Triazine herbicides transfer at the water/1,2-dichloroethane interface

A group of herbicides of the triazine family (atrazine, simazine, ametryn, prometryn, atratone, and terbutryn) at the water/1,2-dichloroethane interface has been investigated by cyclic voltammetry. The formal transfer energy (Delta(w)(o)G(t,i)(o)') was evaluated in acidic conditions (pH < pK(a)(w)). It was found that the chemical structure determines the transfer of these herbicides at the liquid-liquid interface. For thiotriazines the values of Delta(w)(o)G(t,i)(o)' are smaller than for chlorotriazines, indicating that the thiotrizines have more ability to protect the charge in the center of the molecule when it transfers across the interface than chlorotrizines. Ionizable triazine partition diagrams (potential vs pH) demonstrated that for all herbicides two transfer mechanisms were observed: facilitated proton transfer and ion transfer across the interface. (C) 2008 The Electrochemical Society.