Sorption of Aniline on Selected Alfisols From the Eastern Coal Region

The sorptive behavior of aniline was investigated in two Alfisols from eastern coal regions. Batch adsorption/desorption studies (soil/solution ratio 1:5, aniline concentration 25 to 400 μg/ml) were performed on the prominent genetic horizons of each soil. Sorption was evaluated as a function of equilibrium pH and ionic strength (Na2SO4) of the supporting electrolyte and on selected horizons treated to remove organic materials (H2O2 oxidation) and secondary iron components (oxalate and DCB-extractable). The behavior of aniline in the B horizons was concentration-dependent, and at higher concentrations (>75 μg/ml) sorption exceeded that of the upper or A horizons and was reversible. Aniline sorption was pH-dependent, reflecting different mechanisms and sites of sorption in the A and B horizons. Binding of aniline in the A horizons was greater below the compound pKa; maximum sorption in B horizons occurred above the pKa. Sorption in the A horizon was controlled primarily by partially irreversible interaction with organic materials; the high degree of sorption in the lower horizons may have resulted from proton transfer reactions and binding of the anilinium ion to interlayer areas of phyllosilicate minerals.