• journal_title：Clays and Clay Minerals
• Contributor：Hao-Jie Cui ; Xiong-Han Feng ; Ji-Zheng He ; Wen-Feng Tan ; Fan Liu
• Publisher：Clay Minerals Society
• Date：2006-
• Format：text/html
• Language：en
• Identifier：10.1346/CCMN.2006.0540507
• journal_abbrev：Clays and Clay Minerals
• issn：0009-8604
• volume：54
• issue：5
• firstpage：605
• section：Articles

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 (40°C). The poorly crystalline Na-buserite could be converted into todorokite more easily than highly crystalline Na-buserite. Todorokite can be prepared at pH 5–9, 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.