Adsorption and corrosion inhibition behaviour of new theophylline–triazole-based derivatives for steel in acidic medium

Abstract

The design and synthesis of a series of theophylline derivatives containing 1,2,3-triazole moieties are presented. The corrosion inhibition activities of these new triazole–theophylline compounds were evaluated by studying the corrosion of API 5 L X52 steel in 1 M HCl medium. The results showed that an increase in the concentration of the theophylline–triazole derivatives also increases the charge transference resistance ( R ct ) value, enhancing inhibition efficiency and decreasing the corrosion process. The electrochemical impedance spectroscopy under static conditions studies revealed that the best inhibition efficiencies (approx. 90%) at 50 ppm are presented by the all-substituted compounds. According to the Langmuir isotherm, the compounds 4 and 5 analysed exhibit physisorption–chemisorption process, with exception of the hydrogen 3 , bromo 6 and iodo 7 substituted compounds, which exhibit chemisorption process. The corrosion when submerging a steel bar in 1 M HCl was studied using SEM-EDS. This experiment showed that the corrosion process decreases considerably in the presence of 50 ppm of the organic inhibitors. Finally, the theoretical study showed a correlation between E HOMO , hardness ( η ), electrophilicity (W), atomic charge and the inhibition efficiency in which the iodo 7 substituted compound presents the best inhibitor behaviour.

The inhibition performance of a novel benzenesulfonamide-based benzoxazine compound in the corrosion of X60 carbon steel in an acidizing environment

“…7,50 Inhibitor molecules can also interact with the steel surface via the retro-donation mechanism where excess delectrons from the steel surface, are donated to the inhibitor p anti-bonding orbitals. 51,52 From the PDP and the adsorption isotherm results, the BSB molecules could have been adsorbed on the surface of the steel via both the mechanisms of chemisorption and physisorption, with the physisorption being predominant. From the FTIR analysis, we could also suggest a retro-donation adsorption mechanism of the BSB molecules.…”

Experimental and Theoretical Approach of Evaluating Chitosan Ferulic Acid Amide As An Effective Corrosion Inhibitor

“…These values can be corroborated with the initial electrostatic interaction between the FCS inhibitor and the metal surface, leading to physisorption. The transfer of electron pairs from the heteroatoms to the empty d orbitals of Fe 2+ ions and retro donation to the unoccupied π* orbital of the FCS molecule occurs, resulting in the chemisorption process (Espinoza-Vázquez et al 2019). The value of Kads also reflects the increased binding of the inhibitor molecules on the metal surface (Singh et al 2018).…”

“…The Bode plot reveals only one time constant, which can be corroborated with the corrosion inhibition by the charge transfer process and is not changed by the inhibitor's presence (Solmaz 2014). The semi-circle in the Nyquist plot is not perfect due to the metal surface's inhomogeneity, surface irregularities, impurities, surface active sites collectively referred as frequency dispersion effect (Espinoza-Vázquez et al 2019) (Chakravarthy and Mohana 2014).…”

Cu–Al mixed oxide-catalysed multi-component synthesis of gluco- and allofuranose-linked 1,2,3-triazole derivatives

“…Recently, we discovered that Cu-Al mixed oxide, generated by calcination of corresponding hydrotalcite type layered double hydroxide (LDH), in the presence of sodium ascorbate (NaAsc) as a reducing agent, efficiently catalyses the 1,3-dipolar cycloaddition of in situ-generated benzyl azides and phenyl acetylene in short reaction times using EtOH/H 2 O as a solvent [26]. In continuation with our interest in the synthesis of functional triazole derivatives [27][28][29][30], and in order to introduce the use of mixed oxides in carbohydrate CuAAC click chemistry, herein we report a rapid and facile synthesis of a series of carbohydrate-linked 1,2,3-triazole derivatives using as key step a three-component 1,3-dipolar azide-alkyne cycloaddition catalysed by Cu-Al mixed oxide, and an insight into their antimicrobial properties.…”