Effect of bacterial exopolymer on lead (II) adsorption by γAl2O3 in seawater

The influence of exocellular polymeric organic materials on adsorption of Pb(II) by gamma aluminium oxide (γAl2O3) was evaluated for Pb concentrations ranging from 10−7 M to 10−5 M and surface concentrations from 1 m2 l−1 to 100 m2 l−1. Exopolymer produced by two strains of the marine film forming bacterium Pseudomonas atlantica was employed in these studies at concentrations ranging from 1 mg l−1 to approximately 90 mg l−1. No observable influence of exopolymer on Pb(II) adsorption was seen under the experimental conditions considered with the exception of reduced Pb adsorption at pH > 7 for the highest polymer concentration and lowest specific surface area of γAl2O3. The lead binding characteristics of γAl2O3 and exopolymer were independently measured and modelled with multiple binding site models. Calculations using the model parameters confirm that the Pb binding strength of bacterial exopolymer is insufficient to perturb Pb(II) adsorption even at P. atlantica polymer concentrations substantially higher than those which are anticipated in marine environments.