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USGS2000

Forces dictating colloidal interactions between viruses and soil

The fate and transport of viruses in soil and aquatic environments were studied with respect to the different forces involved in the process of sorption of these viruses on soil particles. In accordance with the classical DLVO theory, we have calculated the repulsive electrostatic forces and the attractive van der Waals forces. Bacteriophages have been used as model sorbates, while different clays have been used as model sorbents. The equations used for the determination of the change in free energy for the process (Δ G ) takes into consideration the roughness of the sorbent surfaces. Results indicate that attractive van der Waals forces predominate the process of sorption of the selected bacteriophages on clays.

Chemosphere↗

USGS1999

Adsorption of bacteriophages on clay minerals

The ability to predict the fate of microorganisms in soil is dependent on an understanding of the process of their sorption on soil and subsurface materials. Presently, we have focused on studying the thermodynamics of sorption of bacteriophages (T-2, MS-2, and φX-174) on clays (hectorite, saponite, kaolinite, and clay fraction of samples collected from a landfill site). The thermodynamic study not only determines the feasibility of the process but also provides information on the relative magnitudes of the different forces under a particular set of conditions. The total free energy of interaction during sorption of bacteriophages on clays (Δ G ) has been assumed to be the summation of Δ G H (Δ G due to hydrophobic interactions) and Δ G EL (Δ G due to electrostatic interactions). The magnitude of Δ G H was determined from the different interfacial tensions (γ) present in the system, while Δ G EL was calculated from ζ-potentials of the colloidal particles. Calculated results show that surface hydrophobicities of the selected sorbents and sorbates dictate sorption. Among the selected bacteriophages, maximum sorption was observed with T-2, while hectorite has the maximum sorption capacity. Experimental results obtained from the batch adsorption studies also corroborated those obtained from the theoretical study.

Environmental Science & Technology↗