Comparative study of Cd(II) and Cr(VI) biosorption on Staphylococcus

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Comparative study of Cd(II) and Cr(VI) biosorption on Staphylococcus
xylosus and Pseudomonas sp. in single and binary mixtures

Biosorption of Cd(II) and Cr(VI) ions in single solutions using Staphylococcus xylosus and Pseudomonas sp., and their selectivity in
binary mixtures was investigated. Langmuir and Freundlich models were applied to describe metal biosorption and the influence of pH,
biomass concentration and contact time was determined. Maximum uptake capacity of cadmium was estimated to 250 and 278 mg g1,
whereas that of chromium to 143 and 95 mg g1 for S. xylosus and Pseudomonas sp., respectively. In binary mixtures with Cd(II) ions as
the dominant species, there is a profound selectivity for cadmium biosorption, reaching 96% and 89% for Pseudomonas sp. and S. xylosus,
respectively, at 10 mg l1 Cd(II) and 5 mg l1 Cr(VI). Interesting, when chromium (VI) ions are the dominant species, there is selectivity
towards chromium around 92% with S. xylosus only.


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