Thermodynamic modeling of metal adsorption onto bacterial cell walls: Current challenges

This chapter summarizes research that improves our understanding of metal-adsorption reactions involving bacterial cell walls. The chapter covers two general types of investigations: (1) those that aim to improve our molecular-scale understanding of metal adsorption onto bacteria, thereby improving the accuracy of thermodynamic bacterial adsorption models and (2) those that aim to improve our ability to apply thermodynamic models of metal-bacterial adsorption to complex realistic settings. The first type of research involves a range of experimental approaches, and the most common approaches are described here. The second type of research results from the need to balance the flexibility that comes with chemical sophistication in geochemical models with the practical impossibility of modeling the complexity of real systems at a molecular scale. Hybrid approaches that incorporate some degree of molecular-scale insight with testable simplifying assumptions are described and offer some hope for extrapolating our new-found molecular-scale understanding of metal-bacterial adsorption reactions to estimate mass transport in bacteria-bearing systems. The objective of this chapter is to describe both progress and remaining challenges in order to promote research that ultimately will yield accurate and flexible models of the effects of bacterial adsorption on metal distributions and speciation in natural geologic systems. (c) 2006, Elsevier Inc.