Chloride–induced corrosion of carbon steel reinforcements is one of the most important failure mechanisms of reinforced concrete structures. Organic corrosion inhibitors containing different functional groups were analyzed using cyclic potentiodynamic polarization to determine their effect on the pitting potential of carbon steel reinforcements in a 0.1 M Cl– contaminated simulated concrete pore solution. It was found that organic compounds with π–electrons in a functional group had better performance. This is attributed to the high density of highest occupied molecular orbital energies found in carboxyl group π–bond. Accordingly, increasing the tendency of donating π–electrons to the appropriate vacant d–orbital of the carbon steel, forming an adsorption film. The best corrosion inhibition performance was achieved by poly–carboxylates followed by alkanolamines and amines. In addition, a novel approach to show the significance of corrosion inhibition phenomenon was applied by developing a quantitative structure-property relationship using the Signature molecular descriptor which correlates the occurrences of atomic Signatures in a dataset to a property of interest using a forward stepping multilinear regression. The atomic Signature fragment capturing π–bond was the most influential of all the fragments, which underscores the significance of π–bond electrons in the adsorption process. It was demonstrated that the [O](=[C]) atomic Signature plays a crucial role in the inhibition process at all heights, corroborating the experimental results.

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Corrosion of steel-reinforced concrete exposed to marine environments could lead to structural catastrophic failure in service. Hence, the construction industry is seeking novel corrosion preventive methods that are effective, cheap, and non-toxic. In this regard, the inhibitive properties of sodium phosphate (Na3PO4) corrosion inhibitor have been investigated for carbon steel reinforcements in 0.6 M Cl− contaminated simulated concrete pore solution (SCPS). Different electrochemical testing has been utilized including potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott‒Schottky plots to test Na3PO4 at different concentrations: 0.05, 0.1, 0.3, and 0.6 M. It was found that Na3PO4 adsorbs on the surface through a combined physicochemical adsorption process, thus creating insoluble protective ferric phosphate film (FePO4) and achieving an inhibition efficiency (IE) up to 91.7%. The formation of FePO4 was elucidated by means of Fourier-transform infrared spectroscopy (FT–IR) and X-ray photoelectron spectroscopy (XPS). Quantum chemical parameters using density functional theory (DFT) were obtained to further understand the chemical interactions at the interface. It was found that PO43− ions have a low energy gap (ΔEgap), hence facilitating their adsorption. Additionally, Mulliken population analysis showed that the oxygen atoms present in PO43− are strong nucleophiles, thus acting as adsorption sites.

Purpose This paper aims to prepare a new modified poly(ester amide) (PEA) resins and use it as a binder for anticorrosive and antimicrobial coatings. Design/methodology/approach New modified PEA compositions were prepared based on 4-amino-N, N-bis(2-hydroxyethyl) benzamide (AHEB) as the ingredient source of the polyol used and evaluated as vehicles for surface coating. The structure of the modifier and PEA resin was confirmed by FT-IR, H¹-NMR, MW, thermogravimetric analysis and scanning electron microscope studies. Coatings of 50±5 µm thickness were applied to the surface of glass panels and mild steel strips by means of a brush. The coating performance of the resins was evaluated using international standard test methods and involved the measurement of phyisco-mechanical properties and chemical resistance. Findings The tests carried out revealed that the modified PEA based on AHEB enhanced both phyisco-mechanical and chemical properties. Also, the resins were incorporated within primer formulations and evaluated as anti-corrosive and antimicrobial single coatings. The results illustrate that the introduction of AHEB, within the resin structure, improved the film performance and enhances the corrosion resistance and antimicrobial activity performance of PEA resins. Practical implications The modified PEA compounds can be used as binders in paint formulations to improve the chemical, physical, corrosion resistance and antimicrobial activity properties. Originality/value Modified PEA resins are cheaper and can be used to replace other more expensive binders. These modified PEA resins can compensate successfully for the presence of many the anticorrosive and antimicrobial paint formulations, and thus, lower the costs. The main advantage of these binders is that they combine the properties of both polyester and polyamide resins based on nitrogenous compound, are of lower cost and they also overcome the disadvantages of both its counterparts. Also, they can be applied in other industrial applications.

The present study was designed to determine the possible therapeutic effects of royal jelly against carbon tetrachloride (CCl4) induced oxidative stress and biochemical changes in the kidney of albino rats. A patch of 20 male albino rats averaged weights (190±10 g) at the beginning of the experiment were divided into 4 main groups according to the treatment and requirements of the experiment. The rats injected i.p. with CCl4 at a dose (1 mL/kg, 1:1 in olive oil) twice per week and received, via gavage, royal jelly at a dose (400 mg/kg b. wt) along the experimental period. Each group contains 5 rats that were sacrificed on the45 days from the start of the experiment. The results refer to a significant elevation of renal parameters (creatinine, blood Urea and Uric acid) on the 6 th week in rats injected intraperitoneal with CCl4 as compared to the control groups. The administration of the royal jelly has beneficial and decrease side effects against the deleterious changes of CCl4.In conclusion, according to the results obtained the administration of the royal jelly provides considerable nephroprotective effects against intoxicated with CCl4 in male Wister albino rats by preventing oxidative stress through ROS scavenger and improvement in the former biochemical parameters.

New corrosion compounds were prepared based on acryloyl chloride and the efficiency of the prepared compounds to inhibit carbon steel (CS) corrosion in 3.5% sodium chloride solution were studied through different electrochemical techniques [potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS) and electron frequency modulation (EFM)] and Quantum chemical calculations. The results showed that the investigated compounds are working as good corrosion inhibitor compounds, the inhibition efficiency (%IE) increases as the compound concentration increase. The polarization data revealed that these compounds act as cathodic and mixed type compounds and are adsorbed on CS surface following Langmuir adsorption isotherm.

The inhibiting performance of sodium succinate (Na2C4H4O4) was evaluated as an organic environmentally friendly corrosion inhibitor for carbon steel rebars in 0.6 M Cl− simulated concrete pore solution. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements were utilized to evaluate the inhibitor performance at different temperatures and concentrations. The investigated corrosion inhibitor showed strong corrosion inhibition performance as it adsorbs on the surface of the rebar, creating a protective adsorption film. According to PDP, the inhibitor is classified as a mixed-type inhibitor with an inhibitor efficiency of 77, 69, 59, and 54% for 25, 35, 45, and 55 °C, respectively. EIS validated the PDP tests, showing that sodium succinate displaces the water molecules at the interface, creating an adsorption film by complexing with ferrous ions. The film thickness was calculated, and sodium succinate was able to produce a thicker protective film (span of nanometers) relative to the reference at every temperature. The adsorption of sodium succinate follows the Temkin adsorption isotherm. ΔG0ads was found to be −32.75 kJ/mol, indicating that the inhibitor adsorption is a combined physisorption and chemisorption process. Different surface characterizations were utilized to substantiate the adsorption of sodium succinate, these include scanning electron microscopy, energy-dispersive X-ray spectroscopy, and micro-Raman spectroscopy. Finally, quantum chemical calculations showed that the delocalized electrons in the carboxyl group have high HOMO energies and electrostatic potential, which facilitates the adsorption of sodium succinate corrosion inhibitor onto the carbon steel rebar surface.

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