Date of Award:

5-1970

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Soil Science

Committee Chair(s)

D. W. Hendricks

Committee

D. W. Hendricks

Committee

F. J. Post

Committee

R. L. Smith

Committee

H. B. Peterson

Abstract

The objective of this investigation was to study the effect of chemical competition on thermodynamics of bacterial adsorption. This was done using an experimental system consisting of Mendon silt loam soil as the adsorbent, Staphylococcus aureus as a common adsorbate and sodium chloride (NaCl), sodium lauryl sulfate (SLS), and peptone as competitive adsorbates.

The bacterial adsorption on soil both with and without chemical competition followed Langmuir type isotherms. From the equilibrium data, thermodynamic functions such as free energy, ΔF°, enthalpy, ΔH°, and entropy, ΔS°, were calculated. Observed positive ΔH° values indicated that the bacterial uptake in both noncompetitive and competitive environments is endothermic. Bacteria and soil both have a negative charge. A positive ΔH° value is attributed to the repulsion between the bacteria and soil particles. For a non-competitive system, the observed ΔH° value was 8.50 kcal-mole-1. Relatively higher ΔH° values were obtained in the presence of peptone and NaCl. These values were 24.0 kcal-mole-1 and 23.0 kcal-mole-1 for peptone and NaCl respectively, suggesting that the bacterial uptake is much more endothermic in the presence of these chemicals. The lower ΔH° value (3.72 kcal-mole-1) observed in the presence of SLS indicated that bacterial adsorption is relatively less endothermic in the presence of such a chemical.

In all the sorbent-sorbate systems studied, observed ΔS° values were positive indicating that the bacteria are more disordered in the adsorbed phase than they are in the solution phase. Observed ΔF° values for all the adsorption systems were negative, indicating that the bacterial adsorption in both competitive and noncompetitive environments is spontaneous.

Checksum

49e77819eda6e68edc44e0aff19c6f61

Download

Included in

Soil Science Commons

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .