Extract Preparation of Waste Lady Finger Caps Using Ethanol, Generation of Extract’s Layers on Copper Through Drop Casting Without and with NiO Nanoparticles, and Study of their Corrosion Performances in Saline Water

This work explains the use waste lady finger caps (LFC) coatings to prevent copper (Cu) corrosion in a salty environment (0.5 M NaCl). LFC has been extracted in ethanol (EALFC), and coatings of EALFC on Cu have been developed by drop casting (DC) in layers (1–4). The biomolecules of EALFC have been established by UV-vis and FTIR spectroscopy (UVS and FRS). The corrosion investigation of the coated Cu is conducted by open circuit potential (OCP) curves, Tafel polarization curves (TPC), and electrochemical impedance spectroscopy (EIS). The results have conveyed that three layers of EALFC give the best performance (TPC-89%, EIS-80%) among all tested layers. In further work, NiO nanoparticles (NONPs) are mixed (2, 4, and 6 mg) in EALFC and coated on Cu by DC. The effects on the prevention efficiencies of EALFC coatings have been investigated using OCP, TPC, and EIS. It has been found that NONPs have increased the prevention efficiencies of EALFC coatings. The results have communicated that 4 mg of NONPs with three layers of EALFC have given the best performance (TPC-96%, EIS-87%) among all tested amounts of NONPs. The surface investigations done by field-emission scanning electron microscopy (FESEM), optical microscopy (OM), and atomic force microscopy (AFM) are supporting the above results. The water contact angles (WCA) of the bare and coated surfaces are also measured, which is also in support of the results achieved. The possible reason for prevention is explained using a schematic based on the achieved results.