Experimental Study of Uranyl Adsorption onto Bacillus subtilis

• Published in: Environmental science & technology 2000-09, Vol.34 (17), p.3737-3741
• Main Authors: Fowle, David A, Fein, Jeremy B, Martin, Aaron M
• Format: Article
• Language: English
• Subjects: Applied sciences; Bacillus subtilis; Bacteria; Biological and physicochemical properties of pollutants. Interaction in the soil; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Experiments; Groundwaters; Natural water pollution; Pollution; Pollution, environment geology; Soil and sediments pollution; Soils; Uranium; uranyl; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es991356h

Uranyl adsorption onto the Gram-positive soil bacterium Bacillus subtilis was measured using batch experiments in 0.1 M NaClO4 as a function of pH, time, and solid:solute ratio at 25 °C. The experimental data were interpreted using a surface complexation approach. The experimental measurements constrain the stoichiometry and thermo- dynamic stabilities of the important uranyl-surface complexes. The U adsorption data require two separate adsorption reactions, with the uranyl ion forming surface complexes with the neutral phosphate functional groups and the deprotonated carboxyl functional groups of the bacterial cell wall:  R−POH0 + UO2 2+ ⇔ R−POH−UO2 2+ (log K = 11.8 ± 0.2) and R−COO- + UO2 2+ ⇔ R−COO−UO2 + (log K = 5.4 ± 0.2). These new stability constants, in conjunction with other experimental and predicted stability constants, may be incorporated in surface complexation models to determine the mobility and fate of U in bacteria-bearing water−rock systems.