bentonite, illite, and kaolinite clays were studied for their Mn fixation properties under various pH levels, alternate wetting and drying conditions, and incubation at moisture saturation. Bentonite and illite fixed significant quantities of Mn under wetting and drying. Fixation was directly related to pH and the amount of Mn added. Incubation of treated samples at moisture saturation resulted in considerably less than half the amount of Mn fixed as when subjected to repeated wetting and drying. Kaolinite fixed relatively small amounts of Mn as compared to bentonite and illite regardless of treatment. Since x-ray did not reveal a mineralogical change, it was concluded that Mn was fixed as a result of precipitation, physical entrapment in clay lattice wedge zones, or because it was oxidized to higher valence oxides and/or strongly adsorbed at the exchange sites. Cation exchange capacity (CEC) values were inversely related to Mn fixation. © Williams & Wilkins 1976. All Rights Reserved.

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