Binding of Polar Organic Contaminants at Water-Mineral Interfaces: Experimental and Computational Studies.

A controlling factor in the environmental fate of emerging polar organic contaminants is their sequestration within soil particles in natural soils and waters. However, it is not well understood the mechanisms responsible for the potential physical exclusion of these contaminants within soil particles. Interactions with smectite clay minerals are of particular interest because their structural chemistry can facilitate trapping of ‘guest' organic molecules within the interlayer space. Smectite-type clays are thus important both in natural and engineered soils. The focus of this talk will be on the combined application of spectroscopic experiments and molecular modeling simulations to elucidate the adsorption mechanisms of antibiotics and cyanotoxins at the aqueous-clay interface of montmorillonite. Adsorption was monitored using X-ray diffraction, infrared, and solid-state nuclear magnetic resonance spectroscopies and the structures and interactions deduced experimentally were assessed via Monte Carlo and molecular dynamics simulations. Throughout the activities of my research group, a similar approach is applied to provide complementary insights towards a mechanistic characterization and prediction of the factors underlying the environmental chemodynamics of organic molecules, including organic contaminants and natural organic matter.