Halogen-Substituted Acridines as Highly Effective Corrosion Inhibitors for Mild Steel in Acid Medium

Abstract

A series of acridines were designed and synthesized for the development of effective inhibitors for mild steel corrosion in 1 M HCl solution, in which the halogen-substituted acridines showed better inhibitive performance than the nonhalogen-substituted acridines. The corrosion protection properties of the halogen-substituted acridines, including 2-chloro-9-phenylacridine (CPA), 2-chloro-9-(2-fluorophenyl)­acridine (CFPA), and 2-bromo-9-(2-fluorophenyl)­acridine (BFPA), were further investigated using weight loss test and electrochemical techniques. The results indicated the halogen-substituted acridines have excellent inhibitiion performance, and these acridines act as mixed-type inhibitors with predominant cathodic effectiveness. Adsorption of acridines on a mild steel surface obeyed the Langmuir adsorption isotherm. The adsorption of the inhibitor molecules on the steel surface was further supported by scanning electron microscopy (SEM), scanning electrochemical microscopy (SECM), and FTIR spectroscopy. The inhibition mechanism of the investigated halogen-substituted acridines was derived using DFT-based quantum chemical calculations for their neutral as well as protonated forms. Both experimental and DFT studies suggested that the inhibition efficiency of three halogen-substituted acridines followed the order of η­(BFPA) > η­(CFPA) > η­(CPA).

A Self-Strengthening Epidermis-Like Smart Coating Enabled by Dynamic Iron Sequestration

“…Such effect can be ascribed to the inhibition of charge transfer due to the strengthened network. 64,65 The phase angle in Bode plots only appears in the low-frequency range and with the increase of immersion time, the trend of increasing phase angle is obvious (Figure 5d), suggesting that the barrier effect of ELSC is gradually enhanced. In addition, the impedance modulus (|Z|0.01Hz), which reflects the ability of a coating to restrain the current between the cathodic and anodic areas, increases significantly (Figure 5d).…”

An Exploration about the Interaction of Mild Steel with Hydrochloric Acid in the Presence ofN-(Benzo[d]thiazole-2-yl)-1-phenylethan-1-imines

“…Various acids like hydrochloric acid, sulfuric acid, and phosphoric acid are used for pickling and acidization processes by the pickling industry. These acids used for such pickling processes may cause corrosion and damage to the material used. , …”

Synergistic inhibition effect of N‐(furan‐2‐ylmethyl)‐7H‐purin‐6‐amine and iodide ion for mild steel corrosion in 1 mol/L HCl

“…It was found that a semicircular capacitive loop, which is slightly depressed, was displayed in the Nyquist plots. The imperfect capacitive circuit is usually caused by frequency dispersion due to roughness and other inhomogeneities of the electrode surface . Furthermore, the diameter of the capacitive loop with inhibitor was larger than that of the noninhibitor reference, and it increased further with the addition of KI, suggesting a thicker adsorption layer of FYPA + KI than FYPA alone on the steel surface.…”

“…The imperfect capacitive circuit is usually caused by frequency dispersion due to roughness and other inhomogeneities of the electrode surface. [21][22][23][24][25] Furthermore, the diameter of the capacitive loop with inhibitor was larger than that of the noninhibitor reference, and it increased further with the addition of KI, suggesting a thicker adsorption layer of FYPA + KI than FYPA alone on the steel surface. It was worth noting that there was no significant change in the shape of impedance at distinct inhibitor concentrations, showing that the addition of the inhibitor did not change the corrosion mechanism of the steel electrode.…”