A new electrochemical sensor is reported for the based on the application of noble bimetal nanoparticles (gold and copper) to polymeric-carbon-modifiers for the reduction of nitrate. This sensor was designed for nitrate ion measurement at the surface of pencil graphite electrode modified by a nanocomposite. The modification was the electrosynthesis of gold nanoparticles on the MWCNT/copper-polyaniline (Cu-PANI) nanocomposite. Physicochemical properties of the synthesized hybrid nanocomposites and their surface performance efficiency are characterized using microscopic, spectroscopic, and electrochemical techniques. At optimized pH, the nitrate peak current (at working potential of 1084 mV versus Ag/AgCl reference electrode) was linear in the concentration range 0.8-30.0 μM with a detection limit of 0.09 μM using differential pulse voltammetry. Modified sensor was successfully implemented to quantify nitrate ions in wastewater resulting from the production line for industrial barium chromate and an example of aqueduct water with appropriate recovery levels. • Aniline was polymerized in phosphoric acid solution using peroxydisulfate as an initiator. • MWCNT@CuNPs@PANNSs@AuNPs nanocomposite on PGE electrode was revealed specific recognition for NO3-. • The electrochemical sensor displayed high selectivity and sensitivity for the detection of NO3-.
Keywords: Differential pulse voltammetry; Electrochemical study; Nitrate sensor; Noble metal nanostructures,; Pencil graphite electrode; Polyaniline nanocomposite.