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Adsorption of environmentally important compounds
on the surface

Our electrochemical impedance study was focused on adsorption and surface interactions
of s-triazine-type pesticides, which are important parameters for environmental pollution.
We have found that even a small difference in the chemical structure of bioactive molecule
may cause significant differences in the accumulation properties at heterogeneous interfaces.  Film phase transitions are characterized by a critical transient temperature Tc above which a condensed phase cannot be formed. The critical temperatures of the surface phase transition of monomolecular films from fluid-like form to condensed form at given concentration were estimated. The remarkable difference of these values is one of the reasons why these two herbicides comport so differently at contamination of natural heterogeneous systems.
The results correspond to agronomic observations that terbutylazine is adsorbed better
at upper surface layers than atrazine. Terbutylazine is therefore decomposed faster and
does not contaminate water sources. We suggest that estimation of the critical temperature
of the surface phase transition obtained from EIS enables  prediction of accumulation properties of pesticides at natural interfaces.

 publications   2000-2006