Mitigation of Mild Steel Corrosion in Acid by Green Inhibitors: Yeast, Pepper, Garlic, and Coffee

Abstract

Synthesized organic chemicals, used as inhibitors in mitigating the corrosion of huge quantities of steel articles, pose a major threat to the global environmental problems and health hazards. Naturally occurring products which had been used for natural medication purposes, since the human civilization, are found to inhibit corrosion of steel. Electrochemical studies of the effects of black pepper, garlic, yeast, and coffee on acid corrosion of steel have shown that the corrosion current decreases by manyfold with increase in concentration of the inhibitors. These green inhibitors have been found to get adsorbed maximum up to 70-90%. The polarizing effect is more on cathodic reactions than on anodic reactions, acting as cathodic inhibitor, while a few behaves as anodic to mixed inhibitor. Mechanisms of adsorption are investigated by Frumkin, Temkin, and Langmuir isotherms. The free energy of adsorption is found to be between −15 and −40 kJ/m for most inhibitors, indicating the phenomena of physical adsorption.

Corrosion Inhibition of Carbon Steel in Acidic Environment by Papaya Seed as Green Inhibitor

“…A few natural products such as plant extracts and animal proteins were reported [9] to have been used in pickling acid bath. In the previous investigation by the author [10], corrosion inhibition of carbon steel by few green inhibitors viz. garlic, yeast, pepper, and coffee is studied.…”

Corrosion Inhibition Effect of 4-Hydroxy-N′-[(E)-(1H-indole-2-ylmethylidene)] Benzohydrazide on Mild Steel in Hydrochloric Acid Solution

“…The slopes of the isotherms show deviation from the value of unity. This deviation from unity may be due to the interaction among the adsorbed species on the metal surface; that is, the organic molecules having polar atoms or groups get adsorbed on the cathodic and anodic sites of the metal surface by replacing the initially adsorbed water molecule [27]. The standard free energy of adsorption (Δ ∘ ads ) is related to ads by the following relation [28]:…”

Biomass of Microalgae Spirulina Maxima as a Corrosion Inhibitor for 1020 Carbon Steel in Acidic Solution.

“…There are many studies that focus on the development of cost-effective and environmentally friendly compounds [1][2][3][4][5][6][7][8][9][10][11][12], some of which are dedicated to the use of algae as corrosion inhibitors for mild steel [13][14][15][16][17]. Microalgae are prokaryotic or eukaryotic microorganisms that perform aerobic photosynthesis.…”