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In this work, the corrosion inhibition performance of polyethyleneglycol bisphenol A epichlorohydrin copolymer (PEG-BEC) against mild steel in 1 M HCl was studied by electrochemical and weight loss techniques. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDAX) were applied to characterize the surface morphology of the mild steel samples. The corrosion mitigation efficiency was observed to rise as the concentration of PEG-BEC rises in the corrosive medium while increasing the temperature (25 °C -65 °C) resulting in a drop in the inhibition ability. Furthermore, under hydrodynamic conditions, the corrosion of the mild steel was found to deteriorate both in the absence and presence of PEG-BEC. Just with 10 ppm, an inhibition efficiency (IE) of 97.6% was obtained at 25 °C by EIS. PEG-BEC acts as a mixed-type inhibitor as observed by potentiodynamic polarization (PDP) technique. The observed corrosion inhibition action of PEG-BEC could be ascribed to the adsorption of the molecules and the formation of a protective film on the steel surface as evidenced by static water contact angle (WCA). Langmuir isotherm best describes the PEC-BEG-metal adsorption with large Kads values indicating a thermodynamically stable nature inhibition process. The obtained ∆G°ads = -35.138 to -39.522 kJ/mol indicate that the PEG-BEC spontaneously adsorbed onto the steel with strong tendency to provide protection to the mild steel surface via combination of chemisorption and physisorption processes. The ΔHads -53.07 kJ/mol and ΔSads= +0.048 kJ/mol-k, respectively, suggests an exothermic reaction accompanied by relatively increase in entropy of the PEG-BEC adsorption on the mild steel surface.

This study pioneers a novel approach to achieving sustainable corrosion protection in seawater environments by incorporating layered double hydroxide (LDH) fillers into polymeric polyvinylidene fluoride (PVDF) coatings to create a corrosion-resistant coating for mild steel. LDH composites were successfully synthesized using co-precipitation and hydrothermal methods, with characterization through x-ray diffraction analysis (XRD), fourier-transform infrared spectroscopy FTIR, morphological analysis, and elemental mapping. LDH@PVDF coatings with the thickness of 40 ± 2 µm exhibited improved surface properties, superior adhesion, hydrophobicity, and antifouling characteristics. Corrosion resistance was comprehensively assessed using open circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). ZLDH@PVDF coating outperformed others, demonstrating exceptional long-term corrosion protection (up to 60 days) without diffusion-controlled processes. The mechanism of corrosion protection of ZLDH@PVDF coating has been discussed.

The corrosion inhibition potentials of a cationic gemini surfactant (CGS) on low carbon (LC) steel in highly corrosive environment of 10 wt.% H2SO4 and 15 wt.% HCl (which imitates oil well acidic environment) at elevated temperatures was studied using potentiodynamic polarization (PDP), gravimetric, and surface (XPS, SEM and EDX) analyses. Unprecedented inhibition efficiencies (IE) of 92.2% and 92.5% were repeatedly obtained at CGS concentrations of as low as 0.25 ppm and 1 ppm in 15 wt.% HCl and 10 wt.% H2SO4 at 25 °C by gravimetry, respectively. Higher inhibition efficiencies were obtained at elevated CGS concentrations. The inhibitor act as a mixed type based on the PDP data. The adsorption of CGS on the steel surface further supports a stronger tendency for he CGS adsorption onto the steel surface, thereby establishing an effective protective mechanism of the steel. The CGS performance was enhanced under hydrodynamic condition than static condition in 15 wt.% HCl while the opposite was the case in 10 wt.% H2SO4. Density Functional Theory (DFT) calculations and Monte-Carlo (MC) dynamics simulations supported the experimental findings of the CGS inhibition potentials for steel surface in the studied media. This study showcases the high potential of employing CGS for effective control of the corrosion, even at low dosage, in industrial applications involving the use of highly reactive acids at higher temperatures where economically viable operations are necessary.