FeO-Cu-BTC/MWCNTs modified electrodes for real-time chlorine monitoring in aqueous solution.

A efficient sensor is presented for detecting free chlorine in water by decorating glassy carbon electrodes (GCE) via multi-walled carbon nanotubes (MWCNTs) and FeO-Cu-BTC composite. After the characterization of prepared materials by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) techniques, and N adsorption-desorption isotherm, the electrochemical properties of FeO-Cu-BTC/MWCNTs/GC-modified electrode were assessed with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV and chronoamperometry measurement in phosphate buffer solution with pH 7.0 proved the capability of the designed sensor to detect free chlorine. With amperometric detection, the modified electrode exhibits a linear response in the 0.1 to 400.0 ppm range towards free chlorine with a detection limit (LOD) (S/N = 3) of 0.0044 ppm, sufficient to control swimming pool water. To assay the practicability of the designed sensor in real situations, interferences of common ions and dissolved oxygen were tested on free chlorine determination and showed admirable selectivity. The proposed sensor also provides satisfactory results of free chlorine measurement in different real samples of swimming pool waters. The results of this work affirmed that MOF composite could be a promising material in the architecture of free chlorine electrochemical sensors in aqueous media.