An optimized chemically modified electrode based on copper oxide nanorods for the quantification of chemical oxygen demand in wastewater

• inorganic–organic matrix-based modified glassy carbon electrode was prepared. • investigation methods used were LSW, EIS, and amperometry. • by amperometry technique LOD was 15.75 µM glucose. • Chit-CuONRs /GCE is stable, sensitive, reproducible for COD determination. • Chit-CuONRs /GCE is a sensing architecture for COD determination in wastewater. The present research has used newly prepared copper nanorods (CuONRs) and Chitosan or Nafion polymer, to develop an inorganic–organic-organic matrix-based modified glassy carbon electrode (Chit-CuONRs/GCE or Naf-CuONRs/GCE), as a sensing architecture for chemical oxygen demand (COD) determination in wastewater. The electrocatalytic behavior of the CuONRs in the electrode matrix was investigated by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and amperometry measurements. Furthermore, by using a Box-Behnken response surface experimental design technique, the preparation of the composition of the modifying matrix was optimized. The analytical parameters of the optimized modified electrode (i.e., a large linear domain of the calibration curves against glucose, low LOD, good repeatability and reproducibility) have enhanced values compared with an unoptimized one. Overall, CuONRs from the inorganic–organic matrix of the modified electrode serve as a very efficient electrocatalyst in wastewater analysis, with a recovery percentage equal to 95.65%, when compared with a standardized method.