A Study of Chromium Adsorption on Natural Goethite Biomineralized with Iron Bacteria  

作　　者：SUN Zhenya ZHU Chunshui HUANG Jiangbo GONG Wenqi CHEN Hesheng MU Shanbin 

机构地区：[1]Center for Materials Research and Analysis, Wuhan University of Technology, Wuhan, Hubei 430070 [2]School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan, Hubei 430070 [3]Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang, Jiangsu 222005

出　　处：《Acta Geologica Sinica(English Edition)》2006年第4期597-603,共7页地质学报（英文版）

基　　金：supported by grants from the National Natural Science Foundation of China(Grant Nos.40072015 and 40372028);the National"973"Plan Project(Grant No.2004CB619204).

摘　　要：Goethite, especially biogenic goethite, has high specific surface area and great capacity for the adsorption of many contaminants including metal ions and organic chelates. Chromium is a redox actively toxic metal ion that exists as either Cr^Ⅲ or Cr^Ⅵ in nature, and as such it is essential to understand its behavior of adsorption on natural goethite mineralized by iron bacteria, as Gallionella and Leptothrix in water body. The adsorption of Cr^3＋ and Cr^Ⅵ on naturally biomineralized goethite is studied in this paper. The results show that both Langmuir and Freundlich adsorption isothermal models are able to accurately describe the adsorption of these two ions. Investigation of SEM/EDS, TEM/EDS indicates that the two ions do not adsorb homogeneously on goethite owing to the different microstructures of goethite, and that the microspherical goethite has a greater adsorption capacity for chromium ions than the helical one. XPS data show that redox reaction of chromium on the surface of biomineralized goethite takes place in the adsorption of both Cr^3＋ and Cr^Ⅵ. The CrvI adsorbed on biogoethite is much easier to transform into CrIII than the oxidization of Cr^Ⅲ on the bio-goethite.Goethite, especially biogenic goethite, has high specific surface area and great capacity for the adsorption of many contaminants including metal ions and organic chelates. Chromium is a redox actively toxic metal ion that exists as either Cr^Ⅲ or Cr^Ⅵ in nature, and as such it is essential to understand its behavior of adsorption on natural goethite mineralized by iron bacteria, as Gallionella and Leptothrix in water body. The adsorption of Cr^3＋ and Cr^Ⅵ on naturally biomineralized goethite is studied in this paper. The results show that both Langmuir and Freundlich adsorption isothermal models are able to accurately describe the adsorption of these two ions. Investigation of SEM/EDS, TEM/EDS indicates that the two ions do not adsorb homogeneously on goethite owing to the different microstructures of goethite, and that the microspherical goethite has a greater adsorption capacity for chromium ions than the helical one. XPS data show that redox reaction of chromium on the surface of biomineralized goethite takes place in the adsorption of both Cr^3＋ and Cr^Ⅵ. The CrvI adsorbed on biogoethite is much easier to transform into CrIII than the oxidization of Cr^Ⅲ on the bio-goethite.

关 键 词：biomineralized goethite ADSORPTION CHROMIUM iron bacteria 

分 类 号：P578.2[天文地球—矿物学]