Organic emerging contaminants are a growing concern for drinking water treatment as their presence in the environment continues to grow.  Techniques have recently been developed to accurately model the adsorption of neutral organic contaminants onto polymeric resins.  This study intends to expand the present techniques to include the removal of anions through anion exchange resins.  This was done by performing a training set of Freundlich isotherms and using multiple linear regressions to determine the individual descriptors of the poly-parameter linear free-energy relationships (pp-LFERs).  Three representative resins, Amberlite IRA-910 (strong base polystyrene), Amberlite IRA-96 (weak base polystyrene), and Purolite A860 (strong base polyacrylate), was used to study the removal mechanisms of various neutral and anionic compounds.  A hypothetical bulk phase of ideal gas was applied to determine the exact mechanisms contributing to the ion exchange process by eliminating solute-solvent interactions.  The ion exchange resins consistently showed that ion exchange remained stable and dominated over adsorption forces over the range of water and wastewater pHs (4-10).  Thus far the isotherms have demonstrated that the resins have an affinity for compounds in the following order: aromatic carboxylates > benzenesulfonate > anilines > phenols > nitrobenzene.  This preference is due to the differences in non-electrostatic interactions of the compounds such as their hydrogen donating/accepting capability, their affinity for Van der Waals and p-p interactions, and the size of the molecular cavity in solution.  The isotherms also demonstrate IRA-96 to have a greater removal capacity than IRA-910, followed far behind by A860.  Ion exchange capacity and hydrophilicity are likely responsible for this ordering.  With the above findings and the development of pp-LFERs, a predictive model can be developed to estimate the adsorption of various compounds onto anion exchange resins.

Understanding and modeling the sorption of anion exchange resins using poly-parameter linear free-energy relationships and phase conversion

246th National Meeting (2013)

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