Tunable Anticorrosive Effects of Newly Synthesized Benzothiazole Azo Dyes by Potassium Iodide Synergism for Carbon Steel in 1 M HCl: Combined Experimental and Theoretical Studies

Abstract

Herein, we synthesized three novel benzothiazole azo dyes, including 4-chloro-2-(4-methyl-benzothiazol-2-ylazo)-phenol (CMBTAP), 1-(6-chloro-benzothiazol-2-ylazo)-naphthalen-2-ol (CBAN), and 2-(6-chloro-benzothiazol-2-ylazo)-4-methyl-phenol (CBAMP), and investigated their corrosion inhibition effect on carbon steel. The dyes were characterized by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR), 13C NMR, and mass spectroscopy. Weight loss, electrochemical impedance spectroscopy, and potentiodynamic polarization measurements were performed to investigate the corrosion inhibition effect of the dyes on carbon steel in a 1.0 M HCl solution. The synergistic effects of the dyes with potassium iodide (KI) were also investigated. The inhibition efficiency (IE%) was enhanced by increasing the dose of the dyes (1 × 10–5 to 2 × 10–4 M) and decreased as the temperature increased from 25 to 45 °C. The addition of KI to a 1.0 M HCl solution containing the dyes improved the performance and efficiency as iodide ions promoted the formation of inhibition films on the surface of carbon steel. The dyes are mixed-type inhibitors, according to Tafel polarization. Scanning electron microscopy and energy dispersive X-ray analysis were used to evaluate the surface morphology of carbon steel sheets. Quantum theory calculations were utilized to evaluate the relationship between the dyes’ chemical structures and their inhibitory efficiency, which confirmed the experimental results. The calculations revealed that the dyes have low energy gap and Milliken and Fukui indices. Among all of the dyes, CMBTAP showed the highest adsorption energy. The corrosion IE was in the order CMBTAP > CBAMP > CBAN.

Inhibition Effect of Triphenylmethane Dyes for the Corrosion of Carbon Steel in CO2-Saturated NaCl Corrosion Medium

“…In order to investigate the adsorption mechanism, the adsorption isotherm of CV is shown in Figure 3 d, and its adsorption capacity is calculated for the corrosion inhibitor at 40 °C using the following Langmuir adsorption formula [ 36 ]: where C inh represents the concentration of CV, θ is the coverage rate of the corrosion inhibitor on the steel surface ( θ = η p ), and K ads is the adsorption–desorption equilibrium constant, which could be determined with the intercept of the C inh / θ vs. C inh plots.…”

“…In order to investigate the adsorption mechanism, the adsorption isotherm of CV is shown in Figure 3d, and its adsorption capacity is calculated for the corrosion inhibitor at 40 • C using the following Langmuir adsorption formula [36]:…”

Study of the Electrochemical Behavior of Concrete‐Coated Steel in 1 M Sulfuric Acid Using an Extract of Diplotaxis simplex L.

“…These observations imply that the charge transfer process predominantly governs the corrosion kinetics. [34] Additionally, the presence of surface heterogeneity, likely of structural or interfacial origin, may account for the observed depressed loop. [35,40] In Figure 4, it is evident that the addition of (DS) extract to the aggressive solution results in the most substantial increase in impedance modulus.…”

Green Synthesizing and Corrosion Inhibition Characteristics of Azo Compounds on Carbon Steel under Sweet Conditions: Experimental and Theoretical Approaches

“…The existence of nitrogen atoms within the azo linkage, in conjunction with the versatility afforded by the selection of substituent groups in the structure of the azo dyes, facilitates the design of molecules to meet the structural criteria necessary for organic corrosion inhibitors that reveal easy and robust adsorption onto the surface of steel . Recent research findings indicate that in the past few years, azo dye derivatives have been increasingly employed as corrosion inhibitors for steel in acidic environments ,− (Table ). Azo compounds are very easy for preparation, all starting materials for the synthesis of azo compounds are available and are cheaper, there is no loss of energy in the preparation, the reaction needs only cooling during the synthesis of azo dyes, and the yield of preparation is very high.…”