ELECTROCHEMICAL BEHAVIOR AND ANALYSIS OF MONURON HERBICIDE IN WATER USING VOLTAMMETRIC METHODS AND PRE ACTIVATED CARBON PASTE ELECTRODE

This research work dealt with the electrochemical behavior and voltammetric analysis of monuron, a phenyl urea herbicide. The sensitive enhancement of the monuron electrochemical signal, using a pre-activated carbon paste electrode, and the explanation of its mechanism were the main findings of this study. Unlike most used herbicides (linuron, diuron, fenuron, etc), monuron was rarely studied before by electrochemical methods. Indeed the square wave voltammetry allowed to optimize and to analyze monuron in water samples; the results showed two linear ranges of concentration: from 1.98 to 0.39 µg mL-1 and from 0.35 to 0.08 µg mL-1, with detection and quantification limits of LOD= 0.016 µg mL-1 and LOQ= 0.054µg mL-1 respectively. Besides these quantitative results, the anodic oxidation of monuron has been explained by an irreversible adsorption-controlled process, following a “one electron – one proton” mechanism

Noise spectra of K+ and NH4+ ions at over-limiting current in an electrochemical system with a cation exchange membrane

The present work investigates the effect of the counter ion nature on the noise of the over-limiting current (Iov). Moreover, the electrochemical methods, current voltage curve (I-V) and the chronopotentiometry (V-t) measurements are applied. The over-limiting current is always accompanied by a neat electrical noise. It is a well accepted experimental phenomenon. The study of this noise may contribute to a better understanding of the Iov and the feasibility of electrodialysis operation at this current in terms of energy consumption. The electrical noise depends directly on the counter ion nature. The power spectral density of the membrane's potential fluctuation was obtained via Fourier analysis of the time series recorded during the transport of counter ions (K+ and NH4+). The spectra are evaluated above the limiting current indicating the differences between the K+ and the NH4+. It is found that the cation NH4+ presents a singular behaviour and the noise is minimal