Voltammetric monitoring photodegradation of EDTA based on carbon nanotubes-modified electrode

Abstract

This work described a fast and sensitive voltammetric method developed for monitoring the photodegradation of ethylenediaminetetraacetic acid (EDTA). Due to the unique properties of carbon nanotubes (CNTs) such as negative charges, large surface area and excellent electron transfer ability, metal ion namely Fe 3+ showed a pair of well-defined redox response peaks on the CNTs-modified electrode. When EDTA was present in the solution, the voltammetric response of Fe 3+ was suppressed due to the chelating interaction between Fe 3+ and EDTA. In acetate buffer solution, the concentration of EDTA was found to be inversely proportional to the decreased cathodic peak current in the range of 1.0 × 10 −6 to 1.0 × 10 −4 mol/L with a detection limit (3S/N) of 6.5 × 10 −7 mol/L. While EDTA was degraded by UV irradiation, the voltammetric response on the CNTs-modified electrode was enhanced due to the reduced amount of EDTA species chelating with Fe 3+. Accordingly, the concentration variation of EDTA during the photodegradation was analyzed. The effects of H 2O 2 and pH on the photodegradation of EDTA were investigated. Thus, the proposed CNTs-based voltammetry provided a useful analytical tool for studying the degradation of EDTA.