No abstract

The capacity of 2,6-bis[((2-pyridylmethyl)oxy)methyl)]pyridine (BPMMP) to inhibit the corrosion of mild carbon steel in HCl was analyzed. In a polarization study, both the cathodic and anodic currents were appreciably decreased in the presence of BPMMP, suggesting that this ligand is effective at inhibiting corrosion at the metal surface. This conclusion is consistent with the results of impedance analysis, where only one time constant corresponding to one depressed capacitive loop was detected, and the diameter of the impedance plot was directly related to the concentration of BPMMP. Furthermore, when recurrence analysis was performed, a decrease in regular noise was observed due to the change of Shannon entropy when the inhibitor was present in the corrosive medium, showing that a high degree of recurrence increases the entropy of the system. Electrochemical data on some pyridyl-based inhibitors were collected from the literature and used to plot (i) I (A/cm) vs. inhibition efficiency (η%) and (ii) ΔG° vs. inhibition efficiency (ƞ%) in order to examine the general relationships between these parameters. Furthermore, the interactions of the ligand BPMMP with different iron clusters (Fe, Fe, Fe, and Fe) were analyzed theoretically using density functional theory (DFT). The structural and electronic properties of BPMMP and its protonated form BPMMPH were studied before and after the interactions of BPMMP with the iron clusters. The first protonation was found to occur at pyridine nitrogen atom N1, resulting in a Gibbs free energy ΔG of -10.2 kcal/mol, with an energy difference of 5.3 kcal/mol between the two possible protonated conformers. Graphical abstract Recurrence and Noise signal performance of BPMMP as corrosion inhibitor.

Corrosion inhibitors can trigger health and/or environmental problems due to their toxicity. For this reason, it has been suggested to use plant extracts as natural corrosion inhibitors, because they represent a rich source of chemical compounds, they are non-toxic, biodegradable and abundant in nature. Sorghum halepense is a herbaceous weed, commonly known as johnson grass, belongs to the family gramíneae or poaceae, the choice of this plant is due to its zero cost and easy availability. In this systematic review, were used keywords such as Sorghum halepense johnson grass, phytochemistry, phytotherapy, phytoremediation, antidiabetic, antioxidant, cytotoxicity, antifungal, antimicrobial, anticancer, biological activity, medical activity, allelochemicals, among others. To do this, were used databases such as Scielo, Dialnet, Redalyc, Google Scholar, DOAJ, Wiley online library, BioOne, EBSCOHost, Knovel, ScienceDirect, SpringerLink y VirtualPro. Previous studies on this weed have reported its therapeutic potential against cancer, diabetes, prostatitis, hepatoprotective activity, antioxidant, antimicrobial, antifungal, as well as abortifacient and placental delivery in veterinary medicine. In view of the numerous organic molecules present in this plant, this study proposes Sorghum halepense as a potential natural corrosion inhibitor.

Ascorbic acid (AA) has been reported as a corrosion inhibitor of carbon steel. The combined effect of AA and potassium iodide (KI) in the dynamics of the corrosion process of 1018 carbon steel is studied by electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) in an acid medium. EN data were used for nonlinear analysis by means of recurrence plots and their corresponding parameters, as well as by delay maps. Important information about the corrosion process of carbon steel corrosion in the presence of these two substances was obtained. AA does not behave as an inhibitor in this system, but the influence of KI is significant in inhibitor efficiency. The dynamics is established mainly by the adsorption of the I − ions on the steel surface and confirmed by the information entropy. The action of AA is to increase the degree of chaos when concentration increases. A relevant aspect determined is the relationship between the nonlinear dynamics of a corrosion process and its intensity.