地质学报（英文版）2006，Vol.80Issue(2)：249-256,8.
Oxidation of AsⅢ by Several Manganese Oxide Minerals in Absence and Presence of Goethite
Oxidation of AsⅢ by Several Manganese Oxide Minerals in Absence and Presence of Goethite
摘要
Abstract
Oxidation of AsⅢ by three types of manganese oxide minerals affected by goethite was investigated by chemical analysis, equilibrium redox, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Three synthesized Mn oxide minerals of different types, birnessite,todorokite, and hausmannite, could actively oxidize AsⅢ to AsⅤ, and greatly varied in their oxidation ability. Layer structured birnessite exhibited the highest capacity of AsⅢ oxidation, followed by the tunnel structured todorokite. Lower oxide hausmannite possessed much low capacity of AsⅢ oxidation,and released more Mn2+ than birnessite and todorokite during the oxidation. The maximum amount of Asv produced during the oxidation of AsⅢ by Mn oxide minerals was in the order: birnessite (480.4mmol/kg) ＞ todorokite (279.6 mmol/kg) ＞ hausmannite (117.9 mmol/kg). The oxidation capacity of the Mn oxide minerals was found to be relative to the composition, crystallinity, and surface properties. In the presence of goethite oxidation of AsⅢ by Mn oxide minerals increased, with maximum amounts of Asv being 651.0 mmol/kg for birnessite, 332.3 mmol/kg for todorokite and 159.4 mmol/kg for hausmannite. Goethite promoted AsⅢ oxidation on the surface of Mn oxide minerals through adsorption of the Asv produced, incurring the decrease of Asv concentration in solutions. Thus, the combined effects of the oxidation (by Mn oxide minerals)-adsorption (by goethite) lead to rapid oxidation and immobilization of As in soils and sediments and alleviation of the AsⅢ toxicity in the environments.关键词
Mn oxide mineral/goethite/oxidation/AsⅢ/AsvKey words
Mn oxide mineral/goethite/oxidation/AsⅢ/Asv分类
天文与地球科学引用本文复制引用
FENG Xionghan,TAN Wenfeng,LIU Fan,Huada Daniel RUAN,HE Jizheng..Oxidation of AsⅢ by Several Manganese Oxide Minerals in Absence and Presence of Goethite[J].地质学报（英文版）,2006,80(2):249-256,8.基金项目
We gratefully acknowledge Prof. A. H. Lu and the anonymous reviewers for their helpful comments. We are thankful to Dr. X. W. Liu for his assistance with the TEM analyses. We gratefully thank the National Natural Science Foundation of China (Nos. 40471070 and 40403009) and the Key Project of the Ministry of Education of China (No.105122) for financial supports to this research. （Nos. 40471070 and 40403009）
