Surface Interactions of s-Triazine-Type Pesticides. An Electrochemical Impedance Study

Two pesticides, atrazine and terbutylazine, have very similar chemical structures differing only by iso-propyl and terc-butyl substituents on their 6-amino-groups. This minor structural difference causes profound effects in decomposition rates in the environment leading to a ban of atrazine. Here we present a study of adsorption at ideally polarized electrochemical interface in the absence of specifically adsorbed halides. The interfacial charge and the temperature determine which type of an adsorbed film is formed. The double layer capacitance measurements yield the critical temperature of the surface film transition, which is markedly different for both pesticides. The time- resolved impedance spectroscopy indicates slow changes of the film structure that becomes disordered and can be characterized in terms of the fractal geometry.