Corrosion inhibition, adsorption and thermodynamic properties of 2-aminopyridine derivatives on the corrosion of carbon steel in sulfuric acid solution

Synthesis and characterization of novel dicarbohydrazide derivatives with electrochemical and theoretical approaches as potential corrosion inhibitors for N80 steel in a 3.5% NaCl solution

Two novel ethanoanthracene-11,12-dicarbohydrazide derivatives N'11,N'12-bis((Z)-4-hydroxybenzylidene)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarbohydrazide (H2HEH) and N'11,N'12-bis((Z)-4-methoxybenzylidene)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarbohydrazide (H2MEH) were synthesized and characterized by FT-IR spectroscopy, electronic spectra, and NMR spectroscopy. These two derivatives as novel anticorrosion inhibitors for N80 steel in a 3.5% NaCl solution were studied using electrochemical techniques including potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM). Corrosion parameters and adsorption isotherms were determined from current-potential diagrams (i.e., Tafel slopes). The impact of temperature and inhibitor concentration on the corrosion performance was studied using the PP method. The PP results suggested mixed-type inhibitors. The inhibition prohibition increased and decreased when the dose was increased and the temperature was increased, respectively. The adsorption of the hydrazides on the N80 exterior followed the Langmuir isotherm. The maximum inhibition proficiency for H2MEH and H2HEH were 93.3% and 92.2%, respectively, at 1 × 10-4 M. Moreover, the investigated surface was studied with the synthesized compounds through X-ray photoelectron spectroscopy (XPS) to confirm the construction of an adsorbed shielding barrier. An evident association was established between the corrosion inhibition proficiency and theoretical variables acquired using the density functional theory (DFT) method and Monte Carlo (MC) simulations. The experimental data were in good agreement with the theoretical results.

Corrosion Inhibition, Adsorption and Thermodynamic Properties of Poly (Sodium 4-Styrenesulfonate) on Carbon Steel in Phosphoric Acid Medium

The use of polymers as corrosion inhibitors has attracted much attention due to their low prices, inherent stability, availability and cost-effectiveness. The corrosion inhibiting effect of poly(sodium-4-styrenesulfonate) on carbon steel in phosphoric acid solution has been investigated using weight loss and scanning electron microscopy techniques (SEM) and theoretical calculations based on density functional theory (DFT). In the presence of 1.0×10-3 mol/L of inhibitor, a maximum inhibition effect of 98.06 % was observed. The influence of the concentration of the inhibitor, the temperature of the solution and the immersion time on the corrosion of carbon steel was investigated. Activation parameters such as activation energy (Eact), activation enthalpy (ΔHact), activation entropy (ΔSact), heat of adsorption (Qads) and adsorption free energy (ΔGads) were evaluated based on the effect of temperature on the corrosion and inhibition processes. It was found that the adsorption behaviour of poly(sodium-4-styrenesulfonate) (PSS) follows the Langmuir isotherm and the free energy change values indicate mixed chemical and physical adsorption on the carbon steel surface. The results obtained with the different methods agree well.