Discrete site surface complexation constants for lanthanide adsorption to bacteria as determined by experiments and linear free energy relationships

Ngwenya, B.T., Magennis, M., Olive, V., Mosselmans, F.W. and Ellam, R. (2010) Discrete site surface complexation constants for lanthanide adsorption to bacteria as determined by experiments and linear free energy relationships. Environmental Science and Technology, 44(2), pp. 650-656. (doi: 10.1021/es9014234)

Abstract

Bacteria are abundant in many natural and engineered environments where they are thought to exert important controls on the cycling, mobility, bioavailability, and toxicity of metal contaminants. In order to probe their role in moderating the behavior of lanthanides, pH-dependent adsorption edges of 13 individual lanthanides and yttrium to the Gram-negative bacterium Pantoea agglomerans were used to generate discrete site surface complexation constants. The calculated surface complexation constants were compared with stability constants estimated using linear free energy relationships based on a number of hydroxyl-containing ligands. The experimental data suggests that lanthanide adsorption edges below pH 6.5 are consistent with adsorption to phosphate groups for the light and some of the middle lanthanides (La to Gd), whereas some of the middle and heavy lanthanides appear to favor carboxyl co-ordination (Tb to Yb), although exceptions occur in each grouping. The experimentally derived surface complexation constants for carboxyl coordination were of similar magnitude to stability constants estimated from linear free energy correlations using fulvic acid stability constants. The implication is that the adsorption of lanthanides to bacterial surfaces could be modeled reasonably well using lanthanide stability constants for natural organic matter, except perhaps at low pH where phosphate binding dominates.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ellam, Professor Rob and Olive, Dr Valerie
• Authors: Ngwenya, B.T., Magennis, M., Olive, V., Mosselmans, F.W., and Ellam, R.
• Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Environmental Science and Technology
• Journal Abbr.: EST
• Publisher: American Chemical Society
• ISSN: 0013-936X
• ISSN (Online): 1520-5851
• Published Online: 15 December 2009