Adsorption of benzene from aqueous solutions by bentonite treated with quaternary amines

The adsorptive properties of Wyoming bentonite, which has been tailored using various tetraalkylammonium (TAA+) ions, have been investigated for the selective removal of hazardous organic pollutants found in waters and soils contaminated by petrochemical spills. The effectiveness of the tailoring agents is evaluated by comparing the adsorption isotherms of benzene on both treated and untreated soils. Five TAA+-type compounds are investigated: ammonium (NH4+), tetramethylammonium (TMA+), tetraethylammonium (TEA+), tetrapropylammonium (TPA+), and tetrabutylammonium (TEA+). The optimum dose characteristics are determined for each tailoring cation. The adsorption capacity of the treated clay decreases for doses that exceed the optimum dose because of the increase in organic content in solution, which induces a reduction in the partition coefficient between organically coated solid and the liquid phase. Despite the similarity in nature of the TAA+ cations used in this study, significant differences in the adsorption capacities are obtained for the various compounds.