Gravimetric, electrochemical surface and density functional theory study of acetohydroxamic and benzohydroxamic acids as corrosion inhibitors for copper in 1 M HCl

The inhibition effect of acetohydroxamic acid (AHA) and benzohydroxamic acid (BHA) on corrosive dissolution of copper in 1 M HCl medium was studied using gravimetric, electrochemical (PDP and EIS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and density functional theory (DFT) methods. Inhibition efficiencies of AHA and BHA are increases on increasing their concentrations and decreases as temperature increased. Results showed that AHA and BHA acted as mixed type inhibitors. The BHA and AHA exhibited the maximum efficiencies of 98.49%and AHA 95.90% respectively. Adsorption of the BHA and AHA obeyed the Langmuir adsorption isotherm model. Gibbs free energy of adsorption (ΔGads), adsorption constant (Kads) and activation energy (Ea) values showed that both BHA and AHA strongly and spontaneously adsorbed on the metal (copper) surface/electrolyte interfaces. The gravimetric and electrochemical studies were supported by EDS coupled SEM analyses. Inhibitive properties of BHA and AHA obtained from experimental methods was supported by DFT. Numerous parameters were computed and discussed in order to described their adsorption behaviour. Keywords: Acid corrosion, Copper, Density functional theory, Organic inhibitors, SEM-EDS, Mixed type, Adsorption isotherm

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