Accession Number : ADA583718


Title :   Sorption of VX to Clay Minerals and Soils: Thermodynamic and Kinetic Studies


Descriptive Note : Final rept. Oct 2009-Sep 2010


Corporate Author : SCIENCE APPLICATIONS INTERNATIONAL CORP GUNPOWDER MD


Personal Author(s) : Morrissey, Kevin M ; Schenning, Amanda M ; Cheicante, Richard L ; Sumpter, Kenneth B


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a583718.pdf


Report Date : Dec 2012


Pagination or Media Count : 106


Abstract : Organophosphorus-based chemical warfare agents are unique military chemicals that are extremely toxic and could be found in the soils of military installations and former production facilities. Little data exists on the fate and transport of these chemicals in soil environments, particularly when the agent is present in low concentrations. This report summarizes data from a study in which isothermal titration calorimetry was used to examine the sorption of VX to clay minerals and soils. Thermodynamic characteristics such as observed enthalpy of binding, entropy, free energy, binding and dissociation constants, and saturation capacity were obtained. Complementary sorption/desorption profiles and batch equilibrium sorption isotherms were also generated during the study. Kinetic time-point samples were analyzed using a variety of analytical techniques to provide insights into the sorption pathways, and to distinguish sorption from degradation occurring in the bulk solutions. In a montmorillonite clay, there was a sharp break in the thermodynamic profile that corresponded to the lower critical temperature (LCT) of VX. The predominant mechanism above the LCT was an exothermic physisorption process, consistent with an ion exchange mechanism. Below the LCT, bimodal behavior was observed, with a second type of endothermic interaction occurring after the initial ion exchange.


Descriptors :   *CLAY MINERALS , *SOILS , *SORPTION , *VX AGENT , CALORIMETRY , CHEMICAL WARFARE AGENTS , CLAY , DESORPTION , DISSOCIATION , ENTHALPY , ENTROPY , EXOTHERMIC REACTIONS , FREE ENERGY , ION EXCHANGE , ISOTHERMS , KINETICS , SATURATION , THERMODYNAMICS , TITRATION , TOXICITY , TRANSPORT


Subject Categories : Geology, Geochemistry and Mineralogy
      Chemical, Biological and Radiological Warfare


Distribution Statement : APPROVED FOR PUBLIC RELEASE