Clean Technology 2008
K. Vanka, Y. Houndonougbo, N.R. Lien, J.M. Harris, L.M. Farmen, D.W. Johnson, B.B. Laird, W.H. Thompson
University of Kansas, US
nanocoatings, multilayers, metal binding
Electronic structure and molecular dynamics calculations are being used to investigate ligand-based nanocoatings for use in drinking water purification applications. The aim is to use computational chemistry to aid in the development of design principles for water purification systems based on adsorption of inorganic contaminates by inexpensive mesoporous substrates functionalized with low-cost ligands. These systems can provide simple, low-cost water purifiers that meet the needs of underdeveloped countries (as well as more specialized applications for developed economies). The key to improving existing systems of this type and expanding to other toxic metals is the identification of ligand candidates and the understanding of ligand-metal binding energies and structures. We employ density functional theory calculations to address this, focusing on arsenic and selenium contaminates and thiol- and carboxylic acid-functionalized ligands. Currently there is limited understanding of the binding and structures of such systems. The computations are generating new insight into the ligand-As and ligand-Se complexes by obtaining binding energies for up to three ligands, the characteristics of the lowest energy structures, the energies to form larger complexes, solvation effects, and the dependence of binding upon speciation. These are all important considerations in the design of multilayer nanocoatings for water purification.