The Impact of Ionic Strength on the Adsorption of Protons, Pb, Cd, and Sr onto the Surfaces of Gram Negative Bacteria: Testing Non-Electrostatic, Diffuse, and Triple-Layer Models


Bacterial surface adsorption reactions are influenced by electric field effects caused by changes in ionic strength; however, existing datasets are too sparse to definitively constrain these differences or to determine the best way to account for them using thermodynamic models. In this study, we examine the ionic strength dependence of proton and metal adsorption onto the surfaces of Pseudomonas mendocina and Pseudomonas putida by conducting proton, Cd(II), Pb(II), and Sr(II) adsorption experiments over the ionic strength range of 0.001 to 0.6 M. Chosen experimental results are thermodynamically modeled using a non-electrostatic approach, a diffuse layer model (DLM), and a triple-layer model (TLM). The results demonstrate that bacterial surface electric field effects are negligible for proton, Cd, and Pb adsorption onto P. putida and P. mendocina, and that the discrete site non-electrostatic model developed in this study is adequate for describing these reactions. The extent of Sr adsorption is influenced by changes in the bacterial surface electric field; however, the non-electrostatic model better describes Sr adsorption behavior than the DLM or TLM. The DLM and TLM greatly overpredict the effect of the electric field for all adsorption reactions at all ionic strengths tested.


Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Adsorption; Bacteria; Cadmium; Diffusion; Electric field effects; Electric fields; Lead; Mathematical models; Protons; Strontium; Surface chemistry; Thermodynamics; Adsorption reactions; Datasets; Gram negative bacteria; Thermodynamic models; Ionic strength; proton; bacterial cell; cell surface; controlled study; electric field; electricity; experimental model; Gram negative aerobic rods and cocci; intermethod comparison; mathematical model; nonhuman; prediction; priority journal; Pseudomonas mendocina; Pseudomonas putida; Electrostatics; Metals; Heavy; Models; Biological; Surface Properties; Cd; Diffuse layer; Electrostatic; Pb; Sr; Triple layer

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Article - Journal

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© 2005 Academic Press Inc., All rights reserved.

Publication Date

01 Jun 2005