Smectite-chitosan-based electrodes in electrochemical detection of phenol and its derivatives

In this paper smectite-chitosan bionanocomposite (Sm-C) based on smectite (SM) from Crni Timok (Black Timok) basin, Serbia, was synthesized and characterized using chemical analysis, XRD and FTIR. The SM-C obtained was used for the modification of a glassy carbon electrode (GCE). The modified electrode (GCE/SM-C) was tested in the electrooxidation of phenol and different nitrophenols in acidic and alkaline solutions. Cyclic voltammograms (CV) obtained for GCE/SM-C, contrary to that obtained for the bare glassy carbon electrode, exhibited multiple oxidative peaks. The cathodic limit set to allow encompassing of nitro group reduction increased sensitivity for 4-nitrophenol detection. It also led to the appearance of additional peaks of 2-nitrophenol and decrease of the electrode passivation rate. The first-order derivative linear sweep voltammetry improved the sensitivity of the detection of different phenolic compounds from their mixed solution. The application of GCE/SM-C in alkaline environment led to increased current response while lowering the passivation rate. The quantitative determination of phenol and nitrophenols in a mixture, based on electrooxidation, had some disadvantages in both acidic and alkaline solution. Nevertheless, the concept of electrooxidation as a method for the detection and distinction of phenol and its nitro derivatives from water solution was proven.