Sensitive and Green Method for Determination of Chemical Oxygen Demand Using a Nano-copper Based Electrochemical Sensor

Copper nanoparticles (nano-Cu) were electrodeposited on the surface of glassy carbon electrode (GCE) potentiostatically at −0.6 V vs. Ag/AgCl for 60 s. The developed nano-copper modified glassy carbon electrode (nano-Cu/GCE) was optimized and utilized for electrochemical assay of chemical oxygen demand (COD) using glycine as a standard. The surface morphology and chemical composition of nano-Cu/GCE were investigated using scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDX), respectively. The electrochemical behavior was investigated using linear sweep voltammetry (LSV) which is characterized by a remarkable anodic peak at ∼0.6 V, compared to bare GCE. This indicates that nano-Cu enhances significantly the electrochemical oxidation of glycine. The effect of different deposition parameters, such as Cu2+ concentration, deposition potential, deposition time, pH, and scan rate on the response of the developed sensor were investigated. The optimized nano-Cu/GCE based COD sensor exhibited a linear range of 15 to 629.3 ppm, and a lower limit of detection (LOD) of 1.7 ppm (S/N=3). This developed method exhibited high tolerance level to chloride ion (0.35 M chloride ion has minimal influence). The analytical utility of the prepared COD sensor was demonstrated by investigating the COD recovery (99.8±4.3) and the assay of COD in different water samples. The results obtained were verified using the standard dichromate method.