几种氧化锰矿物的合成及其对重金属的吸附和氧化特性  

The syntheses of several Mn oxide minerals and their adsorption and redox characteristics for heavy metals

作　　者：冯雄汉[1] 翟丽梅[1] 谭文峰[1] 刘凡[1] 贺纪正[2] 

机构地区：[1]华中农业大学资源与环境学院,湖北武汉430070 [2]中国科学院生态环境研究中心,北京100085

出　　处：《岩石矿物学杂志》2005年第6期531-538,共8页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金资助项目(40471070;40403009);高校博士点基金资助项目(2002050411)

摘　　要：以改进或优化的方法合成土壤中常见的几种氧化锰矿物,对其形貌、结构、组成和表面性质进行表征,研究其对几种重金属的吸附和对Cr(Ⅲ)的氧化特性及与其结构和表面性质的关系。结果表明,合成的水钠锰矿、钙锰矿、锰钾矿和黑锰矿均为单相矿物,具有典型的形貌特征。水钠锰矿、钙锰矿和锰钾矿的PZC较低,分别为1.75、3.50和2.10,其表面可变负电荷量的大小顺序为水钠锰矿≥锰钾矿>钙锰矿;黑锰矿的PZC较高,表面可变负电荷量远低于其他3种矿物。供试矿物中,水钠锰矿对Pb2+、Cu2+、Co2+、Cd2+和Zn2+等重金属的吸附能力最强,黑锰矿的吸附能力最弱,除黑锰矿吸附更多的Cu2+外,供试氧化锰矿物对Pb2+的吸附量最大。氧化锰矿物对重金属的吸附受重金属的水解常数和矿物的表面负电荷的影响较大,它们均影响氧化锰矿物表面诱导水解作用及吸附离子形态。供试氧化锰矿物对Cr(Ⅲ)氧化能力和氧化过程中Mn2+释放量不同,受矿物结构、氧化度、表面性质以及结晶度等因素影响,氧化能力顺序为水钠锰矿>锰钾矿>钙锰矿>黑锰矿,最大氧化量分别为1330.0、422.6、59.7和36.6mmol/kg。Several Mn oxide minerals commonly existent in soils were synthesized by the modified or optimized methods. Their morphologies, structures, compositions and surface properties were characterized. Adsorption and redox reactions of heavy metals on them and effects of mineral structures and surface properties were also investigated. The synthesized bimessite, todorokite, cryptomelane and hausmannite are all single-phase minerals and have the typical morphology, as indicated by analyses of XRD and TEM/ED. The PZCs of the synthesized bimessite, todorokite and cryptomelane are 1.75, 3.50 and 2.10, respectively. The magnitude order of their surface variable negative charges is bimessite ≥cryptomelane 〉 todorokite. The PZC of the synthesized hausmannite is much higher than PZCs of other minerals, and it has the least surface variable negative charge. Among the tested Mn oxide minerals, bimessite has the greatest adsorption capacity for heavy metals such as Pb^2 ＋ , Cu^2 ＋ , Co^2 ＋ , Cd^2 ＋ and Zn^2 ＋ , whereas hausmannite has the weakest capacity. Except for hausmannite, these minerals have the greatest adsorption capacity for Pb^2 ＋ . Hydration constants of the heavy metals and the surface variable charges of the Mn minerals remarkably affect the adsorption. Both of the factors affect the hydration induced by surfaces of the minerals and species of the adsorbed ions. Their ability in Cr （ Ⅲ ） oxidation and concomitant release of Mn^2＋ varies greatly depending on the structure, composition, surface property and crystallinity. The maximum amounts of Cr （ Ⅲ ） oxidized by the Mn oxide minerals are in order of （mmol/kg） bimessite （1 330.0） 〉 cryptomelane （422.6） 〉 todorokite （59.7） 〉 hausmannite （36.6）.

关 键 词：氧化锰矿物 重金属 吸附 氧化 表面化学性质 透射电镜 X射线衍射 

分 类 号：X131.3[环境科学与工程—环境科学] S153.61[农业科学—土壤学]