NSF Award
0122761
0122761 Pignatello The objective of this research is to obtain a fundamental understanding of two kinds of adsorption-desorption hysteresis. These include thermodynamically irreversible sorption, in which adsorption and desorption follow different microscopic pathways, and hysteresis due to abiotic surface-catalyzed chemical transformation of the adsorbate where the products remain irretrievably bound to the solid. This research will focus on the principle thermodynamic sorbents of organic compounds in natural settings: macromolecular organic carbon (humic substances) and micrographitic OC (black carbon). Sorption experiments will be performed on well-characterized model sorbents, whose behavior can be better related to mechanism than whole natural geosorbents. Adsorption and desorption data will be used to compute an irreversibility index to quantify irreversible sorption hysteresis. Non-reactive test compounds will be trichloromethane, trichloroethene, benzene, and naphthalene, and the reactive test compounds will be phenol, catechol, and pyrogallol. An understanding of hysteresis is crucial to modeling a chemical's fate, defining soil or sediment quality criteria, developing remediation technologies, and setting standards for acceptable levels of contamination after remediation. This is a collaborative research grant between Connecticut Agricultural Experiment Station (BES-0122761) and Rensselaer Polytechnic Institute (BES-0122863). ***
