Gallic Acid as a Potential Green Corrosion Inhibitor for Aluminum in Acidic Solution

Abstract

Plant extracts are intensively studied as green corrosion inhibitors of aluminum. Because these extracts are complex systems, the influence of their individual constituents on the corrosion of aluminum should be determined. In this work, gallic acid was tested for the first time as a corrosion inhibitor of aluminum in orthophosphoric acid aqueous solution. So far, its potential inhibiting properties in acidic solutions were only suggested based on promising results obtained for various plant extracts. Evaluation of the potential inhibiting properties of gallic acid was performed using electrochemical methods. The corrosion potential, polarization curves, and impedance spectra of aluminum in 0.5 M orthophosphoric acid, at T = 303 K, were determined. The corrosion potential, corrosion current density, and corrosion rate of aluminum in orthophosphoric acid were equal to −1.151 V vs. Ag|AgCl (3M KCl) reference electrode, 36 μA∙cm−2 and 0.39 mm∙year−1, respectively. These values did not change with the addition of gallic acid. The results obtained show that gallic acid does not inhibit aluminum corrosion. UV-Vis absorption spectra of gallic acid solutions and quantum mechanical calculations show that this organic compound did not adsorb onto the aluminum surface under the studied conditions.

An examination of the effectiveness of the expired drug isoprinosine in preventing aluminum corrosion in alkaline solutions using both computational and experimental techniques

“…When aluminum is exposed to corrosive medium, OCP declines rapidly, which may be caused by the quick dissolution of the thin Al 2 O 3 layer that has developed on the metal electrode, according to the exhaustive examination of the OCP vs. time curves. 47,48 Also, isoprinosine shifts the steady-state potential in an increased positive direction. This behavior is connected to the byproducts of the corrosion reaction that isoprinosine adsorbs and/or deposits on the aluminum surface, which may control and slow down the dissolution of aluminum.…”

Ghars date extract/iodide ions system as an eco‐friendly corrosion inhibitor for API 5L X70 steel in sulfuric acid

“…Because of the complex chemical composition of the GDE, it will be very difficult to identify the component responsible for corrosion inhibition. Therefore, some compounds of the GDE that have proven an inhibition efficiency for metals in acidic media (gallic acid [47], apigenin [48], quercetin [49], phenolic components [50] and many other components) cannot be neglected.…”

The Use of Plant Extracts as Green Corrosion Inhibitors: A Review

“…Regardless of the adsorption mechanism, temperature, and immersion time, other parameters such as the density of functional groups, polarizability, and electronegativity are also very important [73]. However, in addition to the nature of the inhibitor and its chemical composition and surface charge of the substrate, the type of corrosive medium is also important [65,134,[141][142][143]. For example, extracts that contain aromatic rings, multiple bonds, and heteroatoms can be easily protonated in an acidic medium, which creates positively charged inhibitory species that can adsorb through chloride ions on the positively charged steel surface [134].…”