Complexes and Compounds: Arsenic, Nickel and Mercury
- PhD student Adrian Adamescu (joint with Hind Al-Abadleh, WLU), is examining the relative stability of outer- and inner-shell complexes of organic arsenic compounds and iron oxides (which are models for soil particles). Solvent effects are included both implicitly (using a solvent model) and explicitly (including 4 or more water molecules in the complex). He is determining the potential energy profile for the outer- to inner-shell reaction.
- MSc student James Vey (joint with Scott Smith, WLU), is examining quenching of the fluoresence of tryptophan (a model for dissolved organic matter) by Ni2+. We will also calculate quantum yields to determine whether the experimentally observed fluorescence quenching is primarily static (rather than dynamic). In this case, experimentally observed quenching could be used to fit equilibrium binding constants for naturally fluorescent ligands which would enable the prediction of Ni speciation. This could be used to predict the equilibrium binding portion of the Ni Biotic Ligand Model.
- We are examining the use of NaClO(aq) spray for the simultaneous control of SO2, NO and Hg0. This is a collaboration with D. N. Shin, Research Institute of Industrial Science and Technology, Korea. Sodium hypochlorite solution has been widely used as an additive for enhancing SO2, NO, and Hg0 removal in wet scrubbers. However, the removal of each of these species is uniquely dependent on the pH, making their simultaneous removal difficult. Also, in the traditional wet scrubber, large volumes of NaClO(aq) are required, adding the problem of a secondary pollutant. Our study proposes a new design to overcome these problems.
- We have examined the oxidation of elemental mercury using pulsed corona discharge (PCD). This was a collaboration with D. N. Shin, Research Institute of Industrial Science and Technology, Korea. Coal-fired power plants are the main anthropogenic source of Hg(0) which is subsequently converted into highly toxic methyl mercury species via natural processes. PCD is a promising approach to control SOx, NOx and HCl in flue gases and concurrent PCD control of Hg0 would therefore be a highly desirable process.
- Adrian Adamescu, MSc student (joint with Hind Al-Abadleh, WLU), examined the binding of arsenic to various organic and inorganic ligands. The biotransformation of organic arsenic to inorganic arsenic under anaerobic conditions may pose a significant environmental risk. For example, it is known that the organoarsenical roxarsone (which is used as a feed additive) can be converted to As(V) which is both more toxic and more water soluble.