Cysteine as an Eco-Friendly Anticorrosion Inhibitor for Mild Steel in Various Acidic Solutions: Electrochemical, Adsorption, Surface Analysis, and Quantum Chemical Calculations

The corrosion of iron in acidic environments has a negative impact on global industry. Herewith, the inhibitory effect of cysteine (Cys.) on mild steel (MSL) corrosion in different acidic solutions (1 M HCl, 1 M H2SO4, and 1 M H3PO4) was investigated through weight loss, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy, scanning electron microscopy (SEM), and theoretical calculations. The measurement results indicated that the adsorption of Cys. molecules on the metal surface caused corrosion inhibition. As a result, a protective layer or insoluble compound, or both, is obtained, blocking the active sites, preventing corrosion. The effectiveness (IE %) of the Cys. was enhanced by increasing concentration and lowering temperature. The maximum IE % of inhibition at 1 × 10-2 M of Cys. obtained are 97.3, 89.7, and 84.4% in HCl, H3PO4, and H2SO4 solutions, respectively. At the same inhibitor concentration, the double-layer capacity decreased, and the charge-transfer resistance increased from 17.17 to 188.5, 3.564 to 31.91, and 1.325 to 8.715 Ω cm2 in HCl, H3PO4, and H2SO4 solutions, respectively. Adsorption and PDP studies confirmed that it obeys the Langmuir adsorption isotherm and acts as a mixed-type inhibitor of physicochemical nature. The corresponding thermodynamic and kinetic parameters were also calculated and discussed. Moreover, the inhibitory effect on the surface was inspected by SEM. The findings demonstrated that the order of IE % using Cys as anticorrosion agent for MSL is HCl > H3PO4 > H2SO4 solutions.

Design and synergistic effect of nano-sized epoxy-NiCo2O4 nanocomposites for anticorrosion applications

This study reports the synthesis of nano-sized epoxy-NiCo2O4 nanocomposites and their anti-corrosive efficiency to attain sustainable development.

Natural Hydroxyapatite: Green Catalyst for the Synthesis of Pyrroles, Inhibitors of Corrosion

Polysubstituted pyrroles have been synthesized in good yields via a four-component one-pot reaction of 1,3-dicarbonyl compounds, amines, aldehydes, and nitroalkanes using natural hydroxyapatite (HAp) as an efficient green catalyst. This strategy provides advantages such as simple experimental and work-up procedures, mild conditions, high selectivity, low cost, high atom economy, and environmental friendliness; it uses a green commercial catalyst and does not require a solvent. The electrochemical behavior of S300 steel in 1 M hydrochloric acidic was studied in the presence of these heterocyclic compounds. The results showed good inhibition efficiency for steel in acidic media.