Titre : Surface Chemistry of Environmentally-Important Organoarsenice Compounds Studied by ATR-FTIR, DFT Calculations, Calorimetry and Surface Complexation Modeling.
Endroit : Pavillon Roger-Gaudry, salle G-815 à 11 h.
Hôte : Professeur Patrick Hayes
La conférence sera prononcée (en anglais) par la professeure Hind A. Al-Abadleh, du Département de chimie et de biochimie de la Wilfrid Laurier University.
Résumé : Organoarsenic compounds are found in the environment from the bio-methylation of inorganic arsenic and from anthropogenic sources. They pose health and environmental risks due to their potential cycling to the most toxic forms of arsenic. The environmental fate of arsenic compounds depends on their surface interactions with geosorbents. Molecular-level understanding of the binding mechanism at liquid/solid interfaces demands integrating spectroscopic, calorimetric, computational chemistry and mathematical modeling methods. In this talk, I will show results on the adsorption/desorption thermodynamic and kinetic behavior of arsenate and methylated arsenicals, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) to/from hematite nanoparticles. Experimental results were complemented with DFT calculations of the geometry and IR frequencies of surface clusters as well as the adsorption state functions of ligand exchange reactions. Thermodynamic binding constants were extracted from applying the triple layer surface complexation model to adsorption isotherm and pH-envelope data. Rates of adsorption and desorption due to phosphate flow were also determined. The significance of these results will be discussed in relation to improving modeling tools and designing arsenic-removal technologies.
