Sorption and Abiotic Transformation of Aniline and α-Naphthylamine by Surface Soils

Abstract

Improving the assessment and subsequent remediation of sites contaminated with aromatic amines requires differentiating between reversible and irreversible sorption processes and quantifying the controlling parameters. The interaction of aniline and {alpha}-naphthylamine with five surface soils from CaCl{sub 2} electrolyte solutions was studied for a 2 month equilibration period using a batch equilibration method. Soils varied in pH, cation exchange capacity, and organic carbon content. Reversible sorption processes reached equilibrium within the first day of equilibration for all soil-solute combinations while irreversible binding and transformation proceeded for much longer times. After 1 day, increases over time in the ratio of reversibly sorbed concentrations to solution concentrations were shown to primarily result from nonlinear sorption coupled to decreasing aqueous solute concentrations from irreversible binding/transformation. Dimer formation hypothesized to be mineral catalyzed was confirmed with GC/MS and UV-vis detection for {alpha}-naphthylamine, but was not observed for aniline. Fast reversible sorption processes reduced aromatic amine concentrations in solution and retarded irreversible reactions indicating processes occur in parallel.