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The studied Schiff-base compounds in this work are multitasked investigated as corrosion inhibitors and also, to improve the physical and mechanical properties of reinforced concrete. The efficiency inhibition of the two novel Schiff-base compounds named (DHSiMF) and (DHSiB) for corrosion of carbon-steel in aqueous media of 1 M HCl was assessed via electrochemical methods and loss in weight. FT-IR, 1H-NMR spectra and elemental analysis were used to confirm the structure of such compounds. It was found to have successful inhibition even at low concentrations in tested media, as an increase in inhibitor concentration led to an improvement in the inhibition efficiency. The weight loss results clearly demonstrate that DHSiMF of C-steel in 1 M HCl has a higher inhibition efficiency than DHSiB, with a maximum inhibition efficiency (85%) attained at 1 × 10–2 M from DHSiMF. Electrochemical experiments likewise revealed the same order, but with a maximal inhibitory efficiency of 98.1%. The addition of inhibitors to the corrosive media dramatically changed the anodic Tafel constants (βa) and cathodic Tafel constants (βc), indicating a mixed type nature. Electrochemical polarization curves illustrated the functions of mixed-type inhibition and the action of adsorption matching with the Langmuir adsorption isotherm. The ∆Gads values for DHSiMF and DHSiB at temperatures (ranging from 303 to 333 K) are − 34.42 kilojoule/mole to − 37.51 kilojoule/mole. These values indicate that the compounds' adsorption types are chemo-physical adsorption. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) experiments were used to check the existence of the protection layer on the surface of carbon steel by analyzing the morphologies of the corrosion effects and the formed chemical compositions of the corrosion outcomes. For the concrete, the findings suggest that the chemical reaction that takes place between the DHSiMF and DHSiB and the concrete mix will result in an increase in the flexural strength, the compressive strength, and the indirect tensile strength of the concrete that is made of the gravel and dolomite aggregate. [ABSTRACT FROM AUTHOR]

[Display omitted] • The anticorrosion effect of two inhibitors on C-steel in 1 M HCl was studied. • The polarization results show that (HBEDA) and (HBDETA) are mixed-type inhibitors. • The impedance data suggest the adsorption of the inhibitors on C-steel surface. • The Langmuir adsorption isotherm governs the adsorption mechanism. • QC and MC show that hetero atoms serve as active sites to facilitate adsorption. As part of the efforts made by many researchers to evaluate a lot of chemical compounds as inhibitors for carbon steel corrosion, this research focuses on novel two compounds of benzamide derivatives. The investigated compounds namely N, N -bis (p-hydroxybenzoyl) ethylenediamine (HBEDA) and N, N -bis (p-hydroxybenzoyl) Diethylenetriamine (HBDETA), were formulated then characterized using FTIR, 1HNMR, and elemental analysis to elucidate the structures chemically. Theoretical and experimental (electrochemical and morphology) studies made clear that (HBEDA) and (HBDETA) improve carbon steel (C-steel) inhibition efficiency in 1 M hydrochloric acid as concentrations increase (25, 50, 100, 150, 200, 250 ppm). The benzamide derivatives acted as interface corrosion inhibitors in an electrochemical impedance spectroscope (EIS) experiment, and they acted as mixed type corrosion inhibitors in a polarization test. They yielded best efficiency gains of 95.8 percent for HBEDA and 99.6 percent for HBDETA. Information collected from the EIS technique was studied in order to represent the corrosion inhibition procedure using an equivalent circuit (EC). The elevated K ads values and negative ΔG ads (-28.71, −28.79 kJ/mol) values of the two compounds (understudy) revealed that they were strongly and spontaneously adsorbed at C-steel/electrolyte connections respectively, and the adsorption isotherm of Langmuir fitted widely with the empirical data. The Surface examination (morphology) of metal employing energy dispersive X-ray (EDX) and scanning electron microscope (SEM) evaluations confirmed the adsorption of (HBEDA) and (HBDETA) on the substrate (C-steel). [ABSTRACT FROM AUTHOR]