Electroreduction of chloroacetic acids (mono-, di- and tri-) at polyNi(II)-tetrasulfonated phthalocyanine gold modified electrode

Abstract

The electroformation of polyNi(II)-tetrasulfonated phthalocyanine (poly-NiTSPC) film, on gold electrodes from an alkaline solution was investigated in order to improve the electrochemical detection of haloacetic acids (mono-, di- and tri-chloroacetic). The data obtained were compared to those obtained at bare Au electrode. The electrocatalytic activity of the poly-NiTSPC towards the chloroacetic acids reduction, promotes a negative shift of the peak potential (by ca. 250 mV) and an increase of the current intensity (by ca. 25%) compared to bare Au electrode. The concentration of chloride-ion in solution was obtained during electrolysis for each chloroacetic acid; and the number of electrons involved in haloacetic acids reduction and heterogeneous rate constant ( k) were evaluated by rotating disk electrode (RDE). These studies showed that the mechanism of catalytic reduction of chloroacetic acids can be expressed on the basis that the current-determining step in the electroreduction of chloroacetate ions must involve the removal of a halogen atom from the anion. The modified electrode showed an excellent sensitivity and detection limit towards haloacetic acid reduction.