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

• Published in: 地质学报（英文版） 2006, Vol.80 (4), p.597-603
• Main Authors: SUN Zhenya, ZHU Chunshui, HUANG Jiangbo, GONG Wenqi, CHEN Hesheng, MU Shanbin
• Format: Article
• Language: English
• ISSN: 1000-9515
• DOI: 10.3321/j.issn:1000-9515.2006.04.016

P5; 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 CrⅢ or CrⅥ 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 Cr3+ and CrⅥ 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 Cr3+ and CrⅥ. The CrⅥ adsorbed on biogoethite is much easier to transform into CrⅢ than the oxidization of CrⅢ on the bio-goethite.