Thompson Rivers University

The environmental fate of arsenicals from the surface chemistry of hematite nanoparticles

Prof. Hind A. Al-Abadleh, of chemistry and biochemistry at Wilfrid Laurier University, Waterloo, Ontario presents as part of the Environmental Sciences Seminar Series.

Abstract:

The environmental fate of arsenic compounds depends on their surface interactions with geosorbents that include minerals and natural organic matter (NOM).

In general, molecular-level understanding of surface processes at solid/liquid interfaces demands using simple model systems and integrating spectroscopic, calorimetric, computational chemistry and mathematical modelling tools.

In this talk, I will show results on the surface chemistry of arsenate and methylated arsenicals, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) with hematite nanoparticles.

Spectroscopic data were collected using attenuated total internal reflection Fourier transform infrared spectroscopy (ATR-FTIR) and experimental results were complemented with density functional theory (DFT) calculations.

Flow calorimetric measurements were also completed to gain insight into surface charge and heats of adsorption. Thermodynamic binding constants were extracted from applying the triple layer surface complexation model to adsorption isotherm and pH-envelope data.

The kinetics of arsenicals interaction with hematite nanoparticles pre-exposed to three types of low molecular weight organics will also be discussed. The significance of these results will be discussed in relation to improving modelling tools and designing arsenic-removal technologies.