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The corrosion hindrance of Cu in 2.0 M HNO3 solution by 2-amino-6-methyl-5-oxo-4-phenyl-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile compound has been studied, using Potentiodynamic Polarization (PP), AC Impedance (EIS), Electrochemical Frequency Modulation (EFM) techniques. Also, EIS test was utilized to confirm the corrosion protection mechanism. 2-amino-6-methyl-5-oxo-4-phenyl-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile compound is suggested as a mixed kind inhibitor. SEM and EDX investigations of the Cu in 2.0 M HNO3 surface revealed that assembles protect Cu from corrosion by adsorption on its surfaces by a forming coating film. Clearly, the assembled mechanisms play a role as a barrier to corrosive solution.

Water pipes and drinking water quality deterioration in distribution systems and sea water desalination impose the use of corrosion inhibitors. The protective effect of spiropyrazole derivatives against Q235 steel and its adsorption performance were examined in solution of 1 M HCl utilizing TP (Tafel polarization), electrochemical frequency modulation (EFM), and electrochemical impedance spectroscopy (EIS) tests. The outcome data from hindrance efficiency rise with the dose of inhibitor. The orders of %IE of spiropyrazole derivatives are given: (1) &gt, (2) &gt, (3).It was noted that the values of EHOMO and ELUMO dropping in order run parallel to the improvement in %IE, which support the preceding order. EIS spectra exhibited one capacitive loop and approve the protective ability. Molecular docking was utilized to get a full picture on the binding mode among spiropyrazoles derivatives and the receptor of 3tt8-hormone of crystal structure examination of Cu human insulin derivative. The morphology of protected Q235 steel was evaluated by checking electron magnifying instrument innovation with energy dispersive X-beam spectroscopy (SEM&ndash, EDX).

Rates of corrosion for copper were monitored in aerated stagnant 2 M HNO3 solutions at different temperatures (25-55 °C) using Tafel extrapolation method, electrochemical impedance spectroscopy technique, non-destructive electrochemical frequency modulation (EFM) technique and weight-loss method, accompanied by EDX examinations, molecular docking, molecular dynamics, and quantum chemical calculations. Some spiropyrazoles derivatives were introduced as corrosion-safe inhibitors. Compound (1) has the best inhibition activity (89.9% at 11 × 10−6M). Tafel plots indicated that these compounds acted mainly as mixed-type inhibitors. The inhibition process was ascribed to the formation of an adsorbed film on the copper surface that protects the metal against corrosive agents. EDX examinations of the electrode surface confirmed the existence of such adsorbed film. The inhibition efficiency increased by increasing the concentration of spiropyrazoles compounds, while it decreased by increasing the temperature, this expresses on the physical adsorption. Activation energy has been calculated in the existence and nonexistence of a number of concentrations from spiropyrazoles derivatives by measuring the corrosion rate obtained from the weight loss method at different temperatures. It was found that the activation energy in the presence of spiropyrazoles derivatives is higher than that in 2 M HNO3 solution alone. The adsorptive behavior of spiropyrazoles compounds followed Freundlich -type isotherm.