Aluminum Corrosion Inhibition by 7-(Ethylthiobenzimidazolyl) Theophylline in 1M Hydrochloric Acid: Experimental and DFT Studies

Abstract

Inhibitive properties of 7-(ethylthiobenzimidazolyl) theophylline (7-ETBT) molecule for the corrosion of alu-minum (Al) in one molar hydrochloric acid medium have been investigated using mass loss and Tafel polariza-tion methods. The results suggest spontaneous and predominant physical adsorption of 7-ETBT on the metal surface which obeys Langmuir isotherm model. The studied inhibitor showed excellent inhibition efficiency up to 94.07 % at 298 K for its optimum concentration (2 mM). Moreover, Tafel polarization method revealed that 7-ETBT is a cathodic-type inhibitor. Further investigation on the morphology using scanning electron microscopy (SEM) has confirmed the existence of a protective film of inhibitor molecules on aluminum surface. Theoreti-cal approach for the performance of 7-ETBT as Al corrosion inhibitor is also done using Density Functional Theory (DFT) level with B3LYP exchange correlation functional for 6-31G (d, p) basis set. The results provided by this theoretical study are consistent with the experimental data. All the results have shown an evidence of the effectiveness of the inhibitive effect of 7-ETBT on Al.

Mild steel corrosion inhibition by synthesized 7-(Ethylthiobenzimidazolyl) Theophylline

“…With increased awareness towards environmental pollution and control, the search for less toxic and environmentally friendly corrosion inhibitors is becoming increasingly important. Thus, researchers have focused their works on several synthesized compounds, for which non-toxicity tests are carried out during their synthesis [11][12][13][14].…”

Chitosan biopolymer effect on copper corrosion in 3.5 wt.% NaCl solution: Electrochemical and quantum chemical studies

“…The determined values of K ads and 0 ads G  have been recorded in Table 3. The negative values of 0 ads G  indicate that the adsorption process proceeds spontaneously and stability of the adsorbed layer [29], and its value -27.977 kJ•mol -1 indicates that chitosan adsorb on copper by both physisorption and chemisorption mechanism [30].…”

Experimental and Theoretical Studies on Acid Corrosion Inhibition of API 5L X70 Steel with Novel 1-N-α-d-Glucopyranosyl-1H-1,2,3-Triazole Xanthines

“…A few reports have disclosed the capacity of theophylline or theobromine derivatives as organic corrosion inhibitors in metals under an acidic medium. For instance, a theophylline derivative bearing a thiobenzimidazole moiety showed excellent inhibition efficiency in preventing the corrosion of aluminum in a 1 M HCl medium [ 34 ]. The inhibitory behavior of a related theophylline derivative was tested as a copper corrosion inhibitor in a 1 M HNO 3 solution [ 35 ].…”