ACETATE SORPTION AND DESORPTION ON BOEHMITE SURFACES: THE INFLUENCE OF H2O UPON BINDING BEHAVIOR

Organic-mineral interactions at the mineral-water interface are of interest to geoscientists due to their controlling effects upon trajectory and rate of biogeochemical reactions such as electron-transfer, mineral dissolution and precipitation, and degradation/stabilization of organic molecules at this interface. Here, focus is placed upon the sorption and desorption of acetate (CH₃COOH) onto a series of synthesized boehmites (amorphous aluminum oxides). The boehmites vary in method procedure which result in differing morphologies and surface behaviors, and are characterized using a series of analytical techniques, including SEM imaging, XRD, and TGA/DSC analysis. Specifically we focus on the influence of the varying amounts of free and structural water present in each boehmite sample when acetate is used to probe the surface heterogeneity of these materials. We investigate the binding energetics and associated mechanics (i.e. bonding types at play here and anion exchange capacity) via flow-adsorption microcalorimetry, a direct and systematic assessment of the energy dynamics in a system.