钙锰矿的研究进展

钙锰矿是土壤、沉积物及海洋锰结核中常见的以3×3结构为主的一族大隧道构造氧化锰矿物.隧道中存在水分子和阳离子,形貌以片状、针状或纤维状为主.水钠锰矿→布塞尔矿→钙锰矿的转化是钙锰矿形成的一个重要途径.这种转化在常压条件下受体系温度、pH、共存粘土矿物、转化时间以及前驱物布塞尔矿亚结构特点,如层间交换离子类型、浓度、以水合离子形态或与MnO6八面体空穴上方键合的强弱、结晶度、Mn(Ⅲ)的含量与迁移特点等因素影响.钙锰矿独特的结构使其所具有的离子吸附、氧化与催化特性及分子级的隧道空间等有望作为特异的分子筛、二次电池正极材料、有机反应催化荆等在环境科学和材料科学等领域具有广阔的应用前景.

Progress in the Study of Todorokite

Todorokite is one of common manganese oxides with a basic 3×3 tunnel structure in soils, sediments and ocean Mn nodules. The tunnels in todorokites are partially filled with water molecules and a variety of cations, and the morphology of todorokites mostly consist of plate-, needle-and fiber-shaped crystallites. The transformation of birnessite→buserite→todorokite is an important pathway for todoroktie formation. The influencing factors, such as type and amount of interlayer cation in buserite precursor, the amount of Mn(III) in the structure of layered precursor, the average manganese oxidation state and crystallinities of the precursors, reaction temperature, pH and clay minerals, would affect the formation of todorokite under hydrothermal and refluxing conditions. The influencing effects are apparent for formation of todorokite at atmospheric pressure. These manganese oxide octahedral molecular sieves could be used widely in sorbents, catalysis, separations, chemical sensors, and batteries due to their unique structure and high surface areas.