Clays and Clay Minerals, Vol. 54, No. 5, 605-615, 2006.
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Authors
Cui, Hao-Jie
Feng, Xiong-Han
He, Ji-Zheng
Tan, Wen-Feng
Liu, Fan
Issue Date
2006-09
Type
Article
Language
en_US
Keywords
Periodicals , Geology , Birnessite , Clay Mineral , Mn Oxide , Todorokite , Transformation
Alternative Title
Abstract
Todorokite is a common Mn oxide (with a tunnel structure) in the Earth surface environment, and can be obtained by hydrothermal treatment or refluxing process from precursor buserite with a layered structure. Several chemical reaction conditions for the phase transformation from Na-buserite to todorokite at atmospheric pressure were investigated, including temperature, pH, crystallinity of precursor Na-buserite, the amount of the interlayer Mg2+ of the Mg-buserite and clay minerals. The results showed that the conversion rate and crystallinity of todorokite decreased with falling temperature, and Mg- buserite could not be completely transformed to todorokite at lower temperatures (40ëC). The poorly crystalline Na-buserite could be converted into todorokite more easily than highly crystalline Na-buserite. Todorokite can be prepared at pH 5ÿ9, but the rate of conversion and crystallinity of todorokite did vary with pH in the order: neutral & alkali > acidic. The conversion rate of todorokite decreased with decreasing interlayer Mg2+ content of the Mg-buserite. The presence of montmorillonite or goethite slowed the formation reaction of todorokite in the refluxing process, and the reaction time was prolonged when the amounts of those minerals were increased.
Description
Citation
Clays and Clay Minerals, Vol. 54, No. 5, 605-615, 2006.
Publisher
The Clay Minerals Society
License
Copyright © 2006-2018.