PARENT SESSION
3A Advances in environmental analytical chemistry
9:00 AM to 7:00 PM, Tuesday, 08 May 2001

(T/EH095) Investigation of sorption isotherms and solute transport in soil columns of aromatic amines on soils from a former gas works.

Trümpler, Isabel¹, Meinzer, Daniel ^1,2, Stingel, Danny ¹, von Löw, Eberhard², Ensinger, Wolfgang¹, ^{1 2}

ABSTRACT- Aromatic amines in soil and wastewater of former gas works were determined to carry out risk assesments of ground water contamination. Due to their high polarity and water solubility amines are very mobile in aqueous systems. However, the amino group is also capable of sorption to the soil matrix. We conducted solute/soil experiments with selected analytes (e.g. anilines, amino toluenes, amino biphenyles) which had previously been identified in gas works ground water samples. As sorbents, two kinds of soil were selected and characterized by gas adsorption and grain size separation. Adsorption isotherms were obtained by batch experiments and calculated according to Brunauer-Emmett-Teller (BET) and Langmuir equations. Comparison of the obtained constants allows a prognosis about the behaviour of the analytes in a solute/soil system. In case of amino toluenes, for example, a lower value of the sorption capacity N_max was obtained with the BET equation than with the Langmuir equation. This indicates that the surface of the sorbent is covered by sorbate multilayers. In contrast, the sorption constant k was found to be highest with diamino toluenes. This might be explained by the fact that these exhibit the greatest polarity. Furthermore, experiments with contact times of about 3 months were undertaken to investigate sorption in narrow pores. To understand the transport processes of aromatic amines in the solute/soil system, experiments with soil columns were performed. First results are in good accordance with sorption parameters obtained by batch experiments. In case of aniline, for example, an early breakthrough was observed, which would have been expected due to the low value of the sorption constant k.

Key words: sorption isotherms, aromatic amines, solute transport, soil columns